Predominant Bacteria in the Rumen of Cattle on Bloat-Provoking Ladino Clover Pasture

Abstract

A study was made on the microorganisms in the rumen of six yearling steers pastured on bloat-provoking Ladino clover. Three animals were selected for study on the basis of being good bloaters and three were nonbloaters. Studies on the bloaters were made before and 24 hr. after they were treated orally with 50 rag. of procaine penicillin to prevent bloat. There were no significant differences between animal groups in pH of ruminal contents, counts of cellulolytic bacteria, total anaerobic bacterial counts, or the occurrence of 11 presumptively identified bacterial groups. Counts of facultatively anaerobic streptococci were significantly depressed in the penicillin-treated group, but no other effects of treatment appeared to be significant. The means of the total anaerobic bacterial counts of the bloaters were higher than those of the two other groups, but the difference only approached significance. It is evident that the occurrence of bloat in animals consuming Ladino clover is not related to large differences in the numbers or species of ruminal microorganisms.