Energy and protein utilization by goats fed Italian ryegrass silage treated with molasses, urea, cellulase or cellulase plus lactic acid bacteria

The effects of different additives on ensiling of Italian ryegrass (IRG) si lage and the resulting silages energy and nitrogen utilization and on metha ne (CH4) emission by Japanese native goats were evaluated. The silages were prepared from IRG harvested at late-bloom stage. Different treatments, 13. 3% molasses, 4.0% urea, 0.02% cellulase and 0.02% cellulase + 0.02% lactic acid bacteria (LAB) were mixed with IRG prior to ensiling, and compared to a control with no preservative. Diets consisted of corn and soybean meal wi th one of the silages. Goats were allocated to examine one of the treated d iets in two metabolism trials. Each trial period lasted 21 days, with a 7-d ay period of adjustment, followed by a 7-day preliminary period and a 7-day period of total collection of digestion and metabolism data. Methane emiss ion was measured in open circuit respiration chambers over three consecutiv e days for each goat. Urea treated IRG had a higher (P < 0.05) volatile amm onia nitrogen (NH3-N/TN, 57%) compared to other silages, All treated silage s had higher (P < 0.05) OM digestibilities except the cellulase treated sil age. The cellulase + LAB treated silage diet had the lowest CH(4)kg(-1) dig estible organic matter intake (DOMI). Goats consumed similar N in all diets except the urea treated silage diet. All treated silage diets produced hig her (P <less than> 0.01) urinary N than that of the control diet. The CP di gestibilities were similar (P > 0.05) in all treated silage diets except th e molasses treated silage diet, where CP digestibility was the lowest. Urea treated silage diet produced a higher digestible N, but had a negative ret ained N due to a higher (P < 0.001) urinary N. Ensiling IRG with the additi ves led to higher digestible nutrient availability, but mixing urea resulte d in increased N losses through feed, feces and urine. This study showed th at IRG harvested at late-bloom stage could be ensiled without any additive, but mixing molasses, cellulase and cellulase + LAB prior to ensiling incre ased the proportion of ME to DE and could reduce the CH4 emission rate per unit of DOM and retained energy (RE). Mixing urea increased the digestible OM and N intake, but increased the N excretion. Cellulase addition resulted in a decreased CH4 production rate. However, IRG treated with molasses cou ld increase retained energy and N besides reducing CH4 and volatile N. (C) 2001 Elsevier Science B.V. All rights reserved.