CHLOROPHYLL AND PROTEIN LEVELS IN BOVINE RUMEN FLUID IN RELATION TO ALFALFA PASTURE BLOAT

Abstract

Rumen-fistulated cattle were fed fresh alfalfa herbage daily during three growing seasons. Two hours after feeding the incidence of bloat and of ruminal frothiness was recorded and samples of feed and rumen fluid were collected for analyses of chlorophyll and soluble protein. These constituents were examined in relation to the bloat-causing potential of the alfalfa and in relation to the occurrence of froth in rumen contents. Chlorophyll in rumen fluid was higher on days when the alfalfa caused bloat, compared to days when bloat did not occur (P < 0.01). Chlorophyll was also higher in frothy rumen fluid than in normal rumen fluid (P < 0.01). Soluble protein concentrations in rumen fluid were adequate to stabilize foams in vitro but did not show any daily changes related to the frothiness of rumen contents. The soluble proteins could be involved in froth formation but another factor, perhaps a component of the chloroplast membranes, appears to be responsible for the immediate onset of frothiness. Key words: Chlorophyll, protein, cattle, alfalfa, bloat, rumen