Animal husbandry is the branch of agriculture concerned with the rearing and care of animals that are raised for food, fibre or other purposes of benefit to humans. It includes not only the practical care of the livestock but also the selective improvements by which genetic qualities and behavior, considered to be advantageous to humans, are further developed. The term husbandry can refer to the practice of selectively breeding and raising livestock to promote desirable traits in animals for utility, sport, pleasure, or research.
Food is a requirement for human life and ultimately comes from the energy of the sun which is used by plants, through the process of photosynthesis, to produce new plant growth. The animals that feed on plants convert this energy into the animal products that humans, being omnivores, appreciate as part of their diet. Before the invention of agriculture, hunter-gatherers supplied those needs, but the domestication of animals provided a much more stable supply of animal products.
Birth of husbandryEdit
The domestication of livestock was driven by the need to have food on hand when hunting was unproductive. The desirable characteristics of a domestic animal are that it should be useful to man, should be able to thrive in his company, should breed freely and be easy to tend.
Animals were progressively domesticated early in the history of agriculture. Pigs were domesticated in Mesopotamia around 13,000 BC. Sheep were domesticated in Mesopotamia between 11,000 and 9,000 BC. Cattle were domesticated from the wild aurochs in the areas of modern Turkey and Pakistan around 8,500 BC. In southern Asia, the elephant was domesticated by 6,000 BC. Camels were domesticated late, perhaps around 3,000 BC.
In ancient Egypt, cattle were the most important livestock; sheep, goats, and pigs were also kept. Poultry including ducks, geese, and pigeons were captured in nets and bred on farms, where they were force-fed with dough to fatten them. The Nile provided a plentiful source of fish. Honey bees were domesticated from at least the Old Kingdom, providing both honey and wax.
In ancient Rome, rabbits were domesticated for food by the first century BC. To help flush them out from their underground burrows, the polecat was domesticated as the ferret, its use described by Pliny the Elder.
In northern Europe, agriculture including animal husbandry went into decline when the Roman empire collapsed. Some aspects such as the herding of animals continued throughout the period. By the 11th century, the economy had recovered and the countryside was again productive. The Domesday Book recorded every parcel of land and every animal in Britain: "there was not one single hide, nor a yard of land, nay, moreover ... not even an ox, nor a cow, nor a swine was there left, that was not set down in [the king's] writ." For example, the royal manor of Earley in Berkshire, one of thousands of villages recorded in the book, had in 1086 "2 fisheries worth [paying tax of] 7s and 6d [each year] and 20 acres of meadow [for livestock]. Woodland for [feeding] 70 pigs."
Selective breeding for desired traits was established as a scientific practice by Robert Bakewell during the British Agricultural Revolution in the 18th century. One of his most important breeding programs was with sheep. Using native stock, he was able to quickly select for large, yet fine-boned sheep, with long, lustrous wool. The Lincoln Longwool was improved by Bakewell and in turn the Lincoln was used to develop the subsequent breed, named the New (or Dishley) Leicester. It was hornless and had a square, meaty body with straight top lines. These sheep were exported widely and have contributed to numerous modern breeds. Under his influence, English farmers began to breed cattle for use primarily as beef. Long-horned heifers were crossed with the Westmoreland bull to create the Dishley Longhorn.
The semi-natural, unfertilized pastures formed by traditional agricultural methods in Europe were managed by grazing. Because the ecological impact of this land management strategy is similar to the impact of a natural disturbance, the agricultural system will share many beneficial characteristics with a natural habitat including the promotion of biodiversity. This strategy is declining in the European context due to the intensification of agriculture, and mechanized and chemical based methods.
Traditionally, animal husbandry was part of the subsistence farmer's way of life, producing not only the food needed by the family but also the fuel, fertiliser, clothing, transport and draught power. Killing the animal for food was a secondary consideration, and wherever possible its products, such as wool, eggs, milk and blood (by the Maasai) were harvested while the animal was still alive.
