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Profitable Farmingof Beef Cows
Editors: Steve Morris
and Duncan Smeaton
2009
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Profitable Farming of Beef Cows
Steve Morris and Duncan Smeaton
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Profitable Farming of Beef Cows
Written by:
Steve T. Morris, Massey University, Palmerston North, New Zealand and
Duncan C. Smeaton, AgResearch, Ruakura Research Centre, Hamilton, New Zealand
Special thanks are expressed to the following wri ters who also contributed:
• John Meban, Veterinarian, Gisborne part Chapter 4
• Chris Morris, AgResearch, Ruakura part Chapters 2 and 4;
sundry technical advice and accuracy checks• David Wells, AgResearch, Ruakura part Chapter 4
• John Pickering, Veterinarian, Whanganui part Chapter 5
• Dorian Garrick, Massey University part Chapter 6
• Kevin Stafford, Massey University Chapter 7
Editorial team:
Duncan Smeaton, Andy Bray, John Meban, Steve Morris, John Journeaux,
Peter Packard, Russell Priest
Printed by: Fusion Print Group Limited, Hamilton
Copyright © NZ Beef Council
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Preface
Professor Steve Morris from Massey University and Beef Production Scientist from
AgResearch, Duncan Smeaton, have, in this book, put together what could be rightfullyconsidered the New Zealand Manual for Beef Cow farming. So complete, thorough andpractical is it that both experienced farmers and new farmers embarking on the bovinetrail will find it as a guiding gospel, complete in its wisdom and forthright in the knowledgeit contains.
Until lately the beef cow has been unable to show just how valuable and profitable shetruly is. Devoted farmers of beef cows of all breeds have known by good old “seat of yourpants” farming that these Queens of the hills have been an integral part of the overallprofitability of their farms. It has been largely due to the eight Beef Focus Farms, in aproject financed by Meat and Wool New Zealand, and the work of the facilitator DuncanSmeaton and his group of scientists from AgResearch, that we now have figures to prove
just how well farmed cows and the relevant backup cattle, have guarded and increasedthe profit of sheep and other stock classes that farm with them. They often do this byeating some of the best feed available, but more often eating the very worst feedavailable too.
The ongoing desire to eat better tasting beef here in New Zealand and supply a bettertasting product to our customers abroad will continually require our beef farmers to haveexpectations of both stock and land that will be hard to fulfil. Confidence that what theyare doing is both technically and financially sound will be a big part in achieving this, andSteve and Duncan and their teams have surely provided a very important footing.
The New Zealand Beef Council had no hesitation in helping sponsor the publication of
this book as an effort in overcoming the somewhat alarming decline in beef cow numbersbeing farmed in New Zealand. Although at the time we were not in complete knowledgeof all the data that the focus farms were producing, we felt that as beef cows were thelynch-pin of the prime beef industry they needed some up-to-date reference material foruse by many sections of the farming industry as well as a reference for teaching.
As with most agricultural sciences in the modern world, beef breeding is a moving targetand improvements and refinements come upon us at a sometimes alarming rate. I’m surethat before too long some of the methods referred to here will have been updated andbrought into line with what-ever edict is coming down the pipe. I am equally sure that thevast amount of learning this publication has to offer can be relied upon as sound sciencefor many years to come.
John Wauchop, Chairman, NZ Sheep and Beef Council and Meat & Wool New Zealand.January 2009
Note to Readers:
There are 2 condition score (CS) systems in place for recording beef cow body condition orfat cover. One system operates on a 0 (emaciated) to 5 (fat) scale, the other systemoperates on a 1 (emaciated) to 10 (fat) scale. The systems are described in the book.
Whenever CS is discussed in the book, the value for the first system is noted, followed bythe value for the second system in brackets. For example, CS 2.0 (4).
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Table of Contents
Chapter 1: Introduction ...................... ...................... ......................... ...................... .............. 1
Summary ........................................................................................................................... 11.1. The importance of the breeding cow to the beef industry ......................... .............. 21.2. Beef breeding cow herds ...................... ....................... ...................... ................... 41.3. Breeding cows versus other sheep/beef enterprises .................... ...................... ... 7
1.3.1 Key points ..................... ...................... ......................... ...................... .............. 71.3.2 High vs. average performance cows .................. ......................... ...................... 71.3.3 Simplistic calculation of enterprise biological and gross margin performance .... 81.3.4 Calculating the full value of breeding cows on sheep and beef farms ................ 9
1.4. Beef herd sizes ........................ ...................... ...................... ......................... ...... 131.5. Further reading .................. ......................... ...................... ...................... ............ 14
Chapter 2: Weight of calves weaned and cow efficiency ...................... ................... ............ 15Summary ......................................................................................................................... 152.1 Introductory comments ....................... ...................... ......................... ................. 162.2 Setting and achieving calving date and calf weaning weight targets .................... 162.3 Optimum cow liveweight and cow efficiency ...................... ...................... ............ 182.4 Genetic selection for cow efficiency .................... ...................... .......................... 192.5 Other pathways to cow efficiency ..................... ....................... ...................... ...... 212.6 Cow liveweight and pasture damage ...................... ......................... .................... 212.7 Weaning date, calf age at weaning .................. .......................... ...................... ... 222.8 Further reading ........................ ...................... ...................... ......................... ...... 23
Chapter 3: Feeding beef cattle........................... ....................... ......................... ................. 24
Summary ......................................................................................................................... 24
3.1 Introduction .................... ...................... ....................... ......................... .............. 253.2 Energy requirements of cattle ..................... ......................... ...................... ......... 25
3.2.1 Requirements for maintenance .................. ......................... ...................... ...... 263.2.2 Requirements for pregnancy ...................... ......................... ...................... ...... 273.2.3 Requirements for lactation and calf growth ...................... ...................... ......... 283.2.4 Liveweight loss or gain ..................... ....................... ......................... .............. 29
3.3 Calculating feed requirements ....................... ...................... ...................... ......... 303.4 Management and nutrition of the beef cow ..................... ....................... .............. 31
3.4.1 General comments ......................... ...................... ...................... .................... 313.4.2 Post-weaning (weaning through to 4-6 weeks pre-calving) .................. ............ 313.4.3 Pre-calving (from 4-6 weeks pre-calving to calving) .................... .................... 323.4.4 Calving to mating ...................... ......................... ...................... ...................... . 333.4.5 Mating - weaning ...................... ...................... ...................... ......................... . 35
3.5 Matching nutritional requirements to the seasonal pasture supply pattern ........... 353.6 Supplementary feeding of beef cows ..................... ...................... ....................... 363.7 Assessing the adequacy of feeding .................. ....................... ...................... ...... 383.8 Condition scoring .................. ...................... ...................... ...................... ............ 393.9 Further reading ........................ ...................... ...................... ......................... ...... 41
Chapter 4: Reproduction in the beef cow herd .................... ......................... ....................... 42
Summary ......................................................................................................................... 424.1 Introduction .................... ...................... ....................... ......................... .............. 434.2 Potential reproductive rate .................... ....................... ......................... .............. 454.3 Reproductive management of beef cattle ..................... ...................... ................. 49
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4.3.1 Management and age at first calving of heifers ..................... ....................... ... 494.3.1.1 Critical minimum weight .................... ......................... ...................... ...... 524.3.1.2 Checklist for successfully mating heifers at 15 months ..................... ...... 52
4.3.2 Time and duration of calving ...................... ...................... ...................... ......... 534.3.3 Age of cow and reproductive performance .................... .................... .............. 544.3.4 Calving difficulty (dystocia) ..................... ...................... ...................... ............ 554.3.5 Post-partum anoestrus interval .................. ...................... ...................... ......... 584.3.6 Bull management ........................ ...................... ...................... ....................... 604.3.7 Pregnancy diagnosis ...................... ...................... ...................... .................... 62
4.3.7.1 Two methods of pregnancy diagnosis..................................................... 624.4 New reproductive technologies for use in beef breeding cows .................... ......... 63
4.4.1 Oestrus synchronisation ...................... ...................... ......................... ............ 644.4.2 Artificial insemination (AI) ................. ......................... ....................... .............. 644.4.3 Producing twin pregnancies ....................... ......................... ...................... ...... 654.4.4 Changing average calf sex ratio ...................... ...................... ......................... . 664.4.5 Cloning .................. ......................... ...................... ...................... .................... 674.4.6 DNA parenting ..................... ...................... ...................... ......................... ...... 67
