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Research Collection
Doctoral Thesis
Growth performance, carcass characteristics and meatpalatability attributes in steers of various beef breeds comparedat a similar level of intramuscular fat content
Author(s): Chambaz, Alain
Publication Date: 2001
Permanent Link: https://doi.org/10.3929/ethz-a-004268179
Rights / License: In Copyright - Non-Commercial Use Permitted
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ETH Library
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Diss. ETHNo. 14316
Growth performance, carcass characteristics and meat
palatability attributes in steers of various beef breeds
compared at a similar level of intramuscular fat content
A dissertation submitted to the
SWISS FEDERAL INSTITUTE OF TECHNOLOGY ZURICH
for the degree of Doctor ofNatural Sciences
presented by
Alain CHAMBAZ
Dipl. Ing.-Agr. ETH
born 3 March 1971
citizen of Arzier (VD)
accepted on the recommendation of
Prof. Dr. M. Kreuzer, examiner
Prof. Dr. N. Künzi, co-examiner
Dr. M.R.L. Scheeder, co-examiner
Zürich 2001
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Seite Leer /
Blank leaf
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Ill
Table of contents
1. Summary 1
2. Résumé 3
3. General introduction 6
4. Sources of variation influencing the use of real-time ultrasound to predict intramuscular
fat in live beef cattle 8
Abstract 8
4.1. Introduction 9
4.2. Materials and methods 10
4.2.1. Animals 10
4.2.2. Live animal measurements 10
4.2.3. Carcass measurements 12
4.2.4. Statistical analysis 12
4.3. Results and discussion 13
4.3.1. Test and validation of the prediction equation 13
4.3.2. Comparisons of the new equations developed with results of the literature 19
4.3.3. Possible muscle characteristics influencing intramuscular fat estimation by ultrasound 22
4.4. Implications 23
5. Characteristics of steers of six beef breeds fattened from eight months of age and
slaughtered at a target level of intramuscular fat. I. Growth performance and carcass
quality 24
Abstract 24
5.1. Introduction 25
5.2. Materials and methods 26
5.2.1. Animals and experimental design 26
5.2.2. Diet 26
5.2.3. Endpoint of fattening 27
5.2.4. Data and sample collection at slaughter 28
5.2.5. Statistical analysis 29
5.3. Results 29
5.3.1. Growth performance 29
5.3.2. Carcass quality 33
5.4. Discussion 34
5.4.1. Growth development of steers of different breeds fattened to a similar IMF content 35
5.4.2. Carcass characteristics of steers of different breeds fattened to a similar IMF content 37
5.4.3. Dietary energy concentration required for steers of different breeds fattened to a similar IMF content..
38
5.5. Conclusions 39
6. Characteristics of steers of six beef breeds fattened from eight months of age and
slaughtered at a target level of intramuscular fat. II. Meat quality 40
Abstract 40
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6.1. Introduction 41
6.2. Materials and methods 41
6.3. Results 43
6.4. Discussion 48
6.4.1. Realized contents of intramuscular fat in steers fed on a forage-based diet 48
6.4.2. Differences in meat quality of steers of different breed fattened to a target IMF level 49
6.4.3. Fattening series differences in meat quality of steers (tied housing vs loose housing) 52
6.5. Conclusions 53
7. Meat quality of Angus, Simmental, Charolais and Limousin steers compared at the same
intramuscular fat content 55
Abstract 55
7.1. Introduction 56
7.2. Materials and methods 56
7.2.1. Experimental design 56
7.2.2. Experimental procedures performed at slaughter 57
7.2.3. Determination of intramuscular fat content and marbling 57
7.2.4. Analysis of meat quality 58
7.2.5. Sensory evaluation 59
7.2.6. Statistical analysis 59
7.3. Results 60
7.4. Discussion 66
7.4.1. Marbling properties 67
7.4.2. Meat colour 67
7.4.3. Meat texture 68
7.4.4. Flavour, juiciness and water-holding capacity of meat 70
7.4.5. Overall sensory preference of meat 71
7.5. Conclusions 71
8. General discussion 73
9. References 76
10. Appendix 91
11. Remerciements 92
12. Curriculum Vitae 94
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1. Summary
Growth performance, carcass characteristics, and palatability attributes in steers of six different
beef breeds (Angus, Simmental, Charolais, Limousin, Blonde d'Aquitaine, Piedmontese; 22
animals/breed) were compared at a target level of intramuscular fat (IMF) content of 3.5%. The
total mix ration, provided ad libitum, consisted of maize silage, grass silage and concentrate
(52%, 26% and 22% of DM, respectively). Steers were purchased from suckler herds at the same
time and entered the trial at a similar age of approximately 8 months. Series 1 was performed in a
tie-stall barn while a loose-housing system with straw bedding was used in series 2. The animals
were assigned to slaughter when the IMF estimation in the M. longissimus dorsi (LD) according
to the estimation with a real-time ultrasound system in the live animals was approximately 3.5 %
or until 15 months of fattening had passed. This target level was fixed on basis of the results of a
preliminary study investigating the visual preference of marbling which can play an important
role for purchase decision.
The actually measured IMF contents in LD were 3.35 ±1.12, 3.47 ± 0.93, 3.49 ± 1.11 and 3.48 ±
1.08 % (± SD), for Angus, Simmental, Charolais and Limousin, respectively. In spite of a longer
fattening period, Blonde d'Aquitaine and Piedmontese did not reach this target with only 2.34 ±
0.64 and 2.40 ± 0.63 % IMF on average. The high variability between animals of the same breed
group in IMF content was due to the still restricted accuracy of the ultrasound method of IMF
determination in live animals.
Angus, Simmental, Charolais and Limousin reached the target of 3.5 % IMF on average at final
weights of 501 ± 43, 628 ± 60, 693 ± 117 and 668 ± 65 kg, respectively. Blonde d'Aquitaine and
Piedmontese did not reach this target, although the average fattening period lasted 15 months,
i.e., was about three times longer than for Angus, at final weights of 758 ± 93 and 647 ± 64 kg,
respectively. Except in Angus, the average slaughter weights were therefore higher than those
commonly found in Switzerland. The corresponding slaughter ages were 381 ± 25, 509 ± 72, 529
± 104, 610 ± 62, 690 ± 35 and 683 days ± 35 for the Angus, Simmental, Charolais, Limousin,
Blondes d'Aquitaine and Piedmontese, respectively.
Under the conditions of this experimental approach, daily gains were highest in Angus, followed
by Charolais, Simmental, Limousin and Blonde d'Aquitaine and lowest with Piedmontese. The
daily feed intake was significantly lower for Piedmontese than for Charolais, Simmental and
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Angus. As a result, Angus expressed the best feed conversion efficiency over the complete
fattening period while this efficiency was lowest in the Piedmontese. Among the four breeds,
which reached the target IMF content, Limousin steers showed the best carcass quality, namely
the highest dressing percentage and greatest proportion of premium cuts and the highest lean to
fat and lean to bone ratio in the sirloin, followed in descending order by Charolais, Simmental
and Angus. However all four groups were graded as too fat for the Swiss market.
Meat quality was measured in the LD and the M. biceps femoris, regio glutea (BF). Chemical
composition of both muscles did not reveal important differences between breed groups. Early
and late postmortem muscle pH was relatively similar among breeds in contrast to water-holding
capacity. Angus and Simmental presented the lowest drip losses and simultaneously the highest
thawing and cooking losses in both muscles (Simmental only LD). Globally the Piedmontese
presented the highest water-holding capacity. The LD of Angus and Charolais showed the palest
meat. In line with lightness, heme iron contents were clearly lowest in both muscles in the Angus
steers. No significant differences in collagen solubility and shear force were measured in the LD
between breed groups in contrast to BF and sensory analyses. In series 1 meat of the Angus was
significantly more tender than Blondes d'Aquitaine, Piedmontese and Simmental. But in series 2
Piedmontese were significantly tender than all other breed groups. Piedmontese and Blonde
d'Aquitaine presented a higher flavor intensity than Simmental and with Limousin and Charolais
a more juicy meat compared to Angus and Simmental. It seems that the higher growth rate and/or
movement in series 2 played an important role on meat quality traits, namely clearly better water-
holding capacity and higher tenderness in series 2 (group housing on straw bed) than in series 1
(tied system), especially in Piedmontese.
In conclusion, the present results revealed:
1. The difficulty with pure beef breeds and a forage based ration to reach the desired extent of
marbling and at the same time favourable carcass conformation, carcass size (except Angus)
and fat cover which meet Continental European, particularly Swiss, market demands.
2. Although slaughtered at a similar intramuscular fat content in the LD and reared under the
same conditions, differences in meat quality traits were still found between breed groups.
Nevertheless all breed groups presented meat of good to very good sensory quality even if
meat from Piedmontese was globally preferred relative to meat from Simmental.
3. The IMF content is therefore not the basic cause of the differences in meat quality observed.
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2. Résumé
Les performances d'engraissement, la qualité de carcasse et de viande de bœufs issus de six races
à viande (Angus, Simmental, Charolais, Limousin, Blonde d'Aquitaine, Piémontais; 22
animaux/race) ont été comparées à un taux de graisse intramusculaire cible de 3.5 %.
L'alimentation a été servie ad libitum et consistait pour 52 % d'ensilage de maïs, 26 % d'ensilage
d'herbe et 22 % de concentrés dans la matière sèche. Provenant d'exploitations de vaches
allaitantes, les bœufs ont débuté l'essai à l'âge de 8 mois environ. La première série
d'engraissement s'est déroulée en stabulation entravée et la deuxième en stabulation libre. Les
bœufs ont été abattus lorsque l'estimation du taux de graisse intramusculaire dans le M.
longissimus dorsi (LD), selon une méthode aux ultrasons, avoisinait 3.5 % ou sinon après 15
mois d'engraissement. Utilisée comme critère d'abattage, cette teneur de graisse intramusculaire
résulte d'une étude de préférence évaluant la qualité visuelle du persillé, cette dernière pouvant
jouer un rôle déterminant lors de l'achat.
Les taux de graisse intramusculaire dans le LD effectivement obtenus ont été de 3.35 ±1.12, 3.47
± 0.93, 3.49 ±1.11, 3.48 ± 1.08 % (SD), respectivement pour les Angus, Simmental, Charolais et
Limousin. Malgré une durée d'engraissement prolongée, les Blonde d'Aquitaine et les Piémontais
ont atteint une teneur moyenne de seulement 2.34 ± 0.64 et 2.40 ± 0.63. La variabilité élevée des
taux de graisse intramusculaire entre les animaux de la même race est due à la précision encore
insuffisante de la méthode d'estimation de la graisse intramusculaire aux ultrasons chez l'animal
vivant.
Les Angus, Simmental, Charolais et Limousin ont atteint l'objectif fixé d'environ 3.5 % de
graisse intramusculaire avec des poids vifs finaux en moyenne respectivement de 501 ± 43, 628 ±
60, 693 ± 117 et 668 ± 65 kg. Avec environ 2.4 % en moyenne, les Blonde d'Aquitaine et les
Piémontais n'ont pas atteint le taux cible de graisse intramusculaire malgré une durée
d'engraissement de 15 mois, soit 3 fois plus longue comparée aux Angus et avec des poids vifs
finaux de 758 ± 93 et 647 ± 64 kg. Hormis pour les Angus, les poids à l'abattage obtenus sont
donc plus élevés que ceux rencontrés habituellement en Suisse. Les âges à l'abattage
correspondants ont été de 381 ± 25, 509 ± 72, 529 ± 104, 610 ± 62, 690 ± 35 et 683 ± 35 jours.
Dans les conditions de cet essai, les accroissements journaliers moyens étaient les plus élevés
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pour les Angus, suivis par les Charolais, Simmental, Limousin, Blonde d'Aquitaine et les
Piémontais. L'ingestion journalière des Piémontais était plus faible (P < 0.05) que celle des
Charolais, Simmental et Angus. En conséquence, calculée sur toute la durée de l'engraissement,
les Angus ont présenté la meilleure et les Piémontais la plus mauvaise efficacité alimentaire.
Parmi les quatre races ayant atteint le taux de graisse intramusculaire souhaité, les Limousin ont
présenté la meilleure qualité de carcasse, à la fois concernant le rendement d'abattage, la part de
morceaux nobles et les rapports viande/graisse ou viande/os dans l'aloyau, suivis dans l'ordre
décroissant par les Charolais, Simmental et Angus. Pour le marché suisse, l'objectif d'un taux de
graisse intramusculaire de 3.5 % en moyenne a correspondu à un état d'engraissement exagéré de
la carcasse.
La qualité de viande a été comparée dans le LD et le biceps femoris, regio glutea (aiguillette
rumpsteak, BF). La composition chimique des 2 muscles étudiés ne révèle pas de différence
importante parmi les races. Les mesures de pH à 1 h et 48 h post mortem sont relativement
similaires entre les races contrairement à la capacité de rétention d'eau. Les Angus et les
Simmental présentent les pertes d'exsudats (drip loss) les plus faibles et simultanément les pertes
de décongélation et de cuisson les plus élevées en moyenne (Simmental seulement dans le LD).
Globalement, les Piémontais ont la meilleure capacité de rétention d'eau. Les LD des Angus et
des Charolais sont légèrement pâles avec une teneur en pigments plus basse dans les deux
muscles pour les Angus que pour les autres races. Dans le LD, aucune différence significative
entre les races n'est mesurée concernant la solubilité du collagène et la force de cisaillement,
contrairement au BF et à l'analyse sensorielle. Dans la première série, la viande des Angus est
significativement plus tendre que celle des Blonde d'Aquitaine, Piémontais et Simmental. En
revanche, dans la deuxième série, les Piémontais ont une viande significativement plus tendre que
toutes les autres races. Les Piémontais et les Blonde d'Aquitaine présentent une flaveur plus
intense que les Simmental et avec les Limousin et les Charolais ont une viande significativement
plus juteuse que celle des Simmental et Angus. Il semble que la vitesse de croissance nettement
supérieure et/ou le mouvement dans la deuxième série, en stabulation libre, ait joué un rôle
important sur les caractéristiques de qualité de viande, avec notamment une amélioration de la
capacité de rétention d'eau et de la tendreté, très marquée pour la tendreté chez les Piémontais
comparativement à la première série en stabulation entravée.
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En conclusion, les résultats démontrent:
1. Il est difficile avec des races à viande pures et une ration constituée principalement par des
fourrages de concilier un taux de graisse intramusculaire considéré comme idéal de 3.5 %
dans le faux-filet et en même temps une bonne charnure, un état d'engraissement et/ou un
poids de carcasse acceptables pour le marché suisse actuel.
2. Des différences de qualité de viande dans les deux muscles étudiés entre les groupes raciaux
sont constatées dans cet essai chez des bœufs ayant un taux de graisse intramusculaire
semblable dans le LD et élevés dans les mêmes conditions. Néanmoins, tous les groupes
raciaux ont présenté une qualité de viande jugée globalement bonne à très bonne, même pour
les Simmental, en retrait par rapport aux autres races et particulièrement aux Piémontais.
3. Les différences de qualité de viande observées ne sont donc pas dues directement à la graisse
intramusculaire.
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3. General introduction
Over the last decades the media have pointed out a lot of problems concerning the production of
meat in general, as for example bovine spongiform encephalopathy, foot and mouth disease,
environment pollution and lack of animals' care (Bonny, 2000). Economic pressures due to
steadily declining beef consumption have challenged the livestock and beef sectors to produce
meat that will regard the consumers' expectations. To be consistent with consumers' preferences,
farmers have attempted to optimize breed, fattening regime and housing. This encouraged the
development of a multitude of beef label programs (Dufey and Chambaz, 1999a). Generally, one
goal of these label programs is to achieve a clear differentiation from the conventional production
as for instance by prescribing a certain type of diet, avoidance of artificially produced feed
ingredients, access to fresh air, fattening of steers instead of bulls and/or the use of beef breeds or
crosses with beef breeds. The beef production in Switzerland is largely a by-product of dairy
husbandry but it has been noted in the last few years a clear shift towards using beef breeds.
There is therefore a need from the producers and the labels sides to be able to rely on
scientifically obtained data about the growth performance, carcass quality and meat quality of
different beef breeds fattened under typical Swiss production conditions. Carcasses and meat of
improved quality are anticipated from these labels particularly in sensory respect.
One component of beef meat quality is marbling, which describes the visible proportion and
distribution of intramuscular fat (IMF). The role of IMF or marbling on palatability traits is a
contentious issue. An abundance of research stretching over the last 30 years indicates that
tenderness and juiciness rating improve slightly as marbling/IMF increases, however
marbling/IMF explains only approximately 5 to 10 % of the variation in tenderness of the
longissimus dorsi (Blumer, 1963; Dikeman, 1996). Wheeler et al. (1994) and Rymill et al. (1997)
concluded that degree of doneness was considerably more important in producing tender and
juicy steaks than was IMF content. Actually IMF seems to be more an attribute which may
accompany high tenderness under certain circumstances rather than causing a direct effect on
tenderness, talking about amounts in the common range for Western beef production (Scheeder,
1998). Nevertheless IMF and palatability of beef meat remains tightly linked together in the mind
ofmost butchers and gastronomy circles. Therefore marbling is often subjectively equated by the
consumers with quality and eye appeal of IMF, i.e. its amount and distribution, can play an
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important role on purchase decision. This is specially the case in branded beef programs. A
preliminary study investigating the visual preference of marbling was conducted in Switzerland
using photographs of loin eye cuts. Excepted the class without marbling (27 % of the responses),
the most frequently selected marbling classes were the ones with 3 % and 4 % IMF with 47 % of
the responses. Going from the principle that the potential consumer of label meat wants a product
which is different from the conventional one, he should not focus on the absence of fat. On this
basis an IMF content of between 3 and 4 % was adopted in this study as slaughter end point.
Selecting a similar IMF content in the longissimus dorsi as slaughter criterion has raised the need
of an appropriate determination tool. Ultrasound technology has already widely been used and
evaluated for estimation of body composition in live beef cattle (Tschümperlin, 1996). In the
United States a new ultrasound method has been developed for about 10 years to permit also the
estimation of IMF in live animal. American farmers were interested in the possibility to estimate
early in the feedlot phase the IMF content of the animals as carcass quality in beef is determined
almost entirely by marbling score. This method was used in this study to determine the slaughter
end point of each animal.
Meat production has often been reproached to be not targeted on consumers' needs but on
carcass, an intermediate product. The concept of this project was therefore to center firstly the
interest on the recognized consumers' needs and to evaluate only secondly the resulting effects
upstreaming from the consumer level, i.e. on the butcher and farmer levels. This approach tries to
live up to consumers' expectations. It must be kept in mind that the volume of meat production is
finally determined in response of the degree of satisfaction aroused by the product.
The objectives of this study were to compare steers of six different beef breeds for a similar
intramuscular fat content of 3.5 % and to determine:
1. which differences can be observed in sensory traits?
2. which slaughter weight will be reached, for a given energy density ofthe diet?
3. which relationship exists between this IMF content and fatness of the carcass?
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4. Sources of variation influencing the use of real-time ultrasound to predict
intramuscular fat in live beef cattle
Based on:
A. Chambaz, P.-A. Dufey, M. Kreuzer, and J. Gresham, 2001
(submitted to Canadian Journal ofAnimal Science)
Abstract
A total of 123 steers of six European breeds (Angus, Simmental, Charolais, Limousin, Blonde
d'Aquitaine, Piedmontese) were used i) to evaluate the precision of the ultrasound predicted
intramuscular fat (USIMF) and its sources of variation using the current Pie QUIP technology ii)
to develop improved models for predicting USIMF. Steers were slaughtered when they reached
the target value of 3.5 % USIMF. Hide samples were obtained 3 d before slaughter by shot-
biopsy. After slaughter, a sample of the longissimus muscle was used for determination of actual
chemical intramuscular fat (EEIMF), collagen content and solubility. Among the variables
available during a chute-side scanning session, hide thickness and ultrasound subcutaneous fat
thickness at the 12th and 13th rib were shown to be significantly correlated with EEIMF. These
two variables were selected as possible independent variables to evaluate the construction of new
models. The model with the best fit included USIMF, hide thickness and live weight and had a
standard error of prediction of 0.96 % which is similar to other published technologies. Breed
group and collagen related traits did not influence USIMF estimation. Finally, the revised Pie
QUIP technology should be considered as one technology of choice to predict EEIMF content in
live animals.
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4.1. Introduction
Marbling, i.e. the visible proportion and distribution of intramuscular fat determined in the
longissimus dorsi muscle, is the most important factor affecting quality grade in the United States
(Boggs et al., 1998) and in Canada (Newman et al., 1994) which even opens markets for
unconventional solutions such as the use of Wagyu crossbred cattle (Mir et al., 1999). In Europe,
the carcass value is solely determined by its conformation and fatness, and no such system exists
for marbling as in the USDA quality grade system (USDA, 1989). Although the influence of
intramuscular fat percentage on the palatability of beef is a contentious issue (Wheeler et al.,
1994; Dikeman, 1996; Rymill et al., 1997), also in Europe marbling is often cited and demanded
as a primary quality attribute of beefby gourmets or in label productions. Marbling influences the
visual quality of beef which is a major component affecting positively or negatively purchase
decision of the consumers. Therefore it would be desirable to be able to accurately assess the
amount of intramuscular fat in the live beef animal prior to harvest to meet the demands of
different markets (Hassen et al. 1999; Brethour 2000) for instance a range of 3 to 4%
intramuscular fat which was the preferred range in a Swiss assessment (Chambaz et al., 2001a)
corresponding to the USDA grade 'Slight Degree of Marbling'. Real-time ultrasound technology
is a non-invasive method of determining on the live animal the percentage of intramuscular fat in
the longissimus dorsi (loin eye) muscle (Kriese, 1996; Herring et al., 1998). Considerable
improvement has been made in the last few years in different ultrasound technologies to estimate
intramuscular fat in live beef animals (Kriese, 1996; Herring et al., 1998; Brethour, 2000; Hassen
et al., 2001; Gresham, 2001). One technology that has not been documented in the literature as
extensively as others is known as the Pie QUIP technology (Gresham, 1997). This technology has
the advantage to provide instant chute-side results but was judged less accurate than four other
real-time ultrasound systems (Herring et al., 1998). But since then the Pie QUIP technology has
been modified.
