Current Developments in Poultry Breeding and Selec

8/17/2019 Current Developments in Poultry Breeding and Selec

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CURRENT DEVELOPMENTS IN POULTRY BREEDING

AND SELECTION

M. R. P TCHELL

Massey University, Palmerston North

SUMM RY

The

emergence of large scale poultry businesses in some

overseas countries is outlined,. and the development of large

scale private breeding orgamzations is discussed. Genetic-

economic considerations and market potential largely deter-

mine the type of breeding plan followed. The New Zealand

Random Sample Test is described, and its usefulness

in

eval;.lating poultry stocks assessed.

THE POULTRY INDUSTRY has in the past been the Cinderella

of agriculture, and is still receiving the Cinderella treatment

from agricultural education. However, in nearly all economi-

cally advanced countries of the Western world it is rapidly

becoming the most progressive branch of agriculture, both

in technical development and in the adoption of modern

business methods.

BUSINESS STRUCTURE

Starting in America, then in Britain after the war and

latterly in Australia, the poultry industry has developed or

is rapidly developing into quite a major industry. It is

characterized by very large business organization, with

substantial capital brought together through integration,

by the employment of top-flight scientists to enable techno-

logical discoveries to be swiftly applied, by organized

marketing outlets for products tailor-made for consumer

demand, all in a situation of fierce competition.

In 1954, the “broiler boom” in Great Britain got under

way after 14 years of feed rationing, and the consequent

technical stagnation of the industry. It was impractical for

the broiler industry to develop under conditions of strict

feed rationing. In America, on the other hand, the reverse

situation applied. The war years gave the American poultry

industry a great stimulus; there was a greatly increased

demand for animal products, and owing to shipping diffi-

culties the export of maize was limited as were exports of

Canadian wheat.

In 1953 the consumption of chicken per cupitn in Great

Britain was estimated (Hunt and Clark, 1962) at less than

1 lb per annum and specialized broiler units were virtually

no,q-existent. In 1960, seven years later, the annual per

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P TCHELL

capiln consumption of chicken meat was estimated by the

British Chicken Association at 9 lb and the production of

broilers had risen to 100 million per annum. Today in

Britain the annual production of broilers is about 220

millions and per capita consumption of chicken meat is

still increasing.

Ninety per cent. of the U.K. broiler production is in the

hands of no more than one thousand growers. Thus, a few

farmers produce efficiently the entire national requirement

of chicken meat with no help f.rom the taxpayer by way of

subsidies, in contrast to some other agricultural products

in Britain. The success of the broiler industry has been due

largely to vertical integration, organized on big-business

lines.

This pattern is now being followed by the egg production

side of the industry with million-bird factories being set up.

The egg empire of Eastwood (1964), being developed in

Britain, owns all the land required for the stock, for grow-

ing much of the feed and the disposal of manure. It has its

own breeding and multiplication farm and hatcheries. It

manufactures its own equipment and has its own process-

ing plants and retail outlets. ‘The situation in the U.S.A.

and other Western countries is very similar.

To compete and prosper, th.e individual broiler or egg

producer must first decide, through market research, the

best market for the product and its potential size. Next, the

whole cycle of operations from production, through manu-

facturing, processing, transportation and merchandizing

must be planned. At evety/stage advantage must be taken

of modern technology. The new poultry industries depend

on highly specialized research, imvolving new approaches to

applied poultry genetics, controlled environment housing,

disease control, nutrition, and to the processing and mar-

keting of eggs and chicken.

An outstanding feature of the poultry industries of

America, Great Britain, and recently in Australia, has been

the evolution of large breeding organizations. Since the

mid-1940s it has been the custom for the larger American

breeders to engage geneticists, and some of the world’s

leading animal geneticists are now employed by these

establishments. The results have been impressive. Largc-

scale selection and testing programmes have been embarked

upon, improved systems of poultry stock evaluation have

been developed, and within a few years stock has been so

improved in all-round performance that commercial poul-

trymen can afford to buy chicks only from those organiza-


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POULTRY BREEDING AND SELEC’I-TON

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tions which have replaced breeding as an art, by breeding

as a science.

This kind of work is costly. Hence, it is imperative that

the breeder mounts large multiplication programmes to

produce chicks of the improved stock by the million, main-

taining strict quality control during the multiplication

stages. By this means he can spread the cost of the work

over a large output of chicks. In the United States in the

1930s there were several thousand so-called poultry

breeders. Today, the bulk of the 250 million pullets raised

annually for the egg industry are bred by 5 breeders, all

of whom are mass-producing stock which, given good man-

agement, averages 230 to 250 eggs per pullet in a laying

season on less than 4r/2 lb of feed per dozen eggs. In the

American broiler industry, with an output of 2,000 million

broilers per annum, the selection of the majority of the stock

is carried out by four breeders of female lines and two

breeders of male lines. Selection programmes costing over

half a million dollars per annum are mounted by some

breeders.

