Breeding

“ Their offspring are then carefully examined, and those which exhibit the peculiarity the most distinctly are selected for breeding, and this operation is repeated until the desired amount of divergence from the primitive stock is reached. It is then found that by continuing the process of selection—always breeding, that is, from well-marked forms, and allowing no impure crosses to interfere,—a race may be formed, the tendency of which to reproduce itself is exceedingly strong ”

“ It is well known that too close breeding, or consanguineous breeding, or breeding in and in, as it is variously called, if continued long, has a bad effect on the offspring, weakening the stock, while judicious crossing of varieties within certain limits of difference has a good effect, strengthening the stock and increasing its fertility. ”

“ Line-breeding is a systematic form of breeding which preserves the excellence and characteristics of the parent stock. In other words, it perpetuates the blood of both sire and dam so that it is not eventually lost as is the case in cross-breeding. ”

“ In breeding, the smallest individuals which are suitable in other respects for breeders, should be selected in order to keep down the size and offset the tendency to breed larger in successive generations. ”

“ But the sterility which must be obtained by the selective breeder in order to convert his morphological species into physiological species—such as we have in nature—must be quite irrespective of breeding in and in. ”

“ These are the two fundamental qualities of animals and plants of which the breeder must avail himself in order to produce new forms. The theoretical principle of breeding is, indeed, extremely simple, but in detail the practical application of this simple principle is difficult and immensely complicated. A thoughtful breeder, acting according to a definite plan, must understand the art of correctly estimating, in every case, the general interaction between the two fundamental qualities of heirship and mutability. ”

“ If even in such minute particulars as these, hereditary transmission may be distinctly seen, it becomes the breeder to look closely to the "like" which he wishes to see reproduced. Judicious selection is indispensable to success in breeding, and this should have regard to every particular—general appearance, length of limb, shape of carcass, development of chest; if in cattle, the size, shape and position of udder, thickness of skin, "touch," length and texture of hair, docility, &c., &c. ”

“ But the case would be quite different if the winning sire and dam came from the same old established herd in which the animals had been bred for generations on similar lines. It is this concentration of certain qualities in generation after generation which renders the pedigree animal so intensely prepotent, particularly when mated with animals of an ordinary character or not possessing concentrated breeding. ”

“ It is interesting at this point to recall one of the most common differences between plant and animal breeding which is seldom clearly recognized by practical breeders. Plant breeders most commonly strive to produce new races or breeds with distinctive characters which will reproduce their desirable qualities without continuous selection; while animal breeders almost wholly limit their attention to selection within the breeds already established, to maintain them in the highest state of efficiency possible. ”

“ Yet with all this advance in our understanding, the methods of breeding that can be recommended for the use of practical breeders have changed but little in the last twenty years, the greatest change being primarily in the greater surety with which we now make recommendations. ”

“ It appears to me that we are dealing in breeding with two markedly distinct types of selection, based on different principles and arriving at different results, both right in principle and productive of equally valuable practical results, but of very different value, when considered from a strictly evolutionary standpoint. ”

“ Breeders have carried this principle so far as frequently to advocate the growing of plants in the environment most likely to produce the change desired, as, for instance, cultivating tall plants like twining beans in the north or at high altitudes if it is desired to produce a dwarf type or, vice versa, breeding the plants in the south and at a low altitude if a giant or tall type is desired. ”

“ When the animal possesses much stamina and peculiar merit, which it is desired to perpetuate in the breed, it may be done either in the ascending or descending line, as in breeding the son to the parent, or the parent to his own progeny. ”

“ The preferable style of breeding for the great majority of farmers to adopt, is neither to cross, nor to breed from close affinities, (except in rare instances and for some specific and clearly understood purpose,) but to breed in the line, that is, select the breed or race best adapted to fulfill the requirements demanded, whether it be for the dairy, for labor or for beef in cattle, or for such combination of these as can be had without too great sacrifice of the principal requisite ”

“ The breeder who wishes to combine fancy and utility properties in any kind of live stock must breed only from specimens that are meritorious in both directions, selecting much more carefully than when breeding for one class of properties. ”

“ First, in regard to artificial breeding, we start from the fact last discussed above, viz., that its products in some cases differ from one another much more than the productions of natural breeding. It is a fact that races or varieties often differ from one another in a much greater degree and in much more important qualities than many so-called species, or “good species,”—nay, sometimes even more than so-called “good genera” in their natural state. ”

“ The risk attending too close breeding as in the breeding of pure breds is also avoided provided that the herd from which the sires are bought is sufficiently large to furnish a change of blood, yet of similar breeding. ”

“ High breeding. When uniformity of plumage can be effected in mixed breeds or varieties without a resort to in-and-in, or close breeding, and without sacrificing the health and vigor of the race, it is desirable ”

“ Suppose then the offspring of any parent to vary in many directions. By cross-breeding among themselves and with the parent stock, these are usually merged in a common type, their differences pooled, and the species remains fixed or else advances slowly by natural selection, along one line, as physical conditions change in geological time. But from time to time there arises a variation in the reproductive organs of some individuals, of such kind that these individuals are fertile among themselves, but sterile or less fertile with other varieties and with the parent stock. ”

