Chapter 30

PRACTICAL AND SCIENTIFIC BREEDING

Science has been defined as the "know how" and art as the "do how." The man who works by art depends upon an unconscious judgment which is inborn or is acquired by long practice. The man who works by science may also have this artistic taste, but he tests its dicta by comparison with known facts and principles. The scientist not only looks before he leaps, but measures the distance and knows exactly where he is going to land.

Breeding has for centuries been an art, but the science of breeding is so new as to seem a mass of contradictions to all except those familiar with the maze of mathematics and biology by which the barn-yard facts must find their ultimate explanation. The science of breeding may in the future bring about that which would now seem miraculous, but it is the ancient art of breeding that is and will for years continue to be the means by which the poultry fancier will achieve his results.

In a volume the chief aim of which is to place the poultry industry, which is now conducted as an art, in the realm of technical science, it might seem proper to devote considerable space to the subject of breeding, That I shall not do so, is for the reason that while theoretically I recognize the important part that breeding plays in all animal production, for the practical proposition of producing poultry products at the lowest possible cost, a knowledge of the technical science of breeding is unessential and may, by diverting the poultryman's time to unprofitable efforts, prove an actual handicap.

For the show room breeder the new science of breeding is too undeveloped to be of immediate service, or I had better say, the show room requisites are too complicated for theoretical breeding to promise results. For the commercial poultryman, I shall review what has been accomplished and state briefly the theories upon which contemplated work is based.

The objects striven after in poultry breeding are: 1st: To create new varieties which shall have improved practical points or shall attract attention as curiosities. 2d: To approach the ideals accepted by fanciers for established breeds, and hence win in competition. 3d: To change some particular feature or habit as, to increase egg production or reduce the size of bantams. 4th: To improve several points at once as, eggs and size in general purpose fowls. This classification is really unnecessary, as the most specialized breeding involves consideration of many points.

Breeding as an Art.

The method by which breeds and varieties of the show room specimens have been developed is essentially as follows: The wonderfully different varieties of fowl from every quarter of the earth are brought together. Crossing is then resorted to, with the result that birds of all forms and colors are produced. The breeder then selects specimens that most nearly conform to the type or ideal in his mind.

Suppose a man wished to produce Barred Leghorns, with a fifth toe. He would secure Barred Rocks, White Leghorns and White or Gray Dorkings. Then he would cross in every conceivable fashion.

Perhaps he might have trouble getting the white color to disappear. In that case Buff Leghorns which are a newer breed might be tried and found more pliable material. By such methods the breeder would in three or four generations of crossing get a crude type of what he desired. Henceforth it would be a matter of patience and selection. Five to twenty years is the time usually taken to produce new breeds of fancy poultry that will breed true to type. In this style of breeding the principles at stake are simple. The first is to secure the variations wanted; second, to breed from the most desirable of these specimens.

The same methods of selection that establish a breed are used to maintain it, or to establish strains. In ordinary breeding there are two other principles that are sometimes called into play. One is prepotency, the other is inbreeding. By prepotent we mean having unusual power to transmit characters to offspring. Suppose a breeder has five yards headed by five cock birds. The male in yard two he does not consider quite as fine as the bird in yard one, but in the fall he finds the offspring of bird from two much better than the offspring from yard one. The breeder should keep the prepotent sire and his offspring rather than the more perfect male, who fails to stamp his traits upon his get.

Normally a child has two parents, four grandparents, and eight great-grandparents. Now, when cousins marry, the great-grandparents of the offspring are reduced to six. The mating of brother and sister cuts the grandparents to two, and the great-grandparents to four. Mating of parent and offspring makes a parent and grandparent identical and likewise eliminates ancestry. Inbreeding means the reduction of the number of branches in the ancestral tree, and this means the reduction of the number of chances to get variation, be they good or bad.

Inbreeding simply intensifies whatever is there. It does not necessarily destroy the vitality, but if close inbreeding is practiced long enough, sooner or later some little existing weakness or peculiarity would become intensified and may prove fatal to the strain. For illustration, suppose we began inbreeding brother and sister with a view of keeping it up indefinitely. Now, in the original blood, a tendency for the predominance of one sex over the other undoubtedly exists and would be intensified until there would come a generation all of one sex, which, of course, terminates our experiment.

Inbreeding has always been tabooed by the people generally. Meanwhile the clever stock breeders have combined inbreeding with selection and have won the show prizes and sold the people "new blood" at fancy prices.

Unintelligent inbreeding as practiced on many a farm, results in run down stock, not so much from inbreeding as from lack of selection. Out-crossing or mixing in of new blood is better than hit-or-miss inbreeding. Intelligent inbreeding is better still.