Animals can be kept extensively or intensively. Extensive systems involve animals roaming at will, or under the supervision of a herdsman, often for their protection from predators. Ranching in the Western United States involves large herds of cattle grazing widely over public and private lands. Similar cattle stations are found in South America, Australia and other places with large areas of land and low rainfall. Similar ranching systems have been used for sheep, deer, ostrich, emu, llama and alpaca. In the uplands of the United Kingdom, sheep are turned out on the fells in spring and graze the abundant mountain grasses untended, being brought to lower altitudes late in the year, with supplementary feeding being provided in winter. In rural locations, pigs and poultry can obtain much of their nutrition from scavenging, and in African communities, hens may live for months without being fed, and still produce one or two eggs a week.
At the other extreme, in the more developed parts of the world, animals are often intensively managed; dairy cows may be kept in zero-grazing conditions with all their forage brought to them; beef cattle may be kept in high density feedlots; pigs may be housed in climate-controlled buildings and never go outdoors; poultry may be reared in barns and kept in cages as laying birds under lighting-controlled conditions. In between these two extremes are semi-intensive, often family run farms where livestock graze outside for much of the year, silage or hay is made to cover the times of year when the grass stops growing, and fertiliser, feed and other inputs are bought onto the farm from outside.
Animals used as livestock are predominantly herbivorous, the main exception being the pig which is an omnivore. The herbivores can be divided into "concentrate selectors" which selectively feed on seeds, fruits and highly nutritious young foliage, "grazers" which mainly feed on grass, and "intermediate feeders" which choose their diet from the whole range of available plant material. Cattle, sheep, goats, deer and antelopes are ruminants; they digest food in two steps, chewing and swallowing in the normal way, and then regurgitating the semidigested cud to chew it again and thus extract the maximum possible food value. The dietary needs of these animals is mostly met by eating grass. Grasses grow from the base of the leaf-blade which allows for continuous growth even when heavily grazed or cut. In many climatological conditions, grass growth is seasonal, so some areas of the crop are set aside to be cut and preserved, either as hay (dried grass), or as silage (fermented grass). Other forage crops are also grown and many of these, as well as crop residues, can be ensiled to fill the gap in the nutritional needs of livestock in the lean season.
Extensively reared animals may subsist entirely on forage, but more intensively kept livestock will require energy and protein-rich foods in addition. Energy is mainly derived from cereals and cereal by-products, fats and oils and sugar-rich foods, while protein may come from fish or meat meal, milk products, legumes and other plant foods, often the by-products of vegetable oil extraction. Pigs and poultry are non-ruminants and unable to digest the cellulose in grass and other forages, so they are fed entirely on cereals and other high-energy foodstuffs. The ingredients for the animals' rations can be grown on the farm or can be bought, in the form of pelleted or cubed, compound foodstuffs specially formulated for the different classes of livestock, their growth stages and their specific nutritional requirements. Vitamins and minerals are added to balance the diet. Farmed fish are usually fed pelleted food.
The breeding of farm animals seldom occurs spontaneously but is managed by farmers with a view to encouraging certain traits that are seen as desirable. These include hardiness, prolificness, mothering abilities, fast growth rates, low feed consumption per unit of growth, better body proportions, higher yields, better fibre qualities and other characteristics. Undesirable traits such as health defects, aggressiveness or lack of docility are selected against. Selective breeding has been responsible for some large increases in productivity. In 2007, a typical broiler chicken at eight weeks old was 4.8 times as heavy as a bird of similar age in 1957. In the thirty years to 2007, the average milk yield of a dairy cow in the United States nearly doubled.
