Abstract:An 8-week feeding trial was carried out to investigate the effects of supplementation on the growth performance, nonspecific immunity-related enzyme activities, and disease resistance-related enzyme mRNA expression in juvenile , with initial average weight of 0.58±0.01 g, was randomly assigned to 7 groups in triplicates, with 40 individuals per replicate. Seven isonitrogenous and isolipid diets were supplemented with 0%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% in a basal diet, respectively. Following results were observed:nonsignificant difference was found in survival among all the groups (>0.05). Weight gain rate (WGR) and specific growth rate (SGR) increased gradually as dietary supplementation increased up to 0.4%, and then showed decline (<0.05). The minimum feed conversion rate (FCR) was observed on feed supplementation with 0.2% , which was significantly lower than that in the other groups (<0.05), while protein efficiency rate (PER) showed the opposite trend. Serum phenoloxidase (PO), alkaline phosphatase (AKP), and acid phosphatase (ACP) activities increased gradually with increasing dietary levels, and then gradually declined. The maximum values of PO, AKP, and ACP were found in the 0.4%, 0.1%, and 0.2% supplementation groups, respectively (<0.05). Activities of serum catalase (CAT), lysozyme (LSZ), and superoxide dismutase (SOD) of all treatment groups were significantly higher than that of the control group (0%) (<0.05). Gene expression levels of CAT and LZM in all treatment groups were significantly up-regulated when compared with the control group (<0.05). At the end of the feeding trial, the shrimps were challenged by for 96 h. Post-challenge survival rate increased with increasing dietary <0.05). Based on the broken-line regression analysis of WGR, when feed was supplemented with 0.23% of Litopenaeus vannamei were found to significantly improve.