A number of these top American breeders are now becom-

ing established in other countries, in Western Europe,

Africa, the Middle East, South America and Asia. Since

1963, with the ending of the official embargo on the import

of U.S. poultry breeding stock into Great Britain, American

breeders are becoming established in that country as well.

However, some British hatchery organizations, notably

Thornber Bros., have developed their own genetic research

techniques with promising results, and Thornber’s have

extensive overseas markets for their stock.

BREEDING METHODS

Modern poultry breeders adopt the well-known systems

of selection based on modern population genetic theory.

Usually several types of breeding programme are under

way, particularly if chick sales are large. The costs of expen-

sive breeding schemes, such as the development of highly

inbred ‘lines and their subsequent crossing, or use of allied

schemes such as reciprocal recurrent selection are high.

These more sophisticated breeding schemes are possible

only if there are large markets to defray costs. Others may

use more conventional selection schemes based on indi-

vidual, full-sister and half-sister performances combined

into an index. Strain crosses for the commercial product

may be used from among the most promising lines being

developed from conventional selection schemes. In the case


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PATCHELL

of broilers, the essential principle consists of the employ-

ment of strain crosses, whereby female lines of relatively

high fecundity, reasonable growth rate and conformation

are crossed with male lines with superior growth and con-

formation to produce the market bird. The initial promise

from blood typing as a useful .tool in breed improvement

now appears to be waning, and there is now less enthusiasm

for this expensive technique (Nordskog, 1964).

Because of competition between breeders and the greater

sophistication of the chick-buying public, breeders have

found it necessary to increase the number of factors for

which they select. This adds greatly to the difficulty of

improving performance.

In breeding for both broiler and egg production there is

increasing awareness of the importance of genotypes

environmental interactions. Bowman and Powell (1962) of

Thornber Bros. reported significant interactions in 8 week

body weight in broiler chickens, and Dickerson ( 1960), of

Kimber Farms, has reported interactions with egg lines,

particularly egg number and mortality. Abplanalp and

Menzie ( 1961) also reported interaction effects for egg

strains from a Swiss co-operat.ive breeding unit. Indeed,

Dickerson (1961) looked critically at the whole concept of

selection theory, particularly the prediction of response to

selection and the problem of plateau situations. He outlined

techniques for the experimental explanation of selection

theory in animals. In discussing genetic interaction, he

presented the results made up from 79 strains of birds at

each of 13 locations in one year and 59 strains of birds

at each of 12 locations in another year with a total of 22,494

pullets. Egg production data were obtained at 22 of the

locations for 19,739 pullets, and body weights and egg

quality measurements were taken at 32 weeks of age at

16 locations for 15,080, and 12,920 pullets, respectively.

These figures perhaps illustrate better than anything else

the scope and size of the testing programmes and it is quite

likely that current problems of selection in animals are

being actively studied in these organizations.

The great expansion of the breeding groups to the stage

where their stock are used in many parts of the world,

covering a large range of environments;:has resulted in their

being confronted with this problem of ‘genotype X,environ-

ment interaction. At the same tirne, however, the inte ti,on

problem

is

becoming evident even within much smaller

geographic regions, particularly for traits where environ-


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POULTRY BREEDING AND SELECTION

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mental factors have a large effect on performance (Hull

et al., 1963).

If the main objective of a breeding programme is the

production of one strain with good performance ability

under a variety of environmental conditions there appears

no way in which genotype~environment interactions can

be exploited for genetic progress. They merely tend to dis-

tract selection decisions from the general aim towards

special adaptation of strains to a given environment unless

strains are tested on several farms. There has been experi-

mentation with multiple location or on-the-farm random

sample testing of egg production stocks, for the purposes

of obtaining more reliable ranking of stocks under typical

commercial condi’tions (Nordskog and Kempthorne, 1960;

Abplanalp et al., 1962). _

The development of genetic control populations for use

in selection experiments with poultry received impetus with

the publication of Gowe et al. 1959). The establishment and

testing of various types of genetic control populations have

been carried out by some of the larger breeding groups

(Bowman and Challender, 1962) ; Goodwin et al. (1960)

published a report describing the repeat mating control

strain technique.

The commercial breeding of chicks for distribution to

industry has replaced breeding schemes previously imp1e.s

mented by Government and other institutions. This is prob-

ably due to increased efficiency of all operations enforced

by free competition. However, private breeding organiza-

tions may not always adopt the breeding programme which

maximizes improvement because of economic considera-

tions. Genetic-economic interrelationships need to be

considered carefully by these breeding establishments. For

example, performance traits of the parent stock as well as

the broiler progeny influence the net income of a broiler

enterprise, and studies have been made to determine the

relative importance of the factors which determine the

profitability of a strain of broilers. Strain and Nordskog

(1962a) concluded that broiler weight and broiler feed

conversion were the most important factors determining

net income in the Maine Random Sample Broiler Tests.