Techniques such as artificial insemination and embryo transfer are frequently used today, not only as methods to guarantee that females breed regularly but also to help improve herd genetics. This may be done by transplanting embryos from high-quality females into lower-quality surrogate mothers - freeing up the higher-quality mother to be reimpregnated. This practice vastly increases the number of offspring which may be produced by a small selection of the best quality parent animals. On one hand, this improves the ability of the animals to convert feed to meat, milk, or fiber more efficiently, and improve the quality of the final product. On the other, it decreases genetic diversity, increasing the severity of certain disease outbreaks among other risks.
Good husbandry, proper feeding, and hygiene are the main contributors to animal health on the farm, bringing economic benefits through maximised production. When, despite these precautions, animals still become sick, they are treated with veterinary medicines, by the farmer and the veterinarian. In the European Union, when farmers treat their own animals, they are required to follow the guidelines for treatment and to record the treatments given.
Animals are susceptible to a number of diseases and conditions that may affect their health. Some, like classical swine fever and scrapie are specific to one type of stock, while others, like foot-and-mouth disease affect all cloven-footed animals. Where the condition is serious, governments impose regulations on import and export, on the movement of stock, quarantine restrictions and the reporting of suspected cases. Vaccines are available against certain diseases, and antibiotics are widely used where appropriate. At one time, antibiotics were routinely added to certain compound foodstuffs to promote growth, but this practice is now frowned on in many countries because of the risk that it may lead to antibiotic resistance. Animals living under intensive conditions are particularly prone to internal and external parasites; increasing numbers of sea lice are affecting farmed salmon in Scotland. Reducing the parasite burdens of livestock results in increased productivity and profitability.
Governments are particularly concerned with zoonoses, diseases that humans may acquire from animals. Wild animal populations may harbour diseases that can affect domestic animals which may acquire them as a result of insufficient biosecurity measures being in place. An outbreak of Nipah virus in Malaysia in 1999 was traced back to pigs becoming ill after contact with fruit-eating flying foxes, their faeces and urine. The pigs in turn passed the infection to humans. Avian flu H5N1 is present in wild bird populations and can be carried large distances by migrating birds. This virus is easily transmissible to domestic poultry, and potentially to humans living in close proximity with them. Other infectious diseases affecting wild animals, farm animals and humans include rabies, leptospirosis, brucellosis, tuberculosis and trichinosis.
Range of speciesEdit
There is no single universally agreed definition of which species are livestock. Widely agreed types of livestock include cattle for beef and dairy, sheep, goats, pigs, and poultry. Various other species are sometimes considered livestock, such as horses, while poultry birds are sometimes excluded. In some parts of the world, livestock includes species such as buffalo, and the South American camelids, the alpaca and llama. Some authorities use much broader definitions to include fish in aquaculture, micro-livestock such as rabbits and guinea pigs, as well as insects from honey bees to crickets raised for human consumption.
Animals are raised for a wide variety of products, principally meat, wool, milk, and eggs, but also including tallow, isinglass and rennet. Animals are also kept for more specialised purposes, such as to produce vaccines and antiserum (containing antibodies) for medical use. Where fodder or other crops are grown alongside animals, manure can serve as a fertiliser, returning minerals and organic matter to the soil in a semi-closed organic system.
Although all mammals produce milk to nourish their young, the cow is predominantly used throughout the world to produce milk and milk products for human consumption. Other animals used to a lesser extent for this purpose include sheep, goats, camels, buffaloes, yaks, reindeer, horses and donkeys. All these animals have been domesticated over the centuries, being bred for such desirable characteristics as fecundity, productivity, docility and the ability to thrive under the prevailing conditions. Whereas in the past, cattle had multiple functions, modern dairy cow breeding has resulted in specialised Holstein Friesian-type animals that produce large quantities of milk economically. Artificial insemination is widely available to allow farmers to select for the particular traits that suit their circumstances.
In many communities, milk production is only part of the purpose of keeping an animal which may also be used as a beast of burden or to draw a plough, or for the production of fibre, meat and leather, with the dung being used for fuel or for the improvement of soil fertility. Sheep and goats may be favoured for dairy production in climates and conditions that do not suit dairy cows.
