Bloat in cattle. XVI. Development and application of techniques for selecting drugs to prevent feedlot bloat.

Abstract

THE prevention of bloat has been the object of many studies, the majority involving use of surface-active agents or antibiotics. Because feedlot bloat is essentially the frothy type (Meyer and Bartley, 1971), the introduction of synthetic detergents provided an abundance of surfactants that could be tested for froth inhibition in the rumen. However, to test in vivo the multitude of drugs available would be a prohibitive task. This paper describes a three-step program for screening drugs for prevention of feedlot bloat. The first step (Experiment 1) determines the effect of the drug on in vitro froth production, surface tension, relative viscosity, and microbial activity. In this step, 235 drugs were tested. The second step (Experiment 2) consists of administering potential bloat preventives to rumen-fistulated cattle fed a feed-lot bloat-provoking ration. The effect of 54 drugs on in vivo rumen froth production was evaluated. The last step (Experiment 3) in testing the efficacy of a bloat prophylactic was to administer the drug as a feed additive to cattle bloating on an all-concentrate ration.