Use of feed additives to reduce ruminal methane production and deaminase activity in steers.

Effects of feeding the methane inhibitor, amicloral, and the deaminase inhibitor (DAI), 4,4'-dimethyldiphenyliodonium chloride, at 1,500 and 25 mg/kg of diet, respectively, were investigated in finishing steers. Digestibility and ruminal VFA and ammonia concentrations were measured in six steers per treatment. Organic matter digestibility was increased significantly by amicloral, DAI and amicloral plus DAI. There were no treatment effects on molar proportions of acetic acid or propionic acid, but butyric acid was highest (P < .05) when both additives were fed. Ruminal ammonia concentrations were lower (P < .05) with all three treatment diets. Ninety-six steers were allotted to eight groups, two pens (replicates) per treatment, in a 112-day feedlot study. Neither amicloral nor DAI had any effect on intake or daily gain, although feed efficiency was increased (P > .05) by 9 and 4%, respectively. Feeding amicloral plus DAI lowered intake by 19% (P < .05) and gains by 8% (P > .05) but increased the efficiency of feed utilization by 12% (P < .05).