Partial replacements of fishmeal by autoclaved shrimp processing by-product modulates the growth, digestive enzymes, immune-antioxidant, and economic performances for Nile tilapia (Oreochromis niloticus) juveniles

In the current investigation, the fishmeal (FM) protein was substituted by shrimp processing by-product (SPB) protein in feeds for Nile tilapia (Oreochromis niloticus) juveniles. Six isonitrogenous and isocaloric feeds were designed to substitute the FM protein with graded levels of SPB protein, i.e., 0% (SPB0), 10% (SPB10), 20% (SPB20), 30% (SPB30), 40% (SPB40) and 50% (SPB50). Nile tilapia juveniles (13—15 g) were allocated into 18 100-L aquaria (15 fish per aquarium) and administered the evaluated feed three times daily until evident satiety for 90 days. It was detected that Nile tilapia given SPB diets exhibited enhanced (P > 0.05) growth indices, especially at SPB40, compared to the control (SPB0). Related to the FM-based diet (SPB0), serum glucose and cortisol did not show substantial (P > 0.05) changes; while, activities of alanine and aspartate aminotransferases were markedly (P > 0.05) declined at SPB40 and SPB50 with no alterations between them. In comparison to the control diet (SPB0), SPB40-fed fish exhibited highest values of total protein, immune, and antioxidant biomarkers. The simple economic assessment suggested that incorporating 40% SPB instead of FM protein in O. niloticus diets represents the optimal choice, where it could reduce the feeding cost by 5.27% for ton fish gain. Interestingly, it is recommended to substitute 40% of FM protein with SPB in feeds for Nile tilapia, O. niloticus.