摘要Background The objective of this study was to evaluate the effects of dietary fatty acids(FA)saturation and lysophos-pholipids supplementation on growth,meat quality,oxidative stability,FA profiles,and lipid metabolism of finishing beef bulls.Thirty-two Angus bulls(initial body weight:623±22.6 kg;21±0.5 months of age)were used.The experiment was a completely randomized block design with a 2×2 factorial arrangement of treatments:2 diets with FA of differ-ent degree of unsaturation[high saturated FA diet(HSFA)vs.high unsaturated FA diet(HUFA)]combined with(0.075％,dry matter basis)and without lysophospholipids supplementation.The bulls were fed a high-concentrate diet(forage to concentrate,15∶85)for 104