Agrochemicals

Contagious diseases of livestock can be an important problem in modern agriculture. This is especially true when animals are being reared at a high density, for example, in feed-lots. Various agrochemicals may be used to control infectious diseases and parasites under such conditions. Antibiotics are especially important in this respect. These chemicals may be administered by injection whenever bacterial diseases are diagnosed. However, antibiotics are sometimes administered with the feed, as a prophylactic treatment to prevent the occurrence of infections. Because of the extremely crowded conditions when livestock are reared in "factory farms," antibiotics must be administered routinely to animals raised under those circumstances.

Sometimes, hormones and other animal-growth regulators are used to increase the productivity of livestock. For example, bovine growth hormone (BGH) is routinely administered in some agricultural systems to increase the growth rates of cows and their milk production.