Livestock is a collective term for domesticated animals that are kept, mostly for meat, milk, wool, or other products. The most common species are cattle, pigs, sheep, goats, horses, and chickens. The term is not used in reference to animals that are kept as pets or companions.
Livestock are domesticated species, which have been genetically modified over time through the artificial selection of desirable traits by humans, with a view to increasing the docility of the animals, their size and productivity, their quality as agricultural products, and other culturally desired features. Some species of
livestock no longer occur in their original, nondomesticated, free-living form, and they are totally dependent on humans for their continued existence. However, humans are also substantially dependent on their livestock for sustenance and other purposes. Consequently, the symbiotic relationship between humans and their domestic livestock could be termed a mutualism, that is, a mutually beneficial relationship between two species.
Some of the domesticated species of livestock have become enormously abundant in cultivation. The world’s population of sheep and goats has been estimated at about 1.7 billion, while there are some 1.3 billion cows, 0.85 billion pigs, 0.12 billion horses, and 0.16 billion camels and water buffalo. Some smaller species of livestock are even more abundant, including an estimated 10-11 billion fowl, mostly chickens. In comparison, the total population of humans is about 5.8 billion individuals. The populations of species of both livestock and humans are growing quite rapidly, in the case of humans at about 1.7% per year or 93 million people per year.
Cows are large animals in the family Bovidae that are kept as sources of meat, hides, and milk. Cows are grazing animals, eating grasses and other types of herbaceous plants.
The domestic cow or ox (Bos taurus ) is a massive animal with a heavy body, a short neck with a dewlap hanging beneath, two hollow horns, and a long tufted tail. The natural tendency of these animals is to live in herds of mature females and their calves, led by a mature bull. One calf is usually born after a nine-month gestation, and these feed on their mother’s milk for six months, after which they are weaned.
Some races of domestic cattle may be descended in part from the golden ox or aurochs (Bos primigenius ) of Europe, which became extinct in the wild in the seventeenth century. Domestic cows are also partly descended from the zebu (B. indicus ) and the Indian ox (B. namadicus ).
The zebu, brahman, or oriental domestic cow is a tropical species of cow with a distinctive, fatty-humped back, and a pronounced dewlap. Relatively minor, domesticated species are the gayal (Bos frontinalis ) of southern Asia, and the banteng (B. sondaicus ) of Southeast Asia.
The domestic cow, however, is by far the most abundant cow in agriculture. This species can be used as a draft animal, in which case they are referred to as oxen. These animals are very strong and are capable of hauling heavy loads or plowing soil. There are various races of domestic cows, which vary in the length and shape of their horns, body size and shape, body color, and other characteristics. The black-and-white blotched Holstein is a familiar variety, as is the uniformly light-brown Jersey.
In modern North American agriculture, beef cattle are born and initially raised on rangelands. They are then herded together and transported to feedlots closer to their markets, where they are fed nutritious foods, and gain a great deal of weight prior to being slaughtered at a central facility. The carcass is dissected into various products, ranging from high-value steaks and roasts, to lower grades of meat that are ground into a composite product known as hamburger. Especially fatty meats, internal organs, blood, and other tissues are generally used to manufacture sausages and hot dogs. The hide is used to make leather. Remarkably little of the carcass is wasted.
Veal is a specialty meat that is produced from young animals that are kept in very close confinement for their entire lives. The highest-quality, epicurean veal is pale-colored and very tender. To achieve this product grade, veal calves are tethered and confined closely so they cannot move very much, and they are fed a diet that is highly deficient in iron, which helps to lighten the color of their flesh. They are also removed from their mothers before they are fully weaned, because a milk diet also promotes the development of a less tender, red-colored flesh.
Dairy cattle are raised for their milk, which is a nutritious fluid rich in sugar, protein, and fat. Dairy cattle are usually kept under relatively confined conditions, although when the weather is suitable they are usually allowed to forage in local pastures. Cow’s milk can be consumed by humans (after pasteurization to kill bacterial pathogens that may be present), or used to manufacture butter, cream, cheese, and other foods. When their milk production starts to decline significantly as they age, dairy cows are typically slaughtered for their meat.
Domestic sheep and goats are horned species of livestock that are commonly raised around the world.
