We evaluated the effects of dietary supplementation with Bacillus subtili on growth, digestive enzyme activity, and non-specific immunity in hybrid sturgeon (Acipenser baeri♂× Acipenser schrenkii 9) juveniles. The hybrid sturgeon fingerlings (n=225, initial average weight: 10.34 g±0.19 g) were randomly assigned to 5 groups (3 replicates/group, n=15 per replicate) that were fed one of five diets containing 0 (control), 0.05% (group I), 0.1% (group II), 0.25% (group III), or 0.5% (group IV) B. Subtilis for 30 d. Growth was improved in hybrid sturgeon fed a diet containing 0.25% B. Subtilis (group III). Weight gain and the specific growth ratio increased by 54.31% and 28.61%, respectively, compared with the control group (P<0.05). The feed conversion ratio was 36.02% lower than in the control group (P<0.05), and was significantly lower than in the other groups (P<0.05). The activities of amylase, lipase, and protease were higher in the intestine in all groups compared with the control group. Furthermore, activity was higher on day 15 than on day 30. Digestive enzyme activity was highest in group III and was significantly higher than in the control group (P<0.05). Similarly, lysozyme, superoxide dismutase, and alkaline phosphatase activity and total antioxidant capacity were higher in group III than in the remaining groups on day 15 (.P<0.05). The indices of non-specific immunity were lower on day 30 than on day 15 in group III and were not significantly different from the control group. Our results suggest that the addition of B. Subtilis to the diet increases digestive enzyme activity and non-specific immunity and promotes the growth of hybrid sturgeon juveniles. The benefits were most pronounced at a level of 0.25% with repeated supplementation every 15 d.%在杂交鲟(Acipenser baeri ♂×Acipenserschrenkii♀)幼鱼日粮中添加不同质量分数(0、0.05％、0.1％、0.25％、0.5％)的枯草芽孢杆菌(Bacillussubtilis)粉剂,分别在培育实验的第15天和第30天采集样本,分析其对幼鱼摄食、生长、肠道消化酶活性及非特异性免疫指标的影响.实验结果:饲料中添加0.25％枯草芽孢杆菌粉剂时,杂交鲟生长最好,增重率和特定生长率较对照组分别提高了54.31％(P＜0.05)和28.61％(P＜0.05),饵料系数降低了36.02％(P＜o.05),也显著低于其他各实验组(P＜0.05).各实验组肠道蛋白酶、淀粉酶、脂肪酶活性均高于对照组；实验第15天时各种消化酶活性均大于第30天,其中第15天添加0.25％组的肠道蛋白酶、淀粉酶和脂肪酶活性最高,显著高于对照组(P＜0.05),且该实验组的血清溶菌酶(LSZ)、碱性磷酸酶(AKP)、总抗氧化能力(T-AOC)及超氧化物歧化酶(SOD)均显著高于对照组和其他实验组(P＜0.05).研究表明,饲料中添加枯草芽孢杆菌可提高杂交鲟幼鱼的生长性能、肠道的消化酶活性及血清非特异性免疫能力,适宜添加水平为0.25％,添加的适宜持续时间为15d左右.
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