Effects of fishmeal substitution with Scenedesmus meal and supplementation of crystalline amino acids on growth performance,muscle nutrient composition,and intestinal health of Litopenaeus vannamei

WANG Ziyi; LIU Cheng; ZHOU Meng; TAN Xiaohong; ZHANG Haitao; YUAN Hailin; WANG Liansheng; TAN Beiping

doi:10.13557/j.cnki.issn1002-2813.2025.19.014

Abstract：This experiment aimed to investigate the feasibility of incorporating Scenedesmus meal into the diet of Litopenaeus vannamei.A total of 480 healthy Litopenaeus vannamei with similar initial body weights were randomly divided into four groups,with four replicates per group and 30 shrimps per replicate.The control group was fed a basal diet,while the groups S3,S6,and S9 were replaced with 3％,6％,and 9％Scenedesmus meal instead of fish meal with an equal protein ratio in the basal diet,and supplemented with crystalline methionine and lysine to maintain the same amino acid levels as the control group.The pre-test period was two weeks,and the formal test period was eight weeks.The results showed that there were no significant differences in survival rate(SR),weight gain rate(WGR),specific growth rate(SGR),feed conversion ratio(FCR),and protein efficiency ratio(PER)among the experimental groups(P＞0.05),but the final weight in the group S9 was significantly lower than that of the group S6(P＜0.05).Except for the calcium content in group S9 was significantly lower than than that of the control group(P＜0.05),the Scenedesmus meal as a substitute for fish meal had no significant effect on the routine nutritional components of muscles(P＞0.05),increased the content of some amino acids.Intestinal morphological analysis indicated that the group S3 had the thickest intestinal muscle layer thickness,and the group S6 had the widest villi width.Compared with the control group,the relative expression levels of Relish protein(Relish),Dorsal protein(Dorsal),and IκB kinase α(IKKα)genes were significantly increased in the group S9.The relative expression levels of tumor necrosis factor-α(TNF-α),transforming growth factor-β1(TGF-β1),and interleukin-1β(IL-1β)were significantly reduced in the experimental group(P＜0.05),while the relative expression level of tight junction protein 1(ZO-1)was significantly upregulated in the group S6(P＜0.05).Intestinal microbiota analysis revealed that Scenedesmus meal substitution of fish meal increased the relative abundance of beneficial bacteria such as Bacillus(P＜0.05),and reduced the abundance of pathogenic bacteria such as Vibrio,with group S6 showing the most pronounced improvement.The study indicates that the feasibility of partially replacing fish meal with Scenedesmus meal and supplementing crystalline amino acids in the farming of Litopenaeus vannamei,with a recommended replacement level not exceeding 6％.