摘要A six-week feeding trial was carried out to determine the feasibility of cottonseed oil(CSO)as a viable substitute for fish oil(FO)in the commercial diet of swimming crabs.Ninety healthy swimming crabs(initial body weight 34.28±0.59 g)were randomly assigned to 90 plastic baskets.Three isonitrogenous and isolipidic diets(450 g/kg protein and 120 g/kg lipid)were formulated replacing FO with CSO at 0％,50％and 100％(CSO-0,CSO-50,and CSO-100),respectively.Each diet was randomly allocated to three replicates,each consisting of 10 crabs.Results indicated that crabs fed with CSO-100 diet had the lowest the percent weight gain(PWG),specific growth rate(SGR)and survival among all treatments(P＜0.05).Albumin(ALB),glucose(GLU),triglyceride(TAG),total cholesterol(T-CHO),low-density lipoprotein cholesterol(LDL-C),non-esterified fatty acid(NEFA)contents and alkaline phosphatase(ALP),alanine amino transferase(ALT)activity in hemolymph were significantly affected by dietary substitution of FO with CSO(P＜0.05).The contents of total saturated fatty acids(SFA),total mono-unsaturated fatty acids(MUFA)and total long-chain polyunsaturated fatty acids(LC-PUFA)in the hepatopancreas and muscle were negatively correlated with the substitution level,whereas total n-6 polyunsaturated fatty acids(n-6 PUFA)and linoleic acid(18:2n-6)contents increased significantly with increasing levels of dietary substitution of FO with CSO(P＜0.05).Dietary substitution of FO with CSO resulted in changes in the composition of volatile substances in muscle,with 16 volatile substances in muscle significantly affected(P＜0.05).The relative expression of genes related to lipid synthesis such as fatty acid synthase(fas),acetyl-CoA carboxylase(acc)and glycerol-3-phosphate acyltransferase 1(gpat1)in the hepatopancreas were significantly up-regulated in the CSO-50 group compared to other treatment groups(P＜0.05).The relative expression of fatty acid anabolism-related genes fatty acyl desaturase 2(fads2)and elongase 4(elovl4)were significantly down-regulated with the increase of dietary substitution of FO with CSO(P＜0.05).In conclusion,50％substitution with CSO had no negative effects on growth performance,promoted lipid synthesis and metabolism,facilitated lipid accumulation.However,complete substitution of FO with CSO inhibited fatty acid synthesis and metabolism,resulting in a lower tissue LC-PUFA content and an altered composition of muscle volatiles.