Scientific Theories of Breeding.

The main tenet of Darwin's theory of racial inheritance or evolution, was that changes in animal life, wild or domestic, were brought about by the addition of very slight, perhaps imperceptible, variations. He argued that the giraffe with the longest neck could browse on higher leaves in time of drought and hence left offspring with slightly longer necks than the previous generation.

Upon this theory the ordinary breeding by selection is based. In case of breeding for show room, the breeder's eye, or the judge's score card, is the tape with which to measure the length of the giraffe's neck. This principle can be applied equally well, even better, to characteristics where accurate measurement may be used.

The last forty years of scientific progress has established firmly the general theories of Darwin, but they have also resulted in our questioning his idea that all great changes are due to the sum of small variations. Many instances have been suggested in which the theory of gradual changes could not explain the facts.

The theory of mutation, of which Hugo de Vries, of Holland, is the chief expounder, does not antagonize Darwin, but simply gives more weight in the process of evolution to the factor of sudden changes commonly called sports. Let us illustrate: In the giraffe of our former forest, one might appear whose neck was not longer because of slightly longer vertebrae, but who possessed an extra vertebrae. This would be a mutation. In other words, a mutation is a marked variation that may be inherited. We now believe that polled cattle, five-toed Dorkings, top-knotted Houdans, frizzles and black skinned chickens arose through mutations.

Burbank's Methods--The wonderful Burbank with his thornless cactus, his stoneless plum, and his white blackberry, is simply a searcher after mutations. His success is not because he uses any secret methods, but because of the size of his operations. He produces his specimens by the millions, and in these millions looks, and often looks in vain for the lonely sport that is to father a new race. Burbank has, with plants, many advantages of which the animal breeder is deprived. He can produce his specimens in greater number, he can more easily find out the desirable character, and in many plants he has not the uncertain element of double parentage to contend with, while with others he is still more fortunate, as he can produce them by seed, stimulate variation until the desired mutation is found and can then reproduce the desired variation with certainty by the use of cuttings. This latter is not true inheritance with its inevitable variation, but the indefinite prolongation of the life of one individual. In this sense there is only one seedless orange tree in the world.

The Centgenitor System--Prof. Hays in breeding wheat at Minnesota, first used in this country a system of breeding which is essentially as follows: A large variety of individual seeds are selected. These are planted separately and the amount and character of the yield observed. The offspring of one seed is kept separate for several generations, or until the character of the tribe is thoroughly established. The advantage of this plan of breeding is in that the selection is not made by comparing individuals, but by comparing the offspring of individuals. Thus, we necessarily select the only trait really worth while; that is prepotency or the ability to beget desirable qualities.

The application of this centgenitor system necessitates inbreeding; it also necessitates large operations. Of the former, breeders have generally been afraid; of the latter they have lacked opportunity. But the centgenitor system, combined with Burbank's principle of large opportunity of selection, is, in the writer's belief, the method by which the 200-egg hen will be ultimately established in America.

Much of the recent stimulus to the study of the Science of Breeding was occasioned by the discovery of Mendel's Law. Briefly, the law states that when two pure traits or characters are crossed, one dominates in the first generation of offspring--the other remaining hidden or recessive. Of the second generation, one-half the individuals are still mixed, bearing the dominant characteristic externally and the other hidden; one-fourth are pure dominants and one-fourth are pure recessives. In future generations the mixed or hybrid individuals again give birth to mixed and pure types apportioned as before, thus continuing until all offspring become ultimately pure. For illustration: If rose and single comb chickens are crossed, rose combs are dominant. The first generation will all have rose combs. The second generation will have one-fourth single combs that will breed true, one-fourth rose combs that will breed rose combs only, and one-half that again will give all three types.

Mendel's Law works all right in cases where pure unit characteristics are to be found. For the great practical problems in inheritance, Mendel's law is utterly hopeless. The trouble is that the chief things with which we are concerned are not unit characteristics but are combinations of countless characteristics which cannot be seen or known, hence cannot be picked out. Thus the tendency to revert to pure types is foiled by the constant recrossing of these types.

Mendel's law is a scientific curiosity like the aeroplane. It may some day be more than a curiosity, but both have tremendous odds to overcome before they supplant our present methods.

Prof. C.B. Davenport, of the Carnegie Institute, is working on experimental poultry breeding in its purely scientific sense. His conclusions have been much criticised by poultry fanciers. The truth of the matter is that the fancier fails to appreciate the spirit of pure science. The scientist, enthused to find his white fowl re-occur after a generation of black ones, is wholly undisturbed by the fact that the white ones, if exhibited, might be taken for a Silver Spangled Hamburg.