4.5 Further reading ........................ ...................... ...................... ......................... ...... 68
Chapter 5: Cow health ......................................................................................................... 70
Summary ......................................................................................................................... 705.1 Grass staggers (Hypomagnesaemia) ..................... ...................... ...................... . 71
5.1.1 Overview ................. ......................... ....................... ......................... .............. 715.1.2 Magnesium supplementation ..................... ......................... ...................... ...... 72
5.2 Facial eczema ...................... ......................... ...................... ...................... ......... 755.3 BVD in beef cattle ...................... ...................... ......................... ....................... ... 76
5.3.1 Persistently Infected (PI) animals .................... ...................... ....................... ... 765.3.2 How does the virus affect cattle? .................... ...................... ....................... ... 775.3.3 Control of BVD ...................... ...................... ......................... ....................... ... 78
5.4 Nitrate poisoning................................. ...................... ...................... .................... 79
5.5 Bloat ....................... ...................... ...................... ...................... ......................... . 795.5.1 Overveiw ................. ......................... ....................... ...................... ................. 795.5.2 Management measures to reduce the risk of bloat ...................... .................... 80
5.6 Further reading ..................... ......................... ...................... ...................... ......... 80
Chapter 6: Genetics of calf production from beef cows ................... ....................... .............. 81
Summary ......................................................................................................................... 816.1 Introduction ................. ......................... ....................... ...................... ................. 82
6.1.1 Selection decisions ......................... ...................... ...................... .................... 846.2 Selection objectives ...................... ...................... ...................... ......................... . 87
6.2.1 Breeding objectives ..................... ...................... ...................... ....................... 876.2.2 Economic weights and values ...................... .......................... ...................... ... 886.2.3 The importance of future prices ......................... ...................... ...................... . 88
6.2.4 Selection criteria .................... ...................... ....................... ......................... ... 896.3 Estimated Breeding Values (EBVs) ..................... ....................... ........................ . 90
6.3.1 Growth EBVs ......................... ....................... ...................... ......................... ... 916.3.2 Reproduction EBVs ..................... ...................... ...................... ....................... 926.3.3 Carcass EBVs ....................... ...................... ....................... ...................... ...... 936.3.4 Additional EBVs available ................. ....................... ...................... ................. 946.3.5 Accuracy of EBVs ..................... ...................... ......................... ...................... . 956.3.6 Profitable use of EBVs ...................... ....................... ......................... .............. 96
6.4 Index Selection (BreedObject) ....................... ...................... ...................... ......... 976.4.1 Angus BreedObject ..................... ...................... ...................... ....................... 986.4.2 Hereford BreedObject ..................... ...................... ...................... .................... 99
6.5 Selecting breeding females ...................... ...................... ...................... ............. 1006.6 Evidence of genetic progress ................... ...................... ....................... ............ 102
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6.7 Choice of breed ......................... ....................... ...................... ...................... .... 1036.8 Breeding systems ...................... ...................... ....................... ...................... .... 1076.9 Crossbreeding ...................... ...................... ...................... ...................... .......... 108
6.9.1 Alternative crossbreeding systems........................ ...................... .................. 1096.9.2 Composite breeds .................... ...................... ...................... ........................ 1126.9.3 Alternating breeds over time ...................... ...................... ................... .......... 1126.9.4 Benefits of crossbreeding ................. ....................... ...................... ............... 1126.9.5 Disadvantages of crossbreeding .................. ....................... ...................... .... 113
6.10 Further reading ..................... ...................... ......................... ...................... ....... 114
Chapter 7: Beef cattle handling and yarding ........................................ ...................... ....... 116
Summary ....................................................................................................................... 1167.1 Introduction ................. ......................... ....................... ...................... ............... 1167.2 Cattle handling: Moving cattle ....................... ...................... ...................... ....... 1177.3 Working in yards ................... ......................... ...................... ...................... ....... 1187.4 Using forcing pens ..................... ....................... ...................... ...................... .... 1197.5 Working in races ................... ......................... ...................... ...................... ....... 1207.6 Yard design .................... ...................... ....................... ...................... ............... 1217.7 Conclusions .................... ...................... ....................... ...................... ............... 1227.8 Further reading ..................... ...................... ......................... ...................... ....... 122
Appendix 1: Condition scoring (CS) for beef cows ....................... ................... .................. 123
Appendix 2: Nutrient composition of commonly available feeds for cattle and sheep ......... 128
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Profitable Farming of Beef Cows Chapter 1: Introduction
1
Chapter 1: Introduction
Summary
The beef cattle industry in New Zealand is made up of 4.3 million cattle of which
1.13 million (2008) are breeding cows. Traditionally, the New Zealand beef herd has been
based upon calves produced by breeding cows. An alternative system involves purchasing
4-day-old calves from the dairy herd and raising these as bulls or sometimes steers for
slaughter, or as replacement heifers in the beef breeding herd.
Achievable production objectives for a commercial beef breeding cow herd are to:
• Rear to weaning 90-95 calves per 100 cows mated each year for 63 days or less
• Grow suckling calves at greater than 1.0 kg/head/day
• Maintain a low death rate in the cow herd (2 to 3% per annum)
• Use the breeding cow herd to promote and maintain pastures.
At an assumed national average calving percentage (calves weaned/cows mated) of 80%,
the beef cow requires around 16 kg of dry matter per kg of calf weaned. The average beef
cow produces 0.30 kg calf weaned/kg cow weaning weight. In contrast, a high performing
cow produces 0.48 kg calf weaned/kg cow weaning weight (calculated as a 450 kg cowweaning 92% calves per cow mated, with calves growing at 1.1 kg/calf/day for 180 days)
and is more profitable. Very few farmers get all the components of high cow productivity
right all the time. Clearly it is a difficult business.
Breeding cows are often seen as being less profitable than other stock but this usually
excludes the effects of the beef cow on pasture quality. Recent results have shown that for
much of the year, many breeding cows consume poor quality herbage which is of little or no
value to other stock classes. On this poor quality feed, cows are more profitable than other
live stock classes. Other benefits include lower labour requirements. The cow needs to
play a complementary rather than competitive role to maximise these extra benefits. If a
farm produces only high quality pasture, then the pasture management benefits from cows
are likely to be low.
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Profitable Farming of Beef Cows Chapter 1: Introduction
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Beef herd sizes are highly skewed because many small holdings (lifestyle blocks) run just a
few beef cattle. About 45% of beef cattle farms have less than 50 cattle and account for
only 7% of total beef cattle. At the other extreme, 6% of farms have over 500 beef cattle.In aggregate, these farms hold 41% of the total beef cattle.
1.1. The importance of the breeding cow to the beef industry
The beef cattle industry in New Zealand is based on a national herd of around 4.3 million
cattle. Considerable variation in the size of the national beef herd has occurred over the last
two decades. Beef cattle numbers peaked at 6.3 million in 1975 then subsequently
declined to 4.5 million in 1983. Currently (2008) the national beef breeding cow herd
numbers 1.13 million.
In New Zealand beef cattle and sheep are usually farmed together, and are complementary
to one another especially under hill country conditions. It is relatively easy for producers to
alter their mix of sheep and cattle to suit current economic conditions and preferences. The
main driving force behind this substitution is the relative profitability between cattle and
sheep. Growth in beef cattle numbers has occurred since 1983 but numbers today are
relatively static at around 4.5 to 5.0 million with fluctuation being mainly due to changes in
the number of dairy and dairy beef cross calves reared for beef production.
Traditionally, the New Zealand beef herd has been based upon the beef breeding cow
producing calves. Normally bull calves are castrated and raised as steers for slaughter
either on breeding or finishing farms. The latter are usually located on better class country.
Heifer calves replace the old and cull cows within the breeding herd and those that fail to
get pregnant. While this management system is practised around the country an alternative
system using calves from the dairy herd has come into prominence. Four-day-old calves
are purchased from the dairy herd and raised as bulls or sometimes steers for slaughter.
