饲用甜高粱青贮对小尾寒羊瘤胃代谢参数的影响

摘要

为探索饲用甜高粱(Sorghum bicolor)青贮影响小尾寒羊瘤胃代谢的机理,本研究选取小尾寒羊母羊8只,体重26.6 kg左右,随机分为两组,每组4 只,分别饲喂甜高粱青贮(sweet sorghum silage,HG)和玉米(Zea mays)青贮(corn silage,HY),精饲料及苜蓿(Medicago sativa)颗粒按动物体重的 1%及 0.5%补饲,于采样期第 1(D1)、7(D7)、30 天(D30)采集瘤胃液,测定瘤胃液 pH、氨态氮(ammonia nitrogen,NH3-N)浓度以及挥发性脂肪酸(volatile fatty acids, VFA)浓度.结果表明,生长期小尾寒羊玉米青贮采食量(520 g·d—1)显著高于甜高粱青贮(310 g·d—1)(P<0.05);在整个适应期,饲粮处理、饲喂时期及其互作对两组试羊瘤胃液pH 无显著影响(P>0.05),但对瘤胃液NH3-N浓度有显著影响(P<0.05),D7期瘤胃液NH3-N浓度最高,D1期最低,在D30期,HG组瘤胃液NH3-N浓度显著高于 HY组;饲粮处理对瘤胃液支链脂肪酸(异丁酸和异戊酸)有显著影响(P<0.05),在D7、D30期,HG组支链脂肪酸显著高于 HY组;饲粮处理和饲喂时期的交互作用对乙酸:丙酸(A:P)有显著影响(P<0.05),D7期 HG组 A:P 高于 HY 组,而在D30期,则相反.综上,小尾寒羊瘤胃内环境对不同青贮型饲粮适应性存在差异,饲喂1个月后,HY组采食量及瘤胃液乙酸:丙酸高于 HG组,但瘤胃液 NH3-N、支链脂肪酸浓度低于 HG组.%This study was conducted to(1)investigate the mechanism of the effects of sweet sorghum(Sor-ghum bicolor)on the rumen metabolism of the meat sheep and(2)provide technical support for the scientific utilization of sweet sorghum.Eight small-tailed han sheep [body weight=(26.6士1.1)kg]were randomly di-vided into two groups and were fed sweet sorghum silage(HG)and maize(Zea mays)silage(HY),respec-tively.The concentrate and alfalfa pellet(Medicago sativa)were fed at 1% and 0.5% of animal weight.The rumen fluid was collected on days 1(D1),7(D7),and 30(D30)of the study period.Subsequently,the pH, concentration of ammonia nitrogen(NH3-N),and volatile fatty acid(VFA)were determined.The results showed that the feed intake of corn silage(520 g·d—1)was higher than that of the sweet sorghum silage(310 g·d—1).There was no effect of the treatment,period,and interaction(P>0.05)on the rumen pH in the two groups.However,the concentration of ammonia nitrogen(NH3-N)was affected by the treatment,period,and interaction(P<0.05),and the concentration of NH3-N was the highest in D7and lowest in D1.Furthermore, the concentration of NH3-N in HG group was significantly higher than that in HY group on D30.The content of branched fatty acids(isobutyric and isovaleric acids)were affected by the feed treatment(P<0.05),the con-tent of fatty acids of HG group was significantly higher than those of HY group on D7and D30.The ratio of ace-tic acid/propionic acid(A/P)was effected by the interaction effects of feed treatment and period(P<0.05), A/P of HG group was higher than that of HY group on D7;however,on D30,the result was contrary.These results suggest that there are differences in the adaptability of different silage diets in the rumen of small-tailed han sheep.