Effects of a Ruminal Methane Inhibitor on Growth and Energy Metabolism in the Ovine

Twenty-four crossbred lambs weighing 14.1 to 27.2 kg were divided into three groups of eight each and balanced for sex and weight. The groups were then assigned to one of the three treatments 0, 1.5 and 3.0 mg bromochloromethane (BCM)/kgW/day for the 105-day growth trial. The lambs were fed a commercial pelleted lamb growing ration ad libitum to which the BCM premix was added at each feeding. No significant differences among treatments were found for average daily DM intake, average daily gain, or feed efficiency. Sixteen respiration calorimetry trials were conducted using four mature Suffolk wether sheep weighing 64.4 to 80.7 kg and randomly assigned to three treatment levels of 1.5, 3.0 and 4.5 mg BCM/kgW/day following a control trial at 0 mg BCM/kgW/day. The wethers were fed the same ration as the growing lambs but at maintenance level. BCM feeding resulted in about an 85% inhibition of methane production, which was a highly significant (P<.01) decrease compared to control values.