Applying the Principles of Poultry Breeding

New Zealand Journal of Agriculture, Volume 79, Issue 6, 15 December 1949, Page 547

Applying the Principles of Poultry Breeding

PRINCIPLES and practices involved in poultry breeding have been described in previous articles in this series by F. C. Bobby, Superintendent, Poultry Industry, Department of Agriculture, Wellington, but so far only a limited attempt has been made to apply these principles to methods on the farm. This article, which will be continued next month, deals with the aspects of the subject and problems which face the poultry breeder. It includes a description of progeny testing, a subject much under discussion by people interested in the breeding of livestock.

1T is comparatively easy for poultry producers interested in breeding to study the fundamental principles of genetics, but putting .those principles into practice with breeding birds is an entirely different problem, particularly if the poultry producer is interested mainly in raising the economic value of his flock, with increased average egg production as a major aim. The fancier, whose main objective is perfection in type and other breed characteristics in a bird has advantages over the poultry breeder interested in egg production and other factors of commercial value in that he can measure by eye the characteristics sought and include as breeders birds which carry these characteristics. However, even the fancier cannot be sure that desirable characteristics present in the breeding male or female will be passed on to all or any of the progeny in a desirable manner. That is perhaps the major factor in breeding and is today a basic fact influencing poultry-breeding programmes for increased egg production. Among economic characteristics desired by the commercial producer are heavy egg production; high hatchability rate, and liveability. As with those sought by the fancier, these characteristics can be measured, though not by eye, but by systems of recording, which often entail much labour, patience, and time. Furthermore, in breeding there are no short cuts to success and no golden rules which, if adhered to completely, must lead to success. Each breeder depends for success on the application of the principles of genetics, intelligent interpretation of the results obtained, and a thorough knowledge of his stock. Difficulties to be Faced The knowledgeable breeder selects a male bird which on sight and handling measures up to a desirable standard. The bird may be from a pen of hens known to have given good egg production, but there is no guarantee that this male will sire pullets which will give high average production. The value of that male bird as a stud breeder is not known until he has proved his worth by the class of pullet he has sired. Similarly, a breeder may select a pullet or hen which appears to carry the characteristics of a good layer, or a hen whose pullet-year egg production has been recorded, yet again there can be no guarantee that this bird will

throw pullets of high average production. Only by measuring or recording the production of those pullets is it possible to assess the true value of the hen as a breeding bird. However, if the breeder has recorded his stock for a number of generations, so that information is available about the parentage of any breeding bird, male or female, predicting the possible value of such a bird becomes easier. Furthermore, selecting year by year what are considered to be the best birds on handling tends to maintain a standard or even to bring about some improvement. Maintaining or Raising Production When contemplating a breeding programme the poultry farmer must decide whether it is intended to maintain a reasonable standard of egg production or whether the object is to raise the level of production substantially. That refers not to a strictly limited number of high producers in a laying flock, but to the average production of the flock. More than one poultry breeder has won egg-laying . competitions with birds giving outstanding production though on his farm the average for the rest of the pullets has hardly attained an economic level. - Statistics indicate that the average annual egg production for flocks of hens and pullets in New Zealand is about 11 dozen per bird. Without doubt there are flocks with averages well above this figuresay, 14 to 15 dozen; average production at this level has been attained by a breeding programme based mainly on selection by handling and observation, backed by first-class management at all stages. However, it is doubtful whether, such flocks have shown much change in egg production over the years beyond limited fluctuations from season to season. Progeny Testing To make appreciable advances in egg production with such flocks and within a limited number of years it is likely that a definite programme of breeding based on progeny testing would have to be adopted. To appreciate what is envisaged it is first necessary to know what is meant by progeny testing. The term implies assessing the worth of a male or female as a breeder by measuring the value of the progeny in terms of the characteristic for which a mating has been made —egg production, hatchability, liveability, disease resistance, or any other desir -