Beef breed x Friesian heifers are raised for replacements in the beef breeding herd. The
advantages for the bull system are two-fold. Firstly, there is no capital overhead tied up in a
beef-breeding herd, so more capital can be used for direct income generation. Secondly,
relatively more feed goes into production than maintenance, making this system more
efficient. Needless to say, some traditional beef cow herds are also very efficient.
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Profitable Farming of Beef Cows Chapter 1: Introduction
3
During the spring of the 2006 season the number of dairy calf retentions for beef production
was estimated at around 529,000, equivalent to around 38% of the total calves entering the
beef herd.
With an increasing percentage of the New Zealand beef herd being derived from the dairy
herd, the ratio of beef breeding cows and heifers in the national herd has declined from
36% in 1972-1973 to 27% in 2007-2008 with a resultant increase in “trading” or finishing
stock (see Table 1.1 where they are classified as “other cattle”). Unless retention of female
beef stock numbers increases, future growth and annual fluctuations in beef cattle numbers
will primarily be due to the number of dairy calves originating from the dairy industry that
are reared for beef production.
Another likely reason for the decline in breeding cow numbers is due to their perceived
poorer profitability. On a gross margin / kg DM basis, they are less profitable, but this
excludes the effects of the beef cow on pasture quality. In fact, the breeding cow is
significantly more profitable than other stock classes on poor quality feed. The cow needs
to play a complementary rather than competitive role to maximise these extra benefits.
About 78% of New Zealand’s beef herd is located in the North Island. While relatively
evenly distributed throughout the North Island, the Northland//Waikato/Bay of Plenty region
has 35% of the total herd. Table 1.2 lists the major beef cattle producing regions. A recent
change in cattle numbers is occurring in the lower part of the South Island where
substantial numbers of dairy beef calves are now being sourced from the increasing
number of dairy farms in the region.
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Table 1.1: Composition of the New Zealand beef herd (000) (as at 30 June).
Year 1973 1993 2008
Total Beef Herd 5,343 4,676 4,253
Breeding Cows 1,907 1,419 1,126
Other Cattle 3,436 3,257 3,127
Breeding cows as% of total
36 30 27
Source: Meat & Wool New Zealand Economic Service.
Table 1.2: Beef cattle numbers by local region (as at 30 June 2008)
Region Number of Beef Cattle (000) % of Total Cattle
Northland/Waikato/BOP 1,489 35
East Coast 1,060 25
Taranaki/Manawatu 509 12
NORTH ISLAND 3,058 72
SOUTH ISLAND 1,196 28
NEW ZEALAND 4,253 100
Source: Meat & Wool New Zealand Economic Service, paper P08031 25 July 2008.
1.2. Beef breeding cow herds
The breeding cow herd is dominated by two breeds, the Angus and Hereford. The heavier
European breeds began to be imported in the late 1960's and some, especially Simmental,
Charolais, South Devon and Limousin have made an impact as terminal sires, where, with
rare exceptions all progeny (both male and female) are sold for slaughter or to finishing
farms. There has also been an increased use of beef x dairy breeding cows to take
advantage of Friesian genes for higher milk and beef production. It is estimated (2007) that
the national herd consists of 23% Angus, 11% Hereford and 11% Hereford x Angus. Angus
and Hereford crosses would also contribute to a group classified as mixed crosses (36%)
while Friesian cross (12%) and others (7%) make up the rest (derived from data from
Meat & Wool New Zealand Economic Service).
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Profitable Farming of Beef Cows Chapter 1: Introduction
5
Achievable objectives for a commercial beef breeding cow herd are to:
• Rear to weaning 90-95 calves per 100 cows mated each year for 63 days or less
• Grow suckling calves at greater than 1.0 kg/head/day• Maintain a low death rate in the cow herd (2 to 3% per annum)
• Use the breeding cow to promote and maintain pasture quality
The national average calving rate (the number of calves weaned as a % of cows mated) is
82% (range 79% to 86%) and has remained at this level for the last 35 years. Age of first
calving is usually 3 years although approximately 30% of all heifer replacements now calve
at 2 years of age. The top third of herds in any year have an average 90% calving rate or
better. There is potential for increased reproductive performance of the beef herd within the
constraint of a natural ovulation rate of 1.0 in cattle.
Because the overall output of a breeding cow herd is dependent on both weaning
percentage and weaning weight of the calf, these are often combined into a term called cow
productivity.
However, the total feed consumed by large cows is greater than that of small cows. To
take account of this the term weight of calf weaned per cow joined (i.e. the productivity)
divided by the cow liveweight (usually autumn or weaning weight but some farmers prefer
to use winter liveweight) is a commonly used measure of biological efficiency in the beef
breeding cow herd.
As a general rule, smaller cows that wean heavy calves (in excess of 50% of their damautumn liveweight) are more efficient. This is probably easier to achieve with some form of
crossbreeding where a larger terminal sire breed is crossed with a smaller dam breed.
The difference in annual feed consumption (kg dry matter/head/year) for three different cow
liveweight types (small, medium and large) means small cows rearing small calves can be
just as efficient and profitable as large cows rearing large calves. Table 1.3 illustrates that
there are a range of cow types that can give similar productivity and returns. If each of the
cows in Table 1.3 rears 50% of their own autumn liveweight to sale as weaner calves they
Productivity =no. of calves weaned x Av. weaning weight
no. of cows joined with bull
Efficiency =Productivity
Cow liveweight
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Profitable Farming of Beef Cows Chapter 1: Introduction
6
are then all equal in terms of $ return per kg of feed eaten or per stock unit. It is high
productivity irrespective of cow size that makes a beef cow herd profitable
Table 1.3: Seasonal liveweights and production data for three different beef breeding
cow types and calculations of efficiency and profitability (note liveweights exclude the
weight of conceptus). The calculations assume that small vs. large weaners are worth the
same per kg liveweight.
Small Medium Large
Weaning (kg) 430 470 550
Mid-winter (kg) 380 420 500
Pre-calving (kg) 380 420 500
Mating (kg) 410 450 530
Calf wean wt (kg) 215 235 275
Feed eaten per cow (kg DM) 2880 3131 3657
Number of cows 100 92 79
Number of calves
(at 80% CW/CM*)80 73.6 63.2
Kg DM/kg Calf weaned 16.7 16.8 16.6
Return/kg feed ($) 0.186 0.187 0.187
Gross margin ($ / SU) 105 107 108
* Calves weaned per cows mated.
If a beef cow herd is not productive then the other benefits of keeping this class of stock
need to be large to compensate (i.e. improved sheep performance). These other benefits
have proven difficult to quantify although recent trial results described below provide more
information.
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Profitable Farming of Beef Cows Chapter 1: Introduction
7
1.3. Breeding cows versus other sheep/beef enterprises
1.3.1 Key points• In single enterprise analyses comparing profitability of breeding cows, finishing
cattle and breeding ewes, breeding cows usually appear less profitable. However,
this analysis does not take into account the other benefits cows may provide within
the farm system.
• Cows can play a valuable complementary role in managing pasture quality on sheep
and beef farms but this is difficult to value. Results from the recently completed
Meat & Wool New Zealand Beef Focus Farm project have shown that for much of
the year, many breeding cows consume poor quality herbage which is of little to no
value to other stock classes. On this poor quality feed, cows are more profitable
than other live stock classes. Other benefits include less labour requirements.
1.3.2 High vs. average performance cows
Accumulated figures for breeding cows on New Zealand hill country farms (Meat & Wool
New Zealand Economic Service) indicate that the average beef cow herd is performing well
below potential in that:
• 80 to 82 calves are weaned per 100 cows mated
• Calves grow at a little over 0.8 kg per day from birth to weaning (accurate figures
not available)
• 0.30 kg calf weaned/kg cow liveweight is produced (calculated as a 500 kg cow
weaning 82% calves per cow mated, with calves growing at 0.90 kg/calf/day for
180 days)
The above implies that one in five cows are non productive, and the pasture these animals
consume therefore represents a lost opportunity. This is partially offset if farmers cull empty
cows at weaning but this has an added cost in terms of higher replacement rates.
