Bacterial changes in the rumen during the onset of feed-lot bloat of cattle and characteristics of Peptostreptococcus elsdenii n. sp.

Slime production by microorganisms in the rumen of cattle and sheep has been advanced as a possible factor in feed-lot bloat by Jacobson and Lindahl (1955), and for frothy legume bloat by Hungate et al. (1955). The slime serves to entrap the fermentation gases and the resulting frothy ingesta blocks the ruminant's gas eructation mechanism. Lindahl et al. (1957) have produced experimental bloat by oral administration of soluble alfalfa saponins to sheep. Rumen bacteria capable of degrading alfalfa saponins with the concomitant production of slime have been isolated from the rumen of cattle (Gutierrez et al., 1958). Hungate et al. (1955) found rumen froth production was correlated with the severity of bloat symptoms in steers on legume pastures. The discovery by Smith et al. (1953) that certain high grain diets supplemented with protein could experimentally produce bloat in cattle offered an opportunity to study the microorganisms involved in the onset of feed-lot bloat. This investigation has been aimed at the enumeration, isolation, and identification of the predominant types of bacteria before and during bloat.