Multi-dimensional evaluation of application effects of cottonseed protein as a feed protein source in Litopenaeus vannamei

An eight-week feeding trial was conducted to evaluate the effects of cottonseed proteins A and B, prepared by different processing methods and substituted for soybean meal at 20 %, 40 %, and 60 %, on the growth performance, immune function, and intestinal health of Litopenaeus vannamei. Cottonseed protein A significantly improved weight gain rate, survival rate, and specific growth rate, and showed higher crude protein digestibility and digestive enzyme activity than protein B (P < 0.05). Cottonseed protein type (factor T) significantly affected weight gain rate, feed conversion ratio, and final body weight (P < 0.05). Both protein types enhanced PO, ALP, and ACP activities in serum and hepatopancreas (P < 0.05) but decreased GPX activity. At low substitution levels, cottonseed protein A significantly upregulated antioxidant-, autophagy-, and immune-related genes (P < 0.05). Histological analysis revealed that protein A caused no notable hepatopancreatic alterations, whereas 60 % substitution with protein B induced hepatocyte vacuolation and intestinal villus shedding. Intestinal microbiota analysis showed that the abundance of Photobacterium increased with substitution level in the protein A groups. In summary, cottonseed protein can partially replace fish meal and soybean meal in shrimp diets, with cottonseed protein A demonstrating superior effects on growth, immunity, and intestinal health. A substitution level not exceeding 40 % is recommended.