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Profitable Farming of Beef Cows Chapter 1: Introduction
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In contrast, high producing cows in the recent Beef Focus Farm Project funded by
Meat & Wool New Zealand (2008):
• Weaned in excess of 92 calves per 100 cows mated
• Grew their calves at 1 to 1.2 kg/head/day from birth to weaning
• Produced 0.48 kg calf weaned/kg cow weaning weight (calculated as a 450 kg cow
weaning 92% calves per cow mated, with calves growing at 1.1 kg/calf/day for
180 days).
• Were more profitable (Table 1.4).
High performing cows are often beef x dairy cross cow mated to a terminal sire thereby
taking advantage of hybrid vigour. In this system, all calves are finished for beef, withreplacements sourced from outside the herd.
Trial results indicate that the high levels of performance described above are routinely
achieved on some farms with the cow still carrying out her complementary role of pasture
management, provided the cow can regain any lost weight during the crucial calving to early
mating period. Even so, very few farmers get all the components of high cow productivity
right all the time. Clearly it is a difficult business. The prioritisation of other stock classes
over breeding cows is often the root cause of poor cow performance. Farmers who achieve
high levels of cow performance while using cows for pasture management have learnt the
critical elements that allow these two conflicting goals to be met.
1.3.3 Simplistic calculation of enterprise biological and gross margin
performance
When various sheep and beef systems are compared on a single enterprise basis, results
such as shown in Table 1.4 can be derived.
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Profitable Farming of Beef Cows Chapter 1: Introduction
9
Table 1.4: Comparison of four single-enterprise systems modelled using Farmax, each
on the same pasture growth curve.
Average **performance
cow
High **performance
cow
HighFertility
ewe1yr bullsystem
GM* $/ha 449 680 717 796
GM c/kg DM 6.6 8.9 8.6 10.7
Net LWG/ha 350 490 591 908
kg DM/kg LWG 20 16 13 8
* Gross Margin
** As described in section 1.3.2
Average performing beef cows are less productive and profitable than some other
enterprises largely because of their high maintenance requirement and the apparently
non-productive period from weaning to just before calving in terms of product gain/kg DM
eaten. If cows could rear and wean two calves via twin pregnancy that would cause a
quantum leap in productivity and probably profit, but that is mostly outside current
technology. Table 1.4 demonstrates that finishing systems, such as the bull system shown,
are more efficient biologically, and also currently more profitable. High fertility ewes are
also relatively efficient, and are often very competitive financially.
However , the above gross margin analysis can be misleading because it takes no account
of the complementary role that one stock class provides for another within a full farm
system.
1.3.4 Calculating the full value of breeding cows on sheep and beef farms
It is generally recognised that cows play an important role in maintaining pasture quality on
many farms, benefiting other live stock. Cows can also lose a lot of weight during poor
winters, freeing up feed for other less resilient stock. This effect was studied in the recent
Beef Focus Farm Project funded by Meat & Wool New Zealand (2008). On the Northland
farm in this project, cows spent summer, autumn and winter cleaning up behind other live
stock. The quality of the pasture being consumed by the cows was monitored on a monthly
basis for the cows, and for the other stock the cows were complementing. On one of the
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10
blocks on the farm, the cows predominantly grazed on medium to steep hill land (with
approximately one quarter of the pasture having a Kikuyu base) and the cows followed
behind ewes and lambs. The other block was rolling to medium hill land with approximately90% of the pasture Kikuyu based and cows grazed among young cattle.
The grazing residual results showed that the cows were restricted most, during
summer/autumn and early winter, when they were cleaning up behind the other stock
classes (Figure 1.1) but that in spring, they fared much better.
Figure 1.1: Average post-grazing herbage mass of breeding cows and other stock
classes (Northland Focus Farm).
In general, the quality (MJ ME/kg DM) of pasture offered to the cows was poorer than that
grazed by the other live stock (Figure 1.2). The quality of the diet offered to the cows
changed with season to a greater extent than that of the other live stock classes, reflecting
the ability of management to prioritise better quality feed to other live stock classes during
seasons when poor quality feed was present (summer and autumn). Over the 3 years of
the study, the average metabolisable energy concentration (ME) of pasture consumed by
cows was 8.8 vs. 10.3 MJ ME/kg DM for the other stock classes the cows were
complementing.
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Figure 1.2: Average metabolisable energy content of pasture offered to the breeding
cows and other livestock classes.
Cow liveweights and condition score peaked during summer in response to good feed
availability during spring and early summer (Figure 1.3) and declined again during late
summer and autumn. Despite the poor quality of feed and loss in cow liveweight, each year
the calves grew at greater than 0.6 kg/day during the late summer/autumn period and
greater than 0.8 kg/day over the whole lactation period. This demonstrates the ability of the
cow to buffer the calf, through liveweight loss and milk production during this period on poor
quality pasture.
Figure 1.3: Average cow (conceptus-free) liveweight and condition score (on a 1 – 10
scale).
Observations on a second focus farm in the same project as reported above, in Southland,
showed similar buffering effects by the cow.
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If the poor quality herbage is not consumed by cows then it either will be consumed by
another stock classes or it will decay. In the Focus Farm Project, the former option was
tested using the computer models Q-Graze and Farmax (see Further Reading). The weightgain or loss of 2-year-old bulls fed the same quality of pasture as the cows was calculated.
As with the breeding cows, the 2-year bulls were predicted to gain weight during spring and
early summer and then lose weight during autumn and early winter (Figure 1.4).
Figure 1.4: Estimated two year bull liveweight gain (kg/head/day) if fed on the same
herbage as the breeding cows on the Northland farm, as calculated by Q-Graze. The
change in value of 2-year bulls ($/head/day) is based on liveweight change and seasonal
store market values.
Total liveweight gain by the bulls for the year was calculated at only 38 kg. The analysis
showed a total annual increase in bull value of $128 per cow equivalent. In contrast, cows
were calculated to be returning $363 per head (after losses). That is, the cows returned a
gross margin income of $235/cow more than the bull equivalent system could have done on
the same feed. A similar exercise on the Southland farm showed a similar result.
No one would normally farm finishing animals in the way shown above, but it does illustrate
the fact that the pasture that the cows are consuming has very little value to other live stock
classes for a large portion of the year. In fact there are times when this herbage could be
considered a liability rather than an asset.
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If a farm produces only high quality pasture, (though intensive subdivision etc) then the
above benefits due to running cows are likely to be much less and returns will be closer to
the enterprise results in Table 1.4. In this situation, cows should be replaced by higherreturn stock classes. However, it should be noted that intensive subdivision is not feasible
on many hill country farms.
1.4. Beef herd sizes
Beef herd sizes are highly skewed because of the many small holdings (lifestyle blocks)
which run a few beef cattle. Figure 1.5 shows that small holdings make up the majority of
farms with beef cattle. However, these small holdings have a relatively small proportion of
the total beef herd. For example, 22% of the beef holdings have less than 10 beef cattle.
In aggregate, these holdings have just over 1% of the total beef cattle. About 45% of beef
cattle farms have less than 50 cattle and account for only 7% of total cattle. This group of
farms are likely to be less responsive to industry conditions than the larger more
commercial farms. At the other extreme, 6% of farms have over 500 beef cattle. In
aggregate, these farms have 41% of the total beef cattle.
Figure 1.5: Beef cattle herd size distribution by % of cattle and % of farms, June 2002
Source: Statistics New Zealand (2002) Agricultural Production Census – Note that this is
the most recent information available.
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1.5. Further reading
AgResearch. 2002. In “Pasture quality: Principles and management, The Q Graze Manual.
A reference document to accompany The Meat New Zealand pasture quality
workshops, Published January 2002 Meat New Zealand, PO Box 121, Wellington,
pp 1-26.
Farmax. A decision support model for livestock farms. www.farmax.co.nz
Marshall, P.R.; McCall, D.G.; Johns, K.L. 1991. Stockpol: A decision support model for
livestock farms. Proceedings of the New Zealand Grasslands Association. 53:
137-140.
Meat & Wool New Zealand Economic Service. Various reports, available onwww.meatandwoolnz.com
Smeaton, D.C. 2003. Profitable Beef Production. A guide to beef production in
New Zealand. Published by the New Zealand Beef Council. ISBN: 0-473-09533.5.
