Submitted to: Proceedings of the Agricultural Biotechnology International Conference
Publication Type: Proceedings
Publication Acceptance Date: March 2, 2001
Publication Date: N/A
Technical Abstract: Diets of herbivorous mammals are of relatively poor quality, containing large quantities of cellulose, hemicellulose, and pectins, which are undegradable by digestive enzymes produced by mammals. Digestion of these materials in herbivores is accomplished by symbiotic microbial populations that inhabit the gastrointestinal tracts of these animals. In ruminants (e.g., sheep, cattle), the major site of microbial digestion is pre-gastri and occurs in a highly specialized organ, the rumen. As a result, most of the diet is fermented by the rumen microbiota with the formation of volatile fatty acids and microbial cells. The organic acid products are absorbed from the rumen and are the major energy source available for the host's metabolism, while the microbial cells are digested in the stomach and small intestine and provide protein and vitamins for the host. Because of this arrangement, ruminants can be fed diets with little concern for amino acid or vitamin composition as the resident ruminal microbes can synthesize those needed by the animal. From a practical point of view, the goal of the study of rumen microbiology is to develop an adequate understanding of the events occurring in the rumen so that strategies can be developed to manipulate ruminal fermentation in order to optimize this process and improve the efficiency of ruminant animal production (e.g., milk, meat, wool production). Suggestions for methods for modification include the use of feed additives and the introduction of genetically altered ruminal bacteria with improved or added abilities. In the current review, factors influencing competitive and cooperative interactions among ruminal microorganisms as well as efforts to manipulate ruminal fermentation are discussed.