1. The cellular proteins of Butyrivibrio fibrisolvens, Lactobacillus casei, Megasphaera elsdenii, Selenomonas ruminantium and Streptococcus bovis were labelled by growth in the presence of L-[14C]leucine, and the breakdown of labelled protein was measured in incubations of these bacteria with rumen fluid to which unlabelled 5 mM-L-leucine was added. The rate of protein breakdown was estimated f...

A model rumen system, dual-flow continuous culture fermenters, was evaluated by two comparative criteria in two experiments using ribosomal (r)RNA-targeted DNA probes to compare key microbial groups in samples. The initial experiment measured temporal changes in population structure during adaptation of ruminal microbial populations in fermenters over 240 h. The fermenter inoculum contained 34....

The cellulolytic activity of rumen contents was assayed by measuring losses in weight and tensile strength of cotton yarn incubated in rumen contents in the presence of dietary additives (barley, tallow) and at different pH values. The addition of barley depressed cellulolysis and the titer of filter paper-degrading bacteria only if the pH was allowed to fall. Lowering the pH from 7.0 to 6.0 by...

OBJECTIVE This study aims to identify the relationship between odd- and branched-chain fatty acids (OBCFAs) and microbial nucleic acid bases in the rumen, and to establish a model to accurately predict microbial protein flow by using OBCFA. METHODS To develop the regression equations, data on the rumen contents of individual cows were obtained from 2 feeding experiments. In the first experime...