Smeaton, D.C.; Boom, C.J.; Archer, J.A.; Litherland, A.J. 2008. Beef cow performance and
profitability. Proceedings of the 38th seminar of the Society of Sheep and Beef
Cattle Veterinarians NZVA, pp 131- 140.
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Chapter 2: Weight of calves weaned and cow efficiency
Summary
The total weight of calves weaned is the key production output of the breeding cow herd
and is the end result of many input factors. About 70% of the variation in weaning weight of
calves is due to differences in milk production of the dam. To achieve high calf weaning
weights cows must be well fed before and after calving. A high level of feeding after calving
is also necessary for a high conception rate at rebreeding. Date of weaning should depend
on feed supply.
The best cow for hill country is a medium sized cow that weans a high proportion of its
liveweight in calf weaning weight. The optimum liveweight of mixed-age Hereford x Friesian
cows is estimated to be 430 to 450 kg at mating. In a trial, cows at optimum weights, and
rearing a live calf, weaned calves at 180 days of age that were 52% of their mother’s
liveweight at mating. Including losses due to empty cows and calving losses, the ratio
dropped to 44%. The average rate of calves weaned per cow mated in this case was 82%.
Selecting to improve the efficiency of feed conversion in a cow herd has been proposed as
an alternative to selecting for growth rate. Feed conversion ratio is a measure of the
amount of feed eaten per unit of bodyweight gain or carcass weight gain. Net feed
efficiency refers to variation in feed intake between animals beyond that related to
differences in growth and liveweight. Selection for this should reduce herd feed costs.
Ranking animals on net feed efficiency requires measuring differences in their feed intake,
liveweight and growth rate over a defined test period.
Selecting cows for lifetime productivity at first weaning can be advantageous but requires
tagging of calves with their birth mothers. The process is complex, but the gains are there iffarmers are willing to invest the time.
Efforts have been made to improve cow productivity through multiple suckling via one
means or other, but commercial success remains elusive because of technical and
biological limitations. In the meantime, the best objectives are to run cows at optimum
weights, take maximum advantage of their ability to gain and lose weight to support milk
production and to maintain pasture quality, achieve high pregnancy rates and survival and
take maximum advantage of genetic opportunities and hybrid vigour.
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2.1 Introductory comments
The total weight of calves weaned by the herd is a key production output of the
breeding cow herd.
It is a reflection of:
• Reproductive success; clearly, empty cows do not wean a calf
• Feeding levels of cow and suckled calf
• Cow and calf genetics, hybrid vigour
• Cow and calf health
• Age at weaning (for comparative purposes, a standardised weaning age of 180 days
is often used).
The weaning weight of an individual calf from a cow is dependent on the above factors and
also more specifically:
• Cow milk production (in turn dependent on numerous factors)
• Age of dam
• Age of calf at weaning, affected in turn by:
• Calving date
All the above are discussed in the various chapters of this book. The material below
discusses management aspects of integrating these factors.
2.2 Setting and achieving calving date and calf weaning weight targets
The ability to wean heavy calves has become progressively more important in conventional
single-suckled breeding-herds because of the trend towards selling cattle for slaughter at a
younger age. This means that growth to weaning represents a higher proportion of total
growth to slaughter.
Calf weaning weight targets will be specific to the farm in question but a minimum liveweight
gain target for a suckled calf on hill country should be 1.0 kg/calf/day. Typically in
New Zealand it is less than this, particularly if the cow is expected to do a lot of pasture
quality management work. Most beef calves are weaned at around 5 to 7 months of age
resulting in calf weaning weights in the range of 180 to 240 kg (assuming a 35 kg birth
weight). Some farmers achieve weights of up to 280 kg/calf. The importance of a
condensed calving (target of 70% of cows calving in the first 21 days of calving) within an
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appropriate calving period (where the planned start of calving is synchronised with pasture
supply) cannot be underestimated because of its effect on calf weaning weight and cow re-
breeding performance. Many commercial beef herds calve too early in the spring. Theusual sign for this is a slow start to calving (less than 50% calved in the first 21 days of
calving) which compromises calf weaning weights and cow rebreeding performance.
The rate of growth of the suckling calf largely depends on the cow’s milk supply, which in
turn depends on the food available to the cow. Some research suggests that about 70% of
the variation in weaning weight of calves is due to differences in milk production of the dam.
A calf can consume 10-15% of its liveweight as milk each day. A 50 kg calf can drink 7-8 kg
milk per day and at this rate will grow at 1.0 kg liveweight gain/day. As the calf grows, its
capacity to drink milk increases and there are obvious advantages if the cow can increase
her milk production to match this demand. A calf at 120 days weighing 150 kg could
consume around 15 kg of milk. It is highly unlikely a cow would produce that much milk at
that stage and so the calf gets its extra nutrients by consuming pasture.
To achieve high calf weaning weights, cows must be well fed before and after calving. A
high level of feeding after calving is also necessary for a high conception rate at rebreeding.
Experience suggests that a feed budget should allow for a cow to eat in excess of 12 kg
DM/day from the day of calving. How this will be achieved depends on the date of calving,
and may require feed saved from late winter. Cows will often buffer their calves against
underfeeding in early lactation by losing liveweight to maintain calf growth. However, this
can not happen in poor conditioned cows (CS 2 (4) or less), so it is therefore desirable to
have cows in a condition score of 2.5 (5) or better at calving. A recent trial at Massey
University indicated that for heifers, a sward (pasture) height of 6 cm is sufficient in the first
month after calving increasing to 10-12 cm during the second month.
Date of weaning should depend on feed supply (it often depends on labour availability and
sale date). If there is ample feed, there is little to be gained from early weaning unless there
is an opportunity to use the cows in a mob for pasture control or preparation for other
classes of stock. However, if hill country pastures dry out badly in summer, calves could be
weaned and put onto what fresh pasture is available and the cows fed hard rations to
relieve grazing competition.
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2.3 Optimum cow liveweight and cow efficiency
The best cow for hill country is a medium sized cow that weans a high proportion of its
liveweight in calf weaning weight. The cow needs to be in good condition at weaning so
she can then use her excess body condition as “supplementary feed” over the winter
months. In fact, cows should be at their maximum liveweight and condition at weaning
indicating they have eaten as much as possible of the excess spring-summer feed that
usually occurs on hill country properties.
It is possible for cows to wean calves (at 180 days age) that weigh 50% to 60% of the cow’s
weight (compared to 35% to 45% on average). This is neither a new objective nor is it easy
to achieve. In a project at Whatawhata Research Centre (Smeaton and others 2000) theoptimum liveweight of mixed-age Hereford x Friesian cows was estimated to be 430 to
450 kg (Figure 2.1). Anecdotally, many farmers run their cows at weights significantly
heavier than this, thereby foregoing productivity advantages and running some risk of
surplus fat in the udder which can jeopardise milk production (especially in heifers). At
optimum weights in the Whatawhata project, cows rearing a live calf weaned calves at 180
days of age that were 52% of their mother’s liveweight at mating. Including losses due to
empty cows and calving losses, the ratio dropped to 44%. In summary cow productivity is
extremely sensitive to:
• Cow liveweight relative to calf weaning weight
• Pregnancy rate
• Cow survival
• Calf survival, mostly around the calving period
Figure 2.1: Illustration of optimum liveweight for Hereford x Friesian breeding cows
Source: Reworked data from Smeaton and others (2000).
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2.4 Genetic selection for cow efficiency
(other breeding traits are discussed in Chapter 6)
Traditionally, beef producers improve their herds by selecting for growth. Growth is an easy
and economical trait to measure and is moderately heritable. Selection for growth traits has
resulted in faster growing cattle, however it has also resulted in the introduction of some
correlated undesirable traits such as increased birth weights leading to calving difficulties,
delayed sexual maturity and increased herd maintenance requirements associated with the
feed costs of larger animals.
In most beef cattle production systems, researchers have established that 65% to 85% of
total feed intake is required by the breeding cow herd, and that half of the total feed intake is
required just to maintain cow liveweight. The costs of maintaining the breeding cow herd is
clearly an important factor determining the efficiency of beef production.