The objectives of this study were: 1) to determine by live animal real-time ultrasound evaluation
the precision and accuracy of utilizing the current Pie QUIP technology in determining time of
harvest animals when between 3.0 and 4.0% intramuscular fat is reached, 2) to determine and
evaluate live animal and muscle tissue characteristics that might influence the precision and
accuracy of using ultrasound to estimate intramuscular fat in live beef animals, 3) to develop new
prediction models for improving the accuracy and precision of the current Pie QUIP technology.
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For this purpose steers of very different breed and highly varying in live weight were used in
order to ensure applicability for a broad range of animals.
4.2. Materials and methods
4.2.1. Animals
Two replicated finishing trials included each 12 steers out of six breeds yielding a total of 144
carcasses. Steers were either purebred Simmental, Charolais, Limousin, Blonde d'Aquitaine,
Piedmontese or Angus (% Angus obtained from grading up of native Swiss dairy breeds). All
steers were purchased from suckler herds at the same time and entered the trial at a similar age of
8.0 ± 0.8 mo (mean ± SD). The animals within each trial were finished under the same conditions
and had ad libitum access to a diet consisting, on a dry matter basis (g kg-1), of maize silage
(520), grass silage (260) and concentrate (220). The complete diet contained 135 g kg-1 crude
protein and 11.2 MJ kg-1 metabolizable energy. Trial 1 was performed in a tie-stall barn while a
loose-housing system with straw bedding was applied in Trial 2. The steers were cared for under
guidelines comparable to those laid down by the Canadian Council on Animal Care. Further
details on the animals and the experimental procedures are described elsewhere (Chambaz et al.,
2001a).
In order to develop and test a reliable prediction equation, two independent sets of experimental
animals were required. One group was needed to develop the equation, and an independent set of
animals was needed to evaluate the accuracy and precision of the equation (Gresham et al.,
1994). In this study, the data from every fourth animal harvested sequentially was designated as
part of the validation set. Animals with incomplete data for variables to be utilized in the analysis
were deleted from the total data set resulting in n = 123. As a result, there were 96 animals used
for developing the prediction equations (test data set) and 27 animals were used to validate the
prediction equations (validation data set).
4.2.2. Live animal measurements
Intramuscular fat content was estimated with a real-time ultrasound system in the live animals.
Images were captured with a Pie Medical scanner 200 (Maastricht, NL) equipped with a 3.5
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MHz, 18-cm transducer (Model ASP-18). Ultrasound estimation of intramuscular fat content
(USIMF) was accomplished with the machine internal analysis program and a software
prediction program available from Classic Ultrasound Equipment, Tequesta, FL, USA (Gresham,
1997). This technology, called Pie QUIP (Quality Ultrasound Indexing Program) technology, is
based primarily on a characterization of regions of analysis in the dorsal and ventral areas of the
tri th
longissimus dorsi muscle at the 12 and 13 rib (Gresham unpublished data). Then a
mathematical analysis is conducted by a proprietary software system that is a part of the
ultrasound scanner to analyze relationships of the regions of analysis by applying a mathematical
model influenced by attenuation and scattering of the ultrasound beam (Haumschild and Carlson,
1983; Brethour, 1990; Park et al., 1994). This program is recommended for beef animals up to 24
months of age (Gresham, 1996). Hair was clipped and linseed oil was applied to the hide surface
before scanning to ensure acoustical contact between surface of transducer probe and hide surface
(Gresham, 1999). The probe was centered directly above the 12th and 13th rib and placed
longitudinal to the mid-line of the animal at a point to approximate a mid-point between the
medial and lateral ends of the longissimus dorsi muscle. This site would then create an ultrasound
image in the area of the 12th/13th rib and 1st lumbar region (Gresham, 1997). Both subcutaneous
fat thickness (USSCF12/13) and QUIP index for USIMF calculations were measured at the same
time without need of a contour-fitting stand-off. Each steer was scanned in 14 d intervals until it
reached the targeted USIMF of about 3.5% as determined by real-time ultrasound evaluation or
after a maximum of 15 months of fattening if 3.5% was not reached. At least three scans were
obtained on each individual animal per scanning session for analysis to increase the precision of
the estimation (Hassen et al., 1999).
Linear live animal measurements included live weight, average daily gain, days on feed and age
at slaughter. As a variable which may influence the result of the ultrasonic measurements, hide
thickness was determined. Cores (8.3 mm diameter) of hide samples were obtained by shot-
biopsy (Biotech, Nitra, Slovakia) 3 d before slaughter. Biopsy was performed at the same site as
the ultrasound measurements on the shaved hide of the live animal. The core sample was
separated from the muscle and subcutaneous fat and the thickness of the hide was determined by
use of an electronic caliper square.
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4.2.3. Carcass measurements
Steers were transported for approximately 1 h to a commercial harvesting facility. Carcasses were
weighed at about 1 h post mortem, then moved to a chilling cooler and allowed to chill for 48 h at
2°C. Carcass subcutaneous fat measurements were obtained two days post mortem between the
9th and the 10th (SCF9/10) and between the 12th and the 13th rib (SCF12/13) to the nearest
millimeter with an electronic caliper square. Carcass grading in terms of fatness was performed
on a five-point scale (1 = low; 5 = high fatness) by experienced official staff according to the
Swiss beef classification grid (Proviande, 2001). A section of the longissimus dorsi muscle was
excised from the left side of each carcass and stored at 2°C until chemical analysis. A slice of
approximately 300 g of longissimus dorsi muscle (region of 12th and 13th rib) was trimmed free
of extraneous fat and muscle epimysial tissue, lyophilized (48 h, under vacuum at -20°C;
Lyophilisator Christ, model Delta 1-24K, Adolf Kühner AG, Birsfelden, Switzerland) and
homogenized. Intramuscular fat was defined as ether extractable fat (EEIMF) and determined by
the Soxhlet procedure using petroleum ether (SLB, 1969). Total collagen content and collagen
hydrothermal solubility were determined by the method described by Arneth and Hamm (1971)
and adapted for the Technicon Autoanalyser II analysis chain (Technicon, Plainfield, NJ, USA).
4.2.4. Statistical analysis
Means, SD, ranges, root mean square errors (RMSE) and correlations were determined and
stepwise regression analyses were performed (SAS, 1985). Statistics generated in the stepwise
regression analysis included R2, Cp, and SE (Mallows, 1973; MacNeil, 1983). The standard error
of prediction (SEP) was calculated according to Herring et al. (1998). The SEP measures the
ability of the technician to rank or predict differences between animals correctly, correcting for a
tendency to consistently over- or under-predict the true measurement. After completion of
regression analyses and generation of prediction equations from the first data set (n = 96), data
from the second set (n = 27) were used to validate the prediction equations.
Page 18
13
4.3. Results and discussion
4.3.1. Test and validation ofthe prediction equation
Table 1 presents the means, standard deviations, minimum and maximum values of all variables
that were used in modeling prediction equations to estimate intramuscular fat in live beef cattle.
There was no significant difference (P > 0.05) in means for the test and validation sets for any
variable listed.
Table 1
Descriptive statistics oflive animal linear and ultrasound as well as carcass traits by data set
Test Data Set (n = 96) Validation Data Set (n == 27)
Trait1 Mean SD Min. Max Mean SD Mm. Max.
EEIMF (%) 3.10 1.35 1.18 9.12 3.46 1.19 1.23 6.37
USIMF (%) 3.25 0.75 1.00 5.67 3.44 0.66 2.44 4.93
SCF9/10 (mm) 19.5 5.4 7.7 36.1 19.4 6.7 8.9 34.0
SCF12/13 (mm) 10.5 4.7 1.7 24.6 11.3 5.1 2.3 19.6
USSCF12/13 (mm) 7.2 2.4 2.3 13.5 7.4 2.2 3.8 11.4
Hide thickness (mm) 7.6 0.9 5.1 105 7.6 0.9 5.7 9.4
Days on feed (d) 331 116 117 497 315 124 117 497
Weight gain (kg/d) 1.09 0.20 0.61 1.58 1.10 0.22 0.63 1.55
Age at slaughter (mo) 18.9 3.9 11.8 24.5 18.2 4.2 11.7 24.0
Live weight (kg) 661 110 458 918 636 88 475 821
Hot carcass weight (kg) 392.5 79.0 251.6 566.2 376.7 69.9 263.8 529.4
Graded fatness (units 1-5) 3.9 0.8 2.0 5.0 40 0.8 3.0 5.0
EEIMF = ether extractable intramuscular fat; USIMF = ultrasound predicted intramuscular fat
content using current Pie QUIP technology; SCF9/10 = carcass subcutaneous fat thickness between 9th
and 10th rib; SCF12/13 = carcass subcutaneous fat thickness between 12th and 13th rib; USSCF12/13 =
ultrasound predicted subcutaneous fat thickness between 12th and 13th rib
When breed group was used as an independent variable in the prediction equations, no significant
breed group effect was observed (data not shown). Therefore, since it was determined that a
single equation could be used across breeds and individual breed equations were not merited or
required, data were pooled for all breeds. While some variables were significantly different
between breeds (hide thickness), this variation can be accounted for by using those variables as
independent vanables in the equations.
Page 19
14
Table 2 presents the simple linear correlations for the traits described in Table 1 for both the test
and validation data sets. Values above the diagonal are correlations for the test data set, while
values below the diagonal reflect correlations for the validation data set. In the test data set,
significant correlations are noted between EEIMF and USIMF (P < 0.001), SCF12/13 (P <
0.001), USSCF12/13 (P < 0.001), hide thickness (P < 0.05), daily weight gain (P < 0.01) and
graded carcass fatness (P < 0.001).
USSCF12/13 was identified on the same scan used for determining intramuscular fat and is thus
immediately available during the chute-side scanning session. Therefore this variable was then
selected as possible independent variable to evaluate the construction of a new equation to
enhance the accuracy and precision of the current QUIP index for estimating USIMF in live beef
cattle. A step-wise regression analysis was conducted using USSCF12/13 and the quadratic of
USSCF12/13 with the stepwise regression presented in Table 3. Therefore, the new prediction
equation including USSCF12/13 as a variable is:
USIMFnewl (%) = -4.211 + [0.899 x USIMF(%)] + [0.516 x USSCF12/13 (mm)
- (0.025 x USSCF12/132(mm2)] + [0.003 x live weight (kg)]
The prediction equation was tested against an independent set of animals (n = 27) described in
Tables 1 and 2 in order to validate it. Table 4 presents the statistics for the validation of the
equation (USIMFnewl). Statistically, an unbiased and valid equation should have an intercept of
zero with a slope of one. This equation meets this test since the slope and intercept values include
one and zero respectively within their standard error values.
Page 20
Table2
Simple
linearcorrelationsforliveanimallinearandultrasoundaswellascarcass
traitsbydata
set1
Trait2
12
34
56
78
910
11
12
EEIMF(%)
(1)
-
0.41
0.18
0.40
0.33
0.24
-0.18
0.26
-0.14
0.09
-0.06
0.52
USIMF(%)
(2)
0.66
-
0.07
0.33
0.38
-0.24
-0.51
0.32
-0.47
-0.22
-0.44
0.45
SCF9/10(mm)(3)
0.39
0.31
-
0.53
0.48
0.15
-0.19
0.26
-0.19
0.28
0.21
0.50
SCF12/13(mm)
(4)
0.65
0.65
0.40
-
0.61
0.32
-0.63
0.61
-0.60
-0.09
-0.24
0.57
USSCF12/13(mm)
(5)
0.39
0.29
0.43
0.60
-
0.31
-0.23
0.17
-0.25
-0.30
-0.22
0.58
Hidethickness(mm)
(6)
-0.10
-0.20
0.25
-0.08
0.41
-
-0.06
0.28
-0.08
0.17
0.03
0.27
Daysonfeed(d
)(7
)-0.17
-0.48
0.08
-0.44
-0.44
0.17
-
-0.79
0.98
0.72
0.85
-0.41
Weightga
in(k
g/d)
(8)
0.34
0.38
0.09
0.43
0.42
0.06
-0.69
-
-0.68
-0.25
-0.46
0.57
Age(mo)
(9)
-0.11
-0.39
0.10
-0.40
-0.49
0.09
0.98
-0.78
-
0.75
0.87
-0.39
Liveweight(k
g)(1
0)0.24
-0.36
-0.02
-0.29
-0.12
0.18
0.67
-0.01
0.69
-
0.95
0.04
Hotcarcasswt(k
g)(1
1)0.05
-0.34
-0.15
-0.46
-0.44
0.02
0.81
-0.22
0.82
0.94
-
-0.15
Graded
fatness(units)(1
2)0.55
0.27
0.35
0.64
0.47
0.09
-0.40
0.49
-0.36
-0.03
-0.17
-
1Valuesabovethedi
agon
alaresi
mple
linearcorrelationsofvariablesusedinthetestdata
set
(n=
96;P<
0.05
ifr>
0.20
;P<0.01
ifr>
0.25
;P<
0.001
ifr>
0.32),
variablesbelowthediagonal
aresimple
linearcorrelationsforthesame
variablesasusedinthevalidationdataset
(n=
27;P<
0.05
ifr>
0.38;P<
0.01
ifr>
0.56;P<0.001
ifr>
0.64
).
2EEIMF=
etherextractableintramuscular
fat;USIMF=ultrasoundpredictedintramuscularfatcontentusingcurrentPieQUIPtechnology;
SCF9/10=
carcasssubcutaneous
fatthicknessbetween
9thand
10th
rib;
SCF12/13=
carcasssubcutaneous
fatthicknessbetween
12th
and
13th
rib;
USSCF12/13=ultrasoundpredictedsubcutaneous
fatthicknessbetween
12thand13
*ri
b.
Page 21
Table
3
New
regressionequationforultrasoundpr
edic
tedpercentageofintramuscular
fat(USIMFnewl)from
live
animalvariablescollected
atharvest
(n=
96)'
Trait
Step
Rz
C„
Partialregressioncoefficients
RMSE(%)
Intercept
USIMF(%)
Liveweight
(kg)
USSCF12/13(mm)
USSCF12/13'(mmz)
USIMFnewl
10.19
1473
1.52
0.202
0.882
20.25
9.30
1.17
-2.471
1.048
0.003
30.30
5.25
1.36
-3.019
0.919
0.003
0.129
40.32
500
1.34
-4.211
0.899
0.003
0.516
-0.025
Cp=Mallow's
stat
isti
c,RMSE=rootmeansquare
error;USIMF=ultrasoundpr
edic
tedintramuscularfatcontentusingcurrentPieQUIP
tech
nolo
gy,
USSCF12/13=ultrasoundpredictedsubcutaneous
fatthicknessbetween
12th
and13*
rib;
USFATnewl=USIMF
equationin
clud
ingUSSCF12/13.
Table4
Regressionofetherextractableintramuscularfa
t(EEIMF)onnewequationsofultrasoundpr
edic
tedliveanimalintramuscular
fat
(n=
27)
Predictioneq
uati
on1
Intercept
+SE
Bi
±SE
R1RMSE
(%)
2
rPr/
SEP4(%)
USIMFnewl
USIMFnew2
-0.464
-0.176
0.625
0.875
1.259
1.099
0.195
0.259
0.63
0.42
0.75
0.93
0.79
0.65
0.78
0.62
1.03
0.96
1USIMFnewl
includesUSSCF12/13;USIMFnew2
includeshidethickness.
2
rp=Pearsoncorrelationcoefficient.
3
rr=Spearmanrankcorrelationcoefficient.
4SEP=standarderrorofpr
edic
iton
.
Page 22
17
In order to detect and evaluate new possible sources of variation in the precision of the
estimation of the USEVIF, a subsequent prospective step was conducted with the variables
available before slaughter in this study. All the variables shown to be significantly correlated
with EEIMF, i.e. USIMF, hide thickness, live weight, USSCF12/13 and daily weight gain,
were used in a stepwise regression analysis as independent variables to generate a new
ultrasound predicted intramuscular fat content value (Table 5). When both hide thickness and
USSCF12/13 are included in the equation, hide thickness becomes a significant variable and
both USSCF12/13 and daily weight gain are eliminated.
Table 5
Stepwise regression analysis for development of a new ultrasound prediction equation to
intramuscular fat (USIMFnew2) from live animal variables collected at harvest (n = 96)
Trait Partial Rz Model Rz cp P>F
USIMF (%) 0.1932 0.1932 19.71 0.0001
Hide thickness (mm) 0.1116 0.3048 6.67 0.0003
Live weight (kg) 0.0429 0.3477 2.88 0.0175
USSCF12/13 (mm) 0.0047 0.3524 4.26 0.4285
Weight gain (kg d"1) 0.0019 0.3543 6.00 0.6734
USIMFnew2 includes hide thickness; Cp = Mallow's statistic; USIMF = ultrasound predictedintramuscular fat content using current Pie QUIP technology; USSCF12/13 = ultrasound
predicted subcutaneous fat thickness between 12th and 13th rib.
Based on Cp statistic, the best model for predicting EEIMF is an equation to include USIMF,
hide thickness and live weight. Therefore, the new prediction equation for ultrasound
prediction of intramuscular fat using hide thickness (Table 6) is:
USIMFnew2 (%) = -5.534 + [0.994 x USIMF (%)] + [0.460 x hide thickness (mm)] + [0.003
x live weight (kg)]
Page 23
Table6
New
regression
equation
forultrasoundpredic
tedpercentageofintramuscular
fat(USIMFnew2)from
liveanimalvariablescollected
atharvest
(n=
96)1
Partialregression
coefficients
Trait
Step
R2
Cp
RMSE
(%)
Inte
rcep
tUSIMF(%)
Hidethickness(mm)
Liveweight(kg)
USIMFnew2
ÎÔ7Ï7
21.11
L24
"
0.715
0.734
20.28
8.27
1.17
-3.503
0.853
0.502
30.32
4.00
1.14
-5.534
0.994
0.460
0.003
USIMFnew2
includeshideth
ickn
ess;
Cp=Mallow's
statistic;RMSE=rootmeansquare
error;USIMF=ultrasoundpr
edic
tedintramuscular
fatcontent
usingcurrentPieQUIPtechnology.
Page 24
19
USIMF is the value produced by the current Pie QUIP technology for estimating EEEVIF in
live beef cattle (Gresham 1997). However, it appears that the current equation predicting
EEIMF can be increased in accuracy and precision by including hide thickness. The test of the
accuracy of the new equation developed (USIMFnew2) to predict EEIMF is presented in
Table 4 using steers from the validation data set. USIMFnew2 was validated because the
intercept contains 0 and the slope contains 1. It presented a lower SEP compared to
USIMFnewl. In addition, the authors have observed that it is more difficult to obtain quality
images with animals (breeds) that possess thick hides. Since the Pie QUIP technology is
based on attenuation and scattering of sound waves, hide thickness might be a contributing
factor to why some researchers have criticized the QUIP technology for not being as accurate
as other documented technologies (Herring et al., 1998; Wilson et al., 1998). For practical
reasons the measurement of hide thickness using biopsy is problematic during a chute-side
scanning session in the field. The hide thickness in the live animal can also be measured on
the same scan as for USIMF but no data about the precision of its estimation is available in
the literature. Nevertheless the very easy determination of upper and lower hide limits on the
scan would lead one to expect a similar high precision compared to the measurement of
USSCF12/13 (Houghton and Turlington, 1992).
4.3.2. Comparisons ofthe new equations developed with results ofthe literature
In order to validate technologies and certify scanning technicians the SEP has been most
commonly used to test models for predicting EEIMF (Kriese, 1996; Herring et al., 1998;
Hassen et al., 2001). The most recent study to evaluate ultrasound technology was reported by
Hassen et al. (2001) comparing the Aloka 500V and Classic 200 scanners using the USOFT
prediction technology (Izquierdo et al., 1996), which is the standard in the United States.
Table 7 compares the results of the data set II reported by Hassen et al. (2001) for the
accuracy of each machine on a test set of animals versus the results of the validation test of
the new Pie QUIP equations generated and validated in this study. In reviewing the data in
Table 7 it is apparent that the new adjusted Pie QUTP equations are quite comparable to the
models and machines reported by Hassen et al. (2001). In addition, the accuracy and precision
for the Pie QUIP technology as reported in this study is superior to the values reported by
Herring et al. (1998) and representative of the field results for the current Pie QUIP
technology summarized by Gresham (2001). The major differences observed in Table 7 is that
the USOFT technology reported by Hassen et al. (2001) has a slightly lower SEP and higher
correlation coefficients compared to the equation generated using hide thickness
Page 25
20
(USIMFnew2). However, the equation generated by using USSCF12/13 (USIMFnewl) is
quite comparable in both correlation coefficients. The difference in the correlation
coefficients might be explained in part by the lower EEIMF content in the loin eye of the
animals reported in this trial and especially a lower standard deviation. Therefore, this trial
presents two new prediction equations that can be used to improve the precision and accuracy
of the Pie QUIP technology while still affording the opportunity to provide instant chute-side
results. Nevertheless the prediction equation using the measurement of hide thickness from
biopsy (USFATnew2) can only be considered for research purposes. Operators using the
USOFT technology described by Amin et al. (1997) and participating in the Centralized
Ultrasound Processing program described by Hays et al. (1999) must capture their images on
a disk and then mail the images to a central laboratory for interpretation. This negates the
opportunity for instant, real-time chute-side evaluation of either breeding or feedlot animals.
