An evaluation of yeast culture in diet of hybrid snakehead (Channa argus ♂ × Channa maculate ♀): Growth, serum biochemical parameters, intestinal histology and microorganisms

Abstract

Yeast culture (YC) is a yeast-fermented product of enzymolysis soybean protein with plenty of small peptide and nucleotide. This study aimed to investigate the effects of YC as a substitute for fish meal (FM) on the growth, serum biochemical parameters, intestinal histology and microorganisms of hybrid snakehead (Channa argus ♂ × C. maculate ♀). In a basal diet containing 250 g/kg FM, YC was included at the levels of 0, 40, 80, 120 g/kg to replace 0, 29.5, 59.0 and 88.5 g/kg FM to form four isonitrogenous diets (CON, YC-40, YC-80 and YC-120). The four diets were fed to hybrid snakehead with initial body weight (9.2 ± 0.1 g) for 70 days. The results showed that there were no significant differences in weight gain (WG), feed conversion ratio, protein efficiency ratio (PER), protein retention (PR) and lipid retention (LR) among the three groups of CON, YC-40 and YC-80 groups (P > 0.05). However, the WG, PER, PR and LR in YC-120 group were significantly lower than those in the CON group (P < 0.05). No significant differences in body indexes and whole fish proximate composition were detected among all the groups (P > 0.05). In serum biochemical parameters, superoxide dismutase activity and total antioxidant capacity in YC-40 and YC-80 groups were significantly increased, and total cholesterol content in YC-120 group was significantly decreased when compared to the control (P < 0.05). In foregut morphology, YC-120 group showed significantly lower muscle thickness and villus height than the control (P < 0.05), but there was no significant difference in villus width among all the groups (P > 0.05). Intestinal microbial analysis showed that the major intestinal microorganisms in all groups were Firmicutes, Spirochaetota, Proteobacteria and Actinobacteria. The relative abundance of Brevinema in YC-120 group was significantly higher than that in CON group (P < 0.05). In conclusion, in a basal diet containing 250.0 g/kg FM, 80 g/kg YC could successfully replace 59.0 g/kg FM without adverse effects on growth performance, nutrient utilization, serum biochemical indices, intestinal histology and microorganisms of juvenile hybrid snakehead.