Despite its economic importance, farmers in New Zealand do not usually assess the cost of
feed for their farming operation. The complementary roles of beef cattle on sheep farms
complicate the economic assessment of feed efficiency in New Zealand’s mixed livestock
farming systems as discussed elsewhere. However, as profitability is a function of both
inputs and outputs, there is a need to consider avenues for reducing inputs in order toimprove efficiency of production and increase profits.
By selecting to improve the efficiency of feed conversion in a herd, the producer can strive
to improve the efficiency of converting feed to gain, rather than concentrating on growth
alone. Different measures of the efficiency of growth have evolved over the years because
of the complex nature of feed use in the animal. The most commonly used definitions to
describe the efficiency of growth are:
Feed Conversion Ratio (FCR)
This is a measure of the amount of feed eaten per unit of bodyweight or carcass weight
gain. Since feed is the numerator, FCR should be minimised. Common values for growing
ruminants grazing pasture are around 7-10 (kg fed consumed / kg liveweight gain) whereas
pigs and poultry aim for values less than 2. The term Feed Conversion Efficiency (FCE) is
also often used but the more correct term is FCR as it is a ratio (i.e. feed eaten per unit of
gain)
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Efficiency of Feed Utilisation
Efficiency of feed utilisation is simply the reciprocal of FCR. The important point to
remember is that more efficient cattle will have a lower FCR and a higher efficiency of feed
utilisation. When comparing efficiencies from different studies or farms, calculations need
to clearly state the measures (units) of inputs and outputs used.
Residual Feed Intake
An issue that is of considerable practical interest is the extent to which individual animals
are more or less efficient than would be expected. Animals can be compared using net
feed conversion efficiency or the residual feed intake. More efficient cattle can
theoretically be found within any desired cattle weight range, and selection will notnecessarily increase mature size.
Net feed efficiency (NFE) refers to variation in feed intake between animals beyond that
related to differences in growth and liveweight. Consequently it is expected that selection
for improved NFE may reduce herd feed costs with little or no adverse changes in growth
performance. Ranking animals on NFE requires measuring differences in their feed intake,
liveweight and growth rate over a defined test period. A high NFE bull will consume less
feed than expected over the test period and have a lower (negative) net feed intake. A low
NFE bull will consume more feed than expected over the test period and have a higher
(positive) net feed intake. An animal’s expected feed intake is predicted from the test
groups’ average feed requirements for a particular growth (say 1 kg/head/day) and
liveweight (say 300 kg). An animal’s net feed intake is simply the difference between its
predicted feed intake and its actual feed intake.
Selecting for efficient cows within a herd (usually when the first calf is weaned)
Calf weaning weight, adjusted for calf sex, calf sire breed and year-of-birth of dam, has a
moderate repeatability as a dam trait1
of 0.37 (if adjusted for date of birth of calf), or 0.29 (ifunadjusted for date of birth). Both of these traits, again as dam traits, are heritable, and the
New Zealand heritability estimates were 0.26 and 0.19, respectively (Morris and others
1993). Cow weights, adjusted for age, or year of birth, are highly repeatable (0.54), and
moderately heritable (0.26).
1 Trait: A measured genetic feature or characteristic
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Selecting cows for a productivity objective is probably best achieved by using a linear index
of calf weight and cow weight (e.g. A x calf weight difference from the adjusted mean, minus
B x cow weight difference from the adjusted mean), rather than by using a ratio of the twoadjusted weights. It is acknowledged that tagging and some recording is required, to get
the best out of this procedure (i.e. calf-to-dam links, calf sex, date of birth), and if done on a
commercial property, comparisons would need to be done within cow breeds or breed
crosses, because of differing amounts of hybrid vigour expected. Managing separate
grazing groups around or after calving may also complicate interpretation of the results.
It is also important to remember that the sire contributes to herd productivity, i.e. the sire of
the calf and also the sire of the cow. The Breeding Values of candidate sires need to be
taken into account when purchasing service sires and when breeding/purchasing heifer
replacements. The above process is rather complex, but the gains are there if farmers are
willing to invest the time and the recording costs.
2.5 Other pathways to cow efficiency
Various efforts have been made to improve cow productivity either via twinning or by using
embryo transfer to put high growth rate calf genetics into small, high milk producing cows,
but commercial success remains elusive because the technology required remainsimmature or inadequate at several stages of the production cycle (see Chapter 4 also).
Therefore, the right system at present would aim to: run cows at optimum weights; take
maximum advantage of their ability to gain and lose weight to support milk production; use
cows to maintain pasture quality; achieve high pregnancy rates and survival; and take
maximum advantage of genetic opportunities and hybrid vigour.
2.6 Cow liveweight and pasture damage
Heavy cows are more likely to cause pasture damage and pugging on wet or steep hill
country than light animals. In wet weather on steep hill country, damage can be severe,
increasing the risk of erosion and weed invasion although this problem is manageable with
care. This is not discussed in detail here (see Further Reading for more information).
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2.7 Weaning date, calf age at weaning
The main advantage of early weaning appears to be in retaining cow body condition. If the
previous management has been correct, this should not be an important issue. However in
case of droughts, and a requirement to graze cows off the farm as part of the drought
management strategy, early weaning can be practiced.
Weaning time is often determined by managerial convenience and timing of weaner sale
dates in the district. Farmers often like to wean on the day of these sales so calves are
trucked to the sale straight off their mothers looking in their best condition. However, if
calves are not being sold at weaning, then weaning date can be related to feed supplies. In
one recent study (Figure 2.2), calves weaned late (9 months of age) had a significant liveweight advantage (55 kg) over calves that were weaned at the normal time (6 months of
age). Most of this advantage was retained through to 18 months of age. This advantage in
weight gain was shown to be due to milk intake. This study also demonstrated that weaned
calves are more susceptible to internal parasites than calves that are still receiving milk.
Figure 2.2: Mean calf liveweights for calves weaned at normal time (20 March), late
weaned (26 June), or late weaned with no suckling from 20 March on.
Source: Boom and others (2003).
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2.8 Further reading
Boom, C.J.; Sheath, G.W.; Vlassoff, A. 2003. Interaction of gastro-intestinal nematodes
and calf weaning management on beef cattle growth. Proceedings of the
New Zealand Society of Animal Production 63: 61-65.
Thorrold, B. 2008. Management to minimise environmental damage, Ch 10 In Profitable
beef production, A guide to beef production in New Zealand. A book, Ed
D.C. Smeaton. Published by Meat & Wool New Zealand, Beef Council. Third
Edition. Meat & Wool New Zealand, PO Box 121, Wellington.
Smeaton, D.C.; Bown, M.D.; Clayton, J.B. 2000. Optimum liveweight, feed intake,
reproduction, and calf output in beef cows on North Island hill country,
New Zealand. New Zealand Journal of Agricultural Research. 43: 71 - 82.
Smeaton, D.C.; Harris, B.L.; Xu, Z.Z.; Vivanco, W.H. 2003. Factors affecting commercial
application of embryo technologies in New Zealand: a modelling approach.
Theriogenology. 59: 617-634.
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Chapter 3: Feeding beef cattle
Summary
This chapter describes the feed and grazing management requirements of breeding cows.
Beef cattle should be fed at levels appropriate to their production target and the long term
sustainability of the farming enterprise. Due to the variability of pasture growth and the
demands of other livestock classes, it is rare for a farmer to get feed allocation absolutely
correct. In calculating feed requirements for cattle, the requirement for maintenance,
liveweight gain, milk production, and pregnancy are estimated separately and then added
together. Requirements for cattle, based on these metabolic processes are provided. In
practice many people calculate metabolisable energy (ME) feed requirements from feedtables or unwittingly by using farm management models that calculate intake as part of
modelling their farm systems.
The feed management strategy for a beef cow-breeding herd is determined by a balance of
feed supply patterns, competing resources and market requirements. There are major
benefits from running beef cows on hill country farms because of their flexible feed demand
which can be aligned with the seasonal pasture growth curve. An additional benefit is their
ability to assist in the management of pasture quality. An important attribute of the hill
country beef cow is her ability to transfer feed from the late spring/summer period to winter
via stored body fat. If this is managed successfully, it is often unnecessary to feed
supplements to cows.