The domestic sheep (Ovis aries ) is an ancient domesticated species, probably native to southern Europe, the Middle East, and North Africa. However, the domestic sheep has been widely kept as livestock for thousands of years, and its exact lineage is not known. Sheep are very hardy animals in alpine, boreal, and temperate environments, and they are most commonly cultivated for their wool, meat (known as mutton), hides, and milk. Sheep are usually kept in relatively open pastures, where they forage on grasses and other herbaceous plants.
Many varieties of sheep have been bred to suit particular climates, or to yield particular types of products. Probably the most widely cultivated variety is the Merino sheep, which is raised for its fine wool, and is well suited to relatively dry climates. This variety is the most common sheep raised in Australia, which is the world’s leading producer of sheep and their products.
The domestic goat (Capra hircus ) is descended from wild goats of the mountains of Asia Minor. The domestic goat is a very hardy animal, capable of finding forage in seemingly barren and arid places, and is resistant to many types of diseases. Goats are raised for their meat, milk, and hides.
There are numerous varieties of domesticated goats. The Swiss or alpine goat is a common breed which is often raised for its milk, which can be consumed directly, or used to make butter or cheese. The Kashmir and angora goats are long-haired varieties that are raised for their long “wool,” which can be woven into warm soft garments.
The yak (Poephagus grunniens ) is a sheep like animal that is kept as livestock on highland plateaus of the Himalayas. This animal is a source of an extremely fine wool, as well as hides, meat, and milk. The related musk ox (Ovibos moschatus ) is a minor species of livestock that is in the initial stages of domestication for its extremely light and fine wool and its gamey meat.
The domestic pig or boar (Sus scrofa ) is descended from the wild boar of Eurasia. It an ancient domesticate and has been bred for thousands of years from the tropics to the temperate zones. Pigs, raised as a source of meat, are an extremely productive type of livestock because they have large litters (as many as 12 piglets at a time), and are quite efficient in converting their feed into body mass.
There are many varieties of pigs, adapted for various climates, cultural conditions, and uses. The white Yorkshire is a commonly cultivated, light-colored, rapidly growing variety, with erect ears.
The domestic horse (Equus caballus ) is descended from the wild horses of the Eurasian steppes. Horses are mostly used for riding and as draft animals, and they are also eaten in some countries.
There are many varieties of horses. The Arabian has been bred for great speed, and is the most common type of riding and racing horse. Although quite fleet, this breed does not have great endurance, and cannot maintain a fast pace for very long. Other horses, such as the Hackney and the American Standard, have been bred to haul lightweight carriages and racing harnesses. Horses bred as draft animals are much larger, and include the Clydesdale, Percheron, and Belgian breeds.
The domestic donkey (Equus asinus ) is derived from the wild ass of Africa. This animal is mostly used for riding and as a beast of burden, but it is also eaten and used as a source of milk. The mule is a hybrid between a male donkey and a female horse, and is highly prized as a draft and riding animal. However, mules are infertile, and the only way to produce them is to keep crossing horses and donkeys.
The dromedary, or Arabian one-humped camel (Camelus dromedarius ) is a species native to the deserts of Asia and northern Africa, although today it only occurs in domestication. This species has a single large fatty hump on its back, and it can tolerate extremely dry conditions. Dromedaries are used as pack and riding animals, and as sources of meat, milk, and hides.
The Bactrian camel (Camelus bactrianus ) is a species native to central Asia, where some wild herds still roam the desert. The Bactrian camel is distinguished by the two large fatty humps on its back and its shaggy pelage. This animal is commonly kept for riding and carrying cargo, and as a source of meat, milk, and leather.
Llamas are closely related to camels, but they are smaller and lack humps. Llamas are found in the highland plateaus and pampas of South America. There are two wild species, the guanaco or huanaco (Llama huanacos ) and the vicunña (L. vicugna ). The domesticated llama is believed to have been derived from the guanaco. These animals are ridden and used as beasts of burden, and they also produce other useful products. A variety known as the alpaca produces an especially fine, highly prized wool.
The water buffalo (Bubalus bubalis ), also known as the old-world buffalo or domestic buffalo, is a common species of livestock in tropical countries. The water buffalo is commonly used as a draft animal, particularly for plowing wet fields, for example, in the cultivation of paddy rice. This species is also utilized for its meat and for milk.
The bison or American buffalo (Bison bison ) is also kept as livestock, although this is a relatively recent phenomenon, and the species is not as yet intensively domesticated. Bison are generally reared on ranches, and utilized mostly for their meat and hide.
