University of Nigeria Research Publications

Aut

hor

NDOFOR, Harriet Mbumwen

PG/M.Sc/99/27110

Title

Estimation of Genetic Parameters of Growth Traits of Local Chicken Ecotypes Reared in

Nsukka in the Derived Savanna

Facu

lty

Agricultural Sciences

Dep

artm

ent

Animal Science

Dat

e

August, 2003

Sign

atur

e

TITLE PAGE

ESTIMATION OF GENETIC PARAMETERS OF GROWTH TRAITS OF LOCAL CHICKEN ECOTYPES REARED IN NSUKKA IN THE DERIVED SAVANNA

NDOFOR, HARRIET MBUMWEN PG/MSC/99/27110

DEPARTMENT OF ANIMAL SCIENCE UNIVERSITY OF NIGERIA, NSUKKA

AUGUST 2003

CERTIFICATION

NDOFOR, HARRIET MBUNWEN, a Postgraduate Studcnt in the Dcpartmcnt of Aninla1

Science, Faculty of Agriculture, University of Nigeria, Nsukka with registration number,

PG/M.SC. 1 991271 10 has satisfactorily conlpletcd the requirements for course and rcscarch

work for the degree of Master of Scicncc in Animal Sciencc.

The work embodied in this Project Rcport is original and has not been submitted in

part or full for any other Diploma or degree of this or any other University, to the best of my

knowledge.

/$rofesessor (Dr) C. C. NWOSU i SUPERVISOR

DEDICATIOIN

For t k i r h e , &ndness andencourienrent

ACKNOWLEDGEMENTS

My sincere gratitude goes to God Almighty for his Grace. To my supervisor Professor (Dr)

C.C. Nwosu for his tireless interest and effort to see me succeed in this programme. I am

much thankful to Dr. L.N. Nwakalor for providing me with all the materials, which were

necessary for the realisation of my programme. I am indebted to all members of teaching staff

in Animal Science Department, who made favourable recommendations towards this research

work. My special thanks goes to all the members of staff of the Poultry Unit of the

Department of Animal Science farm and Dr. Lucas Ngongeh for their various contributions.

Success in the whole programme could not have been possible without the wonderful

cooperation and assistance of my mother, my brothers Calemba Ndofor, Marius, Vally and

Gabo and my sisters Adeline, Ethel, Drl Mrs Musongong, Meta, Afanui, Abongwa, Llody

and Che. During my course, I benefited from pleasures and support of the family of DrIMrs

Manfred Besong. To my friends Relyndise Tabe Engineer Josephine Mbunwe, Peps Tanyi,

Ebene, Andison, Ene, Bro John Wansah, Collins, just to name a few I say thank you for your

support. My profound gratitude goes to Dom Fobellah and Harry Foleng for leading in the

typing of this work and Greg Fombo for giving me his computer to type this work.

To Evaristus Foleng and the Foleng's family, I remain ever grateful for your love,

' moral and financial support. You are wonderful. While acknowledging the contributions of

the above persons, I accept any shortcomings and omissions contained in this work.

Ndofor, H. M University of Nigeria August 2003

Abstract

In a study to investigate the usefulness of two ecotypes of local chickens (light ecotype and heavy

ecotype) in chicken breeding programmes in Nigeria, heritability estimates of body weight,

coefficients of simple correlation between growth traits, and genetic correlation between

bodyweight at four weekly intervals were obtained from the 4th to the 20th week of age.

Heritability was estimated using the sire components of variance on the basis bf data obtained in

a one-way layout. 136, 58 and 60 chicks of both sexes raised from a non-inbred and randomly

mating population of the light, heavy and main cross respectively, were used in the investigation.

The chicks were pedigreed from day-old according to sires and raised under a deep litter system

of management from day-old to 20 weeks of age. Fertility percentages of 58.20,48.78, and 36.97

were obtained for the light, heavy and main cross chickens respectively, while hatchability

percent of 47.89, 72.50 and 76.92 were obtained for light, heavy and main cross chickens

respectively. Mean feed efficiency throughout the experimental period were obtained as 0.29 f

0.04, 0.35 f 0.08 and 0.31 f 0.08 for the light, heavy and main cross chickens respectively. A

mean conversion ratio of 3.79 f 0.66, 3.63 _+ 1.002 and 4.69 f 1.48 were calculated for the light,

heavy, and main cross chickens respectively. There were however, no significant (PB0.05)

differences in mean feed consumption, mean feed efficiency and mean feed conversion ratio,

between the 3 groups.

Average body weights of the birds at day-old were 21.82g, 28.06g, 26.30g; at 4 weeks were

95.413, 143.68, 126.72g;at 8weeks were 349.89g, 561.7lg, 458.57g; at 12 weeks were 568.14g,

816.67g, 714.00g; at 16 weeks were 768.858, 1066.67g, 811.54g; and at 20 weeks 931.34g, 1196.67g,

950.00g, for light, heavy and main cross chickens respectively. There were highly significant

differences in average body weights at 0,4,8,12,16 and 20 weeks in all the 3 groups.

Heritability estimates from sire components of variance averaged 0.40, 0.37, and 0.29

between 4 and 20 weeks for the light, heavy and main cross respectively. Based on these estimates it

could be concluded that the body weight at different ages is moderately to highly heritable and as such

could be improved through breeding and selection.

Genetic correlation estimates of body weight between different ages were obtained.

Similarly, coefficients of simple correlation were obtained among some economically important

growth traits, for the 3 groups. Age and body weight at first egg were obtained as 145 days and

940g, 149 days and 1208.33g and 154 days and 1050g for the light, heavy and main cross

chickens respectively. The average weights of first egg were obtained as 30.0g, 35.248 and

31.60g and for the light, heavy and main cross chickens respectively. The experiment indicates

that the heavy local chickens and the main cross performed better in bodyweight, bodyweight at

point of lay, and egg weight over the light local chickens.

CHAPTER ONE

INTRODUCTION

1.0 Background Information

The total number of poultry in the world has been estimated to be 14,718 million, with 1,125

million distributed throughout the African continent, 1,520 million in South America, 6,752

million in Asia, 93 million in Oceania, 3,384 million in North America and 1,844 million in

Europe (FAO, 1991).

The population of livestock in Nigeria has been estimated to be about 14 million

cattle, 21.1 million sheep, 34.5 million goats (Abubakar et al., 2003), and 70,928 million

chickens of which 68.164 n~illion are raised in rural areas while 2764 are raised in urban

areas '(FDLPCS, 1992). Despite these enormous livestock and poultry resources, a serious

gap has been observed between demand and supply, due to the growth rate of the human

population (Kehinde et al., 2002), leading to the problems of protein malnutrition (Egbunike,

2002). To meet the demand for cheap animal protein in Nigeria, improved breeds of chicken

from developed countries, which require expensive imported inputs dominate the commercial

poultry sector. It has become increasingly difficult to sustain these industries over the years

under a poor economy with high exchange rates required for inputs (Okpeku et al., 2003).

Altlmugh the introduction of these high-yielding chicken breeds in Africa dates back to the

1920s, the local chicken population in most African countries account for more than 60

percent of the total national poultry production (Sonaiya, 1990).

Generally, the local chickens are small-bodied mongrels raised on free range

(traditional or village system) and backyard system called the "family" or subsistence system

(Lul, 1990). On the free range they are allowed to scavenge around household compounds

and because of the absence of shelter, birds perch on high places or take shelter in human

habitations such as kitchens (Sall, 1990). In the backyard system birds spend the night in

constructed shelters with water and supplementary grains generally being provided. In both

systems, birds almost never receive veterinary care (Assan, 1990). A number of studies

(Oluyemi and Oyenuga, 1974; Akinokum and Dettmers, 1977; and Nwosu et a1 1985) on the

indigenous breed as an alternative or complementary source of animal protein reveals that the

local chicken has an early growth rate, early initiation of lay, medium to high heritability of

body weight and a quick response to egg production under improved management and dietary

conditions.

It is obvious that individual animals within a population and between populations of

the same species differ in some characters. Much of these differences are seen when animals

have different genetic constitution, and nutritional status (Sastry and Thomas, 1980). These

variations are the raw materials with which breeders work (Schmidt and Van Vleck, 1974).

The animal breeder is concerned with how to improve those animals in the 'Rock whose

production capacity are below average, to a point of ''maximum production", and how to

maintain such animals in the face of all disturbing factors (Ensininger, 1969).

Statement of Problem

In the mid- 1980s most developing countries suffered a slow down in economy and this

affected the import - dependent sectors such as conlmercial poultry as well as affccted the

intensive and semi-intensive production systems, which mushroomed in the 1970s. This lcd

to a substantial increase in the quantity of rural poultry meat in the market as a result of

decreasing supply of commercial poultry (Suleiman, 1989). Althouph thcre is n gcncrnl

acceptability of poultry products in developing countries this sector of the economy is

plagued with a lot of problems, which must be resolved for any meaningful progress to be

made (Ibrahim et al., 2000). This will mean tackling the problems of input, marketing,

infrastructure and heavy financial requirement for capital development and recurrent

requirement. The problems facing the Nigerian poultry industries today einanatcd from

Nigeria's over dependence on foreign inputs, importation of breeding stock to commercial

day- old chicks and importation of grains (Nwosu, 1979 and Tait, 1980). Replenishment of

parent stock by importation has its toll on the countries foreign exchange earnings (lbe,

1990).

Importation of animals from one climatic zone to the other constitutes a major

problem in breeding work, leading to a genotype x environment interaction, and subscqucntly

to a reduction in fitness (Falconer, 1989). It is important, therefore, that farm anin~als be

improved under the conditions identical to those under which they will bc subjected for

production. There is then the need to improve local fowls, within our cnvironmcntal

conditions, for optimum productivity (Njue el al., 2002). There is equally the problcnl of

.disease importation arising from the importation of exotic fowls, which, to reduce mortality

among the exotic stocks from the endemic diseases, a lot of money has to be cxpended on

health management schemes. If, however, thc local chickens can be dcvclopcd from the

unselected group and they perform wcll with respect to traits such as egg production ant1

carcass weight, then, the path will be paved towards the solution of thc prohlcn~ crcntctl by

heavy dependence of the poultry subsector on foreign sources. This is becaltsc thc Nigcriatl

fowl population has already shown relative rcsistancc to son~c discasc (Oluycnli cl r r l . , 1 970).