For simplicity the annual nutritional requirements of spring calving beef cows are divided
into the following periods: Post-weaning; Pre-calving; Post-calving; Post-mating. Both
liveweight and body condition scoring are useful aids to checking the feeding and
management of the herd at critical periods of the yearly production cycle. Condition
scoring, seemingly less precise than weighing, is a practical way of monitoring the animals.
The main management decision that affects the matching of the cow’s needs to pasture
production is the time of calving. Since most of New Zealand’s beef cows are run on farms
where sheep contribute the majority of stock numbers, the time of calving will also be
influenced by the needs of other stock classes, usually lambing ewes.
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3.1 Introduction
Beef cattle should be fed at levels appropriate to their production target and the long term
sustainability of the farming enterprise. Due to the variability of pasture growth and the
demands of other livestock classes, it is rare for a farmer to get feed allocation absolutely
correct. Pasture growth rate predictions can differ from actual because of variable climatic
conditions. Forage crops other than pasture are not used widely, but supplementary feed of
various types (hay, silage, concentrates) may be used in times of feed shortage during
winter or dry summers.
The management on sheep and beef cattle farms ranges across the spectrum from
extensive, where conservative stocking rates are used and the animal’s body weight acts asthe main buffer between pasture production and feed requirements, through to intensively
managed and planned systems where the farmer makes decisions on a daily basis to
achieve this balance. In the more intensive systems, management to increase animal
production is focused on lambing and calving liveweight targets, weaning date, flushing, and
the timing of the sale of store lambs, weaners, cull ewes, cull cows and finishing steers or
bulls.
The points made above highlight the fact that most beef production is in conjunction with
other livestock classes. When evaluating a beef cattle operation consideration must always
be given to what other stock classes the cattle are complementing or competing against at
various times of the year, and how their performance will change if the beef system is
changed.
3.2 Energy requirements of cattle
Feed requirements represent the amount of feed which must be consumed in order to
sustain a defined level of production. For any specified level of performance(e.g. pregnancy, liveweight gain or milk production), sufficient nutrients and energy must be
supplied to the animal tissues to meet metabolic demands. Requirements can be
conveniently expressed as metabolisable energy (ME) because with most pastures, energy
is the most limiting factor for a given level of production. Other nutrients such as protein,
minerals and vitamins (except where there is a known deficiency) are almost always
present in adequate amounts. However, in some instances e.g. young growing animals,
protein may be limiting, especially on low digestible mature type pastures.
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The major determinants of the energy requirement of grazing livestock are:
• liveweight and body condition
• stage of pregnancy
• level of milk production
• rate of liveweight gain or loss
• composition of liveweight gain or loss
• level of activity in eating and movement
• possible effects of climate
• sex of animal
• walking distance and climbing hills
Obviously it is difficult to include all these variables in tables of ME requirements that are
easy to use. In calculating feed requirements for cattle, the requirements for maintenance,
liveweight gain, milk production, and pregnancy are estimated separately and then added
together. The energy requirements of growing cattle are not covered here. Refer instead to
the Further Reading section (Nicol and Brookes, 2007; Smeaton 2007).
3.2.1 Requirements for maintenance
The ME requirement for maintenance is the amount of ME that must be supplied to provide
energy needed for essential body functions. If this energy is not supplied in the diet it must
be obtained by mobilising body tissue, predominantly fat.
As liveweight increases, so too does maintenance energy requirement (Table 3.1), with
every 100kg increase in liveweight requiring an additional 11 MJ ME/day. Increased
grazing and activity costs on hard hill country are significant. These maintenance
requirements are significantly higher than those used by Geenty and Rattray (1987).
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Table 3.1: The metabolisable energy requirement (MJ ME/cow/day) for maintenance of
beef cows. Source: Nicol and Brookes (2007).
Liveweight (kg)
Land class 300 400 500 600
Easy hill - 55 66 77
Hard hill 50 65 75 -
Notes:
Add/subtract 7% per MJ ME for diets below/above 10.5 MJ ME/kg DM.
Add 15% for adult bulls.
A guideline requirement for maintenance can be given as:
0.62 MJ ME/kg liveweight 0.75 for cows on easy hill country
0.70 MJ ME/kg liveweight 0.75 for cows on hard hill country
3.2.2 Requirements for pregnancy
The amount of energy used for both maintenance and growth of the foetus and the products
of conception depends on:
• Days from conception. The greatest increase in requirements occur in the last third
of pregnancy
• Number of offspring (twins rarely exceed 1% of births in beef cattle)
• Size of the foetus
Guideline requirements for pregnancy for calves of varying birthweights are shown in
Table 3.2. These values are additional to the maintenance requirements of the cow.
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Table 3.2: The metabolisable energy requirement of beef cows (MJ ME/cow/day) for
pregnancy (in addition to maintenance requirement). Source: Nicol and Brookes (2007).
Calf
birth weight (kg)
Weeks before
calving
Total for
Pregnancy
-12 -8 -4 0
MJ ME/cow/day MJ ME
30 6 11 20 34 1700
40 9 15 26 45 2300
50 11 18 32 55 2800
Notes: Add these to the maintenance requirement of the cow.
Adjust proportionately for pregnancy rate of the herd, for example,
Pregnancy rate = 95%, ME for 40 kg birthweight, 4 weeks pre-calving
= 0.95 x 26 = 25 MJ ME/cow/day.
3.2.3 Requirements for lactation and calf growth
The ME requirement for milk production depends on:
• Total milk yield (litres)
• Milk composition - because milk varies in concentration of fat, protein and lactose,
the ME requirement per litre will also vary.
It is extremely difficult to know the milk production of beef cows but it will usually range from
5-10 litres/day for single suckled cows. In addition and as a guideline, 5.8 MJ ME/kg milk is
assumed.
The costs of lactation and calf growth (Table 3.3) are estimated as 60 MJ ME/kg calf
weaning weight (slightly less for very light calves). Assumptions have been made about the
proportion of the requirements of the calf which has been supplied by milk and grazing.
However, this ratio does not markedly affect the total ME requirements for calf growth to
weaning.
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Table 3.3: The metabolisable energy requirements of beef cows and their calves during
lactation (in addition to cow maintenance requirements). Source: Nicol and Brookes (2007).
Calf weaningweight (kg)
Months after calving Total forlactation+1 +3 +5 +7
MJ ME/cow + calf/day MJ ME
150 35 45 55 55 8700
200 40 55 65 75 12000
250 50 70 85 95 15000
300 60 80 100 115 18000
Notes: Add these figures to cow maintenance requirement. (See Table 3.1)
Adjust proportionately for weaning %, for example
85% weaning, 200 kg calves, 5 months = 0.85 x 65 = 55 MJ ME/cow/day.
Add/subtract 8% MJ ME for diets below/above 11.0 MJ ME/kg DM.
3.2.4 Liveweight loss or gain
When animals lose weight, mobilisation of body tissue releases energy which therefore
does not have to be supplied by the diet. In lactating animals, this energy can be used to
maintain milk yield, even though the animal is losing weight. The figure often used for
New Zealand beef cows is 55 MJ ME required per kg of LWG gain, and 1 kg of liveweight
loss in mature cows substitutes for around 30 MJ ME of herbage intake. Thus the net cost
of losing and gaining a kg of liveweight is 25 MJ ME/kg of liveweight.
Condition Score (CS) and liveweight change
Target condition scores are often given for particular stages of the production cycle. When
using the 0 to 5 CS scale, one unit change in CS is equivalent to 75 kg for a 500 kg
Hereford cow. On the 1 to 10 scale, the weight change per unit is about 40 kg
The approximate quantities of ME per 1 unit change of condition score (Scale 0-5) range
from 4815 MJ ME/CS for a non lactating cow of with a CS of 2.0, to 5650 for a non lactating
with a CS of 4. For lactating cows it is 3450 (CS 2.0) and 4500 (CS 5.0) MJ ME/CS
change. These values would be about half for the 1 to 10 scale. Condition scoring is
discussed in more detail later in this chapter.
