Effect of fish meal substitution with fermented soy pulp on growth performance, digestive enzyme, amino acid profile, and immune-related gene expression of African catfish (Clarias gariepinus)

Abstract

Fermented soy pulp (FSP) is currently capturing attention worldwide because of the high price of fish meal and its inconsistent supply in recent years. FSP replaces fish meal as a source of protein and energy towards improved fish health and growth. The protein replacement was employed in this study to assess the growth and health status, digestive enzyme, amino acid profile, and immune-related gene expression of African catfish, Clarias gariepinus. The duration of the feeding experiment was 70 days. Five isonitrogenous. (32% crude protein) diets were prepared with FSP replacing D1 (0% FSP), D2 (25% FSP), D3 (50% FSP), D4 (75% FSP) and D5 (100% FSP) to FM component of the diets. D1 diet with 0% FSP was considered as a control. The fermentation process of FSP was carried out for three weeks. This resulted in the experimental diets having significantly different (p < 0.05) growth parameters. The D3 diet showed the highest weight gain and SGR with a mean and standard deviation of 1552.41 ± 81.67% and 1.73 ± 0.03%, respectively. D3 diet had better relative protein digestibility (RPD) value of 92.33 ± 2.19 compared with fish fed with the control diet. Amylase and lipase activities were found to be significantly higher in the D3 diet. The muscle amino acid profiles (arginine, isoleucine, histidine, and leucine) and gene expression (TGF-ß1, lyzg, NF-kß, and hsp90a) were significantly highest (p < 0.05) in the D3 diet. Fresh insights have been demonstrated by the findings of the study into the production of FSP as a replacement product. These insights would efficiently enhance the generation of aquafeed, which are low in cost and healthy towards the production of African catfish and other freshwater species. In conclusion, a new theory on using FSP as a plant-based replacement material and a protein replacement for fish growth and health status booster may be achieved at 50% of FSP inclusion.