本试验旨在研究小肽对凡纳滨对虾幼虾生长、体成分、非特异性免疫力及抗病力的影响。在基础饲料中分别添加0（对照）、0.5%、1.0%、2.0%、4.0%和6.0%的小肽，共配制6种试验饲料，分别命名为S0、S0.5、S1.0、S2.0、S4.0、S6.0。选取初始体重为（0.19±0.01）g的凡纳滨对虾幼虾，随机分为6组，每组设3个重复，每个重复30尾。饲养试验持续56 d。结果表明：各添加小肽组的增重率（WGR）、特定生长率（SGR）和蛋白质效率（PER）均显著高于对照组（P<0.05），饲料系数（FCR）则显著低于对照组（P<0.05）；各组对虾的存活率无显著差异（P>0.05）。血清中，酚氧化物酶（PO）活性在S1.0和S2.0组显著高于其他组（P<0.05）；超氧化物歧化酶（SOD）活性在S0.5和S1.0组显著高于对照组（P<0.05）；酸性磷酸酶（ACP）活性在S1.0和S2.0组显著高于对照组（P<0.05）；碱性磷酸酶（AKP）和溶菌酶（LSZ）活性各组之间无显著差异（P>0.05）；丙二醛（MDA）含量在S4.0和S6.0组显著低于其他组（P<0.05）。肝胰腺中，LSZ活性在S0.5、S2.0和S4.0组显著高于对照组（P<0.05），在S6.0组则显著低于对照组（P<0.05）；SOD活性各组之间无显著差异（P>0.05）；ACP活性在S0.5和S1.0组较高，但与对照组差异不显著（P>0.05）；AKP活性在S4.0组显著低于对照组（P<0.05）；MDA含量在各小肽添加组均显著低于对照组（P<0.05），同时S4.0组还显著低于S6.0组（P<0.05）。通过哈维氏弧菌攻毒试验发现，小肽添加量为0.5%~4.0%的组凡纳滨对虾幼虾攻毒7 d后的累积死亡率显著低于对照组（P<0.05），但小肽添加量为6.0%的组则与对照组无显著差异（P>0.05）。综上所述，饲料中添加1.0%~2.0%的小肽可促进凡纳滨对虾幼虾的生长，提高其非特异性免疫力及抗病力。

A 56-day feeding trial was carried out to investigate the effects of small peptides on growth, body composition, non-specific immunity and disease resistance of juvenile Litopenaeus vannamei. Six experimental diets were prepared by adding 0 (control), 0.5%, 1.0%, 2.0%, 4.0% and 6.0% of small peptides into the basal diet, and named as S0, S0.5, S1.0, S2.0, S4.0 and S6.0, respectively. A total of 540 Litopenaeus vannamei with the initial body weight of (0.19±0.01) g were randomly assigned into 6 groups with 3 replicates per group and 30 individuals per replicate. The results showed that the weight gain rate (WGR), specific growth rate (SGR) and protein efficiency rate (PER) in small peptides adding groups were significantly higher than those in control group (P<0.05), while the feed conversion rate (FCR) in small peptides adding groups was significantly lower than those in control group (P<0.05); however, the survival rate (SR) of shrimp had no significant difference among groups (P>0.05). In serum, phenoloxidase (PO) activity in S1.0 and S2.0 groups was significantly higher than that in other groups (P<0.05); superoxide dismutase (SOD) activity in S0.5 and S1.0 groups was significantly higher than that in control group (P<0.05); acid phosphatase (ACP) activity in S1.0 and S2.0 groups was significantly higher than that in control group (P<0.05); the activities of alkaline phosphatase (AKP) and lysozyme (LSZ) were not significantly different among groups (P>0.05); malondialdehyde (MDA) content in S4.0 and S6.0 groups was significantly lower than that in other groups (P<0.05). In hepatopancreas, LSZ activity in S0.5, S2.0 and S4.0 groups was significantly higher than that in control group (P<0.05), but it in S6.0 group was significantly lower than that in control group (P<0.05); SOD activity was not significantly different among groups (P>0.05); ACP activity in S1.0 and S0.5 groups was higher, but compared with control group had no significant difference (P>0.05); AKP activity in S4.0 group was significantly lower than that in control group (P<0.05); MDA content in small peptides adding groups was significantly lower than that in control group (P<0.05), and it in S4.0 group was significantly lower than that in S6.0 group (P<0.05). Vibrio harveyi challenge test showed that the cumulative mortality rate after 7 days challenged by Vibrio harveyi in groups with the small peptides addition of 0.5% to 4.0% was significantly lower than that in control group (P<0.05), but it in group with the small peptides addition of 6.0% had no significant difference compared with control group (P>0.05). In summary, adding 1.0% to 2.0% small peptides into the diet can significantly improve the growth, and increase the non-specific immunity and disease resistance of juvenile Litopenaeus vannamei.