Effects of dietary fiber sources on growth, plasma biochemical indexes, intestinal antioxidant capacity and histology of largemouth bass (Micropterus salmoides)

In order to compare and evaluate the differences in nutritional and physiological functions of fiber sources in fish feed, we observed the effects of dietary fiber sources on the growth, plasma biochemical, intestinal antioxidant capacity and histology of M. salmoides. Fish initial weight of (21.59±0.12) g were fed four isonitrogenous and isolipid experimental diets containing same fiber content soybean dregs fiber (SF), fermented soybean dregs fiber (FF), carboxymethyl cellulose (CF) and microcrystalline cellulose (MF) for 8 weeks. The results indicated that the CF group showed significantly lower final body weight (FBW), specific growth rate (SGR) and protein efficiency ratio (PER) compared with other groups, while feed conversion ratio (FCR), heparsomatic index (HSI) and liver lipid content were significantly higher than other groups. The activities of alanine amiotransferase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) and the content of triglyceride (TG) in plasma of CF group were significantly higher than other groups. At the same time, the activities of superoxide dismutase (SOD) and Na⁺, K⁺-ATPase of CF group were significantly lower than other groups, while the content of malondialdehyde (MDA) was significantly higher than other groups. The content of nitric oxide (NO) was the highest in FF group. Compared with the other groups, the liver appearance became white and liver cells were vacuolated seriously with aggravation of mechanical damage of the hindgut villi in CF group. The results showed that dietary fiber source could significantly affect the liver and intestinal health and then affect growth performance of M. salmoides, and the feasibility of carboxymethyl cellulose as pellet binder should be re-evaluated.