摘要Vitamin E(VE)is an essential lipid-soluble vitamin that improves the fish flesh quality.However,the underlying molecular mechanisms remain unclear.This study aimed to investigate the effects of VE on growth performance and flesh quality in sub-adult grass carp(Ctenopharyngodon idella).A total of 450 fish(713.53±1.50 g)were randomly divided into six treatment groups(three replicates per treatment)and fed for nine weeks with different experimental diets(dietary lipid 47.8 g/kg)that contained different levels of VE(5.44,52.07,96.85,141.71,185.66,and 230.12 mg/kg diet,supplemented as dl-a-tocopherol acetate).Notably,the treatment groups that were fed with dietary VE ranging from 52.07 to 230.12 mg/kg diet showed improvement in the percent weight gain,special growth rate,and feed ef-ficiency of grass carp.Moreover,the treatment groups supplemented with dietary VE level of 141.71,185.66,and 230.12 mg/kg diet showed enhancement in crude protein,lipid,and α-tocopherol contents in the muscle,and the dietary levels of VE ranging from 52.07 to 141.71 mg/kg diet improved muscle pH24h and shear force but reduced muscle cooking loss in grass carp.Furthermore,appropriate levels of VE(52.07 to 96.85 mg/kg diet)increased the muscle polyunsaturated fatty acid content in grass carp.Di-etary VE also increased the mRNA levels of fatty acid synthesis-related genes,including fas,scd-1,fad,elovl,srebp1,pparγ,and lxrα,and up-regulated the expression of SREBP-1 protein.However,dietary VE decreased the expression of fatty acid decomposition-related genes,including hsl,cpt1,acox1,and ppara,and endoplasmic reticulum stress-related genes,including perk,ire1,atf6,eif2a,atf4,xbp1,chop,and grp78,and down-regulated the expression of p-PERK,p-IRE1,ATF6,and GRP78 proteins.In conclusion,dietary VE increased muscle fatty acid synthesis,which may be partly associated with the alleviation of endoplasmic reticulum stress,and ultimately improves fish flesh quality.Moreover,the VE requirements for sub-adult grass carp(713.53 to 1590.40 g)were estimated to be 124.9 and 122.73 mg/kg diet based on percentage weight gain and muscle shear force,respectively.