The complete replacement of fish meal with Clostridium autoethanogenum protein in practical diet did not affect the growth, but reduced the flesh quality of Pacific white shrimp, Litopenaeus vannamei

This study evaluated the effects of replacing dietary fish meal (FM) with Clostridium autoethanogenum protein (CAP) on growth and flesh quality of Pacific white shrimp, Litopenaeus vannamei. The control diet was formulated to contain 200 g/kg fishmeal, and then dietary fishmeal was decreased to 150 g/kg, 100 g/kg, 50 g/kg and 0 g/kg by CAP inclusion, respectively (FM -20, FM15, FM -10, FM -5, FM -0). In the fish meal substituted diets, coated tryptophan, arginine, histidine, phenylalanine, methionine and cholesterol were supplemented to reach the same levels as the control diet (FM -20). The five isoproteic and isolipidic diets were fed to shrimp (1.52 +/- 0.10 g) for 8 weeks. The results indicated that the weight gain (821.7% - 831.6%) and feed conversion ratio (1.45-1.47) were not significantly affected by CAP inclusion (P > 0.05). The whole shrimp and flesh composition, flesh steaming and cooking loss, total essential amino acids contents, proportion of n-6 and n-3 PUFAs, TAAs contents and flesh biochemical indexes showed no significant difference among all the groups (P > 0.05). However, when fish meal was completely replaced by CAP (FM -0), flesh hardness, chewiness, gumminess, body redness, yellowness, muscle fiber density, contents of flesh total collagen and heat insoluble collagen were decreased significantly, and the proportion of SFAs, serum glucose and triglyceride contents were increased significantly (P < 0.05). When 75% of dietary fish meal was replaced by CAP, flesh texture characteristics and body surface color parameters were not affected (P > 0.05). In conclusion, in the diet containing 200 g/kg fish meal, with the supplementation of coated amino acids and cholesterol, dietary fish meal could be totally replaced by CAP without affecting the growth performance, flesh flavor, nutritional value and water holding capacity, but the flesh texture and color of shrimp were adversely affected. Considering the growth and flesh quality, the substitution level of fish meal with CAP was suggested to be 75% (150 g/kg).