able characteristic. Not the unknown potential value but the actual breeding value of the male or female is under —hence the terms “proven male” or “tested male.” Progeny testing takes time and labour, but if a male is found that throws progeny giving an egg average appreciably above the previous average for a flock, its value for as long as it will breed is greatfar greater than that of any untried male or even an average tested male. Such males are hard to find. The progeny testing of males entails less work than the testing of females. The male is often spoken of as being “half the breeding pen.” There is little difficulty in obtaining, say, 40 or 50 pullets sired by a single male. If taken at random from all the pullets sired by a single male in a breeding season, that number of birds is a good representative sample and one which it is safe to use as a means of measuring the value of that male. A different and more difficult situation arises in the testing of females. All too often it appears possible to obtain only 4 or 5 mature pullet daughters of the hen being tested, but a sample of 8 to 10 is desirable. Family Testing Though testing males can lead to progress, the greatest advantages are obtained by “family testing” is, testing a number of females and eliminating as breeders any that do not reach a required standard. Two highly desirable economic factors may be used for measuring the value of daughters of any hen — rearability and their liveability as matured birds, the latter being associated with resistance to disease., Thus, if a hen’s progeny suffer undue mortality during the rearing period or heavy losses during the first laying season, that hen and her progeny, male and female, should be eliminated from any future breeding pen.' On the other hand, if the daughters of a hen rear well and show a low mortality rate as pullets in their first laying season, the value of the dam as a breeder may then be judged on their egg production; if it is satisfactory or obviously above the average for the strain of birds, she is valuable as a breeder for as long as she produces a reasonable number -of normal hatching eggs. Furthermore, the full brothers to the pullets are more valuable than males about which little is known beyond their exterior characteristics. Judging the value of a hen by the pullet-year records of her daughters is not as simple as it may appear, as is shown by the following figures for two hens mated to the same sire:— Hen A, Hen B, Family No. 1 Family No. 2 Pullet-year egg records of daughters 280 180 146 220 180 205 105 210 200 232 100 240

Though hen A has produced a daughter giving 280 eggs, this bird is not nearly as valuable a breeder as hen B, the production of whose pullets is far more consistent. The results suggest that hen B is more homozygous or pure for the genetical factors affecting egg ' production than hen A. Though the pullet-year records of both hens may have been high and similar, it is not the egg-production record of the breeder which counts, but the average production of her daughters. The recording of families has been described because the family method of selecting breeding birds is a sound way in which to breed for increased egg production. That it involves work, time, and patience is obvious. Maintaining a reasonable egg average in a flock by efficient management and careful selection of breeders by observation and handling is comparatively easy. The real test of a breeder comes when he endeavours to raise the standard of production to a high average level. Characteristics to: be Recorded Before considering possible breeding programmes applying the principles and practices described it is necessary to decide what desirable characteristics of breeding stock and its progeny are to be recorded. The more important characteristics are hatchability, rearability, egg production, and adult mortality. Hatchability The collection of data about hatchability presents little difficulty but involves time and conscientiousness in recording. If it is desired to record only the general results of a pen or a number of pens of breeding hens mated to a single male in each case, it is necessary only to mark each egg laid with the pen number. Such eggs are then recorded at each stage of incubation as infertile, dead germs, dead in shell, or finally chicks hatched. If results from individual breeding females are required, the breeding birds must ■be trap nested and each bird’s leg band number and pen recorded. A form for summarising results from individual females is illustrated. A similar type of form is necessary for recording the results of each hatch, but only numbers and not percentages need be recorded for each hatch. The final hatching results are expressed on the forms illustrated as “Percentage of fertile eggs” and also as “Percentage of all eggs set.” The former is the figure usually quoted, but the latter is of value because it gives a figure which truly represents the result— many chicks have been obtained for every 100 eggs set. Rearability Data about rearability cannot be collected unless every chick hatched is toe-punched to indicate the pen (or even individual bird if desired) from which the chick came. The toe punch of a chick which dies is recorded in a book or on a sheet. Sixteen combinations of toe punches which may be used are shown on the next page; this number can be doubled if one back toe is removed, and doubled again for

