Optimizing fishmeal replacement with tilapia hydrolysate protein: Effects on growth, metabolism, and gene expression in white shrimp

Hydrolysate fish protein derived from tilapia by-products (THP) was used to evaluate growth performance in the diet of white shrimp (Penaeus vannamei) and its impact on mTOR signaling pathway and gene expression related to metabolism when partially replacing fishmeal with THP. Four diets were formed, with THP substituting fishmeal levels at 0, 5, 10, and 20 %. The 56-day feeding experiment was conducted with 300 juvenile white shrimp (initial weight: 1.12 ± 0.02 g), divided into four groups. At the end of experiment period, there were no significant differences in survival rates between all of the experimental groups; however, those in the 10 % replacement group exhibited a significant increase (p < 0.05) in growth performance. Additionally, shrimp in the 10 % replacement group showed significant improvements (p < 0.05) in digestive enzyme activity and hemolymph biochemical parameters. In comparison to the control group, the 10 % replacement group had a considerably increased (p < 0.05) crude protein level in shrimp muscle. Furthermore, shrimp in 10 % replacement group showed modifications in structure inside the hepatopancreas and intestinal mucosa. The 10 % THP replacement group exhibited significantly upregulated expression of mTOR pathway-related genes (tor, s6k, 4ebp, and akt) as well as key genes involved in amino acid, lipid, glucose, and antioxidant metabolism, indicating enhanced nutrient assimilation, protein synthesis, and cellular metabolic activity in shrimp. Although the 5 % replacement level improved growth performance and expressed genes, the differences were not significant (p > 0.05) compared to the control group. Enhanced growth performance and positive regulation of related genes were most effectively detected at the 10 % replacement level (p < 0.05), whereas the 20 % replacement diet exhibited findings similar to the control group (p > 0.05). As a result, substituting 10 % of fishmeal with THP can boost shrimp growth rates while additionally having a beneficial effect on metabolism and mTOR pathway.