Modern farming practices seek to lessen human involvement, convalesce yield, and advance animal health. Economics, consumer safety and yields all play a role in how animals are reared. Feed supplements and drug use may be controlled, or banned, to ensure yield is not improved at the expense of consumer health, animal welfare or safety. Techniques vary across the globe, for instance, growth hormone use is allowed in the United States, but not in stock to be traded to the European Union. The convalesce of health, using new farming practices, on the part of animals has come into question. For example, feeding corn to cattle, which have in history eaten grasses, the cattle are less adapted, the rumen pH increases to more acidic, leading to liver injuries and other problems.
Livestock herders have agonized from wild animal predation and theft by thieves. In North America, animals like the grizzly bear, gray wolf, coyote and cougar are sometimes regarded as a threat to livestock. In Africa and Eurasia, predators include the tiger, leopard, lion, wolf, Asiatic black bear, dhole, spotted hyena, crocodile and others. In South America, feral dogs, anaconda, spectacled bear and jaguar are a threat to livestock. In Australia, wedge-tailed eagles, foxes, the dingo, are popular predators, with an added threat from domestic dogs because they may kill apparently for fun, leaving the carcass uneaten.
The issue of rearing livestock for human profit increases the issue of the relationship between animals and humans, in conditions of the status of animals and responsibilities of humans. Animal welfare is the perspective that animals under human care should be handled in such a way that they do not suffer unreasonably. What is ‘unreasonable’ suffering may differ. Usually, though, the animal welfare viewpoint is based on an explanation of scientific research on farming techniques. By distinction, animal rights are the perspective that using animals for human profit is, by its nature, usually exploitation, irrespective of the farming techniques used. Animal rights activists would typically be vegetarian, whereas it is steady with the animal welfare viewpoint to eat meat, depending on production processes.