The relationship between volume of rumen contents and genetic susceptibility to pasture bloat in cattle

Abstract

AbstractExperiments were designed to exchange rumen contents and vary the volumes of rumen contents between two pairs of rumen fistulated cows from herds selected for high (HS) or low (LS) susceptibility o t bloat. After exchanges between HS and LS cows the animals were tested on bloat-potent lucerne. The volume of rumen contents was lower in LS than in HS cows by 3·05 1. Increasing the volume of rumen contents of LS cows caused them to bloat to a degree never previously attained. The degree of bloat (i.e. score) was related to the volume of rumen fluid (r = 0·71) regardless of its origin (HS or LS) or the susceptibility of the recipient cow. The results implied that LS cows from this selection experiment did not bloat because they had a lower relative volume of rumen digesta than HS cows.