Egg production in the parent flock was of little importance.

Using egg laying test data, Nordskog (1960) found that egg

production was the most important factor affecting income.

However,’ these studies were based on phenotypic correla-

tions between traits.


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P TCHELL

In a breeding programme, the genetic-economic relation-

ships of traits become important. Genetic changes in the

parent flock influence net returns directly through chick

costs and indirectly through correlated responses in the

broiler progeny. Hence, there can be a see-saw effect in

which emphasis on adult body size may favour broiler

growth rate yet reduce egg production and vice versa. Strain

and Nordskog (1962b)

reviewed these problems and con-

cluded that it was important th.at breeders should make an

assessment of the genetic correlations associated with their

breeder flocks in order to formulate breeding programmes

designed to maximize profit.

Another problem is that the commercial breeder, under

a free enterprise system, must conduct his operation with

a view to obtaining a profit at least in the long run. The

increase in profit through the application of a particular

breeding plan will be determined by the increase in gross

income’ caused by the genetic improvement of the stock

less the increase in cost caused by operating the particular

breeding plan.

A breeding programme can increase the operator’s gross

income through increased sales of eggs and meat caused

by higher production ;

and by more revenue from day-old

chick sales and/or better prices obtained for a better

quality chick. Skaller (1964) has shown that increased chick

sales, direct or through franchised hatcheries, must make

the main contribution towards not only the cost of a breed-

ing programme, but towards profit margin as well. Thus,

volume, or rather potential volume of chick sales, restricts

breeders of Australia and New Zealand because of the

limited market. With a small market even relatively simple

breeding schemes may be too costly to operate. Most breed-

ing schemes require a definable minimum flock size for

th r efficient operation and the cost of this flock must be

distributed over the largest possible number of commercial

chicks sold. This number is set by the reproductive ability

of the population and with poultry this is quite consider-

able. A flock of 1,000 pullets, with a breeding season of

30 weeks, and an expected 30 daughters per pullet, should

after two generations of multiplication yield 27 million

chicks in the fourth generation. The closer the actual output

of salable chicks to this biological potential, the more

profitable will be the breeding operation. In Australia and

New Zealand, with limited markets, it is not easy to expand

chick sales to the point where sophisticated breeding,plans

could be followed, particularly breeding systems such as


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those designed to exploit specific combining ability in which

large flocks must be tested.

Hence, the choice of a breeding plan which will produce

optimal results for a commercial breeding organization

requires the consideration of several factors, some genetic

yet others economic.

PROGENY TESTING METHODS

A major problem with all farm livestock in past years has

been the lack of sound quality and performance evaluation

procedures for assessing breeding stock. Today’s standards

and evaluation procedures for beef cattle, dairy cattle, pigs

and sheep have been developed from traditional stock

judging competitions. The poultry industry has also been

hampered by traditional methods of assessment of per-

formance. Poultry breeders spent 40 years discovering that

if the breeder was allowed to select 6 pullets for submission

to a laying test the results of such a test were of very

dubious merit.

The testing of laying strains of poultry, as carried out in

recent decades, has proved unsatisfactory in many ways.

Most breeders entered pullets in Standard Laying Tests, the

larger breeders entering birds for a number of tests. each

year. The breeders regarded the outcome of these tests as

valuable for publicity and advertising. The practice was for

the breeder to select his entry of some 6 pullets soon after

his pullet flock came into lay. Those pullets which showed

an early promise from trapnest records were selected for

the test. Obviously, both the selection of the birds tested

and the small sample tested meant that test results were of

limied usefulness in predicting performance of unselected

samples of the stock under practical conditions of manage-

ment.

Dissatisfaction with Standard Laying Tests led to an

improved method, the Random Sample Laying Test, which

started in California about 1947. Its objective was to com-

pare the performance of representative samples of commer-

cial grades’of chicks, as offered for sale to poultrymen by

breeders or hatcheries, under uniform but practical condi-

tions of management, and to publish test results for the

guidance of poultrymen as well as the hatcherymen and

breeders. Random’ Sample Tests have since been organized

in many other American states, and in other countries.

The New Zealand Random Sample Test started in August,

1963. It was set up by the poultry industry with the aid of


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PATCH ELI

a Government grant, and the Poultry Board is responsible

for financing the test. By arrangement, Massey University

runs the test on behalf of the Board, and is aided in this

by an Advisory Committee containing representatives of the

Poultry Board, the Department of Agriculture, and Massey

University. Facilities are available for testing 25 different

stocks each year.

