Effects of dietary xylooligosaccharide on growth, antioxidant capacity and intestinal proinflammatory cytokines gene expression in triploid rainbow trout Oncorhynchus mykiss
XU Zhe1,2, WANG Chang’an1*, LIU Hongbai1*, HAN Shicheng1, LU Shaoxia1, FENG Qiyuan1,3
1.Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; 2.College of Wuxi Fisheries, Nanjing Agricultural University, Nanjing 210000, China; 3.College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
Abstract: A feeding trial was conducted to demonstrate the effects of dietary xylooligosaccharide (XOS) on growth performance, antioxidant capacity and immunity of triploid rainbow trout Oncorhynchusmykiss with body mass of (20.85±0.48)g. The juvenile triploid rainbow trout was reared in a re-circulating water system and fed diets containing 0 (control group), 0.25%, 0.50%, 0.75%, and 1.00% mass fraction of XOS for 56 days. Growth performance, antioxidant capacity and intestinal proinflammatory cytokines gene expression were determined. The results showed that the fish fed the diets containing XOS had significantly high weight gain rate (WGR) and specific growth rate (SGR) (P<0.05). The activities of serum superoxide dismutase (SOD) and lysozyme (LZM) were significantly was increased with dietary XOS supplementation (P<0.05), with the maximal activities of SOD (219.60 U/mL) and LZM (14.29 U/mL) in the 1.00% group. The content of malonaldehyde significantly was decreased with dietary XOS levels (P<0.05)， and no different significance was observed in the catalase (CAT) activity (P>0.05). Dietary XOS levels significantly affected the activities of SOD, CAT and LZM in the intestine (P<0.05). The activities of SOD, CAT and LZM were increased first and then decreased with the increase in dietary XOS levels. The maximal activities of SOD (176.93 U/mg prot), CAT (9.75 U/mg prot) and LZM (37.82 U/mg port) were observed in the 0.75% XOS group, without significantly changes in the contents of MDA (P>0.05). The mRNA expression levels of the intestine proinflammatory cytokines (IL-1β, IL-2, IL-8, TNF-α and PepT1 genes) were significantly increased first and then decreased (P<0.05). The maximal mRNA expression levels of IL-1β, TNF-α and PepT1 genes were found in the 0.75% XOS group. In conclusion, the optimum dietary XOS level of 0.75%-1.00% led to enhance immunity and antioxidant capacity in serum and intestine of triploid rainbow trout.
2021, Vol. 36 
