BLOAT IN CATTLE .48. EFFECT OF COPPER IN A BLOAT DRENCH ON RUMEN BYPASS IN CATTLE

A trial was undertaken to determine whether a bloat drench containing copper (Cu), cobalt (Co), selenium (Se), and iodine (I) would by-pass the reticulo-rumen (rumen) of cows. Six rumen-fistulated cows were fed pasture at a range of intakes so that there was an 8-fold range in ru men dry matter (DM) pool size, and the Cu in the drench was used as a marker. The extent to which the rumen Cu pool size increased as a cons equence of drenching was used to indicate the fate of the drench. The increase in the rumen Cu pool with drenching showed 30-100% of the dre nch (mean 71.3 +/- SE 5.15%) remained in the rumen 25-30 min after adm inistration and recovery was not affected by rumen fill or saiety. It is suggested that the low and variable recoveries could be the result of a slow dispersion of drench in the digesta, so that drench which wa s concentrated in the cranial reticulo-rumen passed rapidly to the abo masum. The drench did not appear to elicite a closure of the oesophage al groove.