Effects of nutrition levels and particle sizes of total mixed ration on rumen metabolic parameters of sheep | 全混合日粮营养水平和粒度对绵羊瘤胃内环境的影响

Chinese. 选24只空怀期小尾寒羊母羊，采用2×2二因子析因试验设计，研究了不同营养水平（A11.0倍中国肉羊饲养标准、A21.5倍中国肉羊饲养标准），不同粒度（B1不粉碎、B2粉碎）全混合日粮（total mixed ration，TMR）对绵羊瘤胃内环境的影响。结果表明：食后2～8h，绵羊瘤胃液pH先降低后升高，在6.21～6.80之间波动，1.5倍营养水平极显著降低了绵羊食后2h和4h的瘤胃液pH（P0.01），显著降低了绵羊食后6h的瘤胃液pH（P0.05）。在各时间点，采食1.5倍营养水平TMR的绵羊瘤胃液总氮、尿素氮和蛋白氮浓度，极显著高于采食1.0倍营养水平TMR的绵羊（P0.01）。在食前、食后2h和4h，采食含1.5倍营养水平TMR的绵羊瘤胃液氨氮浓度极显著高于采食含1.0倍营养水平TMR的绵羊（P0.01）。在食后2、4、6h，采食粉碎TMR的绵羊瘤胃液氨氮浓度显著低于采食未粉碎TMR的绵羊（P0.05），但瘤胃液尿素氮浓度变化规律却相反（P0.05）。采食1.0倍营养水平和未粉碎TMR的绵羊瘤胃液挥发性总酸含量极显著高于采食1.5倍营养水平和粉碎TMR的绵羊（P0.01）。据此认为：绵羊饲喂TMR，瘤胃液pH波动范围较小，有利于维持瘤胃内环境的平衡；饲喂1.5倍营养水平TMR，绵羊瘤胃液总氮、氨态氮、尿素氮和蛋白氮浓度升高，促进瘤胃微生物发酵，有利于提高绵羊生产性能。饲喂粉碎TMR，绵羊瘤胃液总氮、蛋白氮和尿素氮浓度升高，氨态氮浓度显著降低，微生物对蛋白的分解减少，过瘤胃蛋白的比例增加，从而提高了蛋白质利用率。

English. 24 Small Tail-han ewes were chosen to measure the effects of different nutrition levels (A1-1.0 NY/T816-2004, A2-1.5NY/T816-2004) and particle sizes (B1 unpulverized, B2 pulverized) of total mixed ration (TMR) on metabolic parameters of rumen fluid with a factional designing of 2×2. The results showed that the pH of rumen fluid decreased after feeding, then increased in following times, and fluctuated between 6.21 and 6.80. The pH of rumen fluid of sheep fed with 1.5 times nutrient level TMR was lower than the sheep fed with 1.0 times nutrient level TMR. The pH value was affected highly significantly by the nutrition levels at 2 h and 4 h after feeding (P0.01), and affected significantly at 6 h after feeding (P0.05) in all treatments. The total nitrogen, urea nitrogen and protein nitrogen concentration of rumen fluid of sheep fed with 1.5 times nutrient level TMR was significantly higher than the sheep fed with 1.0 times nutrient level TMR at each time point (P0.01). The ammonia nitrogen concentration of rumen fluid of sheep fed with 1.5 times nutrient level TMR was highly significantly higher than the sheep fed with 1.0 times nutrient level TMR before eating, 2 h and 4 h after feeding (P0.01). At 2 h, 4 h and 6 h after feeding, the ammonia nitrogen concentration of sheep rumen fluid fed with pulverized TMR was significantly higher than the sheep fed with unpulverized TMR (P0.05), but the concentration of urea nitrogen in rumen fluid was opposite (P0.05). The TVFA content of sheep fed with TMR of 1.0 times nutrient level and unpulverized TMR was significantly higher than the sheep fed with 1.5 times nutrient level and pulverized TMR (P0.01). Fluctuation range of PH of sheep rumen fluid was gently when sheep fed TMR made by machine, which was conducive to maintaining the balance of the rumen environment. The total nitrogen, ammonia nitrogen, urea nitrogen and protein nitrogen concentration of rumen fluid of sheep fed with 1.5 times nutrient level TMR increased, which could promote rumen microorganism fermentation and improve growth performance of sheep. The total nitrogen, protein nitrogen and urea nitrogen concentration increased in sheep fed with pulverized TMR, but ammonia nitrogen concentration decreased, which could reduce microbial decomposition of protein, increase the proportion of rumen protein escaped and elevate protein utilization.