“ The different steps in the process seem to follow one another in ordered sequence. The male inherits a disposition—which for us, of course, has prospective meaning—to seek the appropriate breeding ground and there to establish itself ”

“ We do not obtain such distributions in describing breeding activity, so we may say that the oscillators regulating such activity are not coupled. Present distribution, habitat preference, residency status, foraging adaptation, previous zoogeographic history, and relicts of ancestral adaptation, all bear on the character of the breeding schedule of any bird species. ”

“ 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. ”

“ It is one of Darwin’s great merits to have made use of these observations and to have formulated their results to a large extent as the laws of variation and heredity. As the breeder selects a congenital variation which suits his requirements, and by breeding from the animals (or plants) exhibiting that variation obtains a new breed specially characterized by that variation, so in nature is there a selection amongst all the congenital variations of each generation of a species. ”

“ From a species in this condition modern poultry breeders have made hundreds of distinct varieties. The easiest method of making a variety in domestication is to select specimens for breeding as near the desired type as possible, and to breed only from a few individuals in each generation which come nearest to the ideal type. ”

“ BREEDS AND BREEDING. Breeds may be defined as domestic varieties of animals or plants which man has been able to bring into existence and to maintain in existence. The process of breeding includes all the modifying influences which man may bring to bear on a wild stock for the purpose, conscious or unconscious, of establishing and maintaining breeds. ”

“ When we remember the large number of distinct characters which are presented by the very numerous varieties of any of our cultivated plants, we arrive at an understanding of the possibilities of improvement which the field of hybridization affords, yet I doubt if many of us have even then an adequate conception of the possibilities. Possibly I may make this more clear by an illustration from my timothy breeding experiments. ”

“ The task of the practical breeder who seeks to establish or fix a new variety produced by cross-breeding in a case involving two variable characters is simply the isolation and propagation of that one in each sixteen of the second generation offspring which will be pure as regards the desired combination of characters. ”

“ Hence this difference in habituation may well account for the different action of the reproductive organs when domestic races and when species are crossed. It is a nearly analogous fact, that most domestic races may be suddenly transported from one climate to another, or be placed under widely different conditions, and yet retain their fertility unimpaired; whilst a multitude of species subjected to lesser changes are rendered incapable of breeding. ”

“ The breeder is thus enabled through selecting the traits or characters that are wanted and crossing them with a well-known stock, to produce almost any trait or quality that he desires. This law makes it possible to estimate the results of cross breeding with almost mathematical exactness. Improved varieties of fruits, grains and vegetables have been produced in this manner, and with animals marvelous results have been achieved. ”

“ As cross-bred animals are generally of large size and vigorous, they have been raised in great numbers for immediate consumption. But for breeding they are found to be utterly useless; for though they may be themselves uniform in character, when paired together they yield during many generations offspring astonishingly diversified. The breeder is driven to despair, and concludes that he will never form an intermediate race. ”

“ You will get just exactly what you have to start with, unless you have a system of breeding which makes it possible to advance a step at a time at least.
The usual system of breeding is what is known as cross-breeding. By that we mean that unrelated animals are bred together each generation. ”

“ Breeding from different families of the same race.—Mr Culley, though believing that no great harm can result from breeding in-and-in, yet appears to have in a manner preferred the preferable practice of breeding from different families of the same race ”

“ The two principles above given seem to me to explain these facts in regard to the later embryonic stages of our domestic varieties. Fanciers select their horses, dogs, and pigeons, for breeding, when they are nearly grown up: they are indifferent whether the desired qualities and structures have been acquired earlier or [446] later in life, if the full-grown animal possesses them. ”

“ However extensive the varieties produced by artificial breeding, the essential characters of the species remain, and even its minor characters may be reproduced, while the barriers established in nature between species by the laws of their reproduction, seem to be absolute. ”

“ Most naturalists, however, freely admit that various extremely dissimilar breeds are descended from a single stock, although they do not know much about the art of breeding, cannot show the connecting links, nor say where and when the breeds arose. ”

“ If is well known to stock breeders that the closer animals are bred in-and-in, that is, the nearer the relationship of father and mother, the more prominently the traits of the parents appear in their children and become fixed in the breed. It is evident that in the earliest epoch of the human family, the closest inter-breeding must have prevailed without restriction, as it does in every species of the lower animals. ”

“ Even large and slow breeding mammals, which have only one at a birth but continue to breed from eight to ten successive years, may increase from a single pair to ten millions in less than forty years. ”

“ These great difficulties in the way of selecting extremes for vegetative propagation are of course met with everywhere. They impede the work of the breeder to such a degree, that but few men are able to surmount them. Breeding new varieties necessitates the bending of every effort to this purpose, and a clear conception of [757] the manifold aspects of this intricate problem. These fall under two heads, the exigencies of practice, and the physiologic laws of variability. ”