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3.3 Calcul ating feed requirements
In practice most people calculate ME feed requirements in computer models without even
realising it. Less commonly, they may estimate them from feed tables such as in Table 3.1
to 3.4. Requirements in kg DM/head/day can be determined from these tables once a value
of the energy (ME) content of feed is known. Pasture typically contains 8 to 12 MJ ME/kg of
DM depending on the quality of pasture. Note that some feed tables are quoted in kg DM.
These should be used with caution when using them for pastures of varying energy content.
Table 3.4 provides an example of how the previous information can be used to compute the
annual metabolisable energy requirements for breeding cows with different levels of
productivity on either good or hard hill country. Note the greater (23%) feed requirements ofthe more productive cow in the better environment compared to that of the cow in the hard
hill country.
Table 3.4: The annual ME requirements of beef cows in hard and easy hill country.
Source: Nicol and Brookes (2007).
Specifications Hard hill Easy hill
Liveweight (kg) 400 550
Weight loss/gain (kg total) 30 30Calves born/cow joined 92 97
Calf birth weight (kg) 30 40
Calves weaned/cow joined 86 90
Calf weaning weight (kg) 175 250
ME requirements (MJ ME)
Maintenance 365 x 65 = 23725 365 x 72 = 26280
Weight loss/gain 30 x 25 = 750 30 x 25 = 750
Pregnancy 0.92 x 1700 = 1565 0.97 x 2300 = 2230
Lactation and calf growth 0.86 x 10350 = 8900 0.90 x 15000 = 13500
Total annual (MJ ME/year) 35000 42750
Notes:
Maintenance requirement from Table 3.1
Net cost of loss and regain of weight is 25 MJ ME/kg (Para 3.2.4).
Total requirement for pregnancy from Table 3.2 and number of calves born (NCB).
Total requirement for lactation and calf growth from Table 3.3 and number of calves weaned
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3.4 Management and nutrition of the beef cow
3.4.1 General commentsThe management strategy for a beef cow-breeding herd is determined by a balance of feed
supply patterns, competing resources and market requirements. There are major benefits
from running beef cows on hill country farms because of their flexible feed demand which
can be aligned with the seasonal pasture growth curve. An additional benefit is their ability
to assist in the management of pasture quality. In this respect, they play an important role
on kikuyu pasture in Northland and brown-top dominant swards elsewhere. Hill country
farmers marketing weaners in the autumn will often put in place a strategy to cope with
calving ahead of the spring pasture growth, in order to supply the market with older, and
therefore larger, weaners. Farmers marketing progeny in the following spring or autumn, or
finishing the weaner steers themselves, have the flexibility of being able to calve at a more
appropriate time in relation to their pasture growth curve. An appreciation of the pasture
growth curve of a farm is fundamental to the management of any pasture based production
system. When calving before the spring pasture growth flush, the cow is placed in a more
competitive rather than a complementary position with other livestock classes that might
also be able to utilise that same scarce feed.
For simplicity we can divide the annual nutritional requirements of mature spring calving
cows into the following periods: Post-weaning; Pre-calving; Post-calving; Post-mating. Both
liveweight and body condition scoring are useful aids to checking the feeding and
management of the herd at critical periods of the yearly production cycle. Condition
scoring, while seemingly less precise than weighing, is nevertheless a practical way of
monitoring the animals.
3.4.2 Post-weaning (weaning through to 4-6 weeks pre-calving)
Weaning of beef calves normally occurs at 5 to 7 months of age. It can be carried out
successfully at 4 months (this can be an appropriate drought management strategy)
provided appropriate provision is made for post-weaning feed for the calf. In the beef cow
calendar this leaves 5 months of the year that beef cows are low priority stock and can
function as 'work horses' eating rank pasture and controlling shrub re-growth provided they
were in good condition at weaning . During this time, priority can be given to other classes
of livestock and cows become one of the few groups available that can be restricted in the
interests of pasture development and utilisation. This is a major justification for maintaining
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a breeding cow herd on hill country. Not only has it significant advantages for the farm as a
whole, but it has in fact been shown to be beneficial for the cows to lose around 10% of
their liveweight in the post-weaning period.
Cows losing that order of liveweight have increased longevity and suffer no reduction in
performance; provided their nutritional requirements are met in the pre- and post-calving
periods and lost liveweight is regained. Cows fatter than condition score (CS) 3.5 (7 on 1 to
10 scale) at calving are more prone to calving difficulties and to metabolic disease. A
reduction in intake around calving should not be carried out too rapidly with fat cows, as
they can suffer from hypomagnesaemia if subjected to sudden severe restrictions in intake.
Some farmers rotationally graze their cows behind the ewes in a winter rotation during this
period. In such situations cow intakes are very low e.g. Angus cows can eat as little as
3-3.5kg DM/day. This highlights their efficiency and supports the theory that an efficiently
managed beef cow could have a true winter stock unit cost of 3.5 stock units compared to
the commonly accepted value of 6 to 7. Minimising cow feed requirements during
maintenance periods can have a significant impact on overall feed efficiency and therefore
profitability on a hill country sheep and cattle farm. This should be a consideration when
establishing appropriate stock unit equivalents.
3.4.3 Pre-calving (from 4-6 weeks pre-calving to calving)
Cows that have lost in the order of 10% body weight post weaning need to regain some
condition pre-calving and will need to be on a rising plane of nutrition up to and through
mating. If they do not, there is a risk they will be too weak at calving and prone to metabolic
problems, and calf losses can be high (of the order of 10%-20%).
A relatively short period (4 weeks) of high nutrition (6-8kg DM intake/cow/day) is usually
sufficient. Note that the calf is gaining at 250 grams/day in utero during the last month of
pregnancy. If feed is available, liveweight gain on cows will be easier to achieve pre-calving
than during early lactation and is unlikely to have any significant effect on calf birth weights,
except at extremes of feeding levels. If cows calve at CS 2.5-3.0 (5 to 6) it will make the
mating condition target of 3.0 (6) a lot easier to meet.
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While poor pre-calving nutrition and body condition score can exacerbate post-calving
under-nutrition problems, priority in terms of feed allocation should be given to the
post-calving period. This can be achieved by shedding cows out from a moderate plane ofnutrition to a high plane as they calve, by strip grazing, shifting into saved feed at the start
of calving or calving onto spring growth. Some farmers, by calving late enough are able to
set stock cows amongst ewes and lambs at calving. Whatever system is used to apportion
feed, CS at calving is critical because it affects CS at mating, one of the most critical points
in cow management.
3.4.4 Calving to mating
Research suggests that Angus and Friesian cross beef cows need to eat in excess of 12 kg
DM /day from the day of calving through to mating. Larger breeds will require
proportionately more. How this feed demand is met will depend on the time of calving, but
even herds calving close to their pasture growth curve will need some feed carried forward
from late winter. The area chosen for calving should be of easy contour and free of hazards
like creeks, tomos (underground holes) and swamps as these cause significant calf losses.
Post-calving nutrition is critical for several reasons:
• Cow survival - the majority of cow deaths from hypomagnesaemia occurpost-calving and peak in the second week of lactation as the milk demands of the
calf increase. Provision of high quality pasture above 2500kg DM/ha (12 cm high)
is the key to its prevention. In some conditions, magnesium supplementation may
be required for a period during and after calving. Other metabolic conditions that
can occur at this time of the year are milk fever and ketosis. However they play a
very minor role in beef cow losses and are also prevented by correct cow condition
at calving and post-calving nutrition.
• Calf growth rates - cows under-fed in early lactation will buffer their calves by
losing liveweight to maintain milk production. However, with high milk producing
Hereford x Friesian cows at a CS of 2.5 (5) or better at calving, it may be
necessary to restrict feed for the first 3-4 weeks post-calving. This is because the
calves are unable to consume all the milk produced by these high producing cows.
A recent trial indicates that a pasture sward height of 6 cm is sufficient for
beef x dairy heifers during the first month of lactation, increasing to 10-12 cm
during the second month of lactation.
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Calves should gain at least 1.0kg/hd/day while suckling their dams. Milk makes up
a large proportion of their diet up to 12 weeks of age after which they can consumeup to 50% of total diet as grass.
• Subsequent cow pregnancy rate and calving pattern – There are two aspects to
consider:
1. Whether the cow is pregnant or not
2. When the pregnancy was achieved
Cows fed in excess of