Eggs are selected at random from the entrants’ farms by

Poultry Instructors of the Department of Agriculture. The

eggs are incubated at the Test Unit. At hatching, one hun-

dred pullet chicks per entrant are selected at random. These

are brooded and reared on an intermingled system to about

19 weeks of age. At random, 50 pullets per entry are selected

and placed in the laying shed in two pens each containing

25 birds. Full records of production, mortality, food con-

sumption and egg quality are kept to 490 days of age. The

results are made available to the industry periodically

throughout the test.

The organization of random sample tests in other coun-

tries is very smilar to the New Zealand test. Some take in

chicks not eggs, some run to 500 days or longer, and some

increase the accuracy of the test by testing a larger pullet

sample of up to 100 per entrant:.

The results of a random sample test are published and

serve as a useful guide, particularly when compared over

three or four years, as to where the most promising stock

is likely to be available. The accuracy of the Random

Sample Laying Test is not very great because of the con-

siderable experimental error. Only quite large differences

between stocks can be detected, and there is little point in

emphasizing differences in ranking based on small differ-

ences in performance.

In recent years most of the random sample tests in the

U.S.A. have been collated and published after suitable

adjustments have been made for differences between tests.

Even so, there is still a very considerable experimental error

remaining in the ranking of stocks based upon test cor-

rected averages.

Both in Iowa and in California there has been experi-

mentation with multiple locatidn or on-the-farm random

sample testing of egg production stocks for the purpose of

obtaining more reliable ranking of stocks under typical

commercial conditions. Analyses by Hill and Nordskog

( 1956) and Nordskog and Kempthorne (1960), have demon-

strated the importance of real but unpredictable shifts of

ranking of stocks ,from one location to another. Although


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POULTRY BHEEDtNG .4ND SELECTION

51

multiple location random sample tests or those using

several types of housing at one test location have been

examined in an attempt to reduce the experimental error

from interaction between stocks and management pro-

cedures, experience has shown that, despite these precau-

tions, accuracy in predicting the ranking of entries in

another year, or in another test, from results within any

one test and year is limited.

Hence, although random sample tests are a considerable

improvement on the old standard laying tests, they still

leave much to be desired, but their development is an

example of voluntary co-operation between the poultry

industry, scientists and governments. Apart from the diffi-

culties of ranking stocks accurately, they do provide a

wealth of factual information on the performance of fowls

and also on the success or otherwise of the breeding plans

of the large breeding organizations.

Any breeding plan suggested by genetic research must,

finally, be evaluated in terms of its contribution to food

production.

REFERENCES

ABPLANALP, H.; MARROU, L. F.; GOTO, E. 1962:

Poult. Sci., 41: 927.

ABPLANALP, H.; ME~TZIE, M. 1961: Brit. Poult. Sci.. 2: 71.

BOWM IAN, J.

C.; CHALLENDER, N. I. 1962:

Anim. Prod., 4: 294.

BOWMAN, J. C.; POWELL, J. C. 1962:

Anim. Prod., 4: 319.

DICKERSON, G. 1960:

Poult. Sci., 39:

1244 [Abstr.].

1961: Get-111

Plasm Resources.

Amer. Assoc. Adv. Sci. p. 161.

EASTWOOD, J. B. 1964: Pouft. Frnz. Pucker, 152 (3919): 15.

GOODWIN, K.; DICKERSON, G. E.; LAMOREU~, W. F. 1960:

Biometrical

Genetics.

Pergamon Press, New York. p. 117.

GOWE, R. S.; ROBERTSON,A.

;

LATTER, B. D. H. 1959: Poult. Sci., 38

:

462.

HJLL, J. F.; NORDSKOG, A. W. 1956:

Poult. Sci., 35: 256.

HULL, P.; GOM~E, R. S.; SLEN, S. B.; CRAWFORD, R. D. 1963:

Genet.

Ass. Camb., 4: 370.

HUNT, K. E.; CLARK, K. R. 1962:

Poultry Eggs i.n Britain, 1961-

62. Univ. of Oxford. Res. Inst. in Agric. Eton.

NORDSKOG, A. W. 1960:

Poult. Sci., 29: 327.

- 1964:

World’s

Pocclt. Sci. J.,

20: 183.

NORDSKOG, A. W.; KEMPTHORNE, 0. 1960: Biometrical Genetics. Per-

gammon Press, New York. p. 159.

SKALLER, F. 1964:

Proc. Australasian Poult. Sci. Cotzv., Aust.,

p. 12.

STRAIN, J. H.; NORDSKOG, A. W. 1962 a):

Poult. Sci., 41: 1573.

->

~

1962 b):

Pouft.

Sci., 41: 1892.

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