Livestock

In modern times, livestock is raised using various systems of husbandry, which can vary greatly in their intensity of management. The oldest, and most simple systems commonly involve animals that are locally free-ranging, and are penned in large fenced areas, or return to their designated shelters in 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 as practiced 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. Animals raised on so-called "factory farms" are typically bred with great attention to breeding lineages, commonly 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.