Bloat in Cattle. V. The Role of Rumen Mucinolytic Bacteria

A number of organisms were isolated from the rumen and tested for mucinolytic activity. Five which were capable of breaking down salivary mucin and utilizing free sialic (neuraminic) acid were found. When cultures of these organisms were introduced into the rumina of fistulated cows grazing a mature nonbloat provoking alfalfa pasture, bloat resulted in the majority of instances. Three sets of fistulated identical-twin cows were fed a bloat-producing ration. After frothy bloat developed the minimum amount of coarse, long hay needed to prevent bloat was determined. When bloat ceased, one member of each twin pair was inoculated with a mucinolytic rumen organism. This resulted in a marked increase in the degree of bloat over the uninoculated controls. It was previously shown at this station that bloat foam could be inhibited or dispersed by salivary mucin. Thus, it was proposed that bloat may occur when mucin concentration in the rumen is lowered because of decreased salivation on feeds containing foaming constituents. It is now proposed that the concentration of mucin necessary to prevent bloat can be further reduced by the destructive action of mucinolytic microorganisms.