Effects of dietary lipid levels on lipid accumulation and health status of adult Onychostoma macrolepis

The effects of different dietary lipid levels on lipid accumulation,inflammatory response,serum bio-chemical index and histological features of intestine and hepatopancreas of O.macrolepis was experimentally evaluated in an eight-weeks study.Fish(initial weight 50.11±2.86 g)were fed with five iso-nitrogenous diets(around 390 g/kg protein)varying with lipid level(5%,7%,9%,11%,13%,being LL5,LL7,LL9,LL11,and LL13 respectively)in triplicates.Results showed that the content of crude lipid in carcass and hepatopancreas were not affected by dietary lipid levels(P>0.05).Serum ALT,TP,HDL-c and MDA,etc.,were not significantly affected by diets(P>0.05),while serum total antioxidant capacity in LL9 and LL11 groups were significantly higher than the other groups(P<0.05).Histological features of hepatopancreas and intestine showed no significant difference among the five diets(P>0.05),while the height of intestine villus showed the higher trend in LL9 compared with other groups.The relative expression of lipid metabolism related genes(pparα,cpt-1α,fas,and hsl)and immune response related genes(tlr 22,nrf 2,tnfα,and il-γ)in the hepatopancreas of fish fed diets differing in their crude lipid levels were not significantly different(P>0.05).The results suggested that a proper dietary lipid level of 9%-11%could maintain higher antioxidant and health status of adult O.macrolepis.