A REVIEW OF BLOAT IN FEEDLOT CATTLE

Improvements in feedlot management practices and the use of various fe ed additives have reduced, but not eliminated, the occurrence of bloat in feedlot cattle. Feedlot bloat reduces the profitability of product ion by compromising animal performance and more directly by causing fa talities. In feedlots, bloat is associated with the ingestion of large amounts of rapidly fermented cereal grain and destabilization of the microbial populations of the rumen. An abundance of rapidly fermented carbohydrate allows acid-tolerant bacteria (e.g., Streptococcus bovis and Lactobacillus spp.) to proliferate and produce excessive quantitie s of fermentation acids. As a result, ruminal pH becomes exceedingly l ow, and this impairs rumen motility. Further, the excessive production of mucopolysaccharide or ''slime'' increases the viscosity of ruminal fluid and stabilizes the foam implicated in frothy feedlot bloat. Alt hough protocols have been developed to treat feedlot bloat, the most p rofitable approach is to use management strategies to reduce its likel ihood. Amount of roughage, grain processing techniques, selection of c ereal grain (e.g., corn, barley, and wheat), dietary adaptation period s, and various additives (e.g., ionophores) can influence the occurren ce of bloat in feedlot cattle. Successful management of these factors depends on a thorough understanding of the behavioral, dietary, and mi crobial events that precipitate bloat in feedlot cattle.