Selective breeding

Animal husbandry is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, or other products. It includes day-to-day care, management, production, nutrition, selective breeding, and the raising of livestock. Husbandry has a long history, starting with the Neolithic Revolution when animals were first domesticated, from around 13,000 BC onwards, predating farming of the first crops. During the period of ancient societies like ancient Egypt, cattle, sheep, goats, and pigs were being raised on farms.

Major changes took place in the Columbian exchange, when Old World livestock were brought to the New World, and then in the British Agricultural Revolution of the 18th century, when livestock breeds like the Dishley Longhorn cattle and Lincoln Longwool sheep were rapidly improved by agriculturalists, such as Robert Bakewell, to yield more meat, milk, and wool. A wide range of other species, such as horse, water buffalo, llama, rabbit, and guinea pig, are used as livestock in some parts of the world. Insect farming, as well as aquaculture of fish, molluscs, and crustaceans, is widespread.

Flightless birds are birds that cannot fly, as they have, through evolution, lost the ability. There are over 60 extant species, including the well-known ratites (ostriches (Struthio), emus (Dromaius), cassowaries (Casuarius), rheas, and kiwis (Apteryx)) and penguins (Sphenisciformes). The smallest flightless bird is the Inaccessible Island rail (length 12.5 cm, weight 34.7 g). The largest (both heaviest and tallest) flightless bird, which is also the largest living bird in general, is the common ostrich (2.7 m, 156 kg).

Some domesticated birds, such as the domestic chicken, have lost the ability to fly for extended periods, although their ancestral species, the red junglefowl and others, respectively, are capable of extended flight. A few particularly bred birds, such as the Broad Breasted White turkey, have become totally flightless as a result of selective breeding; the birds were bred to grow massive breast meat that weighs too much for the bird's wings to support in flight.

Animal slaughter is the killing of animals, usually referring to killing domestic livestock. It is estimated that each year, 80 billion land animals are slaughtered for food. Most animals are slaughtered for food; however, they may also be slaughtered for other reasons such as for harvesting of pelts, being diseased and unsuitable for consumption, or being surplus for maintaining a breeding stock. Slaughter typically involves some initial cutting, opening the major body cavities to remove the entrails and offal but usually leaving the carcass in one piece. Such dressing can be done by hunters in the field (field dressing of game) or in a slaughterhouse. Later, the carcass is usually butchered into smaller cuts.

The animals most commonly slaughtered for food are cattle and water buffalo, sheep, goats, pigs, deer, horses, rabbits, poultry (mainly chickens, turkeys, ducks and geese), insects (a commercial species is the house cricket), and increasingly, fish in the aquaculture industry (fish farming). In 2020, Faunalytics reported that the countries with the largest number of slaughtered cows and chickens are China, the United States, and Brazil. Concerning pigs, they are slaughtered by far the most in China, followed by the United States, Germany, Spain, Vietnam, and Brazil. For sheep, again China slaughtered the most, this time followed by Australia and New Zealand. Similarly, the amount (in tonnes) of fish used for production is highest in China, Indonesia, Peru, India, Russia, and the United States (in that order).

Natural selection is the differential survival and reproduction of individuals due to differences in the relative fitness endowed on them by their own particular complement of observable characteristics. It is a key law or mechanism of evolution which changes the heritable traits characteristic of a population or species over generations. Charles Darwin popularised the term "natural selection", contrasting it with artificial selection, which is intentional, whereas natural selection is not.

For Darwin natural selection was a law or principle which resulted from three different kinds of process: inheritance, including the transmission of heritable material from parent to offspring and its development (ontogeny) in the offspring; variation, which partly resulted from an organism's own agency (see phenotype; Baldwin effect); and the struggle for existence, which included both competition between organisms and cooperation or 'mutual aid' (particularly in 'social' plants and social animals).

The domestication of vertebrates is the mutual relationship between vertebrate animals, including birds and mammals, and the humans who influence their care and reproduction.

Charles Darwin recognized a small number of traits that made domesticated species different from their wild ancestors. He was also the first to recognize the difference between conscious selective breeding (i.e. artificial selection) in which humans directly select for desirable traits, and unconscious selection where traits evolve as a by-product of natural selection or from selection of other traits. There is a genetic difference between domestic and wild populations. There is also a genetic difference between the domestication traits that researchers believe to have been essential at the early stages of domestication, and the improvement traits that have appeared since the split between wild and domestic populations. Domestication traits are generally fixed within all domesticates, and were selected during the initial episode of domestication of that animal or plant, whereas improvement traits are present only in a portion of domesticates, though they may be fixed in individual breeds or regional populations.

This page gives a list of domesticated animals, also including a list of animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includes species which are semi-domesticated, undomesticated but captive-bred on a commercial scale, or commonly wild-caught, at least occasionally captive-bred, and tameable. In order to be considered fully domesticated, most species have undergone significant genetic, behavioural and morphological changes from their wild ancestors, while others have changed very little from their wild ancestors despite hundreds or thousands of years of potential selective breeding. A number of factors determine how quickly any changes may occur in a species, but there is not always a desire to improve a species from its wild form. Domestication is a gradual process, so there is no precise moment in the history of a given species when it can be considered to have become fully domesticated.

Zooarchaeology has identified three classes of animal domesticates:

Meat is animal tissue, mostly muscle, that is eaten as food. Humans have hunted and farmed other animals for meat since prehistory. The Neolithic Revolution allowed the domestication of vertebrates, including chickens, sheep, goats, pigs, horses, and cattle, starting around 11,000 years ago. Since then, selective breeding has enabled farmers to produce meat with the qualities desired by producers and consumers. Meat is important to economies and cultures around the world.

Meat is mainly composed of water, protein, and fat. Its quality is affected by many factors, including the genetics, health, and nutritional status of the animal involved. Without preservation, bacteria and fungi decompose and spoil unprocessed meat within hours or days. Meat is edible raw, but it is mostly eaten cooked, such as by stewing or roasting, or processed, such as by smoking or salting.

The Longhorn or British Longhorn is a British breed of beef cattle characterised by long curving horns. It originated in northern England, in the counties of Lancashire, Westmorland and Yorkshire, and later spread to the English Midlands and to Ireland. It was originally a slow heavy draught animal; cows gave a little milk, although high in fat. In the eighteenth century Robert Bakewell applied his methods of selective breeding to these cattle, which for a short time became the predominant British breed. Both the numbers and the quality of the breed declined throughout the nineteenth century and for much of the twentieth. A breed society was formed in 1878, and a herd-book published in that year.

The Longhorn was formerly listed as "priority" on the watchlist of the Rare Breeds Survival Trust, but in 2021 was listed among the "UK native breeds".

Robert Bakewell (23 May 1725 – 1 October 1795) was an English agriculturalist, now recognized as one of the most important figures in the British Agricultural Revolution. In addition to work in agronomy, Bakewell is particularly notable as the first to implement systematic selective breeding of livestock. His advancements not only led to specific improvements in sheep, cattle and horses, but contributed to general knowledge of artificial selection.