Effects of fish meal replacement by three protein sources on physical pellet quality and growth performance of Pacific white shrimp (Litopenaeus vannamei)

Abstract

The study investigated the effects of replacing fish meal with cottonseed protein concentrate (CPC), Tenebrio molitor (TM) and Clostridium autoethanogenum protein (CAP) on physical pellet quality and growth, feed utilization of Pacific white shrimp (Litopenaeus vannamei). A control diet (FM) was designed to contain 200 g/kg fish meal, then, 60 g/kg CPC, TM and CAP were used to replace the same amount of fish meal, respectively, to form four diets by pelleting. After the evaluation of physical quality, the four diets were fed to shrimp with initial body weight of 7.72 ± 0.01 g for 6 weeks. The results indicated that pellet hardness and bulk density were significantly increased (P < 0.05), when fish meal was substituted by CPC, TM and CAP, but no significant differences in starch gelatinization degree and pellet durability index were detected among the four diets (P > 0.05). In addition, the dissolution loss and powder content in CPC and CAP diets were significantly decreased (P < 0.05). Compared to FM group, TM group presented significantly higher feed conversion ratio (FCR) and lower protein retention(P < 0.05), but the other two groups showed no significant differences in growth performance (P > 0.05). Hepatopancreas amylase activity in CPC and CAP groups was significantly higher than that in FM group (P < 0.05), while no significant differences in the activities of hepatopancreas protease and pyruvate kinase, aspartate aminotransferase and alanine aminotransferase were found among the four groups (P > 0.05). The hepatopancreas and intestinal histology were normal in all groups without obvious injury. In conclusion, in the pelleted feed containing 200 g/kg fish meal, the replacement of 60 g/kg fish meal with CPC and CAP improved the physical pellet quality and had no negative effects on growth performance and nutrient utilization, but the replacement of 60 g/kg fish meal with TM decreased the growth performance and nutrient utilization of Pacific white shrimp.