Table 7
Comparison of prediction statistics for predicting intramuscular fat in live beef animals for Pie QUIP
technologies and USOFT
Technology
Machine
Equation2
Pie QUIP
Scanner 200
USIMFnewl
Scanner 200
USMFnew2
USOFT1
Aloka 500 Scanner 200
Trait
Observations (n) 27 27 /1 /1
EEIMF (+ SD) (%) 3.46(1.19) 3.46(1.19) 3.66(1.73) 3.66(1.73)
Difference to EEIMF (%) +0.34 +0.15 +0.42 +0.67
SEP (%) 1.03 0.96 0.84 0.81
rP 0.79 0.65 0.88 0.89
rr 0.78 0.62 0.88 0.91
1
Technology developed by the IOWA State University (see Amin et al. 1997); results of the data set II
reported by Hassen et al. (2001).
2USDVlFnewl includes USSCF12/13; USIMFnew2 includes hide thickness.
3EEIMF = ether extractable intramuscular fat; SEP = standard error ofprediction; rp
= productmoment correlation coefficient; rr
= rank correlation coefficient.
Table 8 compares results for the Pie QUIP technology utilized at the 1997 Beef Improvement
Federation (BIF) proficiency testing program for scanning technicians (Wilson et al., 1998)
with the same technology used by the authors in the current study (n = 123), plus a
comparison of the new formulas (USIMFnewl and USIMFnew2) when tested on the
Page 26
21
validation set of data (n = 27). It is apparent from reviewing the data in Table 8 that both the
USIMFnewl and USIMFnew2 equations have significantly reduced the SEP for predicting
intramuscular fat (measured by EEIMF) in live beef cattle with the Pie QUIP technology. In
addition, the SEP values of 1.03 and 0.96% reported here are in agreement with similar values
(0.98% and 1.03%, data set III) reported by Hassen et al. (2001).
Table 8
Comparison of trials using the Pie QUIP technology
Model USIMF1 USIMFnewl2 USIMFnew2z USIMF"
Traif
Observations (n) 123 27 27 43
EEIMF (± SD) (%) 3.19(1.33) 3.46(1.19) 3.46(1.19) 3.81 (1.54)
Difference to EEIMF (%) +0.11 +0.34 +0.15 not available
SEP (%) 1.18 1.03 0.96 1.32
rP 0.45 0.79 0.65 not available
rr 0.43 0.78 0.62 not available
Results for ultrasound predicted intramuscular fat in this trial on all animals using current Pie QUIP
technology (Gresham 1997).
2
Equations from this study: USIMFnewl includes USSCF12/13; USIMFnew2 includes hide thickness.
3Results obtained at the 1997 Beef Improvement Federation (BIF) proficiency testing program for
scanning technicians (Wilson et al. 1998).
4EEIMF = ether extractable intramuscular fat; SEP = standard error of prediction; rp
= productmoment correlation coefficient; rr = rank correlation coefficient.
Page 27
22
4.3.3. Possible muscle characteristics influencing intramuscularfat estimation by ultrasound
Some reports have questioned the influence of collagen on accuracy and precision of using
ultrasound technology to predict EEEVIF in beef cattle (Brethour, 1990; Park et al., 1994).
Therefore, it would be of interest to investigate whether collagen content and collagen
solubility might be related to the accuracy or precision of estimating EEIMF content of live
beef muscle by real-time ultrasound. These two collagen traits were arbitrarily added as new
independent variables to the previously generated prediction equations (USIMFnewl) and
(USIMFnew2). If either of these variables did in fact influence the prediction of EEIMF, this
should be reflected in the test of the new equations. The following equations were then
generated by step-wise multiple regression analysis as previously described:
USIMFnew3 (%) = -6.785 + [0.830 x USIMF (%)]+ [0.062 x USSCF12/13 (mm)] + (0.010 x
collagen content (mg 100 g"1)] - [0.041 x collagen solubility (%)]+
[0.004 x live weight (kg)]
and
USIMFnew4 (%) = -7.084 + [0.767 x USIMF (%)]+ [0.231 x hide thickness (mm)] + [0.009
x collagen content (mg 100 g"1)] - [0.037 x collagen solubility (%)]+
[0.004 x live weight (kg)]
Table 9 compares the statistics of each of the four prediction equations when collagen content
and collagen solubility are added to the equations previously generated from live animal
measurements only (USIMFnewl and USIMFnew2). When the collagen traits were added as
variables together with USSCF12/13 to the equation (USIMFnew3), both correlation
coefficients and the R2 decreased while the SEP increased from 1.03 to 1.31%. Similar results
were obtained when the collagen traits were added to the USIMFnew2 equation yielding
equation USIMFnew4. Since adding the values to existing equation would not increase
precision or accuracy of the established statistical measures, it would indicate that the
collagen traits were not influencing the ability to estimate EEIMF by real-time ultrasound in
this study.
Page 28
23
Table 9
Comparison of the new equations for ultrasound prediction of intramuscular fat in live beef
cattle with and without inclusion of collagen content and collagen solubility
Prediction equation USIMFnewl USIMFnew2 USIMFnew3 USIMFnew4
Variable(s) added to USSCF12/13 Hide USSCF12/13& Hide thickness <&
USIMF equation thickness collagen traits collagen traits
Trait
Observations (n) 27 27 27 27
EEIMF (±SD) (%) 3.46(1.19) 3.46(1.19) 3.46(1.19) 3.46(1.19)
USIMFnew (±SD) (%) 3.12(0.75) 3.31 (0.70)3.03 (1.11) 3.42 (1.02)
Difference to EEIMF (%) 0.34 0.15 0.33 0.04
RMSE(%) 0.75 0.93 0.92 0.98
R2 0.63 0.42 0.43 0.35
SEP (%) 1.03 0.96 1.31 1.01
rP 0.79 0.65 0.66 0.59
rr 0.78 0.62 0.65 0.56
EEIMF = ether extractable intramuscular fat; USIMFnew = new ultrasound predicted intramuscular
fat content; RMSE = root mean square error; SEP = standard error of prediction; rp= product moment
correlation coefficient; rr = rank correlation coefficient.
4.4. Implications
At the present time, there are several technologies utilized in predicting intramuscular fat in
live beef cattle. It would appear that the Pie QUIP technology should be available as one
technology of choice for operators desiring to use chute-side scanning in order to produce
instant results that can be immediately utilized in selection of potential breeding seedstock, or
determining harvest date for finished cattle by the producer. Evidence is presented that hide
thickness may influence the precision and accuracy of this determination, therefore further
studies with larger numbers of animals are necessary to determine the relationship between
ultrasound and biopsy measures of hide thickness and so develop a new prediction equation
for field use. The results indicate that neither total collagen content nor collagen solubility
should influence the ability to estimate intramuscular fat by this technique. Evidence is
documented that the revised Pie QUIP technology is similar in accuracy and precision to other
reported technologies.
Page 29
24
5. Characteristics of steers of six beef breeds fattened from eight months of
age and slaughtered at a target level of intramuscular fat.
I. Growth performance and carcass quality
Based on:
A. Chambaz, I. Morel, M. R. L. Scheeder, M. Kreuzer and P.-A. Dufey, 2001,
Arch. Anim. Breed. 44:395-411
Abstract
Growth performance and carcass quality of 132 steers originating from six beef breeds, Angus (AN),
Simmental (SI), Charolais (CH), Limousin (LI), Blonde d'Aquitaine (BL), and Piedmontese (PI),
fattened under the same conditions on the same diet, were compared at a target level of 3.5 %
intramuscular fat (IMF) in the M longissimus dorsi. This target level was set on basis of the results of
a preliminary study investigating, with 784 persons, the visual preference of marbling using
photographs. The total mix ration, provided at ad libitum access, consisted of maize silage, grass
silage and concentrate (52 %, 26 % and 22 % of DM, resp.). Series 1 was performed m a tie-stall barn
while a loose-housing system with straw bedding was used in series 2. The animals were assigned to
slaughter either when the target IMF content was reached according to the estimation with a real-time
ultrasound system applied in the live animals or when 15 months of fattening had passed. AN, SI, CH
and LI reached 3.5 % IMF on average at final weights of 501 ± 43, 628 ± 60, 693 ± 117 and 668 ± 65
kg, respectively. BL and PI did not reach this target, although the average fattening period was about
three times longer for BL and PI than for AN and the final weights were 758 ± 93 and 647 ± 64 kg,
respectively. Under the conditions of this experimental approach, daily gains were highest in AN,
followed by CH, SI, LI and BL and lowest in PI. The daily feed intake was significantly lower for PI
than for CH, SI and AN. The AN expressed the best feed conversion efficiency m terms of DM
expenditure per kg gain over the complete fattening period while this efficiency was lowest m the PI
group followed by BL. Among the four breeds, which reached the target IMF content, LI steers
showed the greatest proportion ofpremium cuts and the highest lean to fat and lean to bone ratio in the
sirloin, followed, in descending order, by CH, SI and AN. However all four groups were graded
around 4 m fatness score (high to very high). The present results revealed for all breeds the difficulty
to reach the desired extent of marbling and at the same time favourable carcass conformation, carcass
size (except AN) and fat cover which meet market demands.
Page 30
25
5.1. Introduction
Over the last decades, consumers increasingly demand and purchase beef produced under
conditions as natural as possible (Badertscher Fawaz et al., 1998). This includes suckler cow
systems, forage-based diets and the ban of artificial growth enhancers (Harrington, 1994) and
encouraged the development of a multitude of beef label programs (Dufey and Chambaz,
1999a). Generally, one aim of these label programs is to achieve a clear differentiation from
the conventional production as for instance by prescribing a certain type of diet, fattening
steers instead of bulls and/or the use of beef breeds or crossbreds, the latter particularly in
countries where beef production is largely a by-product of dairy husbandry (Geay and Micol,
1988) like Germany (Augustini et al., 1990) and Switzerland (Dufey and Chambaz, 1999a).
Carcasses and meat of improved quality are expected from these labels when compared with
conventionally produced beef, particularly in sensory respect (Buttery et al., 1997). One major
visual component affecting purchase decision of the consumers is marbling, which describes
the visible proportion and distribution of intramuscular fat (IMF) as determined in the M.
longissimus dorsi (M.l.d.) (Savell and Cross, 1988). Marbling is often monitored in breed
comparisons but was rarely used as the decisive slaughter criterion. Typically, animals in such
studies were slaughtered at the same chronological age (Riley et al., 1986; Dikeman and
Crouse, 1975; Oldigs et al., 1989), physiological age (Geay and Robelin, 1979), or weight
(Dubeski et al., 1997a). Few investigations applied the same fatness score (Schläpfer, 1986;
Kaufmann and Chavaz, 1989) as slaughter criterion or used the same percentage of carcass
fat, applying a posteriori selection (Geay and Malterre, 1973). To our knowledge, only in one
study (Smith et al., 1976) growth and feed efficiency of different beef crosses were compared
at a distinct IMF content (5 %), which was performed by statistical adjustment of means and
the application of a regression for days on feed.
The objective of the present experiment was to compare growth performance, carcass traits
and meat quality of steers at the same target IMF content of 3.5 % in M.l.d. The steers
originated from six beef breeds and were fattened under the same conditions on an identical
forage-based diet for all animals. This first communication focuses on results concerning
growth and slaughter performance. Meat quality issues are described in a subsequent
communication (Chambaz et al., 2001b).
Page 31
5.2. Materials and methods
26
5.2.1. Animals and experimental design
A total of 132 steers originating from six beef breeds, Angus (AN), Simmental (SI; original
without Red Holstein blood), Charolais (CH; line 'maternal quality'), Limousin (LI), Blonde
d'Aquitaine (BL), and Piedmontese (PI), were used in this study. AN and SI were obtained
from Swiss farms, CH, BL and LI were imported from France and PI from Italy. All animals
were purebred, except AN (75% AN blood on average) which had been derived from grading
up native Swiss dairy breeds mainly by the use of American AN bulls. Two subsequent
fattening series were carried out, each including 11 steers per breed. Series 1 was performed
in a tie-stall barn (space allowance per animal: 0.95 x 1.86 m), while a loose-housing system
with straw bedding (10 m2 per animal including an outside area) was used in series 2 due to
the intermediately performed transformation of the barns. All imported animals had to pass a
3-week period of quarantine in the country of origin as well as in Switzerland. During the
quarantine in Switzerland the animals were already adapted to the experimental diet. All
steers were purchased from suckler herds at the same time and entered the trial at a similar
average age of 238 + 22, 236 ± 25, 235 ± 29, 249 + 19, 230 ± 21 and 240 ± 13 d (means ± SD)
for AN, SI, CH, LI, BL and PI (PI, only series 2), respectively. In series 1, the PI had to pass a
prolonged quarantine in Italy and started the experiment at an average age of 281 + 16 d. All
steers were weighed at the start and at the end of fattening (directly before transport to
slaughter) as well as periodically every two weeks during fattening.
5.2.2. Diet
A total mix ration consisting of maize silage, grass silage (early-cut grass-clover mixture) and
concentrate was provided. Table 1 gives the ingredient and nutrient composition of this diet
and its components. The concentrate consisted per kg of 400 g barley, 240 g soybean meal,
200 g triticale, 100 g wheat and 60 g mineral-vitamin premix. Maize silage and grass silage
were offered in a ratio of 2:1 in terms of dry matter based on 2-weekly determinations owing
to the fact that growing cattle have high requirements for energy relative to protein. In
addition, samples from all diet components were taken every two weeks for nutrient
compositional analysis. There were only small differences between the two series in the
nutrient content of forages and concentrate, while certain variations were found within series
particularly when using new batches of grass silage.
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27
Table 1
Composition and nutrient contents of the experimental diet (means ± SD)'
Ingredient Maize silage Grass silage Concentrate Total Mix Ration2
Proportion (g/kg total dietary dry matter) 520 260 220 1000
Dry matter (DM, g/kg) 320 ± 28 385 ±84 879 +07 460 ± 28
Organic matter (g/kg DM) 963.2 ± 3.2 870 7 ±16.7 915.4 ±2 1 928.6 1 4.4
Crude protein (g/kg DM) 73.7 ±34 195 8 ±26.0 207 5 ±5.0 135.0 1 7.8
Crude fibre (g/kg DM) 206.0 ±15.0 211.7 ±24.9 38.0 ±2.6 170.6 ±11.5
Net energy3 (MJ NEV/kg DM) 6.70+ 0.13 6.23+ 0.51 8.12±0.10 6.89 ± 0.14
Metabohzable energy4 (MJ ME/kg DM) 11.0 ± 0.1 10.3 ± 0.6 12.6 10.1 11.2 1 0.2
Absorbable protein3 (g APD/kg DM) 70.5 ± 1.4 80.7 ±48 133 7 ±6.6 87.1 ± 1 9
Average of 61 determinations2Minerals and vitamins content per kg DM: 7 g Ca, 3 g P, 2 g Mg, 1 g Na, 0.18 mg Se, 54 mg Zn, 9 mg Cu, 54
mg Mn,
2'900 IU vitamin A, 56 mg a-tocopherol3
According to RAP (1999)
"According to DLG (1997)
Concentrate proportion was calculated in a way that the complete ration, being provided ad
libitum, generally covered the requirements for both net energy for growth (NEV) and
absorbable protein at the duodenum (APD) at the start of fattening. These requirements were
calculated on the basis of the Swiss recommendations developed for dairy crossbred steers
expecting average daily gains of 1.2 kg/d (RAP, 1999). The mineral-vitamin premix was
designed to supplement deficiencies and imbalances of the ration. Breed specific differences
in nutrient requirements were deliberately not accounted for in this study in order to exclude
direct diet effects. The composition of the ration was not changed during fattening. This
procedure may have resulted in a certain excess of protein as the fattening period proceeded
but ensured that deficiencies were avoided. The increasing demand for energy with growing
live weight was covered by the associated increase of the intake capacity of the steers at a
constant medium energy density of the complete ration. Feed intake of each steer was
recorded daily in both series. In series 2 this was accomplished by the use of electronically
controlled doors (Insentec, NL-Marknesse).
5.2.3. Endpoint offattening
The aim of this investigation was to slaughter all animals when they reached a similar IMF
content. The target IMF level was determined in a preliminary study investigating the visual
preference of marbling. In that study, 784 persons (46 % female, 54% male; 11.3 % < 21,
29.3 % between 21 and 40, 45.1 % between 41 and 60, 14.3 % > 60 years of age) had to select
the most preferred out of six photographs of M.l.d. cuts taken between the 9th and 10th rib,
which represented six classes of IMF content covering the range from 1 to 6 %. The
photographs showed only the central part of the slice to exclude any influence of the shape of
the M.l.d. and were presented without noticeable colour difference to avoid potential bias due
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28
to colour. The most frequently selected marbling classes were either the ones with 3 % and
4 % IMF with 30 % and 17 %, respectively, or the class without any marbling (27 % of the
responses). The 2, 5 and 6 % IMF classes were only chosen by 14, 6 and 5 % of the
participants. A range of 3 to 4 % IMF is also often quoted in other studies as to be the
minimum level necessary for the subjective perception as 'good beef quality' (Campion and
Crouse, 1975; Goutefongea and Valin, 1978; Savell and Cross, 1988). For these reasons a
content of 3.5 % IMF in M.l.d. was chosen as the target value. The IMF content was
estimated with a real-time ultrasound system in the live animals. Images were captured with a
Pie Medical scanner 200 SLC (NL-Maastricht) equipped with a 3.5 MHz, 18-cm transducer
(Model ASP-18) and a computer program, which provides the opportunity for chute-side
evaluation of IMF (Classic ultrasound equipment, Tequesta, USA-Florida). This program was
developed for beef animals up to 24 months of age (Gresham, 1996). The hair was clipped
and linseed oil was applied to the skin before scanning to ensure sufficient acoustical contact
between probe and skin surface. The probe was centred directly above the 12th and 13th rib
and placed lateral from the backbone of the animal at a point situated approximately in the
middle of the M.l.d. Applying this technique finally yielded chemically analysed average IMF
contents of 3.35 ± 1.12, 3.47 ± 0.93, 3.49 ±1.11, 3.48 ± 1.08, 2.34 ± 0.64 and 2.40 + 0.63 for
AN, SI, CH, LI, BL and PI, respectively. This illustrates that the target value was reached on
average only in four breeds whereas this was impossible for BL and PI. However, BL and PI
were kept in the comparison in order to give an impression of their performance under the
specific conditions of this experimental approach. For further details on IMF content see
(Chambaz et al., 2001b).
5.2.4. Data and sample collection at slaughter
The animals were slaughtered without subsequent electrical stimulation of the carcasses at a
commercial slaughter plant. Hot carcass weights were determined at about 1 h post mortem.
Carcass grading was performed by experienced official staff according to the Swiss beef
classification grid (Proviande, 2001), which is widely equivalent to the EUROP grading
system. Subcutaneous fat thickness was measured 2 days post mortem between the 12* and
13th rib at 3/4 of the distance of the lateral length of the M.l.d. from the backbone with an
electronic calliper square. Carcass length was measured from the 1st rib to the head of the
Symphysis ossium pubis and the leg length from the head of the Symphysis ossium pubis up to
the Os malleolare. After chilling for 48 h, the left side of the carcass was divided into fore-
and hindquarter between the 9th and 10th rib. The flank was cut along the distal edge of the M.
Page 34
29
iliocostalis lumborum through the ribs until joining the cut along the 9l /10l ribs. This
procedure divided the carcass into pistola and forequarter with adhered flank. The pistola was
then separated 5 cm cranial of the head of the Symphysis ossium pubis into leg and sirloin
together with the rump. The separation between the sirloin and the rump was done behind the
6th lumbar vertebra. The sirloin was furthermore dissected into striploin (i.e., M.l.d.),
tenderloin (i.e., M. psoas major), bone and fat tissue. The proportion of the so-called 1st
category cuts comprised the trimmed striploin, tenderloin and rump (M. glutaeus médius).
The dressing procedure followed guidelines ofABZ (1997).
5.2.5. Statistical analysis
Data were statistically analysed with the NCSS program (version 1997, Hintze, Kaysville,
Utah, USA). In a first evaluation, data of both series were included in order to be able to
compare overall series differences, using a two-way ANOVA with breeds and series as fixed
effects and breed x series interactions. Because interactions between breed and series occurred
in most growth variables, the data were finally analysed separately for each series with one¬
way ANOVA considering breed as fixed effect in the model. The Tukey test was used for
multiple comparison among means considering p < 0.05 as significant.
5.3. Results
5.3.1. Growth performance
The steers of the different breeds were of a similar age at the start of the experiment, except
for the PI in series 1 which were older by 40 d at the start as explained (2.1), but there were
already certain initial differences in live weight (Table 2). Weight was highest in the CH
steers (significant in series 2) and lowest in the PI steers (series 2) at the start of fattening. At
slaughter, when the target IMF content was reached by AN, SI, CH and LI steers, AN steers
were significantly lightest in both series. All other groups had a similar final live weight in
series 1. However, in series 2, CH were the heaviest group of those large-framed breeds
which reached the target IMF content. Compared with the weight at slaughter, group
differences in age were more pronounced and consequently the duration of fattening greatly
differed. BL and PI did not reach the target IMF content on average despite fattening period
was three times longer than for AN. BL and PI therefore were on average significantly older
at slaughter than all other breeds, and BL were also heaviest while PI remained in the same
weight range as SI, LI and CH (CH series 1 only).
