STOCK BREEDING, the art of producing and rearing domestic animals, particularly those of greater agricultural value known as farm live stock, including cattle, horses, pigs, sheep and fowls. The successful practise of this art depends upon an intimate knowledge of the particular kind of stock to be bred and a familiarity with certain general principles ap plicable to the breeding of stock of various kinds. The special knowledge of each kind of live stock can best be obtained by actual farm experience under skilled supervision but much useful information can be obtained from live stock manuals, which describe the breeds of farm animals and their management. To impart such information is also the aim of courses of instruction in animal husbandry and poultry management given in argicultural col leges.
General Principles.— The discovery of gen eral principles applicable in stock breeding is a work to which agricultural experiment stations are appropriately giving much attention. In vestigators in universities and research insti tutions have made important contributions in this field through their studies of variation and heredity. See article GENETICS.
To propagate any kind of animal success fully the breeder should know its life history thoroughly, under what climatic conditions it attains sexual maturity or becomes sexually active, what is its period of gestation or in cubation, at what age full size and productive ness are attained, when senility begins, what are the best feeds and how to prepare them, and other similar facts.
The successful breeder will employ all knowledge of this sort which he possesses in controlling and utilizing the activities of his animals to serve the purpose which he has in mind. What that purpose is will determine both the choice of foundation stock and his management of it. For example, breeding cattle for milk production, for butter making, for cheese making or for beef require in each case a different choice of foundation stock and different management of. it.
The question of when and how man ac quired domestic animals, while of little present practical concern, has much scientific interest. A complete answer to it might show whether domestication of other animals is likely to occur in the future and if so under what con ditions. Its solution would also throw much light on the early history of man and the rise of civilization. Present knowledge indicates that man as distinct from other primates originated in Central Asia and at first utilized for food and clothing wild plants and wild animals, as the most primitive races of mankind still do. Later, plants began to be cultivated and animals kept and reared in captivity to insure more de pendable supplies of food and clothing. In Asia man domesticated the dog, sheep, goats, the ass, cattle, horses and pigs. All of our more important farm animals originated with man in his old home, Central Asia, in a remote, prehistoric period. With man they were taken in migrations into Europe and Africa. The migration of man into America from Asia oc curred undoubtedly at a very early period. The dog was the only domesticated animal that came with the emigrants from Asia to America. Pos sibly this migration, occurred before other animals had as yet 'been domesticated, cer tainly no others were brought over. A con
siderable degree of civilization was acquired by man in the American hemisphere quite inde pendently of the development of civilization in the Old World, but all the many food plants cultivated here by the natives, as well as their few domestic animals (except the dog), were indigenous. The cultivated food plants of American origin include many of the world's best, such as maize and potatoes, but the domestic animals are of little consequence, in cluding only the llama, alpaca and guinea-pig. That man in America developed so many good food plants but such unimportant domestic ani mals shows that the available material in one case was excellent, but in the other case was poor. Conversely the pre-eminent success of man in central Asia in securing what are still our best domestic animals shows what paleon tology confirms, that herbivorous animals suit able for easy domestication were abundant in the early home of man and were in fact early domesticated. They have been much modified subsequently and many diverse breeds 'have been produced in consequence of the supervision which man exercised over their racial evolution. The study of breeds of domestic animals af forded to Darwin some of the most convincing evidence for his theory of organic evolution descent with modification from, simpler and less specialised ancestors. As compared with their wild ancestors, domestic animals have under gone modification through the agency of selec tion, sometimes exercised consciously and with the definite end in view of perpetuating new and useful variations, sometimes obtained incident, ally and without set purpose. Conscious select Lion for breeding purposes of the most docile individuals and of those which were strong and vigorous has in general given to domestic nth. mals tameness and docility, making them easy of management. It has also given them early maturity. which is usually accompanied with fecundity. Unconscious or natural selection would also favor variations toward early ma turity and fecundity, since such variants in a mixed herd would naturally leave most off spring. Indirect effects of increased tameness and gentleness are greater and more economical consumption of food and more ready fattening, with decline in intelligence unless specially selected for as in the case of the dog and the saddle horse. Products of special utility have by selection been greatly improved or intensified and thus breeds kept for special purposes have originated. Examples are seen in the great milk production of-dairy cattle and much goats; of wool production in sheep and the alpaca, of meat production in pigs, mutton sheep and beef cattle. Under the guiding influence of selec= tion continued through untold centuries breeds of domestic animals have become machines of the greatest efficiency for the production in maximum quantity of a specialized product of supreme quality. No more convincing evidence can be produced of the effectiveness of selection in guiding evolution in useful directions than is afforded by a study of breeds of domestic animals.