All animals need a nutritious diet in order to maintain good health and production. In the wild, animals consume a wide variety of feed ingredients.
Today the nutrient requirements of farm animals and the nutrients provided by different feed ingredients are well understood. Diets for poultry generally consist of cereal grain (mostly corn but also wheat, barley, sorghum, and others are used elsewhere) and a protein source (most commonly soybean meal but there are also several animal and plant protein sources).
The nutritional quality of a feed also depends on a variety of other factors, including feed presentation, microbial contamination, the content of antinutritional factors, digestibility, palatability, and intestinal healthfulness. A variety of feed additives are available to deal with these issues.