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30
Table 2
Growth characteristics of the steers originating from different beef breeds (n=l 1 per series)1
AN SI CH LI BL PI Average SEM
Initial live weight (kg)Series 1 290ab 294ab 295ab 288ab 278b 321a 294z 8.9
Series 2 342" 343b 391a 323b 323b 268e 332y 9.3
Final live weight (kg)Series 1 478b 631a 642a 637a 695a 656a 623z 23.1
Series 2 524d 625c 744ab 698bc 820a 637° 675y 18.5
Age at slaughter (d)Series 1 368d 540c 517c ôos1* 696ab 705a 572 22.5
Series 2 393e 477d 540c 614b 683a 660ab 561 12.3
Days of fatteningSeries 1 146d 319c 304e 371bc 479a 424ab 340y 22.1
Series 2 140e 226d 283c 352b 442a 421a 311z 11.1
Daily gain (g/d)Series 1 1279a loss00 1170ab 951
cd 869d 796d 1025z 39.7
Series 2 1306a 1252ab 1274a 1069e 1123bc 876d 1150y 33.0
DM intake (kg/d)Series 1 7 79abc 8.21ab 8.26a 731e 7.15e 7.5l* 7.70z 0.178
Series 2 8.04b 8.11ab 8 96a 7 79b 8 44ab 6 79e 8.02y 0.213
Total energy intake (GJ NEV)Series 1 7.87c 17.89b 17 20" 18.64ab 23.50a 21.93ab 17 84y 1.240
Series 2 7.41d 12.34° 17.03b 18.51b 23.82a 19.01b 16.36z 0.872
Total protein intake (kg APD)Series 1 101e 226b 218b 236ab 296a 275ab 225 15.5
Series 2 96d 158c 217b 236b 312a 248b 211 11.1
Feed conversion efficiencyFeed DM/gain (kg/kg)Series 1 6.14d 7.66bc 7.1lcd 7 72bc 8.30b 9.63a 7.76y 0.265
Series 2 6.16c 6.5 lbc 7.11ab 7 32a 7.47a 7.79a 7.06z 0.193
NEV/gain (MJ/kg)Series 1 42.6d 52.6bc 49 0cd 53.0^ 57.1b 66.2a 53.4y 1.82
Series 2 40.7C 43.7bc 47.8ab 49.7a 49 3a 51.9a 47.2Z 1.29
APD/gain (g/kg)Series 1 545d ôôô^ 621cd 671bc 720b 830a 675y 22.8
Series 2 529c sôo"0 611ab 634a 646a 677a 610z 16.3
AN = Angus, SI = Simmental, CH = Charolais, LI = Limousin, BL = Blonde d'Aquitaine, PI = Piedmontese
'Means within one line without a common supersenpt differ significantly (P<0 05), series averages within the same variable with different
superscripts are significantly different (P<0 05)
As Figure 1 illustrates, the average live weight gain was quite linear at least in the first 5 to 6
months of fattening, but slightly lower from then on, particularly when regarding the average
final weight and fattening duration. The average daily gains were highest in AN, followed by
CH, SI, and LI. BL had average daily gains similar to LI while PI steers showed the lowest
growth rates from the beginning on. Overall, an inverse relationship between age at slaughter
respectively days of fattening and the average daily gains was observed. The assumed level of
daily gains of about 1.2 kg/d was reached on average only by AN and CH in both series and
SI in series 2 but not by LI, BL and PI.
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31
800
700
_600
f 500
5
400
300
200
-° *'''
•
-Jr
-A-AN
-«-SI
-e— CH
—f—LI
-•—BL
-H-PI
i i i i i l i
0 10 20 30 40
Fattening weeks
50 60 70
Fig. 1 : Evolution of the live weight of steers of different beef breeds (average of series 1 and
2). Curves end when the first animal of the respective breed was slaughtered. The last symbol,
connected with the solid line by a dotted line, indicates the average live-weight at slaughter of
all animals per group.
The average daily feed intake over the whole fattening period was, in part, significantly
lowest for LI compared with CH, SI and AN (Table 2). The evolution of feed intake during
fattening (Figure 2) showed a similar pattern for AN, CH and SI in one group and LI together
with BL in another one while PI where lowest over the whole period. The highest feed intake
was generally recorded approximately in the middle of the fattening period, shortly before the
first individuals of the breed groups reached the target IMF and were assigned to slaughter.
The periodically occurring changes in feed intake (Figure 2) could be mainly led back to
changes in batches of grass silage. Feed conversion efficiency in terms ofDM expenditure per
kg gain over the complete fattening period was highest for AN while this efficiency was
lowest for LI, significant against efficiency of SI in series 2 and AN when only comparing
those breeds which reached the target IMF. PI and BL performed even worse in this respect
(Table 2). As diet composition was not changed during fattening, intake and utilization of net
energy and absorbable protein showed the same relative group difference as DM intake.
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32
According to the days on feed required, the total energy and protein intake was by far lowest
for AN and highest for BL and PI.
10
ë, 8
a>
(04-1
S 7
O
'rä 6a
10 20 30 40 50
Fattening weeks
•x
-A--AN
—--SI
—e--CH
—I--LI
—•--BL
—X—-PI
60 70
Fig. 2: Evolution of daily dry matter intake of the steers of different beef breeds (average of
series 1 and 2). For explanations see Fig. 1.
In series 2, the steers started and finished fattening with a higher weight and had daily gains
higher by 125 g/d on average compared with those found in series 1. The age at slaughter,
however, was similar (Table 2). Differences between the two series in live weight at slaughter
were particularly high for BL, CH, LI and AN with +18, +16, +11 and +10 % in series 2,
respectively, but low in SI and PI. In line with the higher daily gains, feed consumption was
significantly elevated in series 2, but also feed conversion efficiency was improved relative to
series 1, particularly in PI (-19 % feed DM/kg gain), SI (-15 %) and BL (-10 %). Overall, the
steers required 7.4 (6.1-9.6) kg DM, 50 (41-66) MJ NEV and 643 (529-830) g APD per kg
of weight gain.
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33
5.3.2. Carcass quality
Dressing percentage was significantly different between breed groups being particularly high
in LI and also in BL and PI (Table 3). CH were intermediate and AN as well as SI were lower
in dressing percentage by approximately 8 units in relation to LI. This increased the relative
group differences from live weight to slaughter weight, particularly in series 1. Carcass length
increased with increasing slaughter weight but not generally at the same proportion in all
groups. LI and PI were similar in carcass length as SI despite clearly higher slaughter weights
which is reflected in a better conformation of LI and PI carcasses.
Table 3
Carcass quality traits of the steers originating from different beef breeds1
AN SI CH LI BL PI Average SEM
Hot carcass weight (kg)Series 1 261d 347e 375be 39gabc 447a 413ab 374z 15 3
Series 2 282d 333e 426b 424b 514a 40 lb 397y 10 7
Dressing percentage (%)Series 1 54 5e 55 0e 58 0b 62 5a 64 3a 63 r 59 6y 0 59
Series 2 53 9d 53 4d 57 4° 60 8b 62 8a 62 9a 58 5Z 0 39
Carcass length (cm)Series 1 129e 136ab 134abe 134be 140a 137ab 135 16
Series 2 130e 135bc 140ab 136be 145a ns1* 137 15
Carcass gradingConformation score2
Series 1 2 6a 2 3a 12b llb 12b 14b 1 6 0 14
Series 2 2 5a 2 4a 10b 10b 10b 14b 1 5 0 09
Fatness score3
Series 1 4 4a 4 0ab 3 7b 3 9* 3 0e 3 1e 3 7z 0 14
Series 2 4 8a 42ab 4 4ab 4 5ab 3 7b 2 9e 4 1y 0 19
Subcutaneous fat layer (mm)Series 1 11 8a 12 6a 110ab 11 9a ?0bc 5 7e 10 0 109
Series 2 16 2a 12 5ab 13 lab 12 2b 7 3e 3 4d 10 8 0 90
Means within one line without a common superscript differ significantly (P<0 05), series averages within the same variable with different
superscripts are significantly different (P<0 05)Conformation score C=l H = 2, T = 3, A = 4, X = 5 (widely equivalent to EUROP grading with C = E)3Fatness score 1 (low) to 5 (high fatness) equivalent to EUROP grading
Carcass grading led to a differentiation into two distinct groups of breeds. LI, CH, BL and PI
were generally present in the best conformation class while AN and SI were graded
significantly lower. In contrast, fatness score and thickness of the subcutaneous fat layer only
slightly differed among the four breeds reaching the target IMF content although AN showed
a trend to the highest fatness. Generally these breeds were graded above 4. BL and PI, which
did not reach the target IMF, provided significantly leaner carcasses with a far lower
subcutaneous fat thickness, particularly for PI. The within breed correlations between
thickness of the subcutaneous fat layer and IMF content were significant in BL and CH with
0.50 and 0.46 (p < 0.05), respectively, but not significant in LI (0.27), PI (0.18) and SI (0.03)
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34
and even negative in AN (-0.30) due to two AN steers with simultaneously high IMF content
and few subcutaneous fat.
AN carcasses showed the lowest pistola proportion (significant against CH and LI in the first
and against BL and PI in both series) but the differences between breed groups were low
compared with those found in other carcass variables (Table 4). However, AN were also
lowest in percentage of 1st category cuts, significantly so against LI and partly also CH. BL
and PI carcasses were high in percentage of 1st category cuts, striploin proportion of sirloin,
lean to bone ratio and particularly lean to fat ratio. In descending order, these variables were
less favourable in LI, CH, SI and AN. Tenderloin proportion of sirloin was highest in BL
while PI, LI, CH and SI expressed intermediate levels and AN carcasses were lowest in this
respect. Most of these group differences were observed in both series although the level of
differences varied to a certain extent. Average values calculated over all groups were also
similar in both series, except the slightly but significantly lower proportion of 1st category
cuts in series 2 relative to series 1.
Table 4
Properties of the valuable cuts in the carcass of the steers originating from different beef breeds1
AN SI CH LI BL PI Average SEM
Pistola (% of carcass weight)Series 1 413° 41 6bc 43 5a 42 9ab 43 2a 43 3a 42 6 0 34
Series 2 41 3b 42 0ab 42 0ab 42 1ab 42 9a 43 3a 42 3 0 34
1st category cuts2
(% of carcass weight)Series 1 6 8e 7]bc 7 3b 7 9a 8 2a 8 2a 7 6y 011
Series 2 6 6e 7 0be 70bc 7 4b 8 0a 8 1a 7 4z 0 10
Sirlom composition
Striploin3 (% of sirlom)Series 1 36 6b 35 7b 36 6b 40 4a 39 6a 39 4a 38 1 0 60
Series 2 34 2b 35 3b 35 9b 38 6a 40 5a 40 5a 37 5 0 50
Tenderloin4 (% of sirloin)Series 1 12 6e 15 6b 15 5b 16 0b 18 5a 16 5b 15 8 0 40
Series 2 12 8e 14 4b 15 lb 14 6b 17 3a 18 5a 15 5 0 35
Lean / fat ratio
Series 1 4 3e 5 2be 57bc 7 0b 12 0a 10 6a 75 0 62
Series 2 3 5d 5 4e 5 2ed 5 5e 9 0b 13 9a 71 0 43
Lean / bone ratio
Series 1 3 9b 3 9b 4 0b 5 3a 5 0a 4 9a 45 0 13
Series 2 3 8d 3 9d 4 2ed 4?bc 5 6a 5jab 45 0 13
Means within one line without a common superscript differ significantly (P<0 05), series averages within the same variable with different superscripts
are significantly different (P<0 05)2Stnploin, tenderloin and rump'Defined as the part between the 9th rib and the last lumbar vertebra of the M longissimus dorsi
4M psoas major
5.4. Discussion
This study compared steers of different breeds deliberately not slaughtered at the same age or
weight but at a target IMF. This implies that differences in growth rates and carcass size-
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35
related properties between steers of different breed are not reflecting those usually found. The
targeted IMF level was reached on average only in the AN, CH, LI and SI steers, whereas in
BL and PI not a single individual animal was able to reach this level although the fattening
period was largely extended. For this reason, the present results include both a comparison
among those breeds which were potentially able to meet the target level and a comparative
description of properties found in two breeds which were unable to meet this target but were
fattened up to the maximum IMF content possible under the feeding and housing conditions
described.
5.4.1. Growth development ofsteers ofdifferent breedsfattened to a similar IMF content
Steers were already 8 months of age when entering the fattening period because they had been
reared under the relatively extensive conditions of suckler systems. Differences in genetic
growth potential and, possibly, rearing environment led to certain initial weight differences
between breed groups. Using a medium-energy density ration (6.9 MJ NEV/kg DM,
equivalent to 11.2 MJ ME/kg) from then on was found to yield the typical, widely linear
growth development in all breeds with daily gains gradually declining not before several
months of fattening had passed, whereas very intensive feeding gives a clear peak in growth
rate as shown earlier in bulls (Gerhardy et al., 1995). Although the ration was calculated to
provide sufficient energy and protein for average daily gains of 1.2 kg (RAP, 1999), this level
was only reached by the groups fattened for comparably short periods of time (AN, SI and
CH, particularly in series 2). It has to be kept in mind that this assumed level was derived
from data on dairy crossbred steers fattened up to 550 kg. A prolonged period of fattening is
very likely to decrease overall daily gains and, particularly, feed conversion efficiency due to
the increasing proportion of nutrients and energy required to cover demands for maintenance
relative to growth and fat retention (Crouse et al., 1985a).
Accordingly, very low average daily gains and a particularly poor feed conversion efficiency
were found in PI compared with all other breeds. The lower feed conversion efficiency
observed in PI of series 1 is partially due to the age difference at the start of the trial as
animals were older by 41 d in series 1. The BL being slaughtered approximately at the same
age nevertheless performed significantly better than PI although also ranked behind the other
breeds in most fattening performance traits particularly in series 1. This additional difference
to BL could have been at least partly due to the low feed intake capacity of the PI steers which
was obvious throughout the whole fattening period (Figure 2). These findings are in
agreement with the study of Tartari et al. (1988), who compared PI, CH and LI bulls reared
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36
for 251 days under identical conditions kept individually in a tied stall. Accordingly, PI bulls
had the lowest stomach and gut proportions of empty body weight. This anatomical
disadvantage of PI is enlarged by feeding diets of low energy density (Geay and Micol, 1988;
Tartari et al., 1988). Another component particularly affecting the performance of PI and BL
steers were the housing conditions in series 1, which were unsuitable for the long duration of
fattening and the very high live weights reached. Accordingly, in series 1 eight out of eleven
BL steers and five out of eleven PI steers expressed joint and leg problems during the last
fattening weeks, due to restrictions in movement in the tie-stall barn. This explains the
particularly high difference between series in average daily gains of BL steers whereas series
differences were lower in all other groups, especially in AN with the shortest fattening period.
Furthermore, this illustrates that an unfavourable housing system may affect the expression of
breed differences in performance of steers of suckler origin. Other factors such as diet and
season within year did not differ between series and so presumably were without major effect
in the present study. The importance of individual vs group housing of cattle for the result of a
breed comparison has also been reported earlier (Cole et al., 1964; Mir et al., 1999).
Among the breeds reaching the target IMF content, LI required the most extended fattening
period and had lower growth rates than SI and particularly AN and CH steers. LI are known
for their high feed conversion efficiency compared to other breeds at the same slaughter age
(Geay, 1982; Geay and Micol, 1988), but this was obviously more than compensated by the
adverse effect of prolonged fattening in the present study. This is confirmed by the longest
fattening period and the lowest feed conversion efficiency found by Smith et al. (1976) in LI
crosses when comparing carcasses of purebred AN to AN crosses with SI, CH and LI at the
same IMF content of 5%. LI have a lower digestive tract weight percentage of empty body
weight than CH though still far higher than PI (Tartari et al., 1988). Compared to CH,
voluntary intake of bulky diets in LI therefore seems to be more restricted by the volume of
the abdominal cavity, especially that of the rumen, than by energy requirements (Geay and
Micol, 1988) also suggesting the use of diet of a higher energy content for LI. In line with
this, Geay and Robelin (1979) demonstrated that, for a given body weight, a certain
combination of energy intake and growth rate is ideal in terms of feed conversion efficiency.
Typically, in an advanced growth stage late-maturing cattle show higher weight gains at the
same age than early-maturing animals, provided feed quantity and quality are not limiting
factors (Lehmann, 1979; Jenkins and Ferrel, 1984; Shorthose and Harris, 1991) as possibly
was the case in our study.
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37
5.4.2. Carcass characteristics ofsteers ofdifferent breedsfattened to a similar IMF content
Large-framed late-maturing cattle are typically physiologically younger at the same
chronological age than small-framed early-maturing cattle and have a higher priority for
protein accretion, especially at limited growth rates (Byers et al., 1988) as was the case in our
study in contrast to typical feedlot conditions (Micol et al., 1993). These prerequisites made
extended fattening periods inevitable to reach or try to approach the target level in IMF. As a
consequence carcasses were much heavier than in the early-maturing AN steers. This
provided best graded carcasses in conformation scores and high dressing percentages in the
late-maturing breeds. Robelin (1986) and Szücs et al. (2001a) showed that the dressing
percentage increases with age and/or weight. Thus, the great differences in slaughter ages
between groups enlarged the differences in dressing percentage. The ratio of leg length to
carcass weight is an indicator of compactness (Keane and Allen, 1998) and well reflected the
better conformation of the later maturing cattle, i.e. BL, PI and LI (data not shown). Among
the four breeds reaching the target IMF content, LI steers showed the best carcass value in
terms of the lean tissue-related properties. The superiority of LI compared to CH, SI and AN
is in agreement with other studies comparing LI and SI (Byers et al., 1988), LI and CH (Geay
and Malterre, 1973; Geay, 1982) as well as LI, SI and AN (Geay and Malterre, 1973; Geay,
1982; Geay and Micol, 1988). Also dressing percentage of LI steers was clearly higher than
that of AN, SI and CH, an effect which was even obvious in crossbred bulls slaughtered at
similar age or weight when comparing LI and SI (with Red Holstein blood) sired bulls
(Gerhardy, 1994).
However, one unfavourable consequence of slaughter according to a high target IMF was that
the 1st category cuts were too big in size for the common retail market, particularly with the
large-framed breeds. Furthermore, the carcasses were excessively fat. It is well-known that
deposition of fat in the body cavity, between the muscles, and in the subcutaneous site occurs
earlier than the deposition of fat within muscle to be noted as marbling (Smith, 1988). This
explains why carcasses in terms of European continental demand were extraordinarily fat
even before a sufficiently high IMF content was reached. Robelin (1978) found no significant
differences in IMF content among Holstein, Salers, Charolais and Limousins bulls, i.e. four
breeds differing in maturity, when their fatness scores were identical, which supports the
assumption that fat deposition in different body sites is related. However, in our study,
correlations between the thickness of the subcutaneous fat layer and the intramuscular fat
were rather low, if significant at all, or even negative (AN). This can be explained by the
deliberately reduced variation in IMF content by applying a target value but possibly also
from the difference in fat retention during growth phases between adipose tissues and within
Page 43
38
muscle. It should be noted that the genetic correlation reported by the American Angus
Association between marbling score and external backfat thickness at the 12th rib is nearly
zero (AAA, 2001). Similar to the results in the other breeds, Campion and Crouse (1975)
found correlations between the same variables in the range of 0.41 to 0.46 depending on sire
and dam breed, whereas the genetic correlation reported by Geay and Renand (1994) was
even higher with 0.64. Regarding the very similar fatness of the large framed breeds which
reached the same IMF content under identical feeding conditions in our study, it may be
assumed that the ratios of undesired subcutaneous fat and intermuscular fat to IMF is more
variable within than between similarly maturing breeds. The AN, by contrast, already
developed significantly more depot fat in relation to IMF and were not able to develop a
highly favourable conformation or muscling within the period required to reach 3.5 % IMF. In
the later maturing breeds, however, the target IMF content together with a good conformation
was only achieved at a rather late growth stage resulting in very heavy carcasses. Overall, the
very good conformation scores can be assumed to be not sufficient to economically
compensate the unfavourably big-sized cuts and the excessive fatness.
5.4.3. Dietary energy concentration requiredfor steers ofdifferent breedsfattened to a
similar IMF content
A limitation in dietary energy density could have been beneficial in the case of the early-
maturing AN steers in terms of feed conversion efficiency while the contrary is true for the
two late-maturing breeds, PI and BL, but also for LI. When using purebred AN instead of
75 % AN steers, as in the present study, a limitation in dietary energy concentration and/or
restricted feeding would have been even more advisable. Also from the carcass quality aspect
the present study provides indirect evidence regarding the search for the ideal energy density
of the diet. Although energy content of the diet was high enough to reach 3.5 % IMF at least
in four breeds, the fattening period presumably could have been reduced by a more
concentrated ration. This would be particularly advantageous for those breeds whose feed
intake may be a limiting factor, i.e. LI and also BL and of course PI, but is highly
recommendable in all breeds, except AN, in order to obtain smaller-sized valuable cuts. In
contrast, for the AN a slightly extended fattening period would also be tolerable from the
viewpoint of slaughter weight which would increase due to the longer time span required to
reach 3.5 % IMF. The final extent of fat deposition in AN steers, however, would probably
not be reduced under these conditions. From the present results it remains open whether or not
Page 44
39
the genetic limitations in BL and PI would still have prevented to reach the level of 3.5 %
IMF when offering a ration of higher energy density.
