Dietary supplementation of xylooligosaccharides benefits the growth performance and lipid metabolism of common carp (Cyprinus carpio) fed high-fat diets

We aimed to investigate the effect of xylooligosaccharides (XOS) on the growth performances and lipid metabolism of common carp fed high-fat diets. 192 fish were randomly distributed into 24 tanks into six groups (four replicates) and were fed with control diet, high-fat diet (HFD) and HFD supplemented with 5, 10, 20 and 30 g/kgXOS respectively for 8 weeks. Fish fed HFD supplemented with 10 g/kg XOS obtained higher final body weight, weight gain, specific growth rate and protein efficiency ratio compared to those fed control diet and HFD, while feed conversion ratio showed the opposite trend. Fish fed HFD obtained higher hepatosomatic index, abdominal fat, energy intake compared to other groups, whereas the opposite was true for nitrogen retention. High plasma levels of cholesterol, triglycerides, low-density lipoprotein and low high-density lipoprotein were observed in fish fed HFD; opposite was true for fish fed HFD supplemented with 10-20 g/kg XOS. The transcription of lipoprotein lipase was up-regulated, whereas that of carnitine palmitoyltransferase I, peroxisome proliferator-activated receptors alpha, acyl-CoA oxidase and CD36 were down-regulated in fish fed HFD. Opposite trend was observed in fish fed HFD supplemented with 10-20 g/kg XOS as well as the control group. In conclusion, XOS inclusion can benefit the growth performance and lipid metabolism of common carp fed HFD.