The reindeer (Rangifer tarandus ) has long been herded by northern peoples of Eurasia, such as the Lapps of Scandinavia. This animal is mostly raised for its meat, milk, and hides. In recent years, a strong market developed for the reindeer antlers, especially when they are still covered with fur or “in velvet.” These antlers are sold to countries in eastern Asia, especially China and Korea, where they are powdered and used as an ingredient in traditional medicines.
Other deer species are increasingly kept as livestock, often on so-called “game ranches.” Most commonly kept in this way are the American elk or wapiti (Cervus canadensis ) and the Eurasian red deer (C. elaphus ). Both species are in the early stages of domestication, and they may be more important as livestock in the future.
The domestic rabbit (Oryctolagus cuniculus ) has been derived from the old-world or European rabbit. The domestic rabbit is mostly raised as a source of meat, and for its fur, although the latter is of relatively poor quality.
By far the most abundant species of cultivated fowl is the chicken (Gallus gallus ), derived from the red jungle fowl of the tropical forests of Asia. The chicken has been domesticated for thousands of years, and may today be the world’s most abundant bird, albeit in cultivation. Billions of chickens are eaten each year by people around the world, as are even larger numbers of chicken eggs.
Several species of ducks have been domesticated for agricultural purposes. The most commonly cultivated duck is derived from the mallard (Anas platyrhynchos ), which was domesticated in China about 2,000 years ago. The Muscovy duck (Cairina moschata) is less common, and was domesticated by South Americans prior to the European colonization of the Americas.
Two commonly raised species of domesticated goose are derived from the greyleg goose (Anser anser ) of Eurasia. This goose may have been domesticated about 4,000 years ago; it now occurs in various agricultural races, most of which are white in color. A less common, domesticated species is the swan goose (A. cygnoides ).
The common turkey (Meleagris gallopavo ), native to North America and Mexico, was first domesticated by indigenous peoples of Mexico, long before the Spanish conquest. Domestic turkeys are typically white, although some varieties are black. Domestic turkeys are raised for their meat, and for this reason have been selected to have large breast muscles.
Other birds raised as food include the domestic pigeon (Columba livia ), and the domestic Guinea fowl (Numida meleagris ), among others.
In modern times, livestock is raised using various systems of husbandry, which can vary greatly in their intensity of management. The oldest and simplest systems involve free-ranging animals that are penned in large fenced areas, or return to shelter each evening. Whenever these animals are required as food, for milking, or to sell for cash, individual or small numbers of animals are killed or taken to the market, while the breeding nucleus remains conserved. Raising livestock in these relatively simple ways is common in subsistence agricultural systems, especially in poorer regions of the world.
Of course, systems used in modern, industrial agriculture involve much more intensive management of livestock than is practiced by subsistence farmers.
Domestication —The breeding of an animal or plant species to develop varieties that are compatible with living with humans, either under cultivation, or as pets.
Draft animal —A large animal that is used to pull a load, often hitched to a wheeled vehicle, or used to plow a field.
Husbandry —The science of propagating and raising domestic animals, especially in agriculture.
Mutualism —A mutually beneficial relationship between species.
Animals raised on “factory farms” are typically bred with great attention to pedigrees, often using artificial insemination to control the stud line, and embryo implantation to control the maternal lineage.
Industrial farms also keep their animals indoors much or all of the time, usually under quite crowded conditions. The animals are fed a carefully designed diet that is designed to optimize their growth rates. The disposal of sewage wastes is a major problem on factory farms, and animals commonly are kept in rather unsanitary, crowded conditions, standing in fecal materials and urine. Along with the social stresses of crowding, this makes the livestock susceptible to diseases and infections. Close attention must be paid to the health of the animals on industrial farms, and regular inoculations and treatments with antibiotics may be required.
The intensively managed systems by which livestock are raised in industrial agriculture are criticized by ethicists, who complain about the morality of forcing animals such as cows, pigs, and chickens to live under unnatural and difficult conditions.
Serious environmental damage is also associated with many types of industrial husbandry of livestock. For example, serious ecological damage may be caused by the disposal of sewage and other wastes, and by the use of pesticides and other cultural practices to grow the enormous quantities of fodder required as food by the livestock.
The ethical and environmental dimensions of modern systems of raising livestock are increasingly becoming important issues in the debate concerning the relationships of humans with other species, and with ecosystems more broadly.
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