5.5. Conclusions
Out of the six breeds investigated only AN, SI, CH and LI, turned out to be able to reach the
target IMF content of 3.5 % in a fattening system based on a forage-based diet of medium-
level energy concentration following an 8 months rearing period as suckler beef. BL and PI
did not retain the desired amount of IMF, obviously due to the limited feed intake and the
genetic predisposition for a very high protein accretion. All breeds except AN, however, had
to be fattened for unusually long periods and provided carcasses too heavy to be acceptable
for the common beef market as well as for existing label programs. Although the carcasses of
the AN were of common size, the ratio of carcass fatness to IMF was the most undesirable of
all breeds compared. Generally, the carcasses of all those breeds which reached the desired
IMF content were unacceptably fat. Thus, the present results revealed the difficulty to find an
acceptable compromise between a desired extent of marbling as well as favourable carcass
conformation on one hand and carcass size as well as fat cover which meet market demands
on the other hand.
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40
6. Characteristics of steers of six beef breeds fattened from eight months of
age and slaughtered at a target level of intramuscular fat.
II. Meat quality
Based on:
A. Chambaz, M. R. L. Scheeder, M. Kreuzer and P.-A. Dufey, 2001,
Arch. Anim. Breed. 44:473-488
Abstract
Meat quality of Angus (AN), Simmental (SI), Charolais (CH), Limousin (LI), Blonde
d'Aquitaine (BL), and Piedmontese (PI) steers (n=22 per breed group) was measured in the
M. longissimus dorsi (M.l.d.) and the M. biceps femoris, regio glutea (M.b.f.). Animals were
fattened in two subsequent series on a forage-based diet until a target level of 3.5%
intramuscular fat (IMF) was reached according to real-time ultrasound assessments in the live
animals or until 15 months of fattening had passed. Series 1 was performed in a tie-stall barn
while a loose-housing system with straw bedding was applied in series 2. The actually
measured IMF contents in M.l.d. were 3.35, 3.47, 3.49, 3.48, 2.34 and 2.40 % for AN, SI, CH,
LI, BL and PI, respectively. Breed group differences in IMF content were mostly
accompanied by a contrary variation either in muscle water or protein content. Muscle
cholesterol levels were similar for all breeds amounting to 47 and 51 mg/100 g on average in
M.l.d. and M.b.f, respectively. Early and late postmortem muscle pH was relatively similar
among breeds, but water-holding capacity, measured as losses due to drip, ageing, thawing
and cooking, was unfavourably high in AN (drip loss excepted) in both muscles. Cooking loss
tended to be lowest in PI, drip loss in SI. The AN showed the palest meat. In line with
lightness, heme iron contents were clearly lowest in both muscles in the AN steers. There was
no relationship found between IMF and shear force among breed groups. No significant
differences between breed groups occurred in M.l.d. collagen solubility and shear force. Apart
from breed differences, there were several differences noted between fattening series, namely
clearly better water-holding capacity and lower shear force of the meat from series 2 (group
housing) than from series 1 (tied system). The results indicate that in steers of similar IMF
content and raised under the same feeding and management conditions, differences in most
M.l.d. and M.b.f. quality traits were apparent, with the exception of shear force and M.l.d.
collagen solubility.
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41
6.1. Introduction
Interest in label beef production is consistently increasing in Europe (Neumann and Martin,
1991; Gerhardy, 1994; Roche et al., 2000) in a situation of declining consumption of red meat
and a general decrease in acceptance of conventionally produced and marketed beef. Labels
intend to provide a quality which is or can be especially oriented towards consumer demands
including controlled beef quality and a greater consideration of the welfare of the animals
(Boissy et al., 2000). Although pricing systems still heavily rely on carcass rather than on
actual meat quality traits, labels are expected to guarantee a certain level and, particularly,
homogeneity of beef quality (Branscheid and Claus, 1989) in order to fulfil the consumer's
implicit expectations (Temisan, 1990). Current Swiss beef labels encourage both the use of
purebred beef breed cattle in order to profit from a higher carcass quality and, as category,
steers to improve meat quality. This should provide products which can be distinguished from
conventional continental European beef which is based on calves largely representing a by¬
product of dairy husbandry. Visual perception of the products is often associated with beef
quality and can affect purchase decision of the consumers. One main component of visual
quality, together with colour, is marbling which expresses proportion and distribution of
intramuscular fat (IMF) in the M. longissimus dorsi (M.l.d.). It is still unclear in how far
known breed differences in meat quality traits such as water-holding capacity and tenderness
(Dufey, 1987, 1988a; Tatum et al., 1990; Wheeler et al., 1996) can be recovered under the
condition of a similar extent of marbling. Furthermore, the repeatedly postulated low
cholesterol content of Piedmontese beef (Montana Range, 2001) might get lost if really
existing when the cattle is fed to high IMF contents. The objective of the present investigation
was to compare the meat quality of six beef breeds fattened under the same conditions. The
animals of this study were slaughtered at a target level of 3.5 % IMF. This level is higher than
usually found in Switzerland (Dufey and Chambaz, 1999b). As reported in a first
communication (Chambaz et al., 2001a), clear differences in growth and carcass quality
developed between the breeds. Two breeds were unable to reach the target value in IMF, but
were kept in the comparison in order to give information of their meat characteristics under
the conditions applied.
6.2. Materials and methods
A total of 132 steers of six beef breeds, namely Angus (AN), Simmental (SI), Charolais (CH),
Limousin (LI), Blonde d'Aquitaine (BL), and Piedmontese (PI), selected at 8 months of age
from suckler beef rearing systems, were fattened in two subsequent series (11
animals/breed/series). The first series was carried out in a tie-stall barn and series 2 in a loose
Page 47
42
housing system with straw bedding. The animals had ad libitum access to a diet consisting of
maize silage, 520 g, grass silage, 260 g, and concentrate, 220 g per kg of dry matter. Steers
either were slaughtered when the ultrasonically assessed IMF reached 3.5 % in the Musculus
longissimus dorsi (M.l.d.) between the 12th and 13th rib or after a maximum of 15 months of
fattening (Chambaz et al., 2001a). This approach resulted in large differences in slaughter age.
Members of the AN, SI, CH, LI, PI and BL groups finished the experiment at an average age
of 381, 509, 529, 610, 683 and 690 days, respectively. The coefficient of variation in
slaughter age was lowest for AN with 6.6 % and highest for CH with 19.6 %. Further details
on the experimental procedure are given in (Chambaz et al., 2001a).
The animals were slaughtered in a commercial slaughter plant after approximately 1 h of
transport by bleeding after captive-bolt stunning. Measurements of pH were performed 1 h
and 48 h post mortem (p.m.) in the M.l.d. at the 10th rib and in the Musculus biceps femoris,
regio glutea (M.b.f.) with a portable pH meter (WTW 197S, Wissenschaftlich-Technische
Werkstätten GmbH, D-Weilheim) equipped with a Sensor EB4 probe (Wintion, CH-
Gerzensee). Samples of the M.l.d. and M.b.f. were taken from the left carcass side 48 h and
14 d p.m. Meat colour was determined with a Chroma-Meter (CR-300, Minolta, CH-
Dietikon-Ziirich) applying the light source D65, which yielded data for L* (lightness; 0-100 =
dark-light), a* (red-green index) and b* (yellow-blue index) when directly put onto fresh cuts
of M.l.d. and M.b.f. 48 h p.m. These samples were sealed under vacuum as slices of 2 cm
thickness. Separate samples of approximately 300 g were frozen at -30 °C until analysed for
chemical composition, heme iron and cholesterol content. Two slices, also vacuum-packed,
were stored for 12 days at +2 °C for measurements in the aged meat. Weight loss during this
period was determined as ageing loss. Afterwards the samples were stored frozen (-30 °C)
until being thawed at 2-A °C over 24 h and then broiled for 5 min on a grill (type BP-50,
Beergrill AG, CH-Zürich) at 195 ± 5 °C by direct radiant heat with the samples repeatedly
turned during heating. The apparatus was connected to an external electronical
thermoregulator (Ematherm A, Trafag AG, CH-Männedorf) and a thermoprobe (Pt 100,
Moser AG, CH-Hombrechtikon) to control temperature. According to preliminary
assessments, this procedure resulted in a meat core temperature of approximately 68 °C.
Within these procedures, losses due to thawing and cooking (directly after cooking) were
recorded. In independent samples, drip losses were quantified as described by Honikel (1998)
storing fresh 2 cm thick slices of each muscle for 48 h at 2 °C. Cooked samples cooled to
ambient temperature were sheared by the original Warner-Bratzler device (model 3000, G-R
Electric MFG Co, Manhattan, Kansas, USA). Ten cores per sample of 1.27 cm diameter were
Page 48
43
obtained parallel to fibre orientation from the cooked slices according to Kastner and
Henrickson (1969) with an electrical drill at a speed providing uniform samples.
In the raw, homogenised muscle samples, heme iron contents were determined as pigments
according to Barton (1967) by extracting pigments with acetone and spectral photometric
determination at a wavelength of 640 nm on a Lambda 2 photometer (Perkin-Elmer, D-
Überlingen). Heme iron was calculated assuming the conventionally applied value of 9.06 %
heme iron in pigment. Cholesterol was enzymatically determined by a colorimetric method
(Boehringer Mannheim, 1994) with the same spectrophotometer as described for heme iron
analysis, but at a wavelength of 405 nm. As described in the guidelines (Boehringer
Mannheim, 1994), homogenized muscle samples were hot saponified during 30 min in
advance of the cholesterol determination. Lyophilized samples of M.l.d. and M.b.f. were
analysed for their contents of dry matter (3 h, 105 °C) as well as ash (total ash; 4 h, 550 °C;
Naumann and Bassler, 1997), fat (petrol ether extract; SLB, 1969) and protein (crude protein;
KJELDAHL method; AOAC, 1995). Furthermore the lyophilized samples were analyzed for
collagen content (hydroxyproline x 8) as described by Arneth and Hamm (1971) adapted to
the Technicon (Plainfield, New Jersey, USA) analyse chain. Collagen hydrothermal solubility
at 90 °C was determined as outlined by Kopp et al. (1977). All chemical analyses were carried
out in two replicates.
Data were statistically analysed with the NCSS program (version 1997, Hintze, Kaysville,
Utah, USA). In a first evaluation, data of both series were included in order to be able to
compare overall series differences, using a two-way ANOVA with breed and series as fixed
effects and breed x series interactions. Because interactions between breed and series
frequently occurred in meat quality traits, data were finally analysed separately for each series
by one-way ANOVA with breed as fixed effect in the model. The Tukey test was used for
multiple comparison among means regarding P < 0.05 as significant.
6.3. Results
On average of both experimental series the actually measured IMF contents in M.l.d. (means
± SD) were 3.35 ± 1.12, 3.47 ± 0.93, 3.49 ± 1.11, 3.48 ± 1.08, 2.34 ± 0.64 and 2.40 ± 0.63 %
for AN, SI, CH, LI, BL and PI, respectively (Table 1). The corresponding levels found in
M.b.f. were 3.35 ± 0.98, 3.92 ± 0.94, 3.02 ± 1.14, 2.69 ± 0.93, 2.01 ± 0.75 and 1.71 ± 0.65 %.
Therefore, at an overall slightly lower average IMF content of M.b.f. of 2.78 % compared to
3.09 % in M.l.d., the breed differences were roughly also reflected in M.b.f, particularly with
again the lowest contents being found in BL and PI (partially significant against other breeds).
Part of the within-breed variation in IMF content resulted from significant series differences
Page 49
44
as the average IMF content achieved was lower in series 1 than in series 2. The M.l.d and
M.b.f. of BL and PI had the highest protein content of all groups on average of both series,
particularly when compared with AN, SI and CH, whereas LI held an intermediate position.
Breed group differences in IMF content were mostly associated by contrary variations in
muscle water and protein content. In line with protein and dry matter content there was a
small but partially significant variation in ash content of the two muscles. In contrast, no
significant differences were observed between breed groups in cholesterol content of both
muscles ranging at a similar level of around 47 and 51 mg/100 g in M.l.d. and M.b.f.,
respectively.
Table 1
Chemical composition of the M 1 d and the M b f (wet weight) of the steers originating from different beef
breeds (n=l 1 per series)'
AN SI CH LI BL PI Average SEM
M longissimus dorsi
Water (g/100 g)Series 1 74 74ab
Series 2 74 30a
Ash (g/100 g)Series 1 0 99
Series 2 0 99d
Protein (g/100 g)Series 1 2129
Series 2 2106d
Fat(g/100g)Series 1 2 99ab
Series 2 3 70a
Cholesterol (mg/100 g)Series 1 47 5
Series 2 47 1
M bicepsfemonsWater (g/100 g)
Series 1 76 29a
Series 2 74 78
Ash (g/100 g)Series 1 0 96d
Series 2 0 98e
Protein (g/100 g)Series 1 19 78e
Series 2 19 58e
Fat (g/100 g)Series 1 2 80b
Series 2 3 89a
Cholesterol (mg/100 g)Series 1 52 0
Series 2 52 0
AN = Angus, SI = Simmental, CH = Charolais, LI = Limousin, BL - Blonde d'Aquitaine, PI = Piedmontese
'Means within one line without a common superscript differ significantly (P<0 05), series averages within the same vanable with different
superscripts are significantly different (P<0 05)
The differences in early postmortem muscle pH were small and mostly not significant among
groups for both muscles (Table 2). Moreover none of the animals presented a pHi-value
below 6.2, indicating that no PSE (pale, soft, exsudative) meat was found. Ultimate muscle
74 03b
73 64at
101
103ec
2147
21 82bt
3 50a
3 43*
47 5
46 4
74 40e
75 02
0 97e<
1 llal
19 80e
19 57e
4 00a
3 83a
51 9
51 8
74 55al
73 69al
102
106"
2126
21 43el
3 30al
3 69a
48 4
45 8
75 83al
75 33
0 99e<
1 04"
19 88e
19 55e
2 57tx
3 46a
50 2
50 8
74 41at
72 89b
101
106ot
2168
22 24at
2 88at
4 07a
48 8
45 6
7531atx
74 61
101"0
1 18a
20 66b
20 65b
2 28be
3 10ab
51 1
50 4
75 29a
73 86*
0 98
1 10b
2155
22 92a
2 25b
2 44b
48 7
46 4
75 66al
74 98
104al
1 06*
21 18a'
21 16al
173°
2 29"
50 6
50 2
75 17a
74 14a
0 97
1 18a
2149
22 57al
2 49at
2 30b
48 0
47 8
74 98"'
75 21
106a
109al
2160a
2170a
188*
154e
49 7
50 5
74 70y
73 75z
100z
107y
21 46z
22 01y
2 90z
3 27y
48 ly
46 5Z
75 41y
74 99z
101z
1 08y
20 49
20 37
2 54z
3 02y
50 9
510
0 273
0 294
0 015
0 017
0218
0219
0 268
0 280
0 98
0 68
0 239
0 245
0 010
0 032
0 163
0 154
0 254
0 262
146
081
Page 50
45
pH, measured at 48 h p.m., was in the desired range with an average of 5.54 (max: 5.82) in the
M.l.d. and of 5.50 (max: 5.79) in the M.b.f., when pooled over both series (slightly but
significantly higher in series 2). None of the animals expressed an ultimate muscle pH above
6.0, regarded as the threshold level for DFD (dark, firm, dry) meat or DCB (dark cutting
beef). In series 1, LI muscles had a significantly lower pH4g in the M.l.d. compared to PI, with
the other groups remaining intermediate.
Table 2
Development ofpH ofthe M 1 d and the M b f of the steers originating from different beefbreeds (n=l 1 per
senes)1
AN SI CH LI BL PI Average SEM
M longissimus dorsi
pHihSeries 1 6 54 6 57 6 54 6 48 6 67 6 60 6 57 0 054
Series 2 6 61ab 6 62ab 6 65a 6 63ab 6 63ab 651b 661 0 034
pH48hSeries 1 555ab 5 56ab 5 49ab 5 45b 5 53ab 5 58a 5 53z 0 027
Series 2 5 55ab 5 56ab 5 52b 5 56ab 5 58a 5 59a 5 56y 0 014
M bicepsfemorispHlh
Series 1 6 49 6 53 6 56 651 6 58 6 57 6 55z 0 078
Series 2 6 64 6 66 6 66 6 67 6 60 6 64 6 64y 0 039
pH48hSeries 1 5 52 5 49 5 46 5 43 5 52 5 47 5 48z 0 022
Series 2 5 49b 5 52ab 5 51ab 5 52ab 5 54a 5 55a 5 52y 0 012
Means withm one line without a common superscript differ significantly (P<0 05), series averages within the same vanable with different
superscripts are significantly different (P<0 05)
Table 3 describes traits of water-holding capacity of the meat. The LI showed the highest
M.l.d. drip loss on average of both series. In M.b.f. the pattern was not the same, with the BL
having the highest and AN and SI showing the lowest drip loss. Drip loss was higher in both
muscles in senes 2 especially in BL, whereas AN meat showed an inverse pattern. PI had the
lowest ageing losses in both series for M.l.d. and M.b.f, whereas M.l.d. of BL and SI (only
series 2) and M.b.f. of AN showed significantly higher ageing losses. On average of both
series, the AN expressed the highest thawing and cooking losses for both muscles whereas the
losses were lowest in BL and PI. This illustrates that, within the different losses measured for
the same muscle, only thawing and cooking losses, making up the major proportion of total
losses, expressed a similar pattern over breeds. Accordingly, the overall water-holding
capacity was low in AN and high in PI. Muscles of animals in series 2 expressed a lower
cooking loss than those in series 1. Water-holding capacity of M.b.f. was on average better
than that of M.l.d. in all types of losses measured.
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46
Table 3
Water holding capacity of the M 1 d and the M b f of the steers originating from different beef breeds (n=l 1 per
senes)'
AN SI CH LI BL PI Average SEM
M longissimus dorsi
Drip loss (%)Series 1 3 09b 2 57b 3 54ab 4 30a 2 92b 2 54b 3 16 0 271
Series 2 1 76d 3 23"° 372abc 4 26ab 4 29a 2 89c 3 36 0 253
Ageing loss (%)Senes 1 3 94 3 66 3 86 3 47 4 23 3 44 3 77y 0 214
Series 2 3 40ab 3 78a 3 44ab 3 08ab 3 60a 2 72b 3 33z 0 180
Thawing loss (%)Series 1 7 61a 6 66ab 5 97b 5 77b 5 36b 5 18b 6 09z 0 379
Series 2 8 79a 8 14ab 752abc ôsi* 6 30e 6 72"= 7 33y 0 429
Cooking loss (%)Series 1 22 18a 18 55ab 17 00b 15 37b 15 12b 15 58b 17 3(F 0 903
Series 2 17 30a 14 82ab 14 76ab 12 99b 11 70b 12 03b 13 93z 0 824
M bicepsfemorisDrip loss (%)
Series 1 224ab 144b 2 56a 2 62a 2 77a 2 72a 2 39 0 201
Series 2 1 83e 193c 2 75b 2 91ab 3 45a 2 71b 2 59 0 156
Ageing loss (%)Series 1 3 17a 2 58ab 3 08ab 2 63ab 2 96ab 2 39b 2 80 0 180
Series 2 3 16a 2 70ab 2 61ab 2 92ab 2 85ab 2 54b 2 80 0 138
Thawing loss (%)Series 1 7 05a 5 65ab 6 33ab 5 31ab 5]5ab 4 43b 5 65 0 464
Series 2 7 71a 5 81b 6 51ab 5 29b 5 28b 5 14b 5 96 0 351
Cooking loss (%)Series 1 18 67a 13 32b 15 18ab 12 53b 12 37b 1155b 13 94y 0 896
Series 2 13 58a 11 22ab 13 32ab 12 70ab 10 68b 10 72ab 12 04z 0 692
'Means within one line without a common superscript differ significantly (P<0 05), senes averages within the same variable with different
superscripts are significantly different (P<0 05)
Meat-colour related traits are given in Table 4. The M.l.d. and M.b.f. of the AN and CH steers
were lighter than those of the other groups, and PI steers had the darkest M.l.d. and one of the
darkest M.b.f. In both muscles, BL and PI showed a trend to less reddish and yellowish meat
than that of the other breed groups. As expected, during ageing for 12 days colour turned
towards higher lightness and redness in both muscles (data of non-aged meat not shown). The
variation in M.l.d. lightness during ageing was significantly higher in AN than in SI with
intermediate values in the other breed groups (data not shown). Heme iron content was lowest
for AN and CH steers in both muscles and was highest for PI and SI in M.l.d. as well as for SI
and LI in M.b.f. The M.b.f. heme iron content was higher by 44 % compared with that of the
M.l.d. There was a significant negative correlation between heme iron content and L* in both
muscles (r = -0.77 in M.l.d. and r = - 0.65 in M.b.f., P < 0.001).
