精料水平对小尾寒羊瘤胃代谢的影响

RUMEN FERMENTATION OF SHEEP UNDER DIFFERENT CONCENTRATE SUPPLEMENTING LEVEL

6只 8月龄小尾寒羊公羊 (平均体重为 2 9.98kg)安装永久性瘤胃瘘管。采用对比试验设计 ,分 15 0g d、2 5 0g d、35 0g d、4 5 0g d四个混合精料水平。采集瘤胃液测定pH值、氨氮浓度和乙丙酸浓度。试验结果表明 :试羊瘤胃液平均pH值在 6 .4 8～ 6 .89范围内变动。随精料水平的提高 ,pH值下降 (P <0 .0 1)。瘤胃液平均氨氮浓度的变化范围为 2 1.6 8～ 30 .0 4mg 10 0ml,其浓度随精料水平的提高而增加 (P <0 .0 1)。随精料水平的提高 ,瘤胃液乙酸、丙酸摩尔浓度饲喂后峰值随时间点的推移有延迟的趋势。乙酸、丙酸浓度随饲喂精料水平的提高而增加 ,且差异显著 (P <0 .0 5 )。乙丙酸摩尔浓度比随精料水平的提高而下降 ,但不同精料水平间差异不显著 (P >0 .0 5 )。

Six eight-month old little tail type Han rams with average live weight of 29.98 kg were fitted with permanent ruminal fistulae. The experimental diets are composed of mixed concentrate and chopped corn stalk. Mixed concentrate was supplied at 150g/d, 250g/d, 350g/d and 450g/d in each of four experimental periods respectively. Corn stalk was fed ad libitum. Acetate, propionate and ammonia concentrations and pH values of rumen fluid samples were measured. The results indicated that: The pH values and ammonia, acetate and propionate concentrations of rumen fluid increased with concentrate level (P<0.01). Postprandial peak of acetate and propionate postponed with increased concentrate level. The was a trend that acetate/propionate ratio decreased with the level of concentrate supplemented,but the difference was insigrificant between treatments (P>0.05). NH 3-N concentrate was decreased significantly (P<0.01) with increased concentrate level.