中文摘要：

本试验旨在研究苜蓿黄酮对杂交绵羊瘤胃发酵功能和纤维降解酶活性的影响。选择体重为27.02kg±3.03kg、安装有永久性瘤胃瘘管的萨福克羊×小尾寒羊杂交F1代绵羊（公羊）12只,采用单因素随机区组试验设计,分成4组,每组3个重复,每个重复1只。对照组饲喂基础日粮,试验组分别在基础日粮中添加0.1%、0.2%和0.4%苜蓿黄酮。预试期7d,正试期41d。结果表明：①与对照组相比,添加苜蓿黄酮12h后,0.2%组pH显著升高（P〈0.05）,其余各组差异均不显著（P〉0.05）;各试验组氨态氮（NH3-H）浓度均无显著变化（P〉0.05）,浓度变化幅度随剂量增加而变大。②与对照组相比,0.1%和0.4%组乙酸、丙酸、丁酸、戊酸和总挥发性脂肪酸的平均浓度均提高,0.2%组则相反;添加苜蓿黄酮2h后,0.1%、0.2%组异戊酸浓度显著高于0.4%组（P〈0.05）。③与对照组相比,0.1%和0.2%组木糖酶、内切葡聚糖酶、纤维二糖酶和纤维素酶活性均下降,0.4%组则升高,但差异均不显著（P〉0.05）。综上所述,日粮中添加苜蓿黄酮可维持杂交绵羊瘤胃发酵功能稳定,不同剂量苜蓿黄酮对纤维降解酶活性作用不同。在本试验条件下,建议苜蓿黄酮在杂交绵羊日粮中的添加量为0.4%。

英文摘要：

This study was performed to evaluate the effects of alfalfa flavonoids on rumen fermentation function and cellulolytic enzymatic activity of crossbreed sheep.A single factor random block design was used,and twelve crossbreed sheep（F1）Suffolk × Small-tail Han sheep with permanent rumen fistulas and the body weight of 27.02kg±3.03 kg were selected and randomly divided into 4groups with 3replicates per group and 1single sheep per replicate.The control group was fed a basal diet without alfalfa flavonoids,and the experimental groups were fed the basal diets supplemented with 0.1%,0.2% and 0.4% alfalfa flavonoids,respectively.The pretest period lasted for 7days and the trial period lasted for 41 days.The results showed as follows：①Compared with control group,the pH of 0.2% group was significantly increased at 12 hafter adding alfalfa flavonoids（P〈0.05）,and no significant differences were observed in other groups（P〉0.05）;There were no significant differences in NH3-H concentration among all groups（P〉0.05）,and the concentration was increasing with the dose rising（P〉0.05）.②Compared withcontrol group,the average concentrations of acetate,propionate,butyrate,valerate and TVFA in0.1% and 0.4% groups were increased,whereas the concentrations in 0.2% group showed contrary pattern.The isovalerate concentration in 0.1% and 0.2% groups were significantly higher than that in 0.4% group at 2hafter adding alfalfa flavonoids（P〈0.05）.③Compared with control group,the activities of xylanase,endoglucanase,cellobiase and cellulase in 0.1% and 0.2%groups were decreased,but those in 0.4% group were increased and the difference was not significant（P〉0.05）.In conclusion,dietary supplementation of alfalfa flavonoids could keep the stability of rumen fermentation function of crossbreed sheep and this compound in different dose had different effect on cellulolytic enzymatic activity.The recommended supplemental level of alfalfa flavonoids was 0.4%in diet for crossbreed sheep under this test cond