摘要A 10-week feeding trial,followed by 24-h nitrite stress,was performed to evaluate the effects of dietary selenium-L-methionine(Se-Met)on growth,Se accumulation,antioxidant capacity,transcripts of sele-noproteins and histological changes of muscle as well as resistance to nitrite stress in spotted seabass(Lateolabrax maculatus)reared at optimal(27 ℃)and high(33 ℃)temperatures.Five experimental diets were formulated to contain Se-Met at 0,0.9,1.8,3.5,and 7.0 mg/kg.Each diet was fed to fish(2.60±0.2 g)in two parallel treatments at 27 or 33 ℃.The results showed that elevated temperature(33 ℃)induced thermal stress in fish,and fish under thermal stress exhibited lower weight gain and hepatosomatic index but a higher condition factor compared to those reared at 27 ℃.However,the growth and feed utilisation were promoted in L.maculatus with 0.9 to 3.5 mg/kg Se-Met treatments.The protein and lipid content in the muscle increased with the dietary Se-Met level,and the total Se level in the whole body and muscle showed a linear increase with dietary Se-Met supplementation.Thermal stress changed the histology of the muscle,leading to raised levels of malondialdehyde(MDA),reduced antioxidant pa-rameters in the serum and liver,and a decrease in the transcripts of selenoprotein genes in the muscle.Meanwhile,increased antioxidant capacity of serum and liver and up-regulated transcripts of seleno-protein of muscle were observed in L.maculatus reaching a maximum with 3.5 mg Se-Met/kg treatment.After 24 h of nitrite stress,thermal stress exacerbated oxidative damage caused by nitrite stress in L.maculatus.In contrast,dietary Se-Met enhanced the resistance to nitrite stress of L.maculatus fed with Se-Met enriched diets containing 0.9 to 1.8 mg Se-Met/kg.Based on the effects of dietary Se-Met on the growth,antioxidant capacity and resistance to nitrite stress of L.maculatus,this study suggests that the optimal range of Se-Met supplementation in L.maculatus diets is 1.80 to 2.39 mg Se-Met/kg of diet at 27 ℃ and 1.80 to 4.46 mg Se-Met/kg of diet at 33 ℃.