Evaluation of composite mixture of protein sources in replacing fishmeal for Pacific white shrimp (Litopenaeus vannamei): Based on the changing pattern of growth performance, nutrient metabolism and health status

An 8 weeks feeding trial was designed to evaluate the alternative efficiency of composite mixture of protein sources in replacing fishmeal (FM) for Pacific white shrimp (Litopenaeus vannamei) with the initial weigh of 2.55 ± 0.002 g. Four isonitrogenous (44.0%) and isolipidic (6.7%) diets were formulated using different protein sources. Diet-1 (Control diet): used FM as the main protein sources; Diet-2: 50% FM was replaced by poultry by-product meal(PBM) and antarctic krill meal (AKM) (1:1); Diet-3: FM was totally substituted by PBM, AKM and corn gluten meal (CGM) (1:1:1); Diet-4, 100% FM was substituted by CGM, cottonseed meal and rice protein concentrate meal (1:1:1). Results showed that no statistical differences for growth performance were detected after shrimp fed with Diet-2 and Diet-3 compared with the shrimp fed with control diet. However, Diet-4 markedly decreased the growth performance, feed utilization and body composition. Moreover, compared with control diet, Diet-2 and Diet-3 also had no effect on modifying the concentration of total free essential amino acid (EAA), whereas Diet-4 significantly reduced the concentration of EAA in muscle. Further explored the underlying mechanism, present study shown that Diet-2 did not alter the activation of target of rapamycin (TOR) signaling and the gene expression profile of glucolipid metabolism and immune response. Compared with control diet, Diet-3 caused partial variation of the activity of TOR signaling, nutrient metabolism and immune response. However, whole plant proteins replacement diet (Diet-4) significant decreased the growth performance and damaged the health status through inhibiting TOR signaling and further depressing the nutrient turnover and immune response. According, present study demonstrated that composite mixture of PBM and AKM (1:1) might be an effective substitution to replace FM. Meanwhile, composite mixture of PBM, AKM and CGM (1:1:1) is an excellent alternative diet to totally replaced FM in shrimp feeds.