Chemical composition and feeding value of urea-treated corncobs ensiled with additives for sheep

Abstract

This study examined the effects of various additives on ammonia nitrogen (N) capture in urea-treated corncobs (UTC), and measured the effect of UTC ensiled with or without enzose on nutrient intake, digestibility, N balance, and growth performance in sheep. In Expt 1, 5% UTC were ensiled in laboratory silos using enzose, cane molasses, acidified cane molasses, and acidified water (having a pH of 4.4, similar to enzose), each at 0, 4, 5, and 6% of corncobs dry matter (DM). Total N, ammonia N, and neutral detergent insoluble N (NDIN) contents in UTC ensiled with additives were significantly higher than in those ensiled without additives. Total N and NDIN contents of UTC were affected both by additive type and level. Total N and NDIN contents of UTC ensiled with enzose were significantly higher than of those ensiled with other additives. Neutral detergent fibre (NDF) and hemicellulose contents of UTC ensiled with additives were significantly higher than of those ensiled without additives. The NDF and hemicellulose were higher in UTC ensiled with enzose compared with all other additives. In Expt 2, 32 Lohi breed sheep, 4 months of age and of similar weights, were randomly assigned to 4 dietary groups. The control ration contained 30% DM from UTC ensiled without enzose, and the other 3 rations contained 30, 35, and 40% DM from UTC ensiled with enzose. Dry matter, OM, and NDF intakes were significantly increased in sheep fed increasing levels of UTC ensiled with enzose. Dry matter and NDF digestibilities were significantly higher in sheep fed UTC ensiled with enzose than in those fed UTC ensiled without enzose. The DM and NDF digestibilities were similar in sheep fed diets containing varying levels of UTC ensiled with enzose. Nitrogen balance was positive and was significantly higher in sheep fed rations containing UTC ensiled with enzose than in those fed UTC ensiled without enzose. Daily weight gain was higher in sheep fed rations containing UTC ensiled with enzose than in those fed UTC ensiled without enzose. These results indicated that ensiling UTC with enzose improved ammonia N capture. Inclusion of 5% UTC ensiled with 5% enzose up to 40% DM resulted in better nutrient intake, digestibility, N balance, and growth in Lohi sheep.