There is the problem of random and uncontrolled mating between the local and

imported birds and lack of an organized improvement scheme for local birds. This has

resulted in birds characterized by such survival traits as small body size, growth, late

mortality and production, tolerance and resistance to prevalent local diseases and perversities

and hardiness ([be, 1990). With random and uncontrolled mating, it is not possible to define

distinctive feature of the local fowl of the country, which could justify its recognition as a

breed.

In recognition of the above-mentioned problems, and considering the fact that primary

breeders in developed countries may be reluctant in supplying developing countries with

outstanding elite stock for improvement of their local stock, there is need for a systematic and

~nethodological approach for the improvement of the large population of local chickens. This

can be achieved by exploiting the valuable gene resources of different ecotypes of local

chickens for future breeding plans designed to improve their productivity and adaptability to

tropical production system.

The present study focuses on estimating genetic parameters of growth traits of light

ecotype, heavy ecotypes and main cross of local chickens reared in Nsukka, South Eastern

Nigeria. Earlier studies carried out at the local chicken laboratory at the University of

Nigeria, involved assessment of the local, light ecotype chickens and imported breeds'

performance.

Objective of the Study

The general objective of the study is to obtain information on the genetic parameters of body

weight, and assess the differences in some economically important traits of two ecotypes of

~odal chicltens and main cross, reared in Nsukka in the derived savanna.

The specific objectives of the study are:

1) To measure and determine the feed consumption, feed efficiency, feed conversion

ratio, body weight, body weight gain of the light, heavy, and main cross chickens at

day-old, 4 weeks, 8 weeks, 12 weeks, 16 weeks and 20 weeks of age

2) To note age, body weight at first egg and weight of first egg.

3) To compare the light, heavy, and main cross chickens in a number of growth

parameters and assess the suitability of their involvement in future breeding

programmes.

4) To estimate heritability and genetic correlation among body weights at different ages

of the light, heavy, and main cross chickens.

Justification

Through the years, a large number of breeds and varieties of chickens have been developed,

but most of these are of historic significance. Many of these early breeds. have been

eliminated; a few breeders interested in developing uncommon varieties have retained others.

Geneticists do not want to lose these genes forever, which would be the case if all the rare

breeds cease to exist (North, 1978).

For any meaningful progress on the local chicken to take place, there is real need for

the improvement of the local chicken - their body size and egg size. An important

requirement for this improvement is an appropriate breeding method for bringing about rapid

genetic progress. This can only be achieved when there is more systematic information on

physical, productive and reproductive parameters of the local chicken. The choice of brccding

method will depend on estimates of gcnetic parameters of body weight in thc popuht' ion.

Such estimates will be useful in the identification of superior genotypes for sclection, which

is an important tool for genetic improvement (Mshelia and Abubakar, 1997). Estimates of

heritabilities and genetic correlations of body weight reflect the magnitude of the expected

response to selection, which will influence the choice of selection method and breeding plans

to be considered in future.

Hence, the estimation of heritability and genetic correlation of body weight of

different ecotypes is the pivot of this investigation. The result of this study might hclp in

formulating important breeding plans for the light and heavy ecotypes of the Nigerian local

chickens. Secondly, if the cross between light and heavy types achieves fast growth ratc, thcn

breeders might consider it as a parent in broiler chicken development in Nigeria.

CHAPTER TWO

LITERATURE REVIEW

2.1 Origin and History of Poultry

Most scholars believe that the indigenous chickens were domesticated from the red jungle

fowls (Gullus g~il l t~s) on the Indus valley about 2000 B.C. From there, they gradually spread

to the East and West where they eventually encircled the globe (Austic and Nesheim, 1990).

However not all scholars accept this view, some believed that other wild Gallus species may

have contributed to the domestic birds. Some believed that South East Asian chicken stock

were domesticated separately and might have been derived from one or more extinct species

orjungle fowls (Sasimowski, 1997). Others hold the view that there was early domestication

i n Burma, diffusing in all directions with first archaeological evidence appearing in China

and the Indus valley (Craw ford, 1993).

2.2 Importance of Local Chickens in Household and National Economies

l'hc importance of rural poultry in national economies of developing countries and its role in

improving the nutritional status and incomes of many small farmers and landless

coinmunities have been recognised by various scholars and rural development agencies in the

last two decades (FAO, 1982, 1987; Bembridge, 1988; Mokotjo, 1990; Creevey, 199 1).

The rural poultry population in most African countries account for more than 60

pcrcent of the total national poultry production, which has been accorded an asset value of

$ U S 5750 millions (Sonaiya, 1990). In Bokina Faso, Ouandaogo (1990) reported that the 25

inillion rural poultry produce 15 000 tonnes of meat, out of which 5,000 tonnes are exported

a1 a value of U.S. $ 19.5 millions, mainly to Coat D71voire.

Village chickens are more widely distributed in rural Africa than the other livestock

spccics. In the United Republic of Tanzania, a survey of 6,00 households in 20 villages

showed that chickens were the only form of livestock found in most households (Collier et

( I / . , 1986). Similar observations have been reported in Ghana (Van Veluw, 1987), Niger

(Abdou and Bell, 1992), in Cameroon (Ngou Ngoupayou, 1995) and in Nigeria (Adetayo and

Babarunso, 2001). Surveys in some African countries have reported that the main function of

villagc chickens from the farmer's perspective is the provision of meat and eggs for home

consumption [in Nigeria (Nwosu, 1979), Mali, (Kuit et al., 1986); South Africa, (Cairns and

Lea, 1990); and Cameroon, (Ngou Ngoupayou, 1995)l. In addition to this, local chickens are

kcpt for other purposes: barter that is in the context of intra-and inter community exchanges

and/or religious ceremonies (cocl<s as offerings to the deities), (Lul, 1990; Yami, 1995) and

to meet the obligation of hospitality. Chale and Carloni (1982) review the attributes of local

chicken meat and eggs in rural areas. Egg dishes and chicken meat cook fatter than pulses

and red meat, and therefore, use less firewood. Income received from the sale of eggs in a

woman project in Sudan was used to purchase household consumable goods, thus increasing

household welfare. Gittinger et u1 (1987), in a survey on food production by women and it's

impact on food security found that rural households that had cropping as their only source of

food production were more food insecure than households that had livestock including

poultry. However, local chickens do not rate high in the mainstream national economies

because of the lack of measurable indicators of their contribution to macro economic indices

such as Gross Domestic Product (GDP).

2.3 Potentials of the Local Chicken.

There is sufficient scientific evidence to warrant the use of the local chicken as a parent in

breeding programmes aimed at either developing egg-type or meat-type breeds for Nigeria

(Egbunike, 2002). According to Horst (1988), the genetic resource base of the indigenous

chickens in the tropics is rich and should form the basis for genetic improvement and

diversification to produce a breed adapted to the tropics. The established major gene in

exotic/local chicken populations according to Horst (1988), include: Dwarf (dw), Naked neck

(Na), Frizzle (F), Silky (h), Slow feathering (K), Non-inhibitor, Pea comb (P) and Blue Shell

(0), lnformation for the use of these genes for genetic improvement is scanty, but Mathur et

ul (1989) reported an increase in egg production through incorporating naked neck (Na)

genes in a cross breeding programme of local Fayoumi chicken in Egypt. Similarly, Horst

and Mathur (1992) reported favourable effects of naked neck (Na) and frizzle (F) genes on

egg production and egg weight and of the dwarf gene (dw) on feed efficiency of chickens

under heat stress.

Nwosu et a1 (1984) reported that the growth rate of local chickens from day-old to

point of inflection (1 3-14 weeks) was rapid and did not differ from that of an imported stock.

Secondly the local chickens posses the potential to grow fast at the early stages of life and

therefore, fitted for use as a parent in broiler chicken development in Nigeria. Thirdly, they

found out that the local pullets lay their first egg at an average age of 135 days in contrast to

145 days of the Starcross, a difference that could be significant in poultry breeding

programmes. Fourthly, that generally the local birds consumed less food and drank less water

than the Starcross (exotic birds). Obioha et a1 (1983) maintained that the local cocks tended

to be superior in high economic cuts than the exotic cocks, and concluded that the local fowls

to meet the obligation of hospitality. Chale and Carloni (1982) review the attributes of local

chicken meat and eggs in rural areas. Egg dishes and chicken meat cook fatter than pulses

and red meat, and therefore, use less firewood. Income received from the sale of eggs in a

woman project in Sudan was used to purchase household consumable goods, thus increasing

household welfare. Gittinger et a1 (1987), in a survey on food production by women and it's

impact on food security found that rural households that had cropping as their only source of

food production were more food insecure than households that had livestock including

poultry. However, local chickens do not rate high in the mainstream national economies

because of the lack of measurable indicators of their contribution to macro economic indices

such as Gross Domestic Product (GDP).

2.3 Potentials of the Local Chicken.

There is sufficient scientific evidence to warrant the use of the local chicken as a parent in

breeding programlnes aimed at either developing egg-type or meat-type breeds for Nigeria

(Egbunike, 2002). According to Horst (1988), the genetic resource base of the indigenous

chickens in the tropics is rich and should form the basis for genetic improvement and

diversification to produce a breed adapted to the tropics. The established major gene in

exotic/local chicken populations according to Horst (1988), include: Dwarf (dw), Naked neck

(Na), Frizzle (F), Silky (h), Slow feathering (K), Non-inhibitor, Pea comb (P) and Blue Shell

(0). Information for the use of these genes for genetic improvement is scanty, but Mathur et

(11 (1989) reported an increase in egg production through incorporating naked neck (Na)

genes in a cross breeding programme of local Fayoumi chicken in Egypt. Similarly, Horst

and Mathur (1992) reported favourable effects of naked neck (Na) and frizzle (F) genes on ' egg production and egg weight and of the dwarf gene (dw) on feed efficiency of chickens

under heat stress.

