Effect of monensin on meal frequency during sub-acute ruminal acidosis in dairy cows

Abstract

Two experiments were conducted to determine the effects of monensin (Rumensin® controlled-release capsule; exp. 1 and Rumensin® Premix; exp. 2) on meal frequency during grain-induced sub-acute ruminal acidosis (SARA) in Holstein dairy cows. SARA was induced by restricting total mixed ration intake to 85% of ad libitum intake and replacing the remaining 15% with a grain pellet consisting of 50% wheat and 50% barley. In both experiments, meal frequency during SARA was lower (P < 0.05) than meal frequency during the adaptation and recovery periods. In exp. 2, monensin increased meal frequency during SARA (6.0 vs. 7.2, P = 0.04) and meal frequency during the recovery period (7.5 vs. 9.0, P = 0.004). These results suggest monensin premix may increase meal frequency in lactating dairy cows under conditions of SARA. Key words: dairy cows, monensin, ruminal acidosis, meal frequency