Page 52
47
Table 4
Colour after 14 d of ageing and heme iron content of the M 1 d and the M b f of the steers onginating from
different beef breeds (n=l 1 per series)'
AN SI CH LI BL PI Average SEM
M longissimus dorsi
L*
Series 1 39 8a
Series 2 40 2a
Series 1 14 1
Series 2 14 3ab
b*
Series 1 4 0ab
Series 2 4 5a
Heme iron
(mg/100 g wet weight)Series 1 1 1
Series 2 12
M bicepsfemonsL*
Series 1 38 3
Series 2 38 6
Series 1 16 6
Series 2 17 0
b*
Series 1 47
Series 2 61
Heme iron
(mg/100 g wet weight)Series 1 1 65b
Series 2 1 87b
'Means within one line without a common superscript differ significantly (P<0 05), series averages within the same variable with different
superscripts are significantly different (P<0 05)
Shear forces were not significantly different in M.l.d. among groups, but AN M.l.d. tended to
have low values (Table 5). There was a significant decrease in shear values in the second
senes and especially in SI and PI. Unlike as in the M.l.d., there were significant differences
among groups in shear force of M.b.f., but the trend remained similar. As expected, shear
force and collagen contents were higher in the M.b.f. compared to M.l.d. although at similar
collagen solubility. Muscle collagen content was higher in AN, SI and CH than in LI (only
M.l.d.), BL and PI. There were no significant differences in M.l.d. collagen solubility among
breed groups, but AN tended to have the highest solubility in both series, following the same
trend as in shear force. Collagen solubility in M.l.d. increased in series 2 (+22 %) especially
in the PI, LI and SI.
36 T
2,1 T1
40 r
39 0al38 3al
37 4b36 2"
37 7al
34 5e
36 3e
37 6
38 0
0 73
0 60
14 3
14 7a
13 9
14 5a
14 8
14 6a
13 8
13 3b134
13 7al14 1
14 2
0 39
0 25
4 1al
4 3al4 7al
4 5a
5 2a
4 2al3 8al
3 6b3 5°
2 9e
42
40
0 42
021
150a
1 52ab
1 13"
131a
128ab
138ab
146a
136ab
159a
1 61a
135
140
0 075
0 082
36 4"
36 6b38 9a
36 8al374ab
36 2b36 9ab
37 lab36 8ab
36 7ab37 5
37 0
0 58
0 48
17 0
17 3a
169
17 3a
16 7
171ai16 3
16 7al16 3
16 3"16 6Z
17 0y
031
0 22
54 62
5 8al57
5 3al50
5 0al50
4 8"53
55
0 42
0 28
2 22a
217ab
175"
2 12al
2 06al
2 27a
194al
2 03al
199al
2 or1
194z
2 08y
0 101
0 080
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48
Table 5
Collagen properties and shear force of the M 1 d and the M b f of the steers originating from different beef
breeds (n=l 1 per series)'
AN SI CH LI BL PI Average SEM
M longissimus dorsi
Collagen (mg/100 g wet weight)Senes 1 537a 536a 515ab 470ab 481ab 438b 496 197
Senes 2 549a 541a 560a 496ab 426e 476bc 508 154
Collagen solubility (%)Senes 1 30 5 28 8 28 5 23 1 28 4 27 0 21T 1 89
Senes 2 35 6 34 8 31 9 33 0 30 6 36 1 33 7y 136
Warner-Bratzler shear force (N)Senes 1 30 8 34 8 32 4 31 2 33 1 37 3 33 y 1 81
Senes 2 28 5 27 9 30 5 28 8 27 3 26 1 28 2Z 1 28
M bicepsfemorisCollagen (mg/100 g wet weight)
Senes 1 594abc 695a 615ab 539^ sii* 488e 574z 26 9
Series 2 677a 604ab 680a 638a 495e 529be 604y 22 4
Collagen solubility (%)Series 1 35 0a 26 5b 32 8ab 31 lab 28 lb 29 0ab 30 4 1 54
Senes 2 33 8a 33 2a 33 4a 31 4ab 26 5be 25 3° 30 6 143
Warner-Bratzler shear force (N)Senes 1 33 2b 46 0a 38 0ab 40 8ab 37 6ab 34 4ab 38 4y 2 88
Senes 2 28 8be 32 1abc 38 0a 34 4ab 35 0ab 25 8C 32 4Z 1 91
Means within one line without a common superscript differ significantly (P<0 05), series averages within the same variable with different
superscripts are significantly different (P<0 05)
6.4. Discussion
6.4.1. Realized contents ofintramuscularfat in steersfed on aforage-based diet
Steers of four out of the six beef breeds evaluated were able to reach on average a target level
of 3.5 % IMF in the M.l.d. which was desired in order to ensure the favourable impression of
marbling (Chambaz et al., 2001a). However, no single PI and BL steer was able to reach this
target level although age was almost twice as high as in AN when fattening was finally
terminated (Chambaz et al., 2001a). This illustrates that some cattle breeds obviously do not
have the inherent ability to deposit increasing amounts of IMF regardless of the length of the
fattening period, although carcass fatness is still increasing in this period (Smith, 1988). Most
other breeds show a widely linear increase not only in adipose tissue but also in IMF up to
high slaughter ages as described for instance by Szücs et al. (2001a; 2001b) for German SI
bulls. The high variability between animals of the same breed group in IMF content probably
was mainly due to the restricted accuracy of the ultrasound method of IMF determination in
live animals. However previous attempts analysing biopsies, as another potential way of
estimation, proved to be far less precise because of the inhomogeneity of the distribution of
fat in the muscle.
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6.4.2. Differences in meat quality ofsteers ofdifferent breedfattened to a target IMF level
As expected there was an antiparallel relationship of the breed group differences in IMF and
other compositional traits. The differences in chemical composition of muscle between BL
and PI on one hand with low IMF and AN, SI, CH and LI on the other hand are in accordance
with the results of Browning et al. (1990) who reported that muscles of leaner carcasses were
higher in water and protein content. Nevertheless, the close inverse relationship between
moisture and fat content described by these authors and others (Van Koevering et al., 1995)
was less clear in the present study, especially in the M.b.f. where variations in IMF content
were more associated with variations in protein content. This is probably due to the
deliberately low differences in IMF. Accordingly, breed group differences in muscle protein
and fat content were of very low importance in a dietetic sense. This is also true for muscle
cholesterol content which was similar in all groups. Even muscles differed only slightly but
equally by about 2-3 mg/100 g muscle tissue. This is in accordance with the results found by
Eichorn et al. (1986), Baker and Lunt (1990) as well as Gariepy et al. (1999). Rhee et al.
(1982) observed only a significant difference when comparing seven marbling-score
categories when muscles "practically devoid" of marbling were compared with higher
marbling scores which had higher cholesterol levels. However this contradicts findings of
Slover et al. (1987) and Van Koevering et al. (1995) reporting a positive relationship between
fat and cholesterol content of raw beef. Browning et al. (1990) also noted a trend towards
higher cholesterol levels from lean to fatter carcasses, but the difference of only 1.8 mg
cholesterol/100g raw meat found is of little practical importance. Probably based on its low
IMF content, there is a frequently cited opinion that meat of PI cattle has a considerably lower
cholesterol content than meat of other breeds (Montana Range, 2001). However, neither the
present data, where PI steers had been fattened to untypically high IMF contents for this
breed, nor other scientific studies (Baker and Lunt, 1990; Gariepy et al., 1999; Rule et al.,
1999) found any clear differences in muscle cholesterol between PI or PI crosses and other
breeds.
Although PSE meat is not a major problem in beef, Dufey (1987; 1988b; 1989) occasionally
recorded too low pHi-values in meat of bulls fattened in a tied stall, whereas no PSE meat
was found here even in series 1 where the animals were kept under the same housing
conditions as in the studies cited. The absence of DCB in this study is not surprising. DCB is
a result of a reduced glycogen content in the muscle prior to slaughter and is often associated
with stress caused for instance by mixing cattle or shipping fatigue. The duration of transport
to the slaughter plant did not exceed 1 hour. Moreover the use of steers instead of bulls
reduced the probability of DCB as steers have lower stress susceptibility (Warriss, 1990). In
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normal beef, p.m. glycolysis reduces pH to 5.8 or lower within 48 h (Kreikemeier et al., 1998;
Immonen and Puolanne, 2000). In an ultimate pH range of 5.8-6.0, defined as borderline
DCB, meat already tends to have an abnormal colour and an increased risk of spoilage,
particularly when vacuum-packed (Warriss, 1990), although quality is still intermediate
between true DCB and normal beef (Voisinet et al., 1997). This type of borderline dark
cutters was found here in two out of 132 carcasses. Despite the low variation in pH, breed
groups differed to a certain degree in water-holding capacity, meat colour and tenderness
related items. The range in drip loss found in the present study was mostly favourable as a
level of up to 4.5 % is still considered as acceptable (Ender and Augustini, 1998) whereas
higher rates are undesired in retail packaging and so impair the appearance of the product at
sale. Muscle tissue of M.l.d. but not of M.b.f. from LI steers showed drip losses on average
just at the acceptable limit, and several members of this group had too high drip losses from
M.l.d. according to the threshold level given above. Cooking losses were highest in both
muscles in AN steers. Accordingly, differences between breeds were not related between drip
loss and cooking loss, except in PL This can be explained by the different compartments of
bound water being stressed by the procedures. Drip losses are passive losses which strongly
depend on loosely-bound water only affected by gravity, whereas meat was subjected to
mechanical and thermal stressors along with ageing (vacuum), freezing/thawing and cooking.
Accordingly, no correlation between drip loss and cooking loss was noted earlier (Honikel,
1986). Cross et al. (1984) and Crouse et al. (1985b) did not find a difference in cooking losses
between AN, SI, CH and Hereford as well as between AN and SI, respectively. The level of
cooking losses were about two-fold lower in our study compared to those found by Gerhardy
et al. (1995) with meat from 16 and 20 months old bulls and still lower than those found in
young heifers by Scheeder et al. (1996) of 24 % and 25 % for M.l.d. and M.b.f, respectively.
However, variation in cooking methods might have played an important role in this respect.
Apart from marbling, meat colour influences the visual appeal of meat to retail purchasers
(Shorthose and Harris, 1991) and thus is an important criterion for purchase decision of the
consumer (French et al., 2000). Consumers appear to prefer beef which is neither extremely
pale nor dark, with the range of L* values between 34 and 40 being considered as normal
(Ender and Augustini, 1998). On this basis, the meat of some AN and CH steers can be
judged as to be too pale. An increasing IMF content tends to increase meat lightness
(Shorthose and Harris, 1991; Frencia and Monvoisin, 1993), but the differences between BL
and PI on one hand and the four other breeds on the other hand were not consistent.
Obviously some independent breed differences in lightness exist. Similar to the present study,
Liboriussen et al. (1977) found a higher heme iron content of the M.l.d. of SI sires compared
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51
with LI, CH and BL. However, the LI meat was lighter than that of CH which was not the
case in our study. Accordingly, the heme iron content, the effective part of the pigments of
bovine meat (Renerre, 1982), similarly varied between breeds as the L* value. Heme iron is
also of interest for human nutrition because of its high bioavailability (Varnam and
Sutherland, 1995). In this view, AN and, partially, CH beef is inferior to beef of the other
breeds.
Overall, the animals of the present study provided a very tender M.l.d. applying the thresholds
of 38 N in Warner-Bratzler shear force for very tender meat and of 45 N for tender meat as
given by Shackelford et al. (1991) and Van Koevering et al. (1995) which were obtained
under similar measurement conditions. In accordance with Scheeder et al. (1996), the
differences in peak shear force found between M.l.d. and M.b.f. were low. Thus even the
M.b.f, where shear forces were extremely low for PI and AN in series 2, could be used as
steak instead of using it as lower priced cuts, particularly when size of this cut is not limiting
due to big sized carcasses. Only the M.b.f. of the SI in the first series had to be judged on
average as too tough to be marketed as steak. However, Scheeder et al. (1996) noticed that
peak shear force data provide little explanation for the collagen component of tenderness thus
indicating that there might nevertheless exist clear differences in tenderness ofboth muscles.
There was no clear relationship between IMF content and shear force among breed groups.
The residual variation in IMF content among the breeds after fattening to a similar IMF level
was contrary to the repeatedly stated inverse relationship between IMF and shear force
(Augustini and Liidden, 1992; Shackelford et al., 1994a). For instance PI meat in series 2 had
the lowest IMF content and the lowest shear forces in both muscles. This is in accordance
with Shackelford et al. (1994b) who found that meat from PI crosses with AN or Hereford
dams, despite having a lower IMF content as the steers in our study, showed the lowest shear
force among eleven genetic groups including AN and CH. This finding is also well supported
by Tatum et al. (1990) who compared Gelbvieh, Red AN and PI sires. Blumer (1963) and
Dikeman (1996) reported that IMF content is a poor predictor of tenderness and only accounts
for 5 to 10 % of the variability in tenderness. Wheeler et al. (1996) also found an increase in
tenderness at a common marbling end point when using PI crosses with various dams instead
of twelve other breed sires. Koch et al. (1976) observed a difference of less than 3 N in shear
force among AN and CH on one hand and LI and SI on the other hand when data were
adjusted to a similar slaughter age. Though statistically significant, the differences were small
and the values remained in the acceptable range of tenderness. Dufey (1987) compared
tenderness of M.l.d. samples from bulls of purebred SI, SI with 75 % Red Holstein blood,
pure-bred Swiss Braunvieh and its crossing with 75 % Brown Swiss blood. The sensory
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analysis revealed that the SI bulls had the toughest meat apart from the Brown Swiss crosses,
and an improvement in meat quality took place with a high Red Holstein blood proportion. In
another study, Dufey (1988a) compared SI and Brown steers, their crosses with AN, and
Holstein in taste panel evaluations of tenderness for M.l.d. and M. semimembranosus samples
with the result that meat from SI steers was rated low in tenderness. Crossbreeding with AN
positively influenced tenderness. In a third study, Dufey (1989) compared tenderness of
M.l.d. samples from Fl bulls sired by SI and BL with various dams (SI, Brown Swiss,
Holstein). No significant differences were found in tenderness between the sire groups.
Branscheid and Herzog (1996) noted that crossbreeding of German SI with CH and PI
improved tenderness (shear force and panel tenderness). Accoridng to this trend described in
literature, the present data also showed a higher shear force of meat of SI steers compared to
the other breed groups but this tendency was only apparent in the first series.
6.4.3. Fattening series differences in meat quality ofsteers (tied housing vs loose housing)
Steers of the present study originated from two different fattening series, and housing system
was changed from a tied system to group housing on straw beds without change in the diet.
The statistical evaluation of the data revealed several effects of fattening series on meat
quality. In detail, the IMF content was higher, the cooking losses were clearly lower, collagen
solubility in M.l.d. was higher and, finally, shear force was lower in series 2. From the design
chosen, no clear attribution of the effects to housing system is possible and time-dependent
effects as well as random trends in the animals selected from the breeds cannot be excluded.
However, based on the results of other studies, some of the effects might nevertheless be
explained by the variation in the housing situation. Using the tie-stall barn in series 1 resulted
in a restricted movement and subsequent joint and leg problems which reduced growth rate at
the end of fattening for the oldest animals (Chambaz et al., 2001a). Management practices
which alter growth and muscle accretion rates can have a profound effect on muscle
proteinases and collagen characteristics.An improved growth rate may result in a decreased
calpastatin activity at 24-31 h p.m. and consequently in an improved tenderness (Shackelford
et al., 1994b). Thomson et al. (1996) found that meat from steers growing fastest prior to
slaughter was more tender and had higher /i-calpain and calpastatin activities 2 h p.m. They
concluded that a high /x-calpain activity is likely to be related to a high rate of protein
degradation and this should result in an increase of the myofibrillar fragmentation index and,
therefore, tenderness. From their study they presumed that the level of/i-calpain activity close
to slaughter had been more important in determining tenderness than the calpastatin activity at
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2 h p.m.. Fast-growing cattle would also have a more intense protein turnover and therefore
fewer heat-stable intermolecular collagen crosslinks (Fishell et al., 1985; McCormick, 1994).
This could partly explain the higher collagen solubility and the lower shear force in series 2 in
all breed groups. As collagen solubility was higher in M.l.d. in series 2, but not in M.b.f.,
certain additional series differences in the animals selected can be assumed. SI and PI had the
highest series difference in slaughter age (63 days and 45 days younger in series 2 than in
series 1, respectively; Chambaz et al., 2001a) and simultaneously showed the highest
improvement of shear forces in series 2. Although the increase in the toughness of meat with
animal age is well known (Shorthose and Harris, 1990) it can be assumed that these effects
were not determined by age alone. Firstly, all breed groups showed a decrease in shear force
even those which were older in series 2 than in series 1 such as AN, CH and LI (25, 23 and 9
days older in series 2). Secondly, there were no significant correlations between age and shear
forces within breed groups and series (data not shown). However from the age-related
changes in collagen properties, nevertheless a certain decrease in tenderness with age can be
expected. It is difficult to explain the better water-holding capacity found in series 2 by a
single factor since animal genetics, age and slaughter conditions are known to significantly
contribute to the expression of variations in these traits.
6.5. Conclusions
The overall goal of the present study was to compare a wide range in beef breeds in their
differences in meat quality when a constant IMF content of 3.5 % is achieved. The target level
in IMF, however, excluded two breeds, namely PI and BL, as not appropriate for this attempt.
In the other four breeds, the target was reached on average but individual variation in IMF
was still high within breed due to the restricted accuracy of the in vivo ultrasound method
applied for determination. From the present material, without further attempt to reduce
variability in IMF content, certain breed differences in important quality traits such as colour,
water-holding capacity and tenderness-related variables were found. Differences were
particularly high between AN and the other suitable breeds (SI, CH, LI) with unfavourable
properties ofAN beef in total water-holding capacity and favourable estimates for tenderness-
related data. However, differences in shear force among breed groups were small, with all
breed groups being well above minimum levels of acceptance, even in a basically tougher
muscle such as the M.b.f, except in SI. The significantly better growth characteristics
obtained in the steers of the loose housing system compared with those in the tie-stall barn
seemed to be the major cause of the improvement in meat quality in the second series. Apart
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from the inability of the BL and PI to reach a high IMF content under the present feeding and
housing conditions, all breeds were suitable for premium beef quality marketing.
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7. Meat quality ofAngus, Simmental, Charolais and Limousin steers
compared at the same intramuscular fat content
Based on:
A. Chambaz, M. R. L. Scheeder, M. Kreuzer and P.-A. Dufey, 2001
(submitted to Meat Science)
Abstract
Meat quality and marbling properties of Angus, Simmental, Charolais and Limousin steers
(4 x 16) were compared at an average intramuscular fat content (IMF) of 3.25% in the M.
longissimus dorsi. The steers were fattened on a forage-based diet until the desired,
ultrasonically estimated IMF content was reached and therefore differed considerably in
growth and carcass characteristics. Extent and distribution of marbling was equal for all
breeds. Angus and Charolais provided bright meat with low heme iron content. Angus and
Limousin beef was found to be more tender in a sensory assessment than Simmental beef,
corresponding to the differences found in shear force (non-significant) and myofibrillar
fragmentation index. Flavour was similar among breed groups. Juiciness was highly
correlated with cooking loss, with Limousin and Charolais beef being juicier than Simmental
and Angus beef. In conclusion, clear differences in meat quality were observed between
breeds despite a similar IMF content.
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7.1. Introduction
Meat quality of beef breeds has been measured and compared in numerous studies. These
comparisons, however, mostly concentrated on potential breed differences at a similar age,
fattening period, weight, or fatness score of the animals. Only few studies so far investigated
meat quality of different breeds at the same intramuscular fat (IMF) content or marbling score
(Tatum et al., 1996). However, this was done after statistical adjustment of the means and not
by really fattening cattle until a similar IMF content was achieved, probably also because of
the difficulty to accurately estimate IMF in live animals. Cattle breeds clearly differ in their
capacity for IMF retention and, consequently, breed differences in age and weight are
expected to be large when animals are fed on a similar energy level and slaughtered at the
same IMF content (Koch et al., 1976; 1979; 1982). The influence of IMF content on beef
palatability has often been described but its quantitative importance is controversially
discussed (Dikeman, 1996; Lusk et al., 1999). Nevertheless, the visual appearance of IMF,
commonly called marbling, is the primary criterion for quality grading of beef carcass quality
in the United States and Canada (Dubeski et al., 1997). Moreover marbling is often linked
with beef palatability by consumers and can therefore play an important role on purchase
decision. Focus on marbling is especially decisive in branded beef programs where
occasionally a minimum amount and a fine texture of IMF is defined or demanded (AAA,
2001).
The objective of the present study was to compare the meat quality of one early- and three
later-maturing breeds fattened to the same IMF content under controlled conditions in order to
quantify the residual differences in marbling and meat quality between these breeds.
7.2. Materials and methods
7.2.7. Experimental design
The experiment was carried out with Angus, Simmental, Charolais and Limousin steers
originating from suckler herds. They entered the trial at an average age (± SD) of 238 ± 25 d
and were fattened in two subsequent series. The first series was carried out in a tie-stall barn
and the second series in a loose housing system with straw bedding. During the whole
fattening period the animals had ad libitum access to the same diet consisting of maize silage,
520 g, grass silage, 260 g, and concentrate, 220 g per kg of dry matter with a medium energy
density diet representing a typical semi-intensive European-type of fattening. The animals
were assigned to slaughter when the IMF content, estimated by a real-time ultrasound scanner
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200 (Pie Medical, Maastricht, Netherlands), reached the target level of between 3 and 4 %
(Chambaz et al., 2001). However, as a certain inaccuracy of this assessment had to be taken
into account, twelve animals per breed and series were fattened in order to be able to select
the eight animals per breed and series, which matched the requirements in IMF content best
(target content and similar variation within breed).
7.2.2. Experimentalprocedures performed at slaughter
On the day of slaughter, animals were weighed and transported 60 km to a commercial
slaughter plant and slaughtered within 4 h of departure from the research station. Hot carcass
weight was recorded at about 1 h post-mortem (p.m.). Carcasses were chilled for 48 h at 2 °C.