Nwosu et ul (1984) reported that the growth rate of local chickens from day-old to

point of inflection (13-14 weeks) was rapid and did not differ from that of an imported stock.

Secondly the local chickens posses the potential to grow fast at the early stages of life and

therefore, fitted for use as a parent in broiler chicken development in Nigeria. Thirdly, they

found out that the local pullets lay their first egg at an average age of 135 days in contrast to

145 days of the Starcross, a difference that could be significant in poultry breeding

programmes. Fourthly, that generally the local birds consumed less food and drank less water

than the Starcross (exotic birds). Obioha et a1 (1983) maintained that the local cocks tended

to be superior in high economic cuts than the exotic cocks, and concluded that the local fowls

can be developed into a broiler bird if the cocks are fattened like broilers. The local cock is

very vigorous and has a high libido. Another potential of the local chicken is its maternal

ability, a behavioural adaptation normally referred to as broodiness. It involves the hen's

ability to lay a few fertile eggs in a clutch, incubate the eggs by sitting on them naturally and

brood the chicks (Nwosu, 1979). According to Oluyemi et a1 (1979) the most important

physical characteristic of the local chicken is its resistance to economic diseases as well as

other harsh environmental and management conditions. Nwosu and Omeje (1984) reported

on some production and reproduction parameters as follows: clutch size 3.1 + 0.4, number of

pause 1.5 + 0.43, pause length (days) 3.0 k 0.4 and broodiness 4.4 f 0.00.

The local chicken has been shown to have good meat quality, flavour and general

acceptability of cut-up parts when compared with the exotic and crossbred (Nwosu et al.,

1985), and the egg has a biological value close to 100% (Oluyemi and Roberts, 2000). Further

more, the local chicken is reported to have exhibited appreciable heterosis and "nicking" in

body weight and egg production when crossed with exotic breeds (Asuquo, 1984; Nwosu and

Omeje, 1984).

2.4 Fertility and Hatchability

Fertility is defined as the percent fertile of total eggs set (Mack, 1978). The successful

transfer of adequate normal viable spermatozoa to an oviduct suited to enhancing their

survival is necessary for fertility. Therefore, the ability of the female breeder to produce

fertile eggs depends on factors in the laying pen. Good, viable breeding males and healthy

normal breeding female are a prerequisite. Therefore fertility is the result of laying house

management rather than the outcome of hatchery management (Singh, 1990). The egg must

therefore be fertile for it to have the potential to hatch (Austic and Nesheim, 1990).

Hatchability on the other hand is the number of chicks hatched as a percent of the fertile eggs

set (Mack, 1978). The actual process of hatching a chick is complicated and there are many

factors affecting the normal procedure. The environment in which eggs are incubated plays

an important part, as do position and turning of the eggs (Austic and Nesheim, 1990).

Obioha (1992), reported that the hatchability and quality of chicks deteriorate every

day an egg is held after the fifth day of collection. The effects of storage temperature and

storage position seem to be more pronounced if the storage duration is prolonged (Andrews,

1990).

2.5 Health and Disease Control

Poultiy diseases have continued to play very important role in retarding the progress of

poultry industry. This is even more so with native scavenging chickens where there is no

organised disease control programmes through vaccinations and proper hygiene (Njike,

2001). Major diseases of poultry in Africa that have been predominantly identified in

commercial poultry are Newcastle disease, Gumboro Marek disease, fowl typhoid, cholera,

mycoplasmosis and coccidiosis, (Adene, 1996). However, Chabeuf, (1990) reported that the

most devastating disease of village chickens in Cameroon is Newcastle disease, where as in

commercial poultry, coccidiosis, Marek disease and Gumboro are more prevalent. Research

work in other African Countries such as Burkina Faso (Bourzat and Saunders 1990),

Mauritania (Kane and Le Jan, 1990), Benin (Chrysostome et nl., 1995) and Nigeria (Njilte,

2001) support the argument that Newcastle is the most devastating disease of local chickens.

Other health problems in local chickens are external and internal parasites. A study carried

out on ectoparasites of domestic fowls in Nigeria showed that Lice, Meizacunthus stramineiz,

were the major problem in rural poultry (Zaria et al., 1993). From this above study, the

external parasite problem was associated with season-higher rate of infection occurring

during the rainy season.

2.6 Feed Consumption and Feed Efficiency

Feed resources are major inputs in poultry production systems, estimated to account for about

60 percent of total production cost in the commercial poultry sector (Renkema, 1992). In

village chicken production systems, it is difficult to estimate the economic andlor physical

values of these inputs because there are no direct methods of estimating the scavenged feed

resource, which constitute most of the feed input (Roberts and Gunaratne, 1992). Williamson

and Payne, (1978) reported that from 1 - 8 weeks of age a bird will consume 0.014 - 0.051

kg of feed per day, 0.054 - 0.09 kg per day at 9 - 20 weeks and mature birds would consume

more than 0.09 kg of feed per bird per day. However, the local chickens under good

management conditions consumes 0.010 - 0.050 g per bird per day at 1 to 8 weeks old; 0.061

to 0.079 kg per bird per day at 9 - 20 weeks; and above 20 weeks 0.082 kg per day for

matured birds (Obioha, 1992). Safalaoh, (1997) reported a feed consumed per bird per day of

30 g at 0 to 8 weeks.

Extensive work has not yet been done on the efficiency of feed utilisation of the

Nigerian indigenous fowls but they could be expected to utilise less feed to maintain their

small body size. The more feed that is consumed, the less the nutritive utilisation per unit

food. Conversely, the less feed consumed within a certain limit, the higher the utilisation per

unit feed (Obioha, 1992). Feed efficiency gives an insight on nutrient quality availability and

utilisation of the feed by the chicken. It also gives an indication of the efficiency with which a

particular feed is being converted into useful animal products. It is influenced by factors such

as breed, sex, age, health and physiological state of the animal and management (Branckaert,

1992). Rapidly growing chicks require adequate feed to express their rapid growth potential.

This applies also for the expression of optimum feed efficiency. Improvements in feed

efficiency arise fi-om reduction in feed wastage, increase in feed intake, increase in

digestibility of nutrients and reduction in maintenance energy requirements (Obioha, 1992).

2;7 Phenomenon of Growth and Growth Rate

Growth is a complex physiological process that exists from conception until maturity in

animals. Obioha (1 992), defines growth as an increase in weight and/or size that occurs over

time and when this increase in weight is plotted against time an S-shaped sigmoid curve is

obtained. Onuora et a1 (1 979) also define growth as a correlated increase in the mass of body

in definite interval of time in a way characteristic of a species. This indicates that growth

varies with age and genetic make-up. Growth involves the synthesis and deposition of

minerals (bone growth), of protein (tissue growth), but fat deposition is, however not

regarded as growth because fat is expendable. The rate of growth differs from one organ to

the other, some being faster than the other. Another thing about growth is that it is not

uniform from week to week (Crawford, 1993). Ngere (1975), reported important factors

affecting growth: nutrition (which is an important factor in growth because it harnesses

hereditary make up in such a way as to bring about maximum growth possible), hormones,

temperature and heredity. Appropriate mathematical functions have the potential to concisely

and biologically represent the entire growth phase of the chicken. Graphic illustration of these

functions gives rise to growth curves. These curves are universal sigmoid curve, which can

define the growth rates (Crawford, 1993). Growth curve have four characteristics: an

accelerating growth phase following hatch; a point of inflection coincident with maximum

growth rate; a decelerating growth phase; and a limiting mature weight which is approached

asymptotically.

2.7.1 Body Weight

Body weight at a specific age is probably the most frequent used indicator of growth. It is

attractive because it is relatively easy to measure (Craw ford, 1993). Various researchers have

reported different body weight for the local chickens in Nigeria at various ages. Hill and

Modebe, (1 96l), reported weights of 27.22 g, 63.50 g, 272.16 g, 396.89 g, 650.90 g, 1077.28

g 1202.02 g, 1360.788, 1746.33 g at day-old, 4, 8, 12, 16, 20, 24, 28 weeks and one year old

respectively; while Nwosu et al., (1979) obtained average body weight of 27.98 g, 118.73 g,

31 1.04 g, 515.51 g, 802.60 g, 972.71 g, 1090.91 g, 1188.97 g, 1259.27 g, at day-old, 4, 8 12,

16, 20, 24, 28 weeks and one year old respectively. Nwosu et al., (1984) equally obtained

average body weight of 95-20 g, 289.95 g, 580.69 g, 790g, and 980 g at 4, 8, 12, 16,20 weeks

a of age respectively. Akinokun and Dettmers, (1977) found a significant sex difference in

body weight of local chickens at 8 and 20 weeks of age. Oluyemi et al., (1979) reported 50

weeks body weight of 1183.6 g and 938.2 g, 1277.58 and 1021.3 g, 1182g and 915 g, for

males and female multi-coloured white and black varieties of the Nigerian chickens Adetayo

and Babafunso (2001), reported the mature body weight of indigenous chicken to be between

0.9kg and 1.8 kg respectively. Nwosu et a1 (1985) reported an average body weight of the

Nigerian local chicken at point of lay to be 1.14 kg.

2.7.2 Body Weight Gain

Body weight gain during a given interval may be used to indicate average growth rate during

the interval measured. It turns to be highly positively correlated with other weights and gains

during growth (Crawford, 1993). It requires two body weight measurements for the

calculation. Body weight gain gives indication of changes in growth rate during the interval

of measurement. This trait is often measured as part of feed efficiency or feed conversion

ratio (Crawford, 1993).

2.8 The Concept of Heritability.

The idea of heritability dates back to the beginning of the 20"' century. Fisher, (1918)

appears to be the first person to have deduced the general quantitative relationship between

relatives, but J. L. Lush developed the concept of heritability in 1940 (Falconer, 1989).

Heritability expresses the proportion of the total variance attributable to the average effects of

genes (Austic and Nesheim, 1990) but Lush, (1940), defined heritability as the fraction of the

observed variance caused by differences in heredity. He went further to distinguish

heritability in the broad sense, the functioning of the genotype as a whole, from the narrow

sense the average effects of the constituent genes. The former includes variation due to

additive effects of genes, dominance effects, epistatic effects, and effects of interaction

between genes and the environment; the later includes variation due to additive effects of

genes. Heritability in the narrow sense is of most interest to breeders because it is the gene,

not the genotype that is the hereditary unit of transmission.

