Effect of Oyster Shell with and without Roughage in Beef Finishing Rations

Addition of oyster shell to 20% roughage and all-concentrate rations resulted in decreased gain and feed consumption and lower feed efficiency. Steers fed ground ear corn rations gained faster (P<.05) and had a greater (P<.05) feed intake than steers fed shelled corn rations. Feed consumption calculated in 28-day periods was not significantly different among the treatments. Oyster shell greatly increased the incidence of bloat as measured in the last 28 days of the trial. Total VFA concentration tended to be higher in steers fed the ground shelled corn rations. Feeding oyster shell did not significantly alter ruminal fluid pH, VFA concentration, or level of blood calcium or phosphorus. Chronic rumenitis was increased when oyster shell was added to the ground ear corn ration and was also characteristic of steers fed the shelled corn rations. The number of abscessed livers was highest in steers fed the all-concentrate ration followed by rations containing oyster shell. Oyster shell in ear corn and all-concentrate rations reduced performance and increased management problems during the trial. Under the conditions of this experiment, oyster shell was ineffective in improving the performance of steers fed high grain finishing rations.