Nutritional physiological effects of soybean meal substituting for fish meal in the feed of obscure puffer (Takifugu fasciatus) and its relationship with soybean antigenic proteins

To study the effects of soybean antigenic proteins on growth, physiology and biochemistry in obscure puffer (Takifugu fasciatus), the fish with initial weight (39.84±3.09) g were randomly allocated to 8 groups, fed with 8 isonitrogenous and isoenergetic diets which were the practical diets containing high level fish meal (FMH), low level fish meal (FML), fermented soybean meal partially replacing fish meal in FML(FMLF), soybean meal partially replacing fish meal in FML (FMLS) and the semi-purified diets with different levels (0%, 5%, 8% and 12.5%) of soybean antigenic proteins respectively (AP0, AP5, AP8 and AP12.5) for two months. The results showed that the growth performance of FMLF were significantly higher than that of FML, while that in FMLS was not significantly different with FML. The growth of purified diets was increased, followed by decreasing tendency with the level of soybean antigenic protein. The nutritional composition of the muscle was affected by practical feed and semi-purified feed with varying degrees The malondialdehyde (MDA) and total antioxidant capacity (T-AOC) in liver and MDA in serum of soybean meal replacing group were significantly higher than those of FML, but the fermented soybean meal replacing group had no significant difference with the FML . The soybean antigenic proteins level of 8% of purified diets had the peak value in antioxidant capacity that were significantly higher than all the other groups. The glutamic oxaloacetic transaminase (AST) of FMLS in serum was significantly higher than the FML and AST of the FMLF had no significant difference with the FML, while the AST and glutamic-pyruvic transaminase (ALT) of purified diets were fluctuated with the level of soybean antigenic protein. Above results indicated that fish meal partially substituted by fermented soybean meal could promote the growth of obscure puffer compared to soybean meal partially replacing fish meal. Soybean antigenic protein was an important factor affecting the effects of fish meal replacement with soybean meal. The influence of soybean antigenic protein on growth, oxidation resistance and biochemical indexes varied with its content, existence state, alone or in combination with other anti-nutritional factors in diet.