纤维分解酶处理玉米秸秆对肉牛瘤胃发酵和养分消化代谢的影响

Effects of Corn Straw Fermented by Cellulase on Rumen Fermentation,Nutrient Digestion and Metabolism in Beef Cattle

为研究纤维分解酶处理玉米秸秆饲喂肉牛后对瘤胃发酵、养分消化代谢以及氮、磷、甲烷排放和血清生化指标的影响,选用12月龄左右、体况良好、体重近似的西门塔尔牛36头,随机分为4组,每组9头牛。对照组饲喂基础饲粮(混合精料+玉米秸秆;精粗比45∶55),试验Ⅰ、Ⅱ和Ⅲ组分别以0.5%、1.0%和1.5%的纤维分解酶处理玉米秸秆替代基础饲粮中的玉米秸秆进行为期80 d的试验。结果表明:试验Ⅱ和Ⅲ组总挥发性脂肪酸、丙酸、丁酸和氨态氮浓度均显著高于对照组和试验Ⅰ组(P<0.05),但乙酸/丙酸和乳酸浓度却显著低于对照组和试验Ⅰ组(P<0.05);试验Ⅱ和Ⅲ组干物质、有机物、粗蛋白质、粗脂肪、无氮浸出物、中性洗涤纤维和酸性洗涤纤维消化率均显著高于对照组(P<0.05);试验Ⅱ组消化能、代谢能、沉积能以及沉积能/消化能均显著高于对照组(P<0.05);试验Ⅱ与Ⅲ组食入氮、可消化氮和沉积氮均显著高于对照组与试验Ⅰ组(P<0.05);试验Ⅱ与Ⅲ组氮排泄/食入氮、磷排泄/食入磷和甲烷排放量均显著低于对照组和试验Ⅰ组(P<0.05);试验Ⅱ和Ⅲ组血清甘油三酯、葡萄糖、白蛋白浓度和谷草转氨酶活性均显著高于对照组与试验Ⅰ组(P<0.05)。综合以上各项指标,当处理玉米秸秆的纤维分解酶添加量为1.0%时,瘤胃发酵得到显著改善,饲粮养分消化率显著提高,能量及氮利用率提高,氮、磷和甲烷排放降低。

The objective of this study was to evaluate the effects of feeding corn straw fermented by cellulase on rumen fermentation, nutrient digestion and metabolism, the emissions of nitrogen, phosphorus and methane, and serum biochemical parameters in beef cattle. Thirty-six Simmenta beef cattle （about 12 months of age） in good body condition and with similar body weight were randomly divided into 4 groups with 9 beef cattle in each. The control group was fed a basal diet （mixed concentrate and corn straw; concentrate：roughage was 45：55）. Experimental Ⅰ, Ⅱ and Ⅲ groups were fed diets with 0.5%, 1.0% and 1.5% corn straw fermented by cellulose to replace the corn straw of the basal diet, respectively. The experiment lasted for 80 days. The results showed that the concentrations of total volatile fatty acid, propionic acid, butyric acid and ammonia-N in rumen of beef cattle in experimental Ⅱ and Ⅲ groups were significantly higher than those in experimental Ⅰ and control groups （P﹤0.05）, however, the ratio of acetate to propionate and the concentration of lactate were significantly lower than those in experimental Ⅰ and control groups （P〈0.05）. The digestibility of dry matter, organic matter, crude protein, ether extract, nitrogen free extract, neutral detergent fibre and acid detergent fibre of beef cattle in experimental Ⅱ and Ⅲ groups was also significantly higher than that in control group （P〈0.05）. Besides, the digestible energy, metabolizable energy, retention energy and the ratio of retention energy to digestible energy of beef cattle in experimental Ⅱ group were significantly increased compared with control group （P〈0.05）. The intake nitrogen, digestible nitrogen and retention nitrogen of beef cattle in experimental Ⅱ and Ⅲ groups were significantly higher than those in control and experimental Ⅰ groups （P〈0.05）. Furthermore, the ratio of nitrogen excretion to intake nitrogen, the ratio of phosphorus excretion to intake phosphorus and methane mission of beef cattle in experimental Ⅱ and Ⅲ groups were significantly lower than those in experimental Ⅰ and control groups （P〈0.05）. In addition, the concentrations of triglyceride, glucose, albumin and glutamic-oxal（o）acetic transaminase activity of beef cattle in experimental Ⅱ and Ⅲ groups were significantly higher than those in control and experimental Ⅰ groups （P〈0.05）. The results indicate that rumen fermentation, the digestibility of nutrients and the utilization of energy and nitrogen are improved, while the emissions of nitrogen, phosphorus and methane are reduced when beef cattle fed corn straw fermented by 1.0% cellulase.