the back toe on the other leg. The web may be slit with a pair of scissors or a knife instead of using a punch if desired. Here again recording presents no difficulties, time and conscientiousness alone being involved. Egg Production Egg production may be recorded or measured for individual birds or for a flock. Individual layers may be. recorded by the use of trap nests where a number of pullets or hens . are run in a flock. Each bird carries a numbered leg band and eggs are credited to the bird’s number on specially designed sheets. An alternative method is to have a series of single pensone for each layer, or even two layers per pen where a light- and. a heavy-breed bird are run together, the difference in the colour of the eggshell denoting which bird has laid. Trap nesting involves considerable labour, particularly during the flush season of production, and it can be recommended only where full advantage -is taken of the information gathered. Trap-nest sheets afford far more information than merely the total of eggs laid during the period for

which the birds are recorded. Egg sequences, winter egg production, moulting periods, and broodiness are some of the items about which trap-nest sheets can supply valuable data to the breeder. The value of individual pullet-year egg scores will be referred to when breeding programmes are discussed. The recording of egg production for a flock of layers is simple and requires little labour. A card, sheet, or egg book and the will to record daily the number

of eggs produced by a flock or house of birds are the only requirements. The recording of egg totals daily and the addition of these into a total at the end of a period require little effort, but the method of interpreting the results needs more thought. Quite often the average number of eggs per bird is calculated on the basis of the number of birds laying during the year, dead birds and culls being deducted from the number at the start of theseason. However, the average which gives a true picture of the performance of a flock takes into account mortality and culling, and this figure is obtained when the total number of eggs produced is divided by the original number of birds in the flock. This is known as the hen-house average and is the figure by which the real economic value of a flock may be measured. It includes the good and the poor producer and also reflects the great economic value of liveability in the birds in the flock. Flockhouse or hen-house averages compared year by year present a true picture of ground gained or lost. They are also a means of measuring the value of a male bird where the first stages of progeny testing are carried out. Approximate averages based on total eggs produced and the number of birds left at the end of a laying season may look well, but all too often they are highly misleading as to the economic value of the stock. It is recommended that any production figures recorded should be kept for a maximum period of 48 weeks and for the same period each year for comparison purposesfor example, March 1 to January 31. Every producer is faced annually with finding room for the current season’s pullets. Culling starts, flocks are broken up, and houses are amalgamated to make room for these annual replacements, and the keeping of accurate egg tallies by houses or flocks becomes impossible. Therefore it is better to choose a reasonable period for accurate recording and to use the same period each year, whether it be 40, 44, or 48 weeks. Accurate data can then be kept and compared year by year to measure progress. Mortality Many producers would receive an unpleasant shock if accurate figures about losses from day-old birds until the final disposal of stock were recorded on their farms. In any progressive programme of breeding such figures are essential in measuring the value of a strain of birds or the breeding worth of a male bird. They are of greatest value where the cause of death, more particularly in adult stock, is known in each case, but this is rarely practicable for the average breeder of poultry. Nevertheless, where a serious attempt is being made to improve the economic value of a flock, records of losses of both young and adult stock are essential. The method of recording such mortality may be comparatively simple and designed by the breeder to meet his own requirements.

A Dog-chain Fastening Which Will Not Tangle DESPITE their value on the farm, many dogs are not adequately sheltered, and the methods by which they are attached to their kennels often leave much to be desired. Frequently a dog is seen with his chain so completely wound about an old stake, derelict farm implement, or broken-down kennel that freedom of movement is impossible. Such treatment is not conducive to good manners, and obedience.

The illustration shows how by the use of discarded implement parts Mr. A. V. King, of Clydevale, Otago, is able to tether his dog securely by its kennel and allow the maximum amount of freedom. A dog attached to such a device cannot become "hung up." The swivel ring is some Ain. in diameter and revolves on a bolt IBin. long driven through it into the ground. Between the ground and the lower surface of the wheel is a washer 2in. in diameter and 2in. thick, which acts as a bearing and enables the wheel to revolve smoothly. —J. G. RICHARDS, Instructor in Agriculture, Department of Agriculture, Balclutha.