animal husbandry, aspect of agriculture concerned with the care and breeding of domestic animals such as cattle, goats, sheep, hogs, and horses. Domestication of wild animal species was a crucial achievement in the prehistoric transition of human civilization from hunting-and-gathering to agriculture. The first domesticated livestock animal may have been the sheep, which was tamed around 9000 BC in N Iraq. Around 6500 BC, domestic goats were kept in the same region; about 6000 BC the pig was domesticated in Iraq; by 5900 BC (and perhaps 3,000 years earlier) there were domesticated cattle in Chad, while independently about 5500 BC there were domesticated cattle in SW Iran; and around 3500 BC the horse was domesticated on the Eurasian steppes. Nothing is known of the early development of husbandry; selective breeding for the improvement of livestock was already practiced in Roman times. Continuing systematic development and improvement of domestic livestock breeds, established in England following 1760 by Robert Bakewell and others, has been paralleled by advances in animal nutrition and veterinary medicine.