A review of bloat in feedlot cattle.

Abstract

Improvements in feedlot management practices and the use of various feed additives have reduced, but not eliminated, the occurrence of bloat in feedlot cattle. Feedlot bloat reduces the profitability of production by compromising animal performance and more directly by causing fatalities. 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 quantities of fermentation acids. As a result, ruminal pH becomes exceedingly low, 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. Although protocols have been developed to treat feedlot bloat, the most profitable approach is to use management strategies to reduce its likelihood. Amount of roughage, grain processing techniques, selection of cereal grain (e.g., corn, barley, and wheat), dietary adaptation periods, and various additives (e.g., ionophores) can influence the occurrence of bloat in feedlot cattle. Successful management of these factors depends on a thorough understanding of the behavioral, dietary, and microbial events that precipitate bloat in feedlot cattle.

Genome Sequence ofStreptococcus gallolyticus: Insights into Its Adaptation to the Bovine Rumen and Its Ability To Cause Endocarditis

“…Whereas the colonies on TH-glucose medium were small and nonshiny, they were extremely mucoid on medium supplemented with sucrose. This suggests that the glucans produced by these glycosyl transferases represent the mucopolysaccharides produced during feedlot bloat in cattle (14). Thus, among streptococci, S. gallolyticus is the only one known to produce both a capsule and a mucoid extracellular glucan.…”

“…It was shown that the production of mucopolysaccharides by S. bovis increases the viscosity of ruminal fluid and stabilizes the foam implicated in frothy feedlot bloat (14). A second locus identified in the UCN34 genome encodes three different glycosyl transferases where each structural gene is associated with a regulatory gene (Fig.…”

“…For example, ingestion of large amounts of rapidly fermented cereal grains leads to a destabilization of the rumen flora and to the proliferation of acid-tolerant bacteria, including S. gallolyticus. This is accompanied by the overproduction of mucopolysaccharides that stabilize the foam, resulting in feedlot bloat, a significant cause of economical loss (14). Virulence and colonization factors of S. gallolyticus in humans are largely unknown.…”

Feeding subtherapeutic antimicrobials to low-risk cattle does not confer consistent performance benefits

“…The incidence of treatment for bloat in the present study (2 to 5%) would likely have been reduced if ionophores had been included in the diet (Galyean and Rivera 2003), but the presence of monensin in diets would have confounded the observed responses to the other subtherapeutic antimicrobials administered. Feedlot mortalities due to bloat have been estimated at between 0.1 and 0.2% in western Canada (Merrill 1994), although incidence of bloat is thought to be site dependent due to variations in bunk management, diet, grain processing and animal type (Cheng et al 1998).…”

Growth performance and safety of meat from cattle feedlot finished with salinomycin in the diet

“…Another effect of intense proliferation of Streptococcus and protozoa in the rumen is the production of mucopolysaccharides, which increases ruminal fluid viscosity and may cause bloat (BERGEN;BATES, 1984). Ionophores acts reducing the population of these bacteria; however, they do not have an effect over the types of bacteria that use lactic acid produced through rumen fermentation, such as Selenomonas ruminantium, thus controlling the occurrence and severity of conditions such as acidosis and bloat (CHENG et al, 1998).…”