Mendel's law as yet offers little to the fancier and less to the commercial poultryman. Its study is all right in its place, but its place is not on the poultry plant whose profits are to buy the baby a new dress.

Breeding for Egg Production.

Attempts to improve the egg-producing qualities of the hen date from the domestication of the hen, but it has only been within the last few years that rapid progress has been possible in this work. The inability to determine the good layers has been the difficulty.

The great majority of people make no selection of hens from which to hatch their stock. The eggs of the whole flock are kept together and when eggs are desired for hatching they are selected from a general basket. It has been assumed, and is shown by trap-nest records, that eggs thus selected in the spring of the year are from the poorer, rather than from the better layers. This is because hens that have not been laying during the winter will lay very heavily during the spring season. Many breeders have attempted to pick out the good layers by the appearance of the hens. Before the advent of the trap-nest the "egg type" of hen was believed to be a positive indication of a good layer. The "egg type" hen had slender neck, small head, long, deep body of a wedge shape. Various "systems" founded on these or other "signs" have been sold for fancy prices to people who were easily separated from their money. Trap-nest records show such systems to be on a par with the lunar guidance in agricultural operations.

I might remark here that the determination of sex by the shape of the egg or similar methods, is in a like category. Science finds no proof of such theories.

A few methods of selecting the layers have been suggested which, while far from absolute, are of some significance and are well worth noting. The hen that sits upon the roost while other hens are out foraging, is probably a drone. The excessively fat or the excessively lean hens are not likely to be layers. It would naturally be supposed that the active laying hen would be the last one to go to roost at night. At the Kansas Experiment Station, the writer made observations upon the order in which the hens went to roost, and the above assumption was found in the majority of cases to be correct.

A still better scheme of selecting layers is the practice of picking out the thrifty, quickly maturing pullets when they first begin to lay in the fall season. At the Maine Experiment Station, such a selection gave a flock of layers which averaged about one hundred and eighty eggs, when the remainder of the flock yielded only one hundred and forty.

Trap-nests devised to catch the hen that lays the egg are numerous in the market. A trap-nest to be successful, must not only catch the hen that lays, but must prevent the entrance of the other hens.

The more trap-nests that are provided, the less often they will require attention, but the more often the nests are attended the better for the comfort of the hens.

The use of trap-nests is expensive and cannot be recommended for the poultryman who must make every hour of time put on his chickens yield him an immediate income. Fanciers and Experiment Stations can well afford to use trap-nests and must, indeed, use them both for breeding for egg production, and also for determining the hen that laid the egg when full pedigrees are desired in other breeding work.

A scheme that has sometimes been used in the place of trap-nests, is a system of small compartments, in each of which one hen is kept. Such a scheme does not seem feasible on a large scale, but for breeders wishing to keep the records of a small number of hens, it is all right. Because of its cost, this system is wholly out of the question, except for a man following breeding as a hobby and who cannot devote himself during the day to the care of trap-nests.

Having determined the best layers, it remains to breed from these and from their descendants. The tests of pullets hatched from hens are better signs of the hen's value as a breeder than is her own record. It has been surmised that a hen which lays heavily will not lay eggs containing vigorous germs. So far as the writer's experience has gone, the laying of infertile eggs is a family or individual trait not particularly related to the number of eggs laid.

When we have bred from the best layers and have raised our average egg yielder to a higher level, the question arises as to whether the strain will permanently maintain the high yield or drop back to the former rate of production. Theory says that it will not drop back. As a matter of fact it will not do so, for the heavier production will be more trying on the hen's constitution, and naturally selection will gradually cause the egg record to dwindle. Hence the necessity of continued selection or the infusion of new blood from other selected strains.

Whatever may be the change desired in a strain of chickens, specimens showing the trait to be selected should be used as breeders. Those characteristics readily visible to the eye have long been the subjects of the breeder's efforts. But traits not directly visible can likewise be changed by breeding. The number of eggs, size and color of eggs, rapid growth, ready fattening powers, quality of meat and general characteristics, are all matters of inheritance, and if proper means are taken to select the desirable individuals all such characteristics can be changed at the will of the breeder.

It is a fact, however, often overlooked, that the more traits for which one selects, the slower will be progress. For illustration: If in breeding for egg production, one-half the good layers are discarded for lack of fancy points, the progress will be just half as rapid.

A discussion of the work in breeding for egg production at the Maine Experiment Station is taken up in the next chapter.