Meat, mainly from farmed animals, is a major source of dietary protein around the world, averaging about 8% of man's energy intake. The actual types eaten depend on local preferences, availability, cost and other factors, with cattle, sheep, pigs and goats being the main species involved. Cattle generally produce a single offspring annually which takes more than a year to mature; sheep and goats often have twins and these are ready for slaughter in less than a year; pigs are more prolific, producing more than one litter of up to about 11 piglets each year. Horses, donkeys, deer, buffalo, llamas, alpacas, guanacos and vicunas are farmed for meat in various regions. Some desirable traits of animals raised for meat include fecundity, hardiness, fast growth rate, ease of management and high food conversion efficiency. About half of the world's meat is produced from animals grazing on open ranges or on enclosed pastures, the other half being produced intensively in various factory-farming systems; these are mostly cows, pigs or poultry, and often reared indoors, typically at high densities.
Poultry, kept for their eggs and for their meat, include chickens, turkeys, geese and ducks. The great majority of laying birds used for egg production are chickens. Methods for keeping layers range from free-range systems, where the birds can roam as they will but are housed at night for their own protection, through semi-intensive systems where they are housed in barns and have perches, litter and some freedom of movement, to intensive systems where they are kept in cages. The battery cages are arranged in long rows in multiple tiers, with external feeders, drinkers, and egg collection facilities. This is the most labour saving and economical method of egg production but has been criticised on animal welfare grounds as the birds are unable to exhibit their normal behaviours.
In the developed world, the majority of the poultry reared for meat, is raised indoors in big sheds, with automated equipment under environmentally controlled conditions. Chickens raised in this way are known as broilers, and genetic improvements have meant that they can be grown to slaughter weight within six or seven weeks of hatching. Newly hatched chicks are restricted to a small area and given supplementary heating. Litter on the floor absorbs the droppings and the area occupied is expanded as they grow. Feed and water is supplied automatically and the lighting is controlled. The birds may be harvested on several occasions or the whole shed may be cleared at one time. A similar rearing system is usually used for turkeys, which are less hardy than chickens, but they take longer to grow and are often moved on to separate fattening units to finish. Ducks are particularly popular in Asia and Australia and can be killed at seven weeks under commercial conditions.
Aquaculture has been defined as "the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants and implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated." In practice it can take place in the sea or in freshwater, and be extensive or intensive. Whole bays, lakes or ponds may be devoted to aquaculture, or the farmed animal may be retained in cages (fish), artificial reefs, racks or strings (shellfish). Fish and prawns can be cultivated in rice paddy, either arriving naturally or being introduced, and both crops can be harvested together.
Fish hatcheries provide larval and juvenile fish, crustaceans and shellfish, for use in aquaculture systems. When large enough these are transferred to growing-on tanks and sold to fish farms to reach harvest size. Some species that are commonly raised in hatcheries include shrimps, prawns, salmon, tilapia, oysters and scallops. Similar facilities can be used to raise species with conservation needs to be released into the wild, or game fish for restocking waterways. Important aspects of husbandry at these early stages include selection of breeding stock, control of water quality and nutrition. In the wild, there is a massive amount of mortality at the nursery stage, and farmers will seek to minimise this while at the same time maximising growth rates.
Bees have been kept in hives since at least the First Dynasty of Egypt, five thousand years ago, and man had been harvesting honey from the wild long before that. Fixed comb hives are used in many parts of the world and are made from any locally available material. In more advanced economies, where modern strains of domestic bee have been selected for docility and productiveness, various designs of hive are used which enable the combs to be removed for processing and extraction of honey. Quite apart from the honey and wax they produce, honey bees are important pollinators of crops and wild plants, and in many places hives are transported around the countryside to assist in pollination.
