Effects of dietary replacement of fishmeal by cottonseed meal on the growth performance, immune and antioxidant responses, and muscle quality of juvenile crayfish Procambarus clarkii

The current research was aimed to determine the impacts of cottonseed meal substitution levels for fishmeal on the growth performance, immune indices, antioxidant ability, and muscle texture of red swamp crayfish (Procambarus clarkii). Five isonitrogenous and isolipidic diets were formulated to feed the crayfish for 8 weeks. The basal diet contained 20% fishmeal (FM), while the other four experimental diets substituted fishmeal in FM diet with cottonseed meal at levels of 25%, 50%, 75%, and 100%, referred to as CM25, CM50, CM75, and CM100 respectively. A total of 750 crayfish with an average initial weight of 4.00 g were selected and randomly allocated to fifteen cages. Each diet was randomly assigned to triplicate groups of crayfish. Weight gain and specific growth rate declined, and feed conversion rate, asparate aminotransferase and alanine transaminase activities appear to increase as cottonseed meal substitution levels increased. Serum total cholesterol levels declined in crayfish fed CM100 diet compared to crayfish fed the FM diet. Serum phenoloxidase and lysozyme activities, and muscle hardness and mef-2a mRNA expression were the highest for crayfish fed fishmeal-based diet and showed no significant difference among other four groups. Dietary cottonseed meal levels did not significantly influence hepatopancreas index, viscerosomatic index, condition factor, serum glucose, triglyceride, albumin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and creatinine contents, as well as the contents of acid phosphatase, and alkaline phosphatase, and muscle texture profile (cohesiveness, springiness, adhesiveness, and chewiness) and mef-2b and mstn mRNA expression. High dietary fish meal replacement by cottonseed meal tended to upregulate mRNA expression of nuclear factor erythroid 2-related factor 2, glutathione peroxidase, glutathione reductase, manganese superoxide dismutase, glutathione S-transferase, and catalase. Taken together, dietary cottonseed meal reduced growth performance and feed utilization, induced hepatopancreas oxidative stress, and influenced some serum and muscle parameters. The gossypol content and unbalanced amino acid profile are considered the limiting factor influencing the fish meal replacement by cottonseed meal.