用Rusitec系统研究两种粒度日粮对绵羊瘤胃发酵特性的影响

试验旨在应用Rusitec系统研究不同粒度日粮对绵羊瘤胃发酵特性的影响。试验分为两个处理组，日粮颗粒分别为5和0.45 mm，每个处理4个重复，适应期10 d，采样期2 d，测定不同时间发酵液总产气量、甲烷产量及发酵参数。结果显示，5 mm颗粒组的总产气量极显著高于0.45 mm颗粒组（P＜0.01），甲烷产量不受粒度的影响（P＞0.05）；5 mm颗粒组投料后6 h的pH、6和9 h的乙酸、6 h的异丁酸、12 h的乙酸/丙酸、0和12 h的总挥发性脂肪酸、6和9 h的总氮均显著或极显著大于0.45 mm颗粒组（P＜0.05；P＜0.01），而5 mm颗粒组12 h的丙酸及3、6、9、12 h戊酸则显著或极显著小于0.45 mm组（P＜0.05；P＜0.01），不同粒度对其余指标没有显著影响（P＞0.05）。由此可知，人工瘤胃试验中日粮的不同粒度可影响发酵特性，较大颗粒有较高的总产气量、乙酸、乙酸/丙酸、总挥发性脂肪酸和总氮含量。

Effect of Particle Size of Feed on Rumen Fermentation of Sheep Using the Rumen Simulation Technique (Rusitec)

This experiment was aimed to investigate the effects of different particle sizes of feeds on rumen fermentation using the rumen simulation technique (Rusitec). There were two treatments (5 and 0.45 mm) with 4 replicates per group. After 10 days'adaptations,the fermentation parameters were determined for 2 days,and the total gas production,methane production and fermentation parameters were determined. The results showed that the total gas production of 5 nm group was extremely significantly higher than that of 0.45 nm group (P <0.01),while methane production of the two group was no significant difference (P >0.05).The ruminal fluid pH at 6 h,acetic acid at 6 and 9 h, isobutyric acid at 6 h, acetic acid to propionic acid ratio at 12 h,butyric acid at 6 h,total volatile fatty acids at 0,12 h and total nitrogen at 6 and 9 h in 5 mm group were significantly or extremely significantly greater than those in 0.45 mm group (P <0.05;P <0.01). While propionic acid at 12 h and valeric acid at 3,6,9 and 12 h in 5 mm group were significantly or extremely significantly lower than that in 0.45 mm group (P <0.05;P <0.01).Other parameters were not significantly affected by particle size (P >0.05). These results certified that the particle size of feeds in Rusitec did affected the rumen fermentation. Large size improved the gas production,acetic acid to propionic acid ratio,total volatile fatty acids and total nitrogen cotents.