Measurements of pH and temperature were performed at 1, 3 and 48 h p.m. in the M.
longissimus dorsi (LD) at the 10th rib with a portable pH meter (WTW 197S,
Wissenschaftlich-Technische Werkstätten GmbH, Weilheim, Germany) equipped with a
Sensor EB4 pH probe (Wintion, Gerzensee, Switzerland) and temperature probe (TFK 150/E,
Wissenschaftlich-Technische Werkstätten GmbH, Weilheim, Germany). At 48 h p.m.
subcutaneous fat thickness was measured as described by Boggs et al. (1998), i.e. at 3A of the
lateral length of the LD from the backbone between the 12th and the 13th rib.
The left carcass side was cut between the 9th and the 10th rib, and the so-called 1st category
cuts, i.e. striploin, tenderloin and rump were prepared. Starting at the cranial part, the LD was
cut into slices first removing approximately 300 g for chemical analyses (fat and collagen)
after lyophilisation and homogenisation, followed by three 2 cm thick slices for later
determination of drip loss, cooking loss, Warner-Bratzler shear force (WBSF) and sensory
evaluation. Finally, three 1 cm thick slices were obtained for measurements of marbling traits,
heme iron, sarcomere length and myofibrillar fragmentation index (MFI). Samples were
vacuum-packaged and frozen at -28 °C either directly or after an additional ageing period of
12 days at 2 °C which was applied for a second determination of MFI and for analysis of meat
colour, WBSF and sensory evaluation.
7.2.3. Determination ofintramuscularfat content and marbling
The IMF content was analysed using petrol ether extraction (SLB, 1969). In order to
objectively quantify marbling traits, intramuscular fat of the intact slice was chemically
stained according to Albrecht et al. (1996). Briefly, the LD was soaked for 7 d in a formol
calcium solution, then in a solution of oil red (0.5 g oil red dissolved in 100 g isopropanol) for
7 h, followed by 4 h of washing in a 70 % isopropanol solution with agitation. With this
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method it was possible to distinguish IMF from collagen and to intensify the contrast between
IMF and other components of the LD. A digital photo image of the stained slice was then
captured by a computer assisted video camera. Marbling traits were evaluated by an image
analysis software (analySIS, Soft Imaging System GmbH, version 1999, Münster, Germany).
Variables obtained in each sample were: visible fat as a percentage of total muscle area,
average fat particle size, number of fat particles per cm2, the proportion of the area of the
three largest fat particles, and the number of particles > 30 mm2. All measurements were
carried out separately in each quarter of the cross-section of the LD. The coefficient of
variation of visible fat proportion among quarters within steers was calculated.
7.2.4. Analysis ofmeat quality
Meat colour traits (L*, a*, b*) were determined without blooming in the raw LD with the
Chroma-Meter CR-300 (Minolta, Osaka, Japan) applying the light source D65. Heme iron
was analysed as pigments (assuming 9.06 % heme iron in pigment) according to Barton
(1967). Pigments were extracted with acetone and measured photometrically (640 nm,
Lambda 2 spectral photometer, Perkin-Elmer, Überlingen, Germany).
Drip loss was quantified as described by Honikel (1998). Cooking loss was determined by
weighing the samples before and directly after cooking. For this purpose frozen vacuum-
packaged LD slices were thawed during 24 h at 2 °C and were stored for 1 h at room
temperature before cooking. The slices were then broiled for 5 min on a grill (type BF-50,
Beergrill AG, Zurich, Switzerland) at 195 ± 5 °C by direct radiant heat with the samples
turned two times. The grill plate was directly connected to an external electronical
thermoregulator (Ematherm A, Trafag AG, Männedorf, Switzerland) to minimize temperature
variations. According to preliminary assessments, this procedure resulted in a meat core
temperature of approximately 68 °C.
For shear force determinations on the original Warner-Bratzler device (model 3000, G-R
Electric MFG Co, Manhattan, Kansas, USA), the cooked samples were cooled to ambient
temperature. Ten cores of 1.27 cm diameter per sample were obtained parallel to fibre
orientation with an electrical drill to get uniform samples (Kastner and Henrickson, 1969).
The cores were obtained and sheared always in the same order beginning with the five first
dorsal cores followed by five ventral cores starting from the medial to the lateral end of the
slice. The mean WBSF values of the cores 1 and 2, 4 and 5, 6 and 7, and 9 and 10,
respectively, were combined to describe the positions dorsal-medial, dorsal-lateral, ventral-
medial and ventral-lateral.
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Two replicates of 0.5 g, taken from the centre of the raw LD, were analysed for sarcomere
length (Pospiech and Honikel, 1987). The samples were homogenized for 30 s with an Ultra-
Turrax T25 (Janke & Kunkel, IKA Labortechnik, Staufen, Germany) at 9500 rpm in 5 ml
borate buffer (0.1 M KCl, 0.039 M sodium tetraborat decahydrat and 5 mM EDTA, pH 7.1).
The length of five consecutive sarcomeres was measured 12 times per replicate (in total
equivalent to 120 determinations per animal) using an optical microscope (Olympus BX50,
Olympus Optical Co, Tokyo, Japan) and the same image analyzing software as for marbling.
The MFI was analysed in raw LD as described by Culler et al. (1978). The protein
concentration of the suspension produced with this method was determined by the biuret
method (Gornall et al., 1949). After dilution of the myofibril suspension to a concentration of
0.5 ± 0.05 mg/ml, the final protein concentration was controlled using the micro-biuret
method (Bailey, 1967). The MFI is equivalent to the absorption value of the myofibril
suspension, measured at 540 nm and multiplied by 200.
The collagen content (hydroxyproline x 8) was measured in lyophilised LD as described by
Arneth and Hamm (1971) and adapted to the Autoanalyser II chain (Technicon, Plainfield,
New Jersey, USA). Collagen hydrothermal solubility at 90°C was determined as outlined by
Koppetal. (1977).
7.2.5. Sensory evaluation
Sensory analysis was performed by an eight member, in-house trained panel. Panelists
simultaneously assessed four samples, cooked as described for cooking loss, which were
served hot on pre-warmed plates. Samples originated from one representative of each breed
provided in an arrangement which minimised the variation of IMF content within each
session. Panelists were asked to judge the samples on 8-cm unstructured line scales anchored
at each end with the descriptors very tough/tender, very slight/strong, very dry/juicy, very
much disliked/liked for tenderness, flavour intensity, juiciness and preference, respectively.
The marks of the panelists on the line scales were then converted to numbers by measuring
the position of each mark with a computer-assisted FIZZ digitiser (version 1.30, Biosystemes,
Couternon, France).
7.2.6. Statistical analysis
Data was statistically analysed with the NCSS program (version 1997, Hintze, Kaysville,
Utah, USA) by analysis of variance. The model included breed and series as fixed effects, the
interaction of these effects, and IMF as a covariate. The analysis of the sensory traits
Page 65
60
additionally considered the effects of panel session, panelists and IMF group as block nested
within series. The Tukey method was applied for multiple comparison among breed group
means considering P < 0.05 as significant. The tables give the least square means, the
standard ercor of the mean (SEM) and the level of significance of the effects and interactions.
7.3. Results
Fattening the steers of the different breeds under the same conditions and to a similar IMF
content resulted in significant differences between breed groups in most of the growth and
carcass traits (Table 1). The fattening period of the Angus group was only 0.53, 0.50 and 0.41
of that of the Simmental, Charolais and Limousin groups, respectively. The Limousin steers
had a 13 to 21 % lower growth rate compared to the other breed groups. Carcasses of
Charolais and Limousin were significantly heavier than those of the Simmental and
particularly of the Angus steers. Simmental and Angus had the lowest dressing percentage
and proportion of 1st category cuts, which both were highest in the Limousin. However, breed
groups did not significantly differ in the thickness of the subcutaneous fat layer. There were
also effects of fattening series in some growth and carcass traits, but these did not
significantly interact with the breed group effects.
As intended, the IMF content was almost identical for all breeds (Table 2) with an average of
3.25 %, and also the coefficients of variation in IMF content were quite comparable,
accounting for 27, 21, 25 and 21 % in the Angus, Simmental, Charolais and Limousin groups,
respectively. Similarly, for none of the marbling traits measured significant differences
between breed groups were found. However, there was a trend (P = 0.1) in the LD of the
Angus steers to accumulate the highest proportion of visible fat within the three largest fat
particles. There were significant positional effects on visible fat proportion of total muscle
area (Fig. 1) which varied from 5.1 % on average at the dorsal-lateral position to 9.3 % at the
dorsal-medial position. Steers of the two fattening series differed in IMF content and some
marbling traits, but a significant interaction with breed group was only found for average
particle size which remained unaffected by breed group and fattening series alone.
Page 66
61
O)c
Dorsal-medial Dorsal-lateral Ventral-medial Ventral-lateral
Fig. 1. Area of visible fat as a proportion of total muscle area () and Warner-Bratzler shear
force (WBSF, o) measured at different positions within the LD (average of all breed groups).
Means within variable from different positions lacking a common letter are significantly
different (Tukey, P < 0.05).
There was no significant difference between breed groups in pH and temperature of the LD
measured 1 h p.m. (Table 3). The temperature decline from 1 h to 3 h p.m. was significantly
slowest for the Limousin, the group with the heaviest carcasses and the most pronounced
conformation. This was accompanied by a more rapid decrease of pH from 1 h to 3 h p.m.
compared to all other breed groups (significant against Angus). Breed group differences in
ultimate pH (48 h p.m.) were small but significant between Limousin and Simmental. Drip
loss increased in the order of Angus, Simmental, Charolais and Limousin, while the opposite
trend was apparent for cooking loss. When comparing Limousin and Angus, this resulted on
average in differences of 2.0 and 6.5 percentage units in drip loss and cooking loss,
respectively. The LD of the Angus and the Charolais steers was significantly brighter (high
L*) than that of the Simmental steers, with the Limousin taking an intermediate position. This
is in line with the correspondingly lower heme iron content of the LD in Angus and Charolais
relative to Simmental. Accordingly, there was a significant and negative correlation between
heme iron content and lightness (r = -0.68, P < 0.001). Breed groups did not differ
significantly in redness and yellowness of LD.
Page 67
Table
1
Growthandcarcass
traitsoftheselectedsteersfattenedtoasimilarintramuscular
fatco
nten
t1
Variable
Angus
Simmental
Charolais
Limousin
SEM
P-values
Breed
Series
BreedxSenes
Age
(d)
Fatt
enin
gperiod
(d)
Averagedailygains(k
g)Hotcarcassweight(k
g)
Dres
sing
percentage(%)
1stcategorycuts2(%ofcarcassweight)
Subcutaneous
fatlayer3
(mm)
16
16
16
16
381c
499b
513b
594a
16.6
0.000
0.604
0.479
141c
267b
281b
346a
16.3
0.000
0.186
0.474
1.30a
1.18a
1.22a
1.03b
0.325
0.000
0.017
0.741
275c
339b
395a
405a
11.9
0.000
0.099
0.349
54.3c
54.1c
57.9b
61.5a
0.46
0.000
0.011
0.479
6.76c
7.08bc
7.13b
7.62a
0.091
0.000
0.008
0.681
14
12
12
13
0.9
0.330
0.078
0.379
1Leastsquaremeanswithinthesamerowlacking
acommon
lett
eraresignificantlydifferent(Tukey,P<
0.05).
2Sumofthetrimmed
stri
ploi
n,tenderloinandrump
3Measuredbetweenthe
12th
andthe
13th
rib.
Table2
Intramuscular
fatcontentandvideoimagean
alysed
marbling
traitsofM
longissimusdorsi(LD)obtainedfromsteersofdifferentbreeds
Variables
Angus
Simmental
Charolais
Limousin
SEM
P-values
Breed
Senes
BreedxSenes
Intramuscularfat(%)
3.23
3.25
3.25
3.27
0.178
0.999
0.001
0.972
Visible
fat(%ofLD)
CV2ofvisible
fat(%)
Average
fatpa
rtic
lesize(mm2)
Fatpa
rticle
dens
ity(n/cm2)
Three
largest
fatpa
rtic
les(%ofvisible
fat)
Numberoffa
tpa
rtic
les>30mm2
8.0
7.1
7.1
7.2
0.47
0.437
0.051
0.192
34.4
32.0
29.5
28.9
2.74
0.483
0.484
0.153
1.7
1.5
1.7
1.5
0.10
0.216
0.864
0.019
4.6
4.8
4.4
5.0
0.27
0.528
0.039
0.548
31.2
27.2
22.9
25.9
2.32
0.100
0.006
0.064
2.6
2.4
2.8
3.7
0.42
0.176
0.776
0.576
1Leastsquaremeanswithinthesamerowlacking
acommon
lett
eraresi
gnif
ican
tlydifferent(Tukey,P<
0.05).
2Coefficientofvanationbetweenquarters
oftheLD
cut.
Page 68
Table3
Meat
quality
traitsm
theM
longissimusdorsiofsteersofdifferentbreedssl
augh
tere
datasimilarintramuscular
fatco
nten
t1
Variables
Angus
Simmental
Charolais
Limousin
SEM
P-values
Breed
Senes
BreedxSeries
pHih
pH3h
pH48h
Temperaturen,(°C)
Temperature3h(°C)
Drip
loss
48h
I
Cooking
loss14li(%)
Lightness
na(L
*)Redn
essi
4d(a
*)
Yellownessi4d(b*)
Heme
iron«,,(mg/kg)
Warner-Bratzlershearfo
rce1
4d(N
)Sarcomere
lengthigh(imi)
CV
ofsarcomerele
ngth
(%)3
Prop
orti
onofsarcomere=16am(%)
Prop
orti
onofsarcomere>2
3|im(%)
Myof
ibri
llar
frag
mentationin
dex4
8h
Myof
ibri
llar
frag
mentationmdex14d
Coll
agen
48h(mg/100
g)
Coll
agen
solu
biht
y48h
(%)
659
661
659
656
0031
622a
607ab
613ab
602b
0040
554ab
557a
551ab
550b
0018
385
379
379
389
031
314b
313b
323b
344a
040
25c
30bc
36b
45a
021
206a
171b
158bc
14
1c
071
400a
373b
395a
38
lab
054
142
143
142
147
025
43
41
47
49
030
117b
140a
121b
127ab
0050
29
33
32
29
14
185a
178b
177b
176b
0019
67
77
85
88
057
20b
60ab
9lab
122a
188
18
08
15
28
107
110a
88b
107a
Ilia
41
143
131
125
129
52
549a
536ab
525ab
482b
15
5
343a
316ab
296ab
286b
136
0691
0019
0006
0740
0047
0154
0094
0575
0000
0005
0000
0323
0000
0001
0001
0888
0327
0992
0250
0246
0011
0235
0181
0122
0005
0851
0060
0725
0002
0989
0597
0745
0001
0016
0098
0486
0020
0060
0024
0000
0947
0571
0033
0311
0536
0052
0476
0224
0358
0113
0080
0267
0954
0913
0393
0680
0023
0073
0713
0332
Leastsquaremeanswithinthesamerowla
ckin
gacommon
lett
eraresignificantlydifferent(T
ukey
,P<005
)Indicesrepresentthelength
oftheperiod
post-mortem
Coefficientofvariation
(n=
120)
Page 69
64
WBSF was not significantly different between breed groups (Table 3). However, significant
positional differences within LD were found (Fig. 1), with lower shear force in the medial
positions (28 N on average for the dorsal and ventral position) compared to the lateral
positions (34 N). The average sarcomere length was significantly greatest in the Angus meat,
which also had the smallest proportion of sarcomeres equal to or shorter than 1.6 /im
(significant against Limousin). The proportion of sarcomeres exceeding 2.3 /xm and the
variation in sarcomere length did not differ significantly. The MFI was initially (2 d p.m.)
lowest in the Simmental steers compared to all other groups, but differences were no longer
significant after ageing for further 12 days. Shear forces although not significantly different
between groups followed a trend inverse to the MFI at 2 d p.m., i.e. the highest shear forces
conesponded to the lowest MFI values. Content and solubility of collagen were significantly
higher in the Angus compared to the Limousin steers, with the Simmental and Charolais
groups taking intermediate positions. Only few meat quality traits were affected by series of
fattening and only in pH4gh and MFLjgh significant breed group x series interactions occurred.
The meat of the Angus and the Limousin steers was judged significantly more tender than that
of the Simmental steers (Table 4); the Charolais meat was scored intermediate. Conelations
between panel tenderness and various other traits are listed in Table 5. The correlations
calculated within breeds differed to some extent. However, in those variables, which were
significant in the complete dataset, also correlations within breeds mostly were oriented
towards the same direction. In detail, negative conelations of tenderness scores with WBSF
(except Angus) and positive conelations with MFI, inespective of the time p.m. measured
were found. Although pH3h measurements ranged from 5.56 to 6.47 and temperature at 3 h
p.m. from 27.4 to 36.6 °C no significant linear or curvilinear relationship was found among
these variables and both WBSF and tenderness scores within or over all breed groups.
Significant correlations between collagen related traits and tenderness were only observed
within the Charolais group. It has to be mentioned that the variation of slaughter age was
larger in this group with 20.2 % compared to the Limousin, Simmental and Angus with
coefficients of variation of 10.4, 10.2 and 5.3 % respectively. Breed groups did not
significantly differ in flavour scores, but differences between breed groups were found in
juiciness, with the meat of the Limousin and, to a lower extent, of the Charolais steers being
juicier than that of the Simmental and particularly the Angus steers. Juiciness scores were
negatively conelated with cooking losses (r = -0.75, P < 0.001). There was a tendency in the
order of preference (P < 0.06) in the order of Limousin, Charolais, Angus and Simmental. In
the sensory evaluation no breed x series interactions occuned.
Page 70
Table4
Resultsofthesensoryevaluationof14dag
edM.
longissimusdorsiobtainedfromsteersofdifferentbreedsslaughte
red
atasimilarintramuscular
fatcontent1'2
Vanables
Angus
Simmental
Charolais
Limousin
SEM
P-values
Breed
Senes
BreedxSenes
Tenderness
4.80a
3.98b
4.59ab
4.77a
0.178
Flavourintensit
y4.45
4.11
4.35
4.43
0.129
Juiciness
3.62c
3.85bc
4.55ab
4.68a
0.208
Preference
4.61
4.36
4.84
4.95
0.157
Means
withinthesamerow
lack
ing
acommon
letter
aresi
gnif
ican
tlydifferent(T
ukey
,P<
0.05
).2
Sensoryattributeswerescoredusingthefo
llow
ingscalesfortenderness,flavorin
tens
ity,
juicinessandpreference:1=veryto
ugh,
slight,dr
yandmuch
disliked;
8=
very
0.008
0.053
0.472
0.237
0.959
0.706
0.001
0.344
0.850
0.056
0.035
0.744
tend
er,strong,juicyandmuch
liked.
Page 71
66
Table 5
Conelations between selected traits and panel tenderness scores in steers of different breeds slaughtered at a
similar intramuscular fat content1
Panel tenderness score
Angus Simmental Charolais Limousin All data
Observations 16 16 16 16 64
Age (d) 0.07 0.01 0.24 -0.11 0.03
Hot carcass weight (kg) 0.28 -0.32 0.28 -0.23 0.05
Fat thickness 12/13th nb (mm) -0.57* -0.22 0.01 0.45 0.04
pH3h -0.39 -0.38 0.26 -0.42 -0.11
Temperature31l (°C) 0.05 0.03 -0.21 -0.25 0.04
Cooking loss14d (%) 0.10 -0.23 -0.05 -0.13 -0.06
WBSF214d (kg) 0.28 -0.53* -0.53* -0.27 -0.43***
Sarcomere length48h (pm) -0.22 0.09 0.16 0.29 0.15
MFI348h 0.26 0 34 0.31 0.19 0.42***
MFI314d 0.59* 0.61* 0.40 0.05 0 4o***
Collagen«,, (mg/100 g) -0.03 0.27 -0.57* -0.09 -0.16
Collagen solubihty48h (%) -0.32 0.31 -0.57* -0 15 -0 19
1*P< 0.05, *** P< 0 001
2Warner-Bratzler shear force
3
Myofibnllar fragmentation index.
7.4. Discussion
In the present study, steers of four common beef breeds, greatly varying in development
of maturity, were fattened under identical conditions until a similar IMF content was
reached. This procedure resulted in major differences between breed groups in age at
slaughter and carcass size. Together with other genetic differences between breeds, this
was likely to result in major differences also in meat quality and, possibly, in the
distribution of visible IMF in the LD, both of which may be decisive for the purchase
decision of the consumers. The chosen level of IMF of approximately 3.25 %
conesponds to 'slight degree of marbling', a grade, which was found to be prefened in
a study on visual quality and degree of marbling, involving US consumers (Killinger et
al., 2000). Even in pork, a certain consumer segment (21 %) obviously prefered pork
with that level of IMF content although most US consumers refused this degree of
marbling in pork (Brewer et al., 2001). In beef, 47 % Swiss consumers also were found
to prefer IMF contents of 3 to 4 %, whereas 27 % selected beef without any visible
marbling (Chambaz et al., 2001). However, in Europe, carcasses like those investigated
need a specific marketing since the common grading would classify them almost
Page 72
67
without exception as excessively fat and therefore of low value in the prizing system.
As can be seen from the similarly thick subcutaneous fat layer, this restriction cannot be
overcome by the use of a certain breed.
