ABSTRACT
Summary Experiments were conducted to determine the effect of hay ammoniation on hay consumption and weight gain by steers when the hay was fed unsupplemented and supplemented with energy and protein. Mature orchardgrass (Dactylis glomerata L.) hay was baled in early June 1979 and treated with anhydrous ammonia at 30 g/kg of hay. Seven weeks after treatment the hay was uncovered and allowed to aerate for 3 days. It was then fed to weanling steer calves weighing approximately 225 kg each. Similar hay baled from the same field but not ammoniated was fed to separate groups of steers. Both the treated and the untreated hays were fed unsupplemented, supplemented with 1.80 kg corn/head daily, and supplemented with 1.35 kg corn and 0.45 kg soybean meal/head daily. The feeding trial lasted 90 days. Ammoniation increased total nitrogen concentration of the hay from 1.12% to 1.96%. Apparent dry-matter digestibility was increased from 47.7% to 54.8%. Cellulose and hemicellulose digestibilities were increased from 49.5% to 62.1% and from 49.8% to 71.7%, respectively, by ammoniation. Digestibility of nitrogen added to the hay during treatment was slightly greater than digestibility of the native nitrogen. Animals fed ammoniated hay consumed 17% more dry matter daily than animals fed untreated hay. Consumption averaged 66.2 and 77.1 g/kg0.75, respectively, for the untreated and ammoniated hays. Animals consuming ammoniated hay gained 0.21 kg/day more than animals consuming untreated hay. Corn grain increased daily gain of animals consuming untreated hay from 0.16 to 0.45 kg. Similar supplementation for animals consuming ammoniated hay increased daily gain from 0.37 to 0.69 kg. Protein supplementation increased the weight gain of animals fed untreated hay but did not increase the weight gain of animals consuming ammoniated hay. Apparently the nitrogen added to the hay during ammoniation was utilized well enough to preclude the need for additional protein supplementation.
