Effects of different types of non-starch polysaccharides on growth, digestive enzyme activity, intestinal barrier function and antioxidant activity of rainbow trout (Oncorhynchus mykiss)

A 10-week feeding trial was conducted to assess the effects of different types of non-starch polysaccharides (NSPs) on growth performance, intestinal barrier function and antioxidant activity of rainbow trout (Oncorhynchus mykiss). Four experimental diets were formulated without or with supplemental 8% insoluble NSPs (iNSP), 16.8% soluble NSPs (sNSP), and 24.8% NSP (8% iNSP + 16.8% sNSP) at the expense of wheat starch, respectively. Dietary inclusion with 16.8% sNSP or 24.8% NSP significantly decreased daily growth coefficient and protein efficiency ratio, but increased feed conversion rate. Similarly, dietary inclusion with 16.8% sNSP decreased the gastrointestinal pepsin and trypsin activities, but increased the plasma urea nitrogen, endothelin-1 and lipopolysaccharide contents, and diamine oxidase, aspartate aminotransferase and alanine aminotransferase activities, the serum total cholesterol and LDL-C levels and LDL-C/HDL-C ratio. Additionally, dietary inclusion with 16.8% sNSP decreased the plasma and hepatic superoxide dismutase, glutathione peroxidase and catalase activities, but increased malondialdehyde level. However, dietary inclusion with 8% iNSP or 24.8% NSP did not exhibit the above-mentioned effects on intestinal and hepatic health. These results indicated that dietary sNSP rather than iNSP present in plant ingredients depressed the growth performance and damaged the intestinal and hepatic health of rainbow trout.