7.4.1. Marblingproperties
A high degree of marbling is often associated with a good meat quality in the trade and
by the consumers and can therefore play an important role for purchase decision and
price. The actual sensory impression during consumption of the meat, however, seems
to be rather independent from the marbling score. This was reported as a result from
surveys on meat quality, periodically carried out in the USA (Brooks et al., 2000;
Morgan et al., 1991). Nevertheless, marbling is still an important component of e.g. the
US quality grading system and is also considered in the regulations of some US branded
beef programs. These programs not only demand a minimum extent but also a fine
texture of marbling (e.g., AAA, 2001), obviously taking into account a potentially
negative perception when the marbling is too coarse. However, none of the breed
groups investigated in the present study was clearly superior in the traits describing
marbling characteristics. Nevertheless, within LD there were positional differences in
both visible fat proportion and shear force, which appeared to be inversely related (Fig.
1). The latter might reflect a partial substitution of proteinous structures by fat, however
as the relation was not really linear, this also could have been an artefact.
Since the four breed groups were equal in carcass fatness, IMF and marbling it was
possible to compare the sensory and apparatively measured meat quality of the different
breed groups almost independently from the fat-related properties ofthe meat.
7.4.2. Meat colour
Meat colour is a further important determinant of the visual appearance of meat.
Carpenter et al. (2001) showed that consumer preferences for beef colour influenced the
likelihood of purchase but - similarly to marbling - colour did not conespond with
differences in eating satisfaction. As expected, in the present study lightness was
inversely conelated to heme iron content, the effective part of the pigments of bovine
meat. Heme iron content of muscle increases with animal age especially up to 24
Page 73
68
months of age and then remains quite stable (Renene, 1982). This might explain the low
heme iron content of the much younger Angus but not the differences between the other
groups. Thus, the high heme iron content of Simmental beef may be attributed to a
genuine breed characteristic, either resulting from a more rapid increase or a generally
higher total iron content of the muscle.
7.4.3. Meat texture
Tenderness is one of the most important criteria for beef quality and it has been shown
experimentally that a lot of consumers are ready to pay a higher price once they can be
sure that the beef is more tender (Dransfield, 1998). The sensory scoring revealed that
Angus and Limousin beef was most tender, followed by Charolais and Simmental beef.
Although not significantly different between breed groups, the WBSF followed the
same trend and was significantly, however not closely, conelated with sensory
tenderness. Since meat was obtained from steers and was aged for 14 d, the tenderness
level was generally high and the variation in tenderness was relatively low. This
probably contributed to the rather loose relationship between tenderness score and
WBSF. The differences in tenderness between breed groups were basically in agreement
with other studies, which however were not carried out under the precondition of a
similar IMF content: Simmental beef was found to be less tender than that of their
crosses with Angus (Dufey, 1988). Also crossbreeding with Red Holstein (Dufey, 1987)
and Charolais (Branscheid and Herzog, 1996) improved the tenderness of Simmental
beef. When comparing animals of the same age, Angus crosses with Charolais were
found to yield the same tenderness as purebred Angus while crosses with Simmental
and Limousin had less tender meat (Koch et al., 1976). In some contrast, no differences
in tenderness were found between Simmental and Angus crossbred steers when
slaughtered at an equal backfat thickness (Laborde et al., 2001).
Various factors may be responsible for the breed group differences in tenderness found
in the present study. Early post-mortem pH has been proposed as one factor affecting
meat tenderness from the myofibrillar side as it influences the activity of endogenous
enzyme systems (O'Halloran et al., 1997). From several investigations (French et al.,
2000; Marsh et al., 1987; Pike et al., 1993) it appears that glycolysis and the resulting
meat tenderness is highest at a pHßh of 6.0 to 6.1. This can be either achieved by
Page 74
69
electrical stimulation of carcasses (Marsh et al., 1987) or producing heavy carcasses
with a conespondingly slow temperature decline (Pike et al., 1993) as was the case with
the Limousin group in the present study. However, ageing of the meat for 14 d
decreased initial tenderness differences in other studies (O'Halloran et al., 1997; French
et al, 2000) and can also be seen from the development of MFI in the present
investigation. Accordingly no significant relationship between pH3h and sensory
tenderness of meat aged for 14 d was found in our and also other studies (Shackelford et
al., 1994). Both Limousin and Simmental beef showed an ideal pH3h, but Simmental
beefwas graded significantly lower in tenderness.
Another important factor of the myofibrillar compound of tenderness could have been
sarcomere length, particularly when pH3h is greater than 6.3 (Smulders et al., 1990),
although not always a clear relationship between sarcomere length and tenderness is
found (O'Halloran et al., 1997). One precondition for a close conelation seems to be the
occunence of cold or heat shortening (Shorthose and Harris, 1991). Some contraction
obviously occuned in Limousin and, to a smaller extent, in Charolais and Simmental
probably not due to cold but heat shortening. Lochner et al. (1980) have shown that
carcass size and fatness have a great influence on cooling rate and can be at least as
important in determining muscle cooling rate as the temperature and velocity of the
chiller air. Moreover it is unlikely that cold shortening occuned in Limousin because
they had the lowest pH and the highest muscle temperature at 3 h p.m. and so should
have the lowest risk of cold shortened muscle from the four breed groups. Lee and
Ashmore (1985) observed contracted mean sarcomeres length (1.66 pm) and increased
toughness due to heat shortening in carcasses with similar backfat thickness and
temperature at 3 h p.m. although carcasses were about 100 kg lighter as in the Limousin
group of our study. In cold-shortened fibres often both contracted and stretched
sarcomeres are present resulting in a greater variation of sarcomere length (Locker et
al., 1975). This was not the case in this study and it can be presumed that the 14 d-
ageing period was sufficient to offset or overcome the effect of shortening as Limousin
panel tenderness scores were as good as that of the Angus which had almost no
sarcomeres contracted to less than 1.6 /im. Accordingly, the weak relationship between
the sarcomere properties investigated and tenderness scores as well as shear force
remained unclear in terms of both breed group differences and conelations.
Page 75
70
In the present study MFI turned out to be a suitable indicator for tenderness and breed
group differences in tenderness of the aged LD, which was also observed in other
studies (Culler et al., 1978; Vestergaard et al., 2000). MFI particularly reflects changes
occurring during ageing of meat. In the present experiment, MFI was measured at 48 h
and at 14 d p.m. In this period MFI increased by 30, 49, 17 and 16 % in the Angus,
Simmental, Charolais and Limousin groups, respectively, thus decreasing the initial
variation among breeds (particularly Simmental vs others). Therefore it can be assumed
that Simmental beef would have been even clearer inferior in tenderness against all
other groups without or with a shorter period of ageing.
The connective tissue-related traits were described by collagen content and collagen
solubility. As expected, steers from breeds which were slaughtered at a higher age
expressed a lower collagen solubility reflecting the increasing formation of mature or
heat-stable crosslinks (Purslow, 1994). In the Limousin group, this was obviously
compensated by a lower collagen content which actually could reflect a kind of dilution
of connective tissue by other muscle tissues. The only significant conelations between
collagen related traits and panel tenderness were found in the Charolais group, which
also showed the greatest variation in age. Nevertheless the negative relationship
between collagen solubility and tenderness in the Charolais is contradictory to the
expectations.
7.4.4. Flavour, juiciness and water-holding capacity ofmeat
Studies comparing beef breeds in meat flavour mostly reported no substantial
differences (Koch et al., 1976, 1979, 1982; Wheeler et al., 1996, 2001). In contrast,
Laborde et al. (2001) noted higher flavour scores in Simmental crossbred steers than in
Angus steers slaughtered at a similar backfat thickness, but the Simmental crossbreds
were 73 d older and their beef had a 31 % higher IMF content. Since in the present
study clear breed group differences in slaughter age also occuned and intensity of
flavour is known to develop with increasing animal age (Lawrie, 1991), differences in
flavour were expected but not found.
In contrast, the present study revealed clear breed group differences in water-holding
capacity and juiciness of the meat, traits which closely conelated. It seems that, due to
the great differences in age at slaughter which represent indirect effects of breed
Page 76
71
through the breed-specific rate of IMF accretion, breed group differences in juiciness
were far more pronounced than in other studies comparing beef not at the same IMF
content but at the same age or weight of the animals (e.g., Crouse et al., 1985). This
age-dependance may be at least partly a result of the decline in muscle water content
with age, shown to be closely associated with cooking loss in Simmental cattle by
Lüdden (1991). Another factor pronouncing beef group differences in cooking loss
could have been the differences in size of the LD slices (small in Angus). However, no
direct relationship between surface, weight and surface to weight ratio of the LD slice
and the level of cooking loss was found. Ranking in drip loss was opposite to that in
cooking loss and juiciness. Drip loss stresses other compartments of bound water than
cooking loss and therefore does not conelate with cooking loss (Honikel, 1986). In the
present study, overall group differences in cooking loss were of far greater importance
than those in drip loss.
7.4.5. Overall sensory preference ofmeat
Panelists tended (P < 0.06) to prefer the LD of Limousin and Charolais steers. This can
be explained by the lower juiciness of the Angus beef and, additionally, the lower
tenderness of the Simmental beef. Generally, the results of other studies, although not
carried out under the precondition of a similar IMF content, indicate that differences in
meat palatability are small between Bos taurus breed groups (Koch et al., 1979; Monin
and Ouali, 1991) and not very consistent due to the large variability within relative to
that between breeds (Wheeler et al., 1996).
7.5. Conclusions
The present study illustrated that beef from different breeds may differ in quality, when
the animals are fattened under the same conditions until they reach a similar IMF
content, particularly when early and late maturing animals are compared. These
differences might be less pronounced when age differences at slaughter would be
reduced by a variation of the feeding intensity. However, semi-intensive feeding
systems could be very competitive by reducing feeding costs particularly in grassland
regions. Under these conditions, Charolais and Limousin could have a certain advantage
which is expressed in favourable juiciness and tenderness, low cooking losses and
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certain cost-effective carcass traits. On the other hand, these breeds will provide very
heavy carcasses and an unusually long fattening period is required when an IMF content
of more than 3 % is demanded. For these reasons intensive fattening systems would be
advisable. Angus, with also very tender beef but inferior water-holding capacity, would
have the advantage of a much shorter fattening period at simultaneously higher average
daily gains providing the best choice for extensive systems. Simmental beef was ranked
inferior; therefore, crossbreeding might improve the Simmental offspring's beef quality.
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8. General discussion
The choice of an intramuscular fat content of approximately 3.5 % as slaughter criterion
was higher than the one commonly found in beef cattle in Switzerland as this ranges
between 1 and 2.5 % (Dufey and Chambaz, 1999b). The determination of this content in
living animals is not easy. The ultrasound technology permits to select animals for
constituting fattening groups conesponding to distinct markets but this technology is
still in development and therefore too preliminary to determine accurately enough the
slaughter end point when determined at a fixed level or a nanow range of intramuscular
fat.
The condition of a similar intramuscular fat content as slaughter criterion had a great
influence on growth characteristics of the different breed groups of this study, as well as
the use of steers instead of bulls and beef breeds instead of crossbreds with dairy cattle.
Since these last few years there is a tendency of fattening pure beef breeds and supply is
cunently lower than demand. These type of cattle convey a positive image at the same
time to the consumers, butchers and producers also. However most of the pure breeds
used in this study, Angus excepted, are later maturing than animals in conventional
fattening coming from dairy husbandry. Fattening duration, again Angus excepted, was
therefore longer than usual in conventional fattening with, in increasing order of
duration, the Simmental and Charolais, followed by the Limousin and lastly the Blonde
d'Aquitaine and Piedmontese. The slaughter order reflected the differences in maturity
rate of the different breeds. These results are in agreement with those found in the
literature and allowed to refute the widespread opinion that Limousin is an early
maturing breed. Using late-maturing cattle and slaughtering the animals at 3.5%
intramuscular fat prolonged the fattening duration which raised considerably the live
slaughter weights and the feeding duration and therefore feeding costs. Growth
performance in the conditions of this study was generally better for the earlier maturing
breeds or respectively for the youngest animals.
The finding concerning carcass quality was inverse with the later maturing animals
presenting the best carcass quality if the problems of high carcass weight are excluded.
The high dressing percentages added to the high slaughter weights in the later maturing
animals indeed increased the difficulty or made it impossible not to exceed the limits of
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carcass weights in force in Switzerland. It means that on one side the animals of the
later maturing breeds such as Blonde d'Aquitaine and Piedmontese should be fattened
longer to obtain a sufficient fat cover and on the other side they should be slaughtered
earlier than the earlier maturing breeds such as Angus to avoid that carcass weight limits
are surpassed. For example in our study no single animal succeeded to obtain
simultaneously 3.5% intramuscular fat content, optimal carcass fatness (conesponding
to the score 3 ofthe CH-TAX) and a carcass weight below 350 kg. It is concluded that it
is very difficult to reconcile the interest of the different contributors of the meat market
(producers, butchers and consumers) in any case in the conventional market.
Piedmontese meat is often vaunted for its low cholesterol content. It is probably due to a
subjective association with the low fat content of this later maturing breed. However the
present results as well as those of the literature showed that cholesterol content was not
conelated with fat content firstly and secondly that Piedmontese had not less cholesterol
than the others breeds.
Meat quality obtained in this study was judged good to very good from the panelists
which confirms that this type of production could meet the consumers' expectations
regarding sensory quality of labeled meat. In spite of a similar intramuscular fat content
important differences in tenderness, juiciness and flavor were observed between breed
groups (see appendix). Intramuscular fat is therefore not the basic cause for the
differences observed. Piedmontese meat was finally prefened to Simmental meat
whereas the four other breed groups were not different in preference.
In conclusion, no breed group of this study excels in all economically important traits.
The Angus for example were the most rapid to reach 3.5% intramuscular fat with the
least feeding costs. On the other hand carcass quality was the lowest of the six breed
groups of this study whereas sensory quality was judged good. On the other extreme,
Piedmontese had the worst fattening performance at an excellent carcass and meat
quality in accordance with results of the literature. The fattening of steers of this breed
is certainly economically not profitable for the producers who sells animals through the
cunent conventional Swiss market. Namely Piedmontese would need a feedlot-type
ration to reach a sufficient carcass fatness in reasonable fattening duration as well as
carcass weight conesponding to the cunent conventional Swiss market. The still high
cost of concentrate in Switzerland as well as the limited added value through the CH-
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TAX of the very good lean to bone ratio are unfavorable. However, as part of the
marketing through direct selling for example, the producer could compensate the higher
fattening costs by direct benefit from the higher lean yield of the carcass and the high
sensory quality. This last aspect is essential in direct selling knowing that consumers are
ready to pay more for this type of meat but their expectations are also higher. The ideal
breed combining all qualities in growth performance, carcass and sensory quality does
not exist but choice of one breed instead of another one must be determined by the
characteristics specific to the farm, i.e., quantity, type and cost of feed available as well
as economical environment and type of marketing. It remains open whether
crossbreeding of dairy dams with beef cattle sires, which is at present more usual in
Switzerland as the fattening of pure beef breeds, would have better reconciled the
complete range of objectives followed in this study.
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10.Appendix
Resultsofthesensoryevaluationof14dagedM
longissimusdorsi
obtainedfrom
steersofdifferentbreedsslaughtered
atasimilarintramuscular
fatcontent
Variables
Angus
Simmental
Charolais
Limousin
Blonde
d'Aquitaine
Piedmontese
SEM
P-values
Breed
Series
BreedxSeries
n16
16
16
16
16
16
Tenderness
3
Series
1513a
3.95c
488ab
4.94ab
4.15bc
4.18bc
0.314
0.046
Series2
448b
4.02b
430b
4.60b
4.42b
5.61a
0.232
0.001
Flavourintensity
445ab
4.11b
434ab
4.43ab
4.59ab
4.67a
0.120
0.027
0.494
0.095
Juiciness
362c
3.85bc
455abc
4.68ab
4.70ab
4.88a
0.219
0.000
0.059
0907
Preference
4.6lab
436b
484ab
495ab
4.61ab
5.22b
0.165
0.008
0.264
0390
1Meanswithm
thesamerow
lacking
acommon
letter
aresi
gnif
ican
tlydifferent(Tukey,
P<
0.05).
2
Sensory
attributeswerescoredusingthefollowingscalesforte
nder
ness
,flavorintensity,
juicinessandpr
efer
ence-1=verytough,
slight,dr
yandmuch
disliked,
8=
very
tend
er,strong,juicyandmuch
liked
3
Separa
tepresentationoftendernessscores
forseries
1and2becauseofasi
gnif
ican
tinteractionbetweenbreedand
series.
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92
11. Remerciements
J'aimerais remercier en tout premier lieu Piene-Alain Dufey, l'instigateur de ce projet
qui a suscité beaucoup d'intérêt dans les milieux agricoles et de la boucherie. Piene-
Alain a été à la fois un conseiller et un ami. Le travail à ses côtés restera pour moi le
meilleur souvenir de la thèse.
Je suis reconnaissant au Professeur Michael Kreuzer pour la lecture attentive et très
rapide des manuscrits ainsi qu'au Dr. Martin Scheeder pour les discussions à chaque fois
passionnées et stimulantes.
Merci au Prof. Nikiaus Künzi pour avoir accepté de fonctionner en tant que
corapporteur.
Je suis particulièrement reconnaissant à la station fédérale de recherches en production
animale à Posieux (RAP) et à sa directrice Mme Danielle Gagnaux de m'avoir donné
l'occasion de faire ce doctorat dans d'aussi bonnes conditions. Merci spécialement à
Isabelle Morel pour la planification et la conduite de la partie engraissement des
animaux et pour avoir participé comme coauteur à la rédaction d'une des publications de
la thèse. Merci à l'équipe du laboratoire des viandes pour les nombreuses analyses
effectuées dans le cadre de ce projet. La compétence et la disponibilité de Claudine
Biolley et Giuseppina Bächler furent très précieuses, merci aussi à Aude Auriou,
Ghislaine Kutnar, Jessica Messadène, Georges Guex, François Buchs et Denis Robatel.
Un merci particulier à Yves Arrigo, "Monsieur système D", pour pratiquement tous mes
problèmes informatiques et à Edi Lehmann pour sa gentillesse, sa compétence et sa
patience légendaire.
J'aimerais remercier pour leurs conseils précieux et la collaboration agréable André
Chassot tout d'abord, Monique Delacombaz, Gerhard Mangold, Peter Stoll, Josef
Sturny, Roger Daccord, Andreas Gutzwiller et Jean-Yves Deru. La période passée à la
RAP m'a permis aussi de nouer des contacts chaleureux non seulement avec les
personnes ayant directement collaboré au projet mais aussi avec d'autres collègues que
je profite de saluer ici: Bernard Papaux, Claude Chaubert, Franz Jans, Marco Meisser,
Roland Cotting, Walter Stoll, Giuseppe Bee, Ueli Wyss, Andreas Münger, Fredy
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Castella, Marcel Barman, Jean-Louis Gafner, René Vogel, Maria Rodrigues, Léon
Grand, Juliette Sciboz, Guy Maikoff et Hans Schnyder.
Pour terminer les remerciements aux collègues de la station, j'aimerais encore féliciter
l'équipe de l'atelier, Jean-Piene Mettraux, Jean-François Bise, Robert Chassot et Peter
Schäfer, pour leur ingéniosité et remercier les responsables des animaux, Michel Folly
et Gérard Brodard en particulier.
Je tiens à remercier le Prof. Jeny Gresham de l'université de Martin au Tennessee chez
qui je suis allé apprendre la technique ultrasons de détermination in vivo de la graisse
intramusculaire. Il a su par sa motivation me redonner l'énergie nécessaire quand les
résultats obtenus ne conespondaient pas à mes attentes. Je le remercie aussi vivement de
sa contribution active dans la rédaction du papier concernant la technique aux ultrasons.
Merci à la maison SUTER SA et à son directeur Ueli Gerber pour avoir accepté de
participer à ce projet de recherche et surtout pour avoir persévéré malgré la taille et l'état
d'engraissement non conventionnels des carcasses de cet essai. Merci à Hans-Ruedi et
Peter Gerber, Kurt Zenger, Joël Suter, Yvan Mercanton, Max Knecht, Stefan Seiler,
François Caula et Radosavljevic Ratomir pour l'excellente collaboration, leur flexibilité
et les bons moments passés ensemble.
Je remercie Piene Berchier pour les conseils statistiques de même qu'André Chassot.
Mes remerciements vont pour terminer à l'ASVNM (Association suisse des détenteurs
de vache nourrices et mères) et à PROVIANDE pour leur intérêt dans le projet et leur
contribution financière.
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12. Curriculum Vitae
Name:
Born:
Citizen of:
Alain Chambaz
3 March 1971
Arzier, VD
1977-1983
1983-1986
1986-1989
1989
Primary school in Vevey
Secondary school in Vevey
High school in La Tour-de-Peilz (CESSEV)
High school graduation (matura Type B)
1989-1991 Farm apprenticeship at Hans Dumermuth, Belp, Bern and
at Jean-Claude Joliquin, Combremont-le-Grand, Vaud
Agricultural school at Marcelin-sur-Morges
1991-1996 Study of Agricultural Science at the Swiss Federal Institute of
Technology, ETH Zurich, Departement of Agriculture and Food
Science including traineeship in human nutrition at the University
of Lausanne, Faculty of Medicine
1996 Graduation as Dipl. Ing.-Agr. ETH in Animal Sciences
1996-1997 Research assistant in human nutrition at the Nestle Research Center
in Vers-chez-les-Blancs, Lausanne
1997-2001 Doctoral Student at the Swiss Federal Institute of Technology
(ETH) and the Swiss Federal Research Station for Animal
Production, Posieux (RAP)
