Abstract

This article discusses feedstuffs and feed additives that are incorporated into ruminant diets based on various physiological states of the animal. The ruminant animal is unique because it can utilize highly fibrous feedstuffs that are unsuitable for consumption by monogastric animals. Primary feedstuffs include forages/roughages, high energy feeds, supplements, feed additives, and juvenile animal feeds. Forages/roughages (fibrous feeds) are the predominant feedstuffs consumed by ruminants throughout the major portion of their lifetimes. Ruminants consume fibrous feeds either by grazing or by being fed preharvested forage. High energy feeds are those that are more energy dense than forages/roughages. These consist primarily of readily fermentable carbohydrate sources (grains) and lipids—either of plant or animal origin. A large number of supplemental sources of protein, energy, macrominerals, microminerals, and vitamins are discussed. Primary classes of feed additives include ionophores, ion-exchange compounds, direct-fed microbials, bloat preventatives, ruminal buffers, hormones, and antibiotics. Situations in which young ruminants consume feed other than mother's milk are discussed. Various feed sources for these young animals are identified. Because of the extreme diversity in ruminant production systems, the sources of ruminant feeds are extremely diverse.