Kempthome and Tandom (1953) associated the concept of heritability with the

relative importance heredity and environment plays in influencing the variation in a given

trait. The partitioning of the variance of a trait into components (genotype and environment)

pcrmits estimation of the relative importance of the various determinants of phenotype in

particular, the role of heredity versus environment. The genetic components are influenced by

changes of gene frequencies, and therefore may differ from one population to another, while

the environmental variance will depend on the conditions of management with more variable

conditions reducing heritability and more uniform conditions increasing heritability

(Falconer, 1989). The different estimate of heritability of the same trait may show some

considerable range of variation due to statistical sampling, methods of estimation, real

differences between the populations and conditions under which the studies are carried out.

Heritability, therefore, is not a fundamental constant. Its magnitude depends on the

magnitude of its determining components. This enables the breeder to decide on the type of

selection or breeding plan to carry out in order to obtain rapid genetic progress (Nwosu,

2002). It is accepted that when heritability is less than 20 %, mass selection may not be

useful, with high heritability (h2> 40%) individual selection results in rapid genetic response

(Nwosu, 2002).

2.8.1 Estimating Heritability

Estimation of heritability is only valid provided that the mating system is random and

environmental deviations among groups of relatives are not correlated. Deviations from this

condition will distort estimate of heritability (Becker, 1992). Due to the difficulty of

measuring variance components directly, Wright (1922) used the degree of resemblance

between relatives as a measure of estimating variance components from which heritability

could be calculated This is based on the fact that the phenotypic variance can be partitioned

into various components. From designed mating, measurements of the observable

components of variance 02s, 02d, 02e are obtained following analysis of variance by equating

the mathematical expectation of each of the mean squares of the classification to the expected

mean squares and solving this system of equation (Becker, 1992). According to Becker,

(1992), One-way Lay out, Nested design, Factorial design, Diallel and Regression of off

spring on parents are different procedures of estimating heritability.

2.8.2 Estimation of Heritability of Body Weight

In terms of body weight heritability, it is obvious that studies will and do valy with the

procedure used, the strains or breeds of chickens used, the sizes of the parental / filial flocks,

and the sexes contributing to each estimate. There is little report in literature of estimate of

heritability of body weight of Nigeria local fowls at various ages. Nwosu et ul., (1984)

obtained estimates of heritability for 4 and 8 weeks as 0.36, 0.38 and 0.37; 0.32, 0.36 and

0.34 for sire, dam and combined components respectively. Oluyemi and Oyenuge, (1974)

reported 12Ih week body weight heritability of 0.32 (h2s), 0.29 (h2d), and 0.31 (h2 (s +d)).

Altinokum and Dettmers, (1977) using full-sib analysis obtain 0.41 as estimate for same age

and parameter in the local fowl. Kinney Jr., (1969) reported that body weight heritability

estimate in chickens' ranges from 0.01 to 1.07. There is considerable information on

heritability estimate for body weight in exotic chickens population. Goodman and Godfrey,

(1 956) reported heritability estimate of 0.43 and 0.49 for 9-week body weight in a population

of New Hampshire cross with Silver Oklabars. El-lbiary and Shaffner, (1951) obtained

estimates of 0.14 to 0.38, 0.22 to 0.37 and 0.26 to 0.58 at 6, 8 and 10 weeks of age in a

population of New Hamphire. ~ e r n e r et al., (1950) reported estimates of 0.45, 0.60, 0.51

from sire, dam and combined sire and dam components respectively in population of single

comb White Leghorn.

2.9 Estimation of Genetic Correlation.

The estimation of genetic correlation depends on the resemblance between relatives in

the manner analogous to the estimates of heritability (Falconer, 1989). Genetic correlation

can be estimated for pairs of traits using either variance or covariance components (Becker,

1992), or the regression of one of the pair of traits of offsprings on the other trait of parents.

Very little information exists in literature on estimates of genetic correlation between body

weight at different ages, and, body weight and weight gain. Kinney Jr., (1969) summarised

genetic correlation between body weight at various ages and other growth traits of economic

importance for unspecified strains. Estimates of genetic correlations are very scanty in the

local chickens but estimates of correlations between broiler weight and gains and feed

consumption were generally high (0.5 to 0.9) (Pym and Nicholls, 1979; Chambers et ul.,

1984; Friars, 1984).

CHAPTER THREE

MATERIALS AND METHOD

3.1 Study Location

The experiment was carried out at the poultry unit, University of Nigeria, Teaching and

Research Farm Nsukka. The farm is situated within the equatorial rainforest belt of the

tropics and falls specifically within the derived savanna vegetation zone. It has well-defined

rainy seasons (April - October) and dry seasons (November - March).

3.2 The Parent Populations

The genotypes that were used for the investigation were the light ecotype (LE) of the local

chickens purchased from Oye-Orba, Ibagwa Nkwo, AforIwollo, Oye Ayu, Udi (Derived

savanna); Pie-Zarama, Yenegoa (Swamp forest), Obo-hag in Rot-Ekpene in Akwa Ibom

State and Ndoro in lkwuano local government area of Abia state (Rain forest) areas of South

Eastern Nigeria and the heavy ecotype (HE) of local chickens purchased from Vandekiya

Kastina Ala of Benue state, Obudu, a montane region of South Eastern Nigeria. The acquired

birds were quarantined to check and monitor their health conditions and left to acclimatise

with the environment before introducing them into the experimental units. 88 non-pedigreed,

unselected and unimproved random bred males and females of the light local birds housed at

the farm formed the base population for light ecotype (LE) while 55 males and females that

were non-pedigreed, unselected and unimproved, formed the base population for the heavy

ecotype (HE). This study was carried out between June 2001-February 2003.

3.3 Breeding Procedure

The parents were arranged into the following mating groups:

Table: 1 Breeding Procedure

Group Breeding Groups Number of Breeders Mating Ratio

Males Females

LE males x LE females 8 80 1:lO

HE males x HE females 5 50 1:lO

HE males x LE females 5 50 1:lO

The above arrangements resulted in 3 breeding parent groups (plates 1 ,2 and 3) from

where the "purebred" and main cross progeny populations were derived.

PLATE 1: LIGHT MALE X LIGHT FEMALES

PLATE 2: HEAVY MALE X HEAVY FEMALES

PLATE 3: HEAVY MALE X LIGHT FEMALES

The mating design used was onc-way layout (Becker, 1992) in which each sirc was

mated randomly to 10 dams. In each brceding group, the males were allowed to stay with thc

females for a week to ensure that mating was effected, at the end of which cggs werc

collected, pedigreed and stored in crates inside a room under ambic~lt tcmperaturc. Thc

incubator was cleaned and disinfected prior to setting of the eggs. Eggs incubated wcrc

candled for each group on the 8th and 18th day of incubation.

3.4 Fertility and Hatchability

3.4.1 Fertility

Fertility was tested at the 81h day of incubation by directing candlelight across an cgg in thc " dark. Fertile eggs showed a dark spot at the ccntre with radiating streaks of blood vcsscls.

mimicking the structure of spider. Infertile eggs wcrc removed and fertility pcrcentagc

computed thus:

Total nttmber of fertile eggs 1 00 Fertility Percentage = x-

Total rlurrlber of eggs sel 1

3.4.2 Hatchability

These were the proportion of fertile eggs that hatched.

Total numbcr of hatched eggs 100 ~ a t c h a b i l i t ~ percentage = X- Total number of fertile eggs 1

3.5 Management Procedure

Prior to chicks' arrival, the broodcr house and cquipmcnt wcrc disinfcctcd and then frcsh

litter was put to a depth of about 6cm. On the day of hatching all chicks wcrc pedigrccd by

sire. The chicks were given chick mash and watcr on arrival, and proper managcmcnt and

hygiene were ensured. Thc recoinmcndcd schcdule and the evcntual programmc of

vaccination practiced are as follows:

Reconlmended programme

Newcastle (1ntraocular)- Day - old

'~asota - 3-4 weeks, and 6 weeks

Merek's Disease vaccine- Day-old

Gumboro vaccination -10-14 days, and Sweeks

Fowl Pox vaccine - 12 weeks

Fowl typhoid vaccinc 4weeks

Cholera vaccine

Vaccines givcr~

Newcastle (Tntraocu1nr)- 1 Otlays

Lasota vaccination - 3 wccks and

----- Gumboro vaccination - 16 days

Fowl Pox vaccinc - 12 wccks old

-----

-------

Coccidiostat was given to all birds for the prevention of coccidiosis. Chicks were

brooded in pens for 4 weeks; and management conditions were the same for all chicks. At the

end of brooding, chicks were transferred and managed in rearing pens with feeding and

drinking troughs provided. Birds were reared up to 20 weeks of age.

3.6 Measurements

Three commercial diets were used in feeding the birds. The diet comprised: chick mash fed

up to 8 weeks, growers' mash fed until 18 weeks and layers mash fed up to 20 weeks. These

feeds were analysed for proximate composition. Water was given ad libitum, whereas

weighed feeds were given.

Table: 2 Analysed composition of commercial diets

[ Layers mash 1 16.5 1 2.5 3.6 1 0.32 1 3.71 1 2870

Diet Chick mash Growers mash

3.6.1 Feed Consumption

A measured quantity of the analysed feed was given to the groups daily for seven days after

which left over feed accumulated over the week, was weighed to determine by difference the

Protein 19.58 15.75

amount of food'consumed by each group. It was possible from the above to determine the

mean feed consumption per bird per week.

Fat 3.47 4.4

Total amount of feed served -Total amount of leftover feed Mean feed consumption =

Average number of birds housed and fed during the week

3.6.2 Feed Conversion Ratio

Fibre 5.03 4.8

It is the ratio of the weight of feed consumed to one unit of weight gain.

- - Feed consumed Feed coversion ratio

weight gained

P .076 0.35

3.6.3 Feed Efficiency

It is the ratio of live-weight gain per unit of feed intake in grams.

