Animal Breeding

There are many reasons why animal breeding is of paramount importance to those who use animals for their livelihood. Cats have been bred largely for aesthetic beauty; many people are willing to pay a great deal of money for a Siamese or Persian cat, even though the affection felt for a pet has little to do with physical appearance. But the most extensive animal breeding has occurred in those areas where animals have been used to serve specific practical purposes. For instance, most dog breeds are the result of a deliberate attempt to isolate traits that would produce better hunting and herding dogs (although some, like toy poodles, were bred for traits that would make them desirable pets). Horses have also been extensively bred for certain useful qualities; some for size and strength, some for speed. But farm animals, particularly food animals, have been the subject of the most intensive breeding efforts.

The physical qualities of economic importance in farm animals vary for each species, but a generalized goal is to eliminate the effects of environment and nutrition. An ideal strain of milk cow, for instance, would produce a large amount of high-quality milk despite the type of food it is fed and the environment in which it is reared. Thus, animals are generally all bred for feed efficiency, growth rate, and resistance to disease. However, a pig might be bred for lean content in its meat, while a hen would be bred for its laying potential. Many cows have been bred to be hornless, so they cannot inadvertently or deliberately gore each other.

Although maximum food production is always a major goal, modern animal breeders are also concerned about nutritional value and the ability of animals to survive in extreme environments. Many parts of the world are sparsely vegetated or have harsh climatic conditions, and a high efficiency producer able to endure these environments would be extremely useful to the people who live there. In addition, many people of industrialized countries are concerned not about food availability but about the quality of this food; so breeders seek to eliminate the qualities that make meat or milk or eggs or other animal products unhealthy, while enhancing those qualities that make them nutritious.