Fermentable Fiber for Diet Formulation

Feed formulation is the art of combining ingredients to meet nutritional requirements of animals. Ruminants have a 4-compartment stomach made up of the rumen, reticlum, omasum, and abomasum or true stomach. The largest compartment is the rumino reticulum, which contains bacteria and protozoa and functions as a fermentation vat in which fiber is digested. Thus, appropriate feed components are needed for normal ruminal bacteria and protozoa to flourish in order to develop (Warner et al., 1956) and maintain proper rumen function. Diets for ruminants should, therefore, be formulated to provide: 1) feed components for fermentation by and multiplication of ruminal microbes; and 2) feed components that are directly digested into nutrients in the true stomach and intestines. The major end product categories of fermentation by ruminal microbes are 1) volatile fatty acids (VFA: acetate, propionate, butyrate), which are absorbed through papillae of the rumen wall; and 2) more bacteria and protozoa. The VFA are metabolized by ruminants into glucose and other carbohydrates or used directly as fuel and to synthesize tissues and milk. The bacteria and protozoa are passed to the abomasum and small intestine where they are digested to provide high quality protein and other nutrients.