Ca 1.02 0.58

Feed Efficiency

M.E.Kcal/kg 2800 2900

Gain =- Feed

3.6.4 Body Weight

Birds from each mating group were weighed first at day-old and then at 4 weekly intervals

subsequently up to 20th weeks, using a mettler D lOOON sensitive scale with a capacity of

1000 grams (lkg) from day-old to 8 weeks and a lOkg capacity "Salter" scale from 9-20

weeks. The birds were weighed individually, and then the mean for each group computed.

3.6.5 Body Weight Gain

The most common way of expressing growth in terms of weight is by absolute gain in weight

per unit time. This can be expressed as average daily gains, average growth rate or rate of

gain (Oparaugo, 1988). The rate of growth was computed thus:

Final weight - Initial weight Average growth rate = -.

Time interval

After obtaining this, a growth curve was plotted for body weight against age to get the growth

curve while plotting live weight changes against time gave the Rate of growth (Rate of gain).

3.6.6 Disease Incidence and Mortality: It was recorded as it occurred.

3.6.7 Age, Body Weight at First Egg and Weight of First Egg

Age was recorded as the time the hens dropped their first egg, after which the egg, and the

hens were weighed to get the weight of the first egg and the body weight at first egg.

3.7 Statistical Analysis I

3.7.1 Descriptive Statistics: Descriptive statistics such as mean @), standard error (S.E), I

coefficient of variation (C.V) and 95% confidence limit were used to describe the parameters

measured.

3.7.2 F- test was used to compare all genotypes simultaneously and Duncan's Multiple

Range Test was used to test for significant differences.

3.7.3 Body weight data of the 3 ecotypes offsprings were compared at day-old and during

subsequent age periods, to obtain differences between ecotypes. This was done by means of a

one-way ANOVA in a completely randomised design (CRD) involving unequal subclass

numbers, as well as the Duncan's Multiple Range Test. The statistical model used was:

Xij = U+ Si+ eij

Where:

Xij= the record of the j th progeny of the ith sire

U = the overall mean

Si = Effect of the ith sire

eij= the uncontrollable environmental and genetic deviations attributable to the

individuals. All effects are random, normal and independent with expectations

equal to zero.

3.7.2 Components of variance and covariance were computed using SPSS (2001)' from

which heritability from Paternal Half Sib and genetic correlation were estimated according to

the procedures outlined by Becker (1992).

CHAPTER FOUR

RESULTS AND DISCUSSION

The results obtained for the parameters measured of the local chicken ecotypes are presented

in the appropriate tables and figures on subsequent pages.

4.1 Fertility

Table 3 shows the fertility percentage of 58.20 % for light chickens, 48.78 % for the heavy

chickens and 36.97 % for the main cross chickens. These values are far less than the 80.6%,

98.0%, 93.0 %, for young flock reported by Kuit et a1 (1986), Andrews (1990), and Singh

(1990), respectively. Age, light, nutrition, mating ratio, semen quality and rate of egg

lkoduction are some of the factors that affect fertility (Austic and Neshmein, 1990). The low

fertility in this work might have resulted from the fact that the parents stock spent most of the

time getting acclimatised to the environment and had a high rate of disease incidence, which

affected the frequency of mating and probably fertilisation.

4.2 Hatchability

Table 3 shows hatchability percentage of 47.89 %, 72.50% and 76.92% for the light, heavy

.and main cross chickens respectively. These values are lower than the 91.0 % hatchability for

young stock observed by Singh (1 WO), but not different from the 4O.l6%, 37.08%, and 65%

obtained by Okeke (2002). The poor values could be attributed to longer holding time of

eggs, sub-normal storage temperature and relative humidity conditions, disease incidence, as

well as fluctuations in temperature during incubation and poor incubator environment.

Obioha (1990) and Jordan and Pattison (1990) reported that the above factors affect

hatchability adversely. Austic and Nesheim (1990) recommended egg holding room

temperature of 65 to 75 OF (18.3"C to 21.1 OC) and 75 % relative humidity. Mack (1978)

reported that the optimum temperatures in which chicken eggs hatch is 95 to 105 OF (35 to

40.5 OC).

4.3 Liveability Rates

From Table 3, liveability percentages of 75 %, 93.33% 60.34% were obtained between 0 to

12 weeks for light, heavy and main cross chickens respectively. Liveability percentages based

on females were 74.58%, 64% and 66.67% were obtained for light, heavy and main cross

chickens respectively. The high mortality recorded was as a result of Newcastle disease and

coccidiosis. This probably was due to the fact that the proper vaccination programmes was

not followed because of scarcity of vaccines and the ones used were not too reliable due to

their storage conditions. The high mortality rate caused by Newcastle disease goes a long

way to confirm the report of Chabeuf (1990) that the most devastating disease of local

chickens is Newcastle disease (Bell et al., 1990; Chrysostome et al., 1995; Yongola, 1996).

Adene (1996) reported that the high rate of mortality of local chickens is as a result of

confinement and bad management during the period of confinement. It is therefore,

reasonable to believe that if local chickens are given optimum veterinary care and good

management at all levels of husbandry, their liveability figures will improve over time.

4.4 Feed Consumption, Feed Efficiency and Feed Conversion Ratio

Mean feed consumption per bird per week is presented on Table 4. There was a tendency for

mean feed consumed per bird per week (g) to be highest for the heavy chickens, followed by

the main cross and then the light chickens throughout the experimental period. Table 5 shows I

the feed efficiency of the light, heavy and main cross chickens at various ages. It was

observed that the mean feed efficiency throughout the experimental period was 0.29 f 0.04, i 0.35 f 0.08, 0.31f0.08 for light, heavy and main cross chickens. Therefore it could be I

koncluded that there was a tendency for the heavy chickens to have had the highest feed

efficiency among the groups. However, the younger birds had a higher feed efficiency than

the older birds. This trend is in accordance with the report of Jurgens (2002) that feed

efficiency is higher for young birds, which reduces, as the birds grew older. Statistically,

there were no significant differences (p>0.05) in the mean feed consumed, and the feed

efficiency for the three groups of birds (Tables 4a and 5a). Though much work has not been

done so far on feed utilisation of the local birds, these values obtained would be expected

since the birds require less feed to maintain their small body size. Therefore, the highest

value obtained for the heavy bird, and the least values for the light bird were expected

possibly because of the difference in body size.

The mean feed conversion ratio of 3.79 + 0.66, 3.63 + 1.002 and 4.69 + 1.48 and

obtained for the light, heavy chickens and main cross (Table 6) were not different from the

3.50 obtained by Obioha (1992). Feed conversion ratio is the opposite of feed efficiency,

which increases, as the birds grow older. These differences (Table 6a) however were not

significant.

Table 3: Fertility (%) and Hatchability (Oh) of Incubated Eggs of light, heavy

chickens and main cross chickens

Light chickens Heavv chickens Main cross chickens Numbers of eggs set 488 164 21 1 Number fertile 284 80 78 Number unfertile 204 84 133 Number hatched 136 5 8 60 Fertility percent 58.20 48.78 37.97 Hatchability percent 47.89 72.50 76.92 Liveability(%) 0-12 weeks, 12-20 weeks 75; 74.58 93.33; 64 60.34; 66.67

Table 4: Mean feed consumed /bird/ week by light, heavy and main cross

chickens

Age (weeks) Light chickens Heavy chickens Main cross chickens 4 210.01 250.01 200.03 8 607.50 700.04 700.01 12 750.30 850.01 800.00 16 850.40 900.06 9 10.00 i

20 950.40 960.08 950.01 Total 3368.3 1 3660.20 3560.05

Table 4a: ,Analysis of variance of mean feed consumed /bird/week by light, heavy

chickens and main cross chickens

Source of variation d.f SS MS Fcal. F tab (5%) F tab (1%) Total 14 Between ecotypes 2 8799.60 4399.8 0.051 3.89 6.93NS Error 12 1026258.86 85521.54

Table 5: Feed efficiency of light, heavy chickens and main cross chickens

Age (weeks) Light chickens Heavy chickens Main cross chickens 4 0.35 0.46 0.50 8 0.42 0.59 12 0.29 0.30 16 0.24 0.28 20 0.16 0.14

Total - 1.46 1.77 Mean 0.29 f 0.04 0.35k 0.08

Table 5a: Analysis of variance of feed efficiency Ibirdlmonth of light, heavy

chickens and main cross chickens

Source of variation d.f SS MS Fcal. F tab (5%) F tab (1%) Total 14 Between ecotypes 2 0.0104 0.0052 0.216 3.89 6.93NS Error 12 0.2884 0.0240

Table 6: Feed conversion ratio of light, heavy chickens and main cross chickens

Age (weeks) Light chickens Heavy chickens Main cross chickens 4 2.85 2.16 1.99 8 2.39 1.69 2.12 12 3.42 3.29 3.1 1 16 4.09 3.60 9.48 20 6.18 7.39 6.79 Total - 18.93 18.13 23.49 Mean 3.79 f 0.66 3.63 + 1.002 4.70 + 1.48

Table 6a: Analysis of variance of feed conversion ratio of light, heavy chickens and

main cross chickens -

Source of variation d.f SS MS Fcal. F tab (5%) F tab (1%) Total 14 Between ecot'ypes 2 3.344 1.672 0.276 3.89 6.93NS Error 12 72.206 6.058

4.5 Body Weight Statistics of the Local Chicken Offspring

The mean (5, standard deviation (S) variance (s2), standard error (S.E), coefficient of

variation (C.V), 95 % confidence interval limit and, minimum and maximum body weights of

. light, heavy chickens and main cross at 0-, 4-, 12-, 16-, and 20- weeks are presented on

Tables 7, 8, 9, 10, 11, and 12 respectively. Generally, the heavy ecotype chickens had the

highest mean body weight followed by main cross chickens and the least, the light chickens

at all ages. Data (Tables 7a, 8a, 9a, 10a, lla,andl2a) reveal that body weight in the three

groups were significantly (pC0.05) different among all ages but at the 2oth week there was a

significant difference between heavy and the other two groups, but no significant difference

