Abstract: In order to make better use of silage in fisheries,the effects of silage prepared from alfalfa (Medicago sativa L.) at different harvest times on the growth performance,intestinal digestion and meat quality of grass carp (Ctenopharyngodon idella) in autumn in Nanjing were studied. The experiment was divided into a control group (CON),an early-bloom group (CH) and a full-bloom group (KH). A total of 150 grass carp with an initial body weight of (1000±50) g were randomly divided into three groups with 50 grass carp in each group,and samples were taken for analysis after feeding for 60 days. The results showed that compared with the CON group,the CH group and the KH group had no significant effect on the final body weight,mass gain rate and specific growth rate of grass carp (P>0.05),the intestinal protease of grass carp in the CH group was significantly increased (P<0.05),the intestinal protease of grass carp in the KH group was significantly decreased (P<0.05),and the muscle texture index of grass carp in the CH group and KH group was not significantly affected (P>0.05). The aspartate aminotransferase and alanine aminotransferase in the KH group were significantly higher than those in the CON group and CH group (P<0.05). In conclusion,the substitution of 15% protein premix by alfalfa silage at early flowering and full flowering stage did not affect the weight gain of grass carp in autumn,but showed a trend of improving the meat quality of grass carp,and the alfalfa silage substitution group at early flowering stage increased the intestinal protease activity of grass carp. Therefore,alfalfa silage at the early flowering stage has greater potential to replace 15% protein premix for grass carp.

Key words: Alfalfa, Silage, Grass carp, Digestive enzyme, Meat quality

摘要： 为了更好地在渔业中利用青贮饲料，本试验研究了不同收获期紫花苜蓿(Medicago sativa L.)调制而成的青贮饲料在南京秋季对草鱼(Ctenopharyngodon idella)生长性能、肠道消化力和肉质等的影响。试验设对照组(CON组)、初花期(CH组)和盛花期(KH组)紫花苜蓿青贮饲料替代15%蛋白预混料。挑选150条初始体重为(1000±50) g的草鱼，随机分成三组，每组50条，饲喂60 d后取样分析。结果表明，与CON组相比，CH组和KH组对草鱼最终体重、质量增加率和特定生长率无显著影响，CH组草鱼肠道蛋白酶活性显著增加(P<0.05)，KH组草鱼肠道蛋白酶活性显著降低(P<0.05)；CH组和KH组草鱼肌肉质构指标均无显著差异；KH组谷草转氨酶和谷丙转氨酶显著高于CON组与CH组(P<0.05)。综上所述，初花期和盛花期紫花苜蓿青贮饲料替代15%蛋白预混料未影响秋季草鱼增重，呈现提高草鱼肉质的趋势，且初花期紫花苜蓿青贮饲料替代组提高了草鱼肠道蛋白酶活性。因此，初花期紫花苜蓿青贮饲料替代15%蛋白预混料饲养草鱼的潜力巨大。

关键词: 紫花苜蓿, 青贮饲料, 草鱼, 消化酶, 肌肉品质