Effects of Replacing Fishmeal with Soybean Meal on Growth Performance, Liver Antioxidant Capacity and Intestinal Health Juvenile Asian Red-Tailed Catfish (Hemibagrus Wyckioides)

Abstract

The present study was to evaluate the effects of different levels of soybean meal (SBM) substitute for fish meal (FM) on the growth performance, antioxidant capacities, and intestine health of Asian red-tailed catfish, Hemibagrus wyckioides. Five isonitrogenous and isolipidic diets were prepared: the FM diets contained 50% fish meal, based on which four SBM diets was formulated as substitutes for 15%, 30%, 45% and 60% FM in the FM diets, namely SBM15, SBM30, SBM45, and SBM60. The results of the broken-line regression analysis for WGR indicate that the optimal SBM substitution level for H. wyckioides is estimated to be 36.83%. Compared to the FM group, significantly elevated serum GPT levels and liver oxidative stress injury, accompanied by a decrease in triglycerides (TG), and total cholesterol (TC), were observed in the SBM45 and SBM60 groups (P < 0.05). Besides, hepatic antioxidant enzyme activities and nrf2 gene expression levels were markedly upregulated in the SBM45 and SBM60 groups (P < 0.05). The intestinal mucosa of the SBM45 and SBM60 groups exhibited epithelial vacuolization and villous damage, accompanied by a significant downregulation of intestinal tight junction proteins and an upregulation of intestinal pro-inflammatory factors (P < 0.05). The SBM45 and SBM60 diets contributed to significant alterations in the intestinal microbiota. In the SBM60 group, the relative abundances of Cetobacterium and Lawsonia significantly increased, and the intestinal microbiota function was predicted to undergo upregulation of complex carbohydrate metabolism and fermentation. In conclusion, replacing 36.83% of FM with SBM can meet the growth performance requirements of H. wyckioides, while 45% and 60% SBM replacement levels adversely affect the health of liver and intestines.

Keywords: Hemibagrus wyckioides, Growth performance, Soybean meal, Fish meal alternative, Intestine.