(p>0.05) between the main cross and the local chickens. Omeje and Nwosu (1984) showed

that the Gold-link parents weighed heavier than the local chickens. The mean body weight of

the two crossbred groups was about equal to that of the Gold-link but higher than the local

chickens. On the other hand, the heavy ecotypes chicken in this work performed better than

the main cross and the light. The mean body weight of the main cross group even though

different from the heavy bird was higher than the light ecotype chickens. Crossing of the

local chicken with the parent stock of Gold-link was effective in bridging the gap in body

weight between the exotic and the local chickens (Nwosu and Omeje 1984). From this study

it could equally be concluded that crossing the heavy ecotype chickens with the light chicken

was effective in bridging the gap in body weight between the light and heavy ecotype

chickens. The main cross of this experiment were significantly (p<0.01) inferior to the heavy

ecotype due partially to the heterotic or hybrid effect of crossing inherently low yielding

genotypes in the main cross, and due mainly to the maternal influence. The important factor

which may be responsible for the light chickens having the least body weight through out the

experimental period could be gene effect. The below expectation in body weight performance

of the main cross was probably due to maternal and genic effect. It meant that in the main

cross chickens of this study, the expected crossing effect as well as sire influence were

probably absent or were suppressed by the overpowering maternal influence. Hutt (1964)

observed that the original size of the chick was limited completely by the size of the egg shell

in which if was incubated because dams would not "wrap up goods in packages bigger than

they could deliver". This might have been the case with the main cross whose small sized

dam with her small sized egg completely controlled the chick size. The maternal influence in

' main cross chicks as a result of suppression by their mothers small size was apt to clear after

8 weeks of age, which was to correspond with the gradual emergence of paternal inheritance

and the expected hybrid advantage. These effects probably did not take upper hand as was

expected from then onwards to 20 weeks of age because of the disease conditions of these

birds. When the mean body weight of the Gold-link at day-olds, 4-, 8-, 12-, 16-, 20-weeks of

age (30.97 g, 108.73 g, 292.65,660.00 g, 1041.00 g, and 1195.42 g respectively (Nwosu and

Omeje, 1984) are compared with the heavy ecotype chickens at day -old, 4-, 8-, 12-, 16-, and

20- weeks of age (28.06 g, 143.68 g, 561.7 g, 714.00 g, 1066.67 g, and 1196.67 g

respectively), it could be concluded that the heavy local chickens showed superiority at 4-, 8-,

12-, 16-, and 20- weeks of age; and as such should be used for breeding programmes rather

than importing exotic chickens which may require huge financial expenses, and involved

genotype x environment interactions and disease importat ion.

The growth curves presented in Fig. 1 elucidate the picture presented in Tables 7,8,

9,10,11 and 12. The differences between these three groups started after the first week,

widened each month but between the 16- and 20- weeks the light and main cross had little

difference while the gap between the two and the heavy chicken became very conspicuous.

Therefore, both the light and main cross showed marked inferiority to the heavy chickens.

There is little or no previous work reported on the main cross chickens and the heavy

chickens (Tiv) of the montane area of South Eastern Nigeria.

Table 7: Descriptive statistics for body weight for day- old for light, heavy

chickens and main cross chickens

Statistics (Day-old) Light Heavy Main cross chickens chickens chickens

Ecotype mean (g) 21.82' 28.06a 26.30~ Ecotype S Ecotype s2

.. Ecotype S.E. (g)

Ecotype C.V. (%) 7.77 16.70 16.98 Ecotype Number 136 58 60 95 % confidence interval: lower bound 21.53 26.83 25.14 95 % confidence interval: upper bound 22.10 29.39 27.46 Minimum day-old body weight 18.64 22.07 20.79 Maximum day-old body weight 25.54 39.03 37.98

a,b,c.. ... Means of a parameter followed by different letter is significantly different at

Table 7a: Analysis of variance of ecotype effect on body weight at day- old.

Source of variation d.f SS MS Fcal. Ftab (5%) Ftab (1%) Total 253 Between ecotypes 2 1897.420 948.710 84.15 3.00 4.61 Error 251 2829.78 11.27

Table 8: Descriptive statistics for body weight at 4 weeks for light, heavy chickens and main cross chickens

Statistics (4-weeks) Light Heavy Main cross chickens chickens chickens

Ecotype mean (g) 95.41' 143 .68a 126.72' Ecotype S2 3.48 22.89 8.27 Ecotype S 12.1 1 524.36 68.39 Ecotype S.E. (g) 0.33 3.58 1.10

Ecotype C.V. (%) 3.65 15.94 6.36 Ecotype Number 113 41 5 6 95 % confidence interval: lower bound 94.76 136.45 124.50 95 % confidence interval: upper bound 96.06 150.90 128.93

Minimum 4-weeks body weight 80.20 106.18 111.60 Maximum 4-weeks body weight 110.10 178.24 153.21

a,b,c.. ... Means of a parameter followed by different letter is significantly different at 5%level.

Table 8a: Analysis of variance of ecotype effect on body weight at 4-weeks old

Source of variation d.f SS MS Fcal. Ftab (5%) Ftab (1%)

Total 209 Between ecotypes 2 8407.47 42037.24 333.54 3.00 4.61 - - Error 207 2608.04 126.034

Table 9: Descriptive statistics for body weight at 8 weeks for light, heavy chickens and main cross chickens

Statistics (&weeks) Light Heavy Main cross chickens chickens chickens

Ecotype mean (g) 349.89' 561.71a 458.57' Ecotype S2 25.28 48.84 34.77 Ecotype S 639.08 2385.35 1208.95 Ecotype S.E. (g) 2.65 8.26 4.65

Ecotype C.V. (%) 7.23 8.63 6.99 Ecotype Number 9 1 3 5 5 6 95 % confidence interval: lower bound 344.64 544.94 449.26 95 % confidence interval: upper bound 355.15 578.49 467.88 Minimum 8-weeks body weight 300.00 450.00 400.00 I

I

Maximum 8-weeks body weight 400.00 650.00 560.00 a,b,c.. ... Means of a parameter followed by different letter is significantly different at 5%level

I I

Table 9a: Analysis of variance of ecotype effect on body weight at &weeks old. I

. Source of variation d.f SS MS Fcal. Ftab (5%) Ftab (1%)

Total 181

Between ecotypes 2 1230509.50 615254.73 537.01 3.00 4.61

Error 179 205081.76 1145.71

Table 10: Descriptive statistics for body weight a t 12 weeks for light, heavy chickens and main cross chickens

Statistics (12-weeks) Light chickens Heavy chickens Main cross chickens

Ecotype mean (g) 568.14' 816.67a 714.00' ~ c o G e S

-

Ecotype s2 Ecotype S.E. (g)

Ecotype C.V. (%) 2.98 7.2 8.22 Ecotype Number 5 9 15 25 95 % confidence interval: lower bound 563.71 784.13 689.78 95 % confidence interval: upper bound 572.56 849.2 1 738.22

Minimum 12-weeks body weight 550.00 750.00 650.00 Maximum 12-weeks body weight 600.00 900.00 850.00 a,b,c.. ... Means of a parameter followed by different letter is significantly different at 5%level.

Table 10a: Analysis of variance of ecotype effect on body weight at 12-weeks old

Source of variation d.f SS MS Fcal. Ftab (5%) Ftab (1%) Total 98 Betweenecotypes 2 909088.92 454544.46 295.58 3.07 4.98 Error 96 147628.25 1537.79

Table 11: Descriptive statistics for body weight at 16 weeks for light, heavy chickens and main cross chickens

Statistics (16-weeks) Light chickens Heavy chickens Main cross chickens - - - - -

Ecotype mean (g) 768.85' 1 066.67a 81 1.54~ Ecotype S 46.22 48.79 45.40 Ecotype s2 2136.29 2380.46 2061.16

.. Ecotype S.E. (g) 6.41 12.59 8.90

Ecotype C.V. (%) 4.70 4.57 5.63 Ecotype Number 5 2 15 26 95 % confidence interval-lower bound 755.98 1039.64 793.20 95 % confidence interval -upper bound 781.71 1093.69 829.89 Minimum 16-weeks body weight 650.00 1000.00 700.00 Maximum 16-weeks body weight 850.00 1 150.00 850.00 a,b,c.. ... Means of a parameter followed by different letter is significantly different at 5%level

Table l l a : Analysis of variance of ecotype effect on body weight at 16-weeks old

Source of variation d.f SS MS Fcal. Ftab (5%) Ftab (1%) Total 92 Between ecotypes 2 1043367.3 521683.66 242.27 3.07 4.98 Error 90 193802.56 2153.36

Table 12: Descriptive statistics for body weight at 20 weeks for light, heavy chickens and main cross chickens

Statistics (20-weeks) Light Heavy Main cross chickens chickens chickens

Ecotype mean (g) 93 1.34~ 1 196.67" 950.00° Ecotype S2 28.79 83.38 36.12 Ecotype S 828.86 6952.22 1304.65 Ecotype S.E. (g) 4.34 21.53 7.37

Ecotype C.V. (%) 3.09 6.97 3.80 Ecotype Number 44 15 24 95 % confidence interval: lower bound 922.38 1 150.49 934.75 95 % confidence interval: upper bound 939.89 1242.84 965.25 Minimum 20-weeks body weight 850.00 1000.00 900.00 Maximum 20-weeks body weight 980.00 1250.00 1000.00 a,b,c.. ... Means of a parameter followed by different letter is significantly different at 5%level

Table 12a: Analysis of variance of ecotype effect on body weight at 20-weeks old

Source of variation d.f Total 8 2 Between ecotypes 2 829083.73 41454 1.82 203.49 3 .07 4.98 Error 80 162976.52 2037.2 1

Statistically, however, there are highly significant (P < 0.001) differences in mean

body weight across the ages and genotypes (Tables7a, 8a, 9a, 1 Oa, 1 1 a, and 12a). The genetic

implication of this difference is that since there is a genetic gap between the 3 groups, with

the heavy chickens being significantly heavier, the best option is to continue using the main

cross chickens and back cross with the heavy chickens so as to increase the body size of the

local chickens. Fig 2 is a graphic representation of the trend in body weight gain of the 3

breeding groups. From this figure, it was observed that the rate of body weight gain increased

up to 8 weeks in the 3 groups. This was followed by decline after the 81h week of age to 20 &LC WB'

weeks of age for the main cross and heavy chickens; while the increase of body weight gain Y

continue for the light chickens. The trend observed for the light chickens is in agreement

with the report of Nwosu and Asuquo, (1984). The drop observed after the 81h week for the

main cross and the heavy chickens in this study might have been caused by the out-break of

coccidiosis which attacked the birds. Nwosu, (1979) reported that the local chicken reaches

its point of inflection at 13 weeks. Oluyemi and Oyenuga, (1974), earlier observed this early

'fast growth in the indigenous fowl. This could be advantageous in dual-purpose bird

development in future breeding programmes and genetic improvement of growth through

selection (Okpeku et al., 2003).

