不同生育期白羊草的瘤胃降解特性及其对瘤胃内环境的影响

摘要

以安装永久性瘘管的本地绵羊15只为试验动物，采用尼龙袋法对不同生育期白羊草的绵羊瘤胃降解特性及其对瘤胃内环境的影响进行研究。结果表明：干物质(DM)和粗蛋白质(CP)的有效降解率均在拔节期为最高，且拔节期 DM 的有效降解率显著高于其他3个生育期(P <0.05)。DM 的有效降解率随着生育期的推进不断降低，而 CP 的有效降解率无一定变化规律；加入不同生育期白羊草后，瘤胃液铵态氮浓度和总挥发性脂肪酸、乙酸、丙酸、丁酸、戊酸和异丁酸浓度均呈现先上升后下降的趋势，并在4 h 时达到峰值，且4 h 时，拔节期的铵态氮浓度和总挥发性脂肪酸、乙酸、丙酸浓度显著高于开花期(P <0.05)，其中以拔节期白羊草的增加幅度最大，开花期的最低，表明拔节期白羊草具有较高的瘤胃降解特性，最利于瘤胃发酵，由此可见，添加装有不同生育期白羊草的尼龙袋后均会对绵羊的瘤胃内环境产生影响，其原因主要与不同生育期白羊草的蛋白质含量和结构有关。%Fifteen local sheep fitted with permanent rumen fistula were selected to study the rumen degrada-tion dynamics and the influence on ruminal environment of Bothriochloa ischaemum during different growth pe-riods by using the nylon bag technique.Results showed that the degradability of dry matter (DM)and crude protein (CP)were highest in jointing stage,and the degradability of DM in jointing stage was significantly high-er than other stages (P <0.05).The degradability of DM declined along with the growth and the degradability of CP did not show a regular pattern.The concentration of NH 3-N and total volatile fatty acid,acetate,propio-nate,butyrate,valerate and isobutyrate showed a downward trend after the peak value (occurred after 4 hours). The concentration of NH 3-N and total volatile fatty acid,acetate,propionate in jointing stage were significantly higher than that in flowering period (P <0.05).The highest increment was in jointing stage,and the lowest in-crement was in flowering period,which indicated that the jointing stage had the highest ruminal degradation characteristics.It suggested that nylon bags filled with B .ischaemum in different growth periods could affect the ruminal environment,and it was caused by the protein content and structure of B .ischaemum in different growth periods.