THE RELATIONSHIP OF RUMEN CATIONS AND SOLUBLE PROTEIN WITH PREDISPOSITION OF CATTLE TO ALFALFA BLOAT

Abstract

Rumen-fistulated cattle were fed fresh alfalfa herbage daily during two growing seasons. Samples of rumen fluid were collected daily prior to feeding and the frothiness of the rumen fluid was assessed. Concentrations of soluble protein nitrogen in the rumen fluid were higher in animals that subsequently bloated than in those that did not (P < 0.01). There was no relation between soluble protein nitrogen and the occurrence of foam in the rumen prior to feeding. The concentrations of Na and K in the rumen fluid were negatively correlated. Bloat was associated with a low concentration of Na and a high concentration of K (P < 0.01). Concentrations of Ca and Mg were lower than those of the two monovalent ions but were also positively associated with bloat (P < 0.01). The high concentration of chlorophyll associated with a predisposition to bloat may be the result of a colloidal aggregation of chloroplast particles stabilized by cations. Key words: Pasture bloat, alfalfa, chlorophyll, ions, cattle