As a means of comparing variances of different populations, the coefficient of

variations of the different groups of chickens have been plotted against age (Fig. 3). This is

because variance of some characters especially body weight is known to be under " scale

effect" and as such is dependent upon the mean: when the mean changes, the variance

automatically changes with it, and plotting the variance as the coefficient of variation will

eliminate the scale effect (Falconer, 1989). The light, heavy and main cross chickens fall

under three categories of variability viz: high, middle and least respectively. Nwosu et nl.,

(1984) obtained a high variability for the local chicken while for the main cross (a cross

between Gold- Link and local chickens) had the least variability. The lower variance in the

main cross compared to the parents in this work agrees with the findings of and Nwosu and

Omeje, (1984) which implies that main cross chickens were more uniform, possessing

identical heterozygous genotypes as compared to their more homozygous parental counter

parts, a situation that is in tune with the Mendelian expectation of uniformity of FI

individuals. This variability of the parental is indicative of their coming from a population

that has yet to undergo improvement in body weight.

Fig 1. Mean body wi& ag& age in \;cieel(s

I --t Main cross chickens

+Heavy chickens -

Age (weeks)

Fig. 2: Rate of weight gain against age in weeks

4.6 Age, Body Weight at First Egg and Egg Weight of First Egg

Table 13 shows the age, body weight at first egg and egg weight of first egg. The ages at first

egg were 145 days, 149 days, and 154 days for light, heavy and main cross chickens

respectively. The 145 days for the light chicken fall within the range reported by Akinokum

and Dettmers (1977). According to their report, the average age at first egg for the local

chickens ranges between 127 to 168.7 days. The difference in the age at first egg between

the three groups could be significant in poultry breeding programmes involving the different

ecotypes of local chicken. The average body weights at first egg were 940 g, 1208.33 g, 1050

g and for the light, heavy and main cross chickens. The average body weight at first egg for

the local chickens was in agreement with the range (0.9-1.8kg) reported by Nwosu and

Omeje (1984), Adetayo and Babafunso (2001) and Okpeku (2003) The average egg weight at

first egg were 30.6 g, 35.24 g and31.60 g, for the light, heavy chickens and main cross

respectively. Nwosu and Omeje, (1 984) obtained average weight of first egg as 25.978, There

is no in information literature on age, weight of first egg and body weight at first egg of the

main cross (heavy males and light females) and heavy chickens (Tiv). Egg weight is highly

heritable, and therefore could be manipulated easily by genetic selection, although the genetic

correlation with rate of lay is negative (Austic and Neisheim, 1990). Equally, the genetic

'control of egg weight is highly correlated to body weight, so that selection for egg weight

tends to produce a larger hen and vice versa. Age is a major determinant of egg size in all

fo~ms of poultry. At the onset of lay, egg weight is much smaller than in subsequent weeks.

4.7 Heritability Estimate of Body weight

For a given trait, heritability is the amount of the superiority of the parents above their

conten~poraries, which on the average is passed on to the offspring. Heritability estimate of

body weight derived from sire components of variance are shown on Table 14. The

heritability estimate for the light ecotype chicken was 0.40 f 0.44. This estimate is similar to

0.35 _+ 0.06 obtained between 4 and 20 weeks of age by Nwosu and Asuquo (1 985) and those

reported by Oluyeini and Oyenuga, (1974), Akinokum and Dettmers (1977), and Ebangi and

Ibe (1995). On the other hand heritability estimate for heavy and main cross chickens were

obtained as 0.37f 0.90 and 0.29 f 0.57 respectively. This is probably the first time the body

weight heritability of chickens from the montane area and that of the main cross (heavy males

crossed with light females) has been estimated. A comparison of the heritability estimate of

the main cross and the "pure" parents reveal that body weight is more highly heritable in the

light ecotypes than the main cross and the heavy. Based on these observations it can be said

that the body weight of all the 3 groups is moderately to highly heritable. These estimates

suggest that with mass selection much improvement can be achieved in the three populations.

With these high heritabilities of body weight, flock improvement will be rapid and the

progress in improving future generations will be fast. The magnitude of heritability is

important in choosing the method of selection and breeding plan, in determining the relative

amount of emphasis to be given to each trait when selecting breeding stocks, in determining

the breeding value of individual animals and in the estimation of the rate of progress in a

selection programme.

4.8 Coefficients of simple Correlation.

Table 15 shows the coefficients of simple correlation of some traits for the 3 groups studied.

From this table it can be concluded that there is a positive coi-relation between:

Body weight and feed intake

Body weight and feed conversion ratio

Feed intake and feed conversion ratio

It also shows a negative correlation between

Feed intake and feed efficiency

Feed efficiency and feed conversion ratio

Body weight and feed efficiency for all the 3 groups studied

Positive correlation means that there is favourable association between two traits and

negative correlation indicates an unfavourable association of the traits. The correlation

. coefficient measures the strength and indicates the direction of relationship between two

variables (Falconer, 1989). The coefficient of correlation between body weight and feed

intake was very high (0.96). Ibe (1981) reported 0.976 as coefficient of correlation between

body weight and shank length in broilers. Generally there is little or no information on

coefficients of simple correlation of the parameters studied on local chicken ecotypes.

Table 13: Age, body weight a t first egg and weight of first egg

- Light chickens Heavy chickens Main cross chickens Age at first egg (days)' 145 149 154 Mean body weight at first egg (g) 940 1208.33 1050 Weight of first egg (g) 30.60 35.24 3 1.60

Table 14: Heritability estimates for Body weight of light, heavy and main cross chickens from sire component of variance

Age (weeks) Light chicken Heavy chickens Main cross chickens 4 0.46k0.35 0.25k0.49 0.1 2kO.33 8 0.23k0.29 0.43k0.64 0.26k0.37 12 0.56k0.51 0.2Sf 0.92 0.43k0.80 16 0.53k0.52 0.42k1.26 0.1 8k0.71 20 - 0.23+0.50 0.46k1.21 0.46*0.68 Mean ' 0.40k0.44 0.37k 0.90 0.29k0.57

Table 15: Coefficients of simple correlations of some economic traits of light, heavy and the main cross chickens

Light Heavy Main cross chickens chickens chickens

Feed intake-body weight 0.96 0.96 0.96 Feed intake- .feed conversion ratio 0.7 1 0.62 0.68 Feed intake- Feed efficiency -0.006 -0.003 -0.82 Body weight- feed conversion ratio 0.85 0.77 0.74 Body weight- Feed efficiency -0.86 -0.79 -0.90 Feed efficiencv - feed conversion -0.95 -0.89 -0.95

Table 16: Genetic correlations among body weight a t various ages of the two ecotypes and main cross chickens

Traits correlated rc (light - chickens) rG(heavy chickens) rc ( main cross chickens) 4 -8weeks 0.02 0.08 0.23- 4 -1 2 weeks 0.05 0.054 0.14 4 -1 6 weeks 0.18 0.06 0.3 1 4 -20 weeks 0.23 0.28 0.39 8 -1 2 weeks 0.2 1 0.37 0.04 8 -1 6 weeks 0.02 0.03 0.05 8 -20 weeks 0.09 -0.18 0.09 12 -1 6 weeks 0.28 0.11 0.14 12 -20 weeks -0.01 -0.20 0.1 1 16-20weeks -0.04 0.02 0.16

4.9 Genetic Correlation of body weight

Genetic correlation estimates between of body weights at various ages for the three breeding

groups are presented in Table 16. The result shows that most of the genetic correlation

estimates are positive and consistent with reported values in literature (Nwosu and Asuquo,

1985). The differences within groups could be due to differences in genetic effects at the

various stages of growth (Jaap et al, 1962). Negative genetic estimates were obtained in some

cases but this is not consistent with reports of other workers in literature, probably due to

sampling error. Secondly, the positive gene actions at the self- accelerating phases of growth

could possibly explain the positive genetic correlations obtained at the early ages. The

negative genetic correlations could be due to the de-accelerating phase of growth, which was

controlled more by environmental influences rather than the genetic factors (Falconer, 1989).

However, genetic correlation estimates are of more interest to the breeder than either the

phenotypic or environmental correlation values. The genetic correlation and heritability

estimates of a population enable the breeder to predict the future performance of his flock

with some degree of accuracy (Falconer, 1989). This could be advantageous in animals where

selection may be used to increase body weight in the following generations. Mack (1978)

reported that body weight in broilers is closely correlated with the weights of the parents at 8

'weeks of age. From a genetic standpoint, certain quantitative characters have positive genetic I coi-relation, for instance, when selection is made to improve liveability within the line, egg

production also increases (Asuquo, 1984).

CHAPTER FIVE

CONCLUSION AND RECOMMENDATIONS

Native fowls still have a position in the genetic improvement of tropically oriented stock.

Although only small genetic response can be expected in pure breeding, the local fowl

genome will still be usefbl in breeding for special conditions in extensive production systems.

Heritability estimate for the 3 groups show that, on the average, body weight is

moderately heritable. This indicates that appreciable improvement in the trait could be

achieved if the pure parents are individually selected at the age of 12 or 16 weeks. The

performance of an animal in terms of growth rate, feed intake and utilisation depends on the

genetic potentialities of the animal, and the environment. The reported values for the growth

rate are highest for the heavy ecotype chickens followed by the main cross and the light

ecotype at all ages.

