High dosages of pectin and cellulose cause different degrees of damage to the livers and intestines of Pelteobagrus fulvidraco

Abstract

Non-starch polysaccharides (NSPs) are important anti-nutritional factors in plant by-product sources, and the adverse impact of high doses of NSPs on fish physiology has not received sufficient attention. A feeding trial was conducted to investigate the physiological effects of high dietary pectin and cellulose, two NSPs with different water solubilities, on the yellow catfish, Pelteobagrus fulvidraco. A diet with 300 g kg−1 dextrin was used as the control (CON diet). In test diets, dextrin was replaced with 300 g kg−1 pectin (PEC diet), cellulose (CEL diet), or a mixture of pectin and cellulose (1:1, MPC diet). Each diet was randomly assigned to triplicate groups of juvenile yellow catfish (5.80 ± 0.20 g). Fish were fed twice daily to apparent satiation for 8 weeks. The growth performance, apparent digestibility coefficients, hepatosomatic index, serum concentration of triglycerides, total cholesterol, total protein, albumin, seroglobulin and the activities of alkaline phosphatase and cholinesterase were significantly decreased in fish fed the PEC diet compared with those in fish fed the CON diet (P < .05). The liver showed obvious adipose degeneration and fibrosis, and the fold height and width of the hindgut significantly decreased (P < .05). Fish fed the MPC diet had a similar but weak response, and fish fed the CEL diet had the weakest response. However, the concentration of total bile acid in the serum of fish fed the MPC diet was 74.5 times higher than that of fish fed the CON diet, while total bile acid in the serum of fish fed the PEC and CEL diets was 4.9 and 1.2 times higher, respectively, than in fish fed the CON diet. The green liver symptom occurred in 11.67% and 10.0% of fish fed the CEL and MPC diets, respectively, while the liver was pale in fish fed the PEC diet. These results indicated that high doses of pectin and cellulose caused different degrees of damage and dysfunction to the livers and intestines of yellow catfish.