Animal Husbandry

V

Cattle

Modern cattle are usually divided into three types: beef, dairy, and dual purpose, an intermediate type used for both milk and meat. It is believed that cattle were domesticated about 8,500 years ago in southeastern Europe, with Southeast Asia a probable second center of domestication. The world cattle population is more than 1.4 billion, with half concentrated in Asia and South America, and the rest in Africa, Europe, the countries of the former USSR, and the United States. Most beef cattle are raised on large rangelands, but following weaning, the young animals to be used for meat may be fattened in feedlots. Dairy cattle are managed in relatively large herds under intensive conditions near centers of dense population. Cheese, dried milk, and other specialized products, however, usually come from small farms with cattle set out to pasture. See Dairy Farming.

VI

Poultry

Poultry includes chickens, ducks, geese, guinea fowl, peacock, pigeons, swans, and turkeys. Each of these domesticated groups is descended from a closely related wild bird and was probably first developed in the areas where the wild bird was indigenous. World numbers are estimated at more than 15 billion chickens, about 1 million ducks, 245 million geese, and some 250 million turkeys. Chickens are numerous in most regions of the world. Most of the ducks are produced in Europe and Asia and most of the turkeys in the U.S. In the developed countries, production units for meat and eggs are large and intensive, with individual birds housed singly in cages or housed together in large numbers. Under these conditions, one operator can care for large numbers of birds with high labor efficiency and good control of disease and the environmental factors affecting production. See Poultry Farming.

VII

Other Animals

Other domesticated animals of importance include, in the cattle family, the yak in Tibet, the mithan in India, and the banteng in Southeast Asia. The reindeer is important in the northern regions of North America, Europe, and Asia.

Although a few specialized farms have raised various animals (primarily mink and foxes) for their pelts, most furs are obtained from wild populations by hunting and trapping. In North America, muskrats and raccoons provide slightly more than half the total revenue. The former USSR was also a leading fur nation. See Fur Industry.

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VIII

Current Trends

The major concern of animal husbandry today is the extent to which production can be maintained as the human population increases. The goal of research has been to increase the efficiency of the production of animal products by genetic selection and genetic engineering. For example, scientists have increased the size of sheep by inserting growth-hormone genes into embryos, and the same method can be applied to cattle and other animals.

Research is also being directed toward the development of animal strains in areas deficient in protein. Thus in South America the capybara is being exploited by Venezuela for its meat; it is taken from the wild in large numbers to lands devoted to cattle raising. In Peru, the government is encouraging the raising of guinea pigs for their food value, and elsewhere in Latin America research is being conducted into the farming of the iguana lizard.

Intensive methods for producing animal products include confinement of poultry in small cages, swine in small pens, and sheep and cattle in small lots. Confinement leads to savings in labor, feed, and other production costs. Confinement in individual pens may also afford savings from improved disease control and better protection from predators. Such practices have come under attack as cruel to the animals, and protective legislation has been advocated (see Animal Rights: Animals as Food and Products). Livestock and poultry farmers, on the other hand, claim that the animals are probably not under much stress because disturbed animals would show sharp decreases in productive capacity.

Also at issue are special additives, including hormones, antibiotics, vitamins, and other substances used to increase growth or productivity. In the United States, most of these substances are under the control of the Food and Drug Administration (FDA). The general guidelines are that any supplement must be proved safe and effective in the amounts used. The two most controversial growth additives are the hormone diethylstilbestrol (DES) and antibiotics. DES is now banned because in high doses it was found to be capable of causing cancer. Scientists who advocate the banning of antibiotics argue that resistant strains of bacteria in animals might transfer their resistance to bacteria that infect humans. The first proven instance of this occurred in 1984, when an outbreak of human salmonella infections in four midwestern states was traced to drug-resistant salmonella bacteria from calves in South Dakota that had been fed chlortetracycline.

In 1997 a new concern regarding animal production surfaced when researchers in Scotland announced that they had successfully produced a cloned (see Clone) sheep. In addition to ethical questions about cloning, the practice of cloning could eventually stop genetic progress achieved through regular breeding programs. However, it is doubtful that cloning would be economical for normal animal production. Its eventual widespread use could be in genetically modifying individual animals within a breed so all of them would carry a desired trait, such as increased growth potential or resistance to disease.

Scientists have recently expressed concern that the focus on producing specialized and fewer breeds has led to diminished biodiversity among livestock, as well as threatened the extinction of remaining breeds that, although currently unpopular, might have traits needed in the future. For example, high-yield Holstein milk cows now represent a full 91 percent of the United States’ dairy stock. But with a diminished gene pool, each generation of Holsteins becomes more genetically similar. If a disease developed for which these cows had an inherited susceptibility, milk production would collapse nationwide. Or, if economic conditions caused dairy farmers to seek a different breed than Holsteins, they would have fewer breeds to choose from. According to the United Nations Food and Agriculture Organization (FAO), at least 1,500 of the approximately 5,000 domesticated livestock breeds are now rare and approaching extinction. Recently, several organizations have established conservation programs for threatened domestic breeds of cattle, sheep, horses, and swine. These programs will not only ensure survival of these breeds, but also provide invaluable genetic resources for currently popular breeds.

Eventually the physiological limits of all domestic animals may prevent further increases in yield. If the human population continues to expand and food supplies become scarcer, the proportion of food that can be used to feed animals will then decrease, and animal products will be in shorter supply and more expensive. See Food Supply, World.

Scientific classification: The tarpan, Przhevalski’s wild horse, and the European forest horse are subspecies of Equus caballus. Camels, llamas, and alpacas make up the family Camelidae. Sheep and goats form the subfamily Caprinae of the family Bovidae. Swine make up the family Suidae. Modern cattle belong to the family Bovidae, and are classified under the genus Bos. The yak is classified as Bos grunniens, the mithan is classified as Bos gaurus, the banteng is classified as Bos javanicus, and the reindeer is classified as Rangifer tarandus. Chickens, guinea fowl, peacocks, and turkeys belong to the order Galliformes; ducks, geese, and swans belong to the order Anseriformes; and pigeons belong to the order Columbiformes.

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