The local chickens show a lot of variations in body weight and other growth traits.

With such variability and knowing well that variation is the breeders' tool for animal

improvement genetically, the result indicate that the potentials for the local fowls are yet to

be tapped hence the need to improve them.

The mean mature body weight of 940 g, 1050 g, and 1208.66 g observed for the light,

' main cross and heavy chickens indicate that the local chicken is a small bodied strain when

compared to some exotic chicken breeds (Gold-link) at the same age. A continuous cross of

the heavy males with the light females (main cross) will not be favourable for body size

improvement because the light chickens had the least mean body weight whereas the cross of

light males on heavy males (reciprocal cross) would advantageously elevate the body size of

the light locals towards the heavy ecotype chickens. There is, therefore a real need for genetic

improvement in growth traits for any meaningful and objective economic productivity to be

attained in both the meat and egg producing enterprise.

The local chicken of Nigeria so far presents a great diversity as in its adaptation to

harsh environmental conditions as well as in its performance. This large diversity can serve

as the base for the creation of foundation stock for national poultry industry. A concomitant

improvement of the husbandry and management conditions will result to a net improvement

notably the productivity (egg/meat) of the local fowl and to make in source of cheap and

quality protein.

In view of the fact that native fowls meet a high proportion of total human food

requirement and that it is still an important source of livelihood or income to marginal

farmers, they surely deserve more attention as a genetic reserve, and also as a source for

genetic improvement of breeding stock for tropical locations as well as for unfavourable

environments. These conclusions could be supported by the report of Horst (1988) that the

genetic base of the indigenous chickens in the tropics is rich and should form the basis for

genetic improvement and diversification to produce a breed adapted to the tropics.

Given these potentials and in addition that they are more adapted to the local

prevailing climatic conditions more than the exotic breeds, it is recommended that a new era

of the poultry industry be opened in Nigeria, which should totally be dependent on the

indigenous local stock. The best tool to start with to achieve this objective will be through the

creation of a reasonable baseline population of the local chicken through selection of

indiscrete population of the available local chicken stock. This will facilitate genotype

~ate~orisation and conservation of the native chicken for the national poultry industry. This

should be followed closely by more purposeful and scientific crossbreeding work by

geneticists and breeders to improve on the economic traits and vigour of the local chickens by

the use of tested / proven local chicken ecotypes.

To understand the genotypic and chromosomal characteristics of the local chickens,

detailed cytogenetically research on the indigenous fowls should be undertaken. This will

help in distinguishing the local chicken ecotypes as genetically different and help also in

identifying different breeds or strains of the native birds. Imrnunogenetic studies should also

be carried on the local fowl to understand its genotype with regards to resistance to different

diseases.

From the results of this study, there are indications that crossing the two ecotypes of

local chickens -the light males and the heavy females (reciprocal crosses), reasonable hybrid

vigour could be generated. Future studies should estimate the amount of heterosis involved.

Secondly, studies should assess their nutrient requirements and different types of

management systems.

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A1qxmdis S: ( 'a lculat ions 011 I lcsitabilily ol'ninin cross chickens (12-wecks)

I F F - I MS - ems

:. (11 ?.s) L- 0:lO i 0.08 Alywntlix I 1 : ('illculalions o n Ilcrilability of hcnvp chickens (4-wccks)

A N O V A 'l'nhlc

- - .- -- -- - - - - - -

- . - - . -. - . - - - - . - -. . . . - - - -- - -- - - -- - - - - 3083.76 - -- 770.94 a'c-1- k a-s - - - -

1'1.opcny \vihin sirus 36 - - - -. -. - - - . - - - - - - - -. 1789 1.08 496.97 - - TI-c

A~I)L'IK!~X 12: ( ' ; \ I C ~ I I ~ ~ I ~ O I ~ S on I lcritability ol'henvy chiclicns (8-wcclis)

Appc~dis I ? : ( ';llculi\~ion~ on I Icr-ilabilily of heavy chickens (12-weeks)

1 I

&\,\.\. = -L---- -- C'.F - 10020000- C:,F = 15833.33 t r i .

:. (h ' s )= 0.28 1 0.02 ill qw~idis 14: C'illculahns on I leritahility of heavy chickens ( 1 6- weeks)

a's = 255.7 1

.\ppcntlis 28: ('ocl'licicut of' corrclntiotr b c t w c c ~ ~ body weight awl f'cctl c o l ~ v c r s i o ~ ~ ratio ot' tllc 11c;ir~y chickcns - - .. - .L. - . . - -- - - --

klca~i .- Ootly .. - - - wig111 - - (s) - . - - T r e e d conversion ralio - - (y)

i)ppcnclix 29: ('hefficicat of corrclntio~~ I ) e t ~ v e c ~ ~ body weight :mi f'ccd cfficicncy of (Ilc

Appendis 3 1 : ('ocflicicats of correlation between feed conversion ratio and feed

I)iSi'crcncus bctwecn grol~ps are not significant

Appc'11dis.34: 1;cctl c ' o ~ ~ s l ~ ~ ~ l l ) t i o ~ ~ l l ) i r t l / ~ ~ c ~ c l < ......... of tlic 3 groups .... ......

Age (wucl.;) j 1..igl~l iiiickins Ilea\/y chickens Main cross chickens ----

4 1250.01 1200.03

f. -- - - ---- - --

I 700.0 1 --- .- -- . . 12 185O.O I --

1800.00 .. - -- -, -- .... - ....

. 1900.00 19 10.00 1900.08 1950.0 1 8660.20 - 8566T05 -- 2558856 -- - - - -

15 2.SS'T-- 84740000-C.17=1035058.45 3 .SSgr1)-83~6.3 1 1 '-I-. .......... .8600.20' -C.I;=8799.60

5 4.SSIi-:I -- . - - 2 1053.20 1 - . - -. -- - -

c1.f - -.

I'otal 14 . - - .

-- - - -. - -- - 0.05 1 12

I )il'li.rcnces Iwl\vwn groups arc not significant

. . . . . . . . . . . . . . . -- -

S.V ---- S S h4 S Fcal l:ti11)(5~%,) I'oI:1I 1 4 - - - -

-- 2 0.0 104 0.0052 0.2 I6 3.89 !!I 1 . 0 1 . 12 - - - - -. -- - - . 0.2884 0.0240 i ---

1)il'fkl.cnccs I~clwccn groups arc not significant

,Ippwdi\: 30: 1;cctl convcl-sion ratio for t l ~ c 3 g r o u p - .- - .7 - - -- - - - .- - /-Age ( u C C ~ ) ( I .ipllt chickcris I 1 Iwvy chickens mz cross T i x . 1

ESI'IMATION OF GENETIC CORIIEIATION

Ap~cndis : 38 rc; 0 f4 - \vcelis alltl 1 2 - \ \ r ~ ~ k ~ -- -- - - .. - - - - SV 1- 1 ti.1' I SCI' I MCP !

,\1)1)~'11(lis: 40 I-(; of 4- we l t s awl 20-\veel<s I)od wei@t for light c l~ icke~is -- . ~.

;. 1 sc: I> -T-F -4 TGFY~ -- - - -

I'otnl - P - - - - - Siws 2074.347 . . . -. - . - - . - -. . - . - -- -- -. -. -- 296.347 - .- - C'OVw-kC0Vs .

, I~:rsos - - - - . .. 128 - - 33893.983 264.797 COVw - - - -. - - - - - - - .- -- - . - - - - - - - - - -

( ' o \ ' s 12.035 ciZ(x)- 1.42 CT 2(y)=~7,68 1

1 .oo.i ; - jiLTjpzq

I,(; 0 . 2 3

for li@t cl~icl<cns S V -~ - ~ - -- Sircs - -.

20 15.05 .. . -- 287.950 l i r ror . - - 30035.05 239.34 1 - .------ - -

!:MCP .- . .

- -7

COVwt-kC'OVs ('OVw -

( 'ovs --2.075 c r ? ( s ) - 1.42 CJ Z(Y)=l 70.54

2.035 -. -- I - ( ; . ~ ) ( I .-!?)(I 70.54)

I i : 4.3 I - ; of 8- \~ccl ts and 20-wcclts body weight for light chicliens

- -- - -. . 7; MC P - -- -- - - - - - - 'l'o~al 135

. . - -. - . . - - ~

Sircs . . - . . 9823.53 ~ 1403.36 COVw+kC'OVs

la;~-ror 28 127202.50 993.77 ('OVw . - - -- -- I

h. = ill 36 - -1 = l h.00 8

q)rnrli\. 45 1.c- of' 12- wucks n ~ ~ t l 20-\vecl<s Imly \vci@t for ligllt cllickct~s 41 - . , #-:--I

r s \ ~ -pE---- yc:r - - -- - k h 4 ~ 1 ) y I - . . - - l o t I t t- 1

( ' o ~ L, -3 47 ( s ) 7 4 a '(y)= 47.0 1

. - - - - - I Siras 1 :I4 p 2 . 7 6 8 1 - - - . . - - .. - - - - .

5168.192 -- - I II1-1.01.

-- - -. - . . . . -- 2777 1 8.975 - 5 142.944 --- - covw

'I'otnl - - - - -- -

S ir-cs - - - --- -- I*:rror

i\l,l)clltlis: 49 r(; 01.4- \vccl<s 16-weeks body weight for main cross cl~icl<c~ls

:tppc~~tl is: 50 I-,; of 4- \vccks 20-wccl<s I)ocly weight for rl~ain cross chickens

( - 0 ~ s -5.4 I ( s ) I . I cr L)(y)= 379.01

/lppc~~dis: 5.3 I.(

S V . . - - - - - . - -

'I 'olal S i rr:s

I ;1.1.01. - - - -. - I< = I 1 .oo

- .

- -

-

Sircs 807.13 1 .- C'OV\v-t -- k('OVs -- .- -

54 2000 I .793 404.29 -- COVw K I l , O r ) ( -OW 20.:70 o o &+=~sn.os

0. I 7. I=: ~ ~ j ~ )