Effects of two types of chicken meal substitutes for fish meal on growth performance, antioxidant capacity, blood parameters, growth gene expression, and intestinal microbiota in Pacific white shrimp (Litopenaeus vannamei)

This study aimed to evaluate the impact of substituting fish meal with two commercial chicken meal products (CM1 and CM2) on the growth performance, antioxidant capacity, immune response, hematological parameters, growth-related gene expression, and intestinal microbiota composition in Litopenaeus vannamei. Juvenile shrimp (0.9 ± 0.05 g) were randomly assigned to five dietary treatments: T0 (20% fish meal), F1 (10% CM1), F2 (15% CM1), M1 (10% CM2), and M2 (15% CM2). After a 43-day feeding trial, shrimp in the F2 and M2 groups exhibited significantly lower final body weight (FBW) and hepatosomatic index (HSI), along with a significantly higher feed conversion ratio (FCR), compared to the control group. The substitution of fish meal with chicken meal significantly altered antioxidant enzyme activities, immune enzyme activities, and hematological parameters. Moreover, the expression of growth-related genes (GH, IGF-I, and IGF-II) was significantly upregulated in the F1 and M1 groups, while being downregulated in the M2 group. Proteobacteria, Bacteroidota, and Actinobacteria were identified as the dominant phyla in the shrimp gut. Although microbial richness and diversity remained relatively unchanged, community composition varied significantly among groups. Notably, Bacteroidota showed higher abundance in F1, F2, M1, and M2, while Actinobacteria was less abundant in F1, F2, and M2. Both CM1 and CM2 diets enhanced the ecological stability of the intestinal microbial network. Based on the evaluation of growth and health parameters, a 50% replacement of fish meal with either CM1 or CM2 is recommended for optimal shrimp performance.