Sericulture, the rearing of silkworms, was first adopted by the Chinese during the Shang dynasty. The only species farmed commercially is the domesticated silkmoth. When it spins its cocoon, each larva produces an exceedingly long, slender thread of silk. The larvae feed on mulberry leaves and in Europe, only one generation is normally raised each year as this is a deciduous tree. In China, Korea and Japan however, two generations are normal, and in the tropics, multiple generations are expected. Most production of silk occurs in the Far East, with a synthetic diet being used to rear the silkworms in Japan.
Insects form part of the human diet in some cultures, and in Thailand, crickets are farmed for this purpose in the north of the country and palm weevil larvae in the south. The crickets are kept in pens, boxes or drawers and fed on commercial pelleted poultry food, and the palm weevil larvae live on cabbage palm and sago palm trees, which limits their production to areas where these trees grow. Another delicacy of this region is the bamboo caterpillar, and the best rearing and harvesting techniques in semi-natural habitats are being studied.
Animal husbandry is responsible for 20%-33% of all fresh water consumption in the world today. Livestock, and the production of feed for them, occupy about a third of the earth's ice-free land. Livestock production is a leading cause of species extinction, desertification, ocean dead zones, water pollution, and habitat destruction. Animal agriculture contributes to species extinction in various ways. Habitat is destroyed by clearing forests and converting land to grow feed crops and for animal grazing, while predators and herbivores are frequently targeted and hunted because of a perceived threat to livestock profits; for example, animal husbandry is responsible for up to 91% of the deforestation in the Amazon region. The widespread use of pesticides, herbicides and fertilizers used in the production of feed crops often interferes with the reproductive systems of animals and pollute waterways. Livestock and their byproducts account for at least 32 billion tons of carbon dioxide per year, or 51% of all worldwide greenhouse gas emissions, contributing substantially to climate change. In addition, cows produce some 570 million cubic metres of methane per day. Livestock is responsible for 65% of all human-related emissions of the powerful and long-lived greenhouse gas nitrous oxide. Since animal husbandry causes the emission of non-CO2 greenhouse gases, it is being studied to identify ways to mitigate its environmental impact. Strategies include using biogas from manure.
Since the 18th century, people have become increasingly concerned about the welfare of farm animals. Possible measures of welfare include longevity, behavior, physiology, reproduction, freedom from disease, and freedom from immunosuppression. Standards and laws for animal welfare have been created worldwide, broadly in line with the most widely held position in the western world, a form of utilitarianism: that it is morally acceptable for humans to use non-human animals, provided that no unnecessary suffering is caused, and that the benefits to humans outweigh the costs to the livestock. An opposing view is that animals have rights, should not be regarded as property, and should never be used by humans.
Since the 18th century, the farmer John Bull has represented Englishness, first in John Arbuthnot's political satires, and soon afterwards in cartoons by James Gillray and others including John Tenniel. He likes food, beer, dogs, horses, and country sports; he is practical and down to earth, and anti-intellectual.
Farm animals are widespread in books and songs for children, though these often depict a rural idyll of happy animals in attractive countryside, glossing over the realities of farm life such as intensive indoor rearing and slaughter. For example, pigs appear in several of Beatrix Potter's "little books", as Piglet in A. A. Milne's Winnie the Pooh stories, and somewhat more darkly (with a hint of animals going to slaughter) as Babe in Dick King-Smith's The Sheep-Pig, and as Wilbur in Charlotte's Web. The children's song "Old MacDonald Had a Farm" describes a farmer named MacDonald and the various animals he keeps, celebrating the noises they each make.
Many urban children experience animal husbandry for the first time at a petting farm; in Britain, some five million people a year visit a farm of some kind. This presents some risk of infection, especially if children handle animals and then fail to wash their hands; a strain of E. coli infected 93 people who had visited an interactive farm in an outbreak in 2009. Historic farms offer farmstays and "a carefully curated version of farming to those willing to pay for it", sometimes giving visitors a romanticised image of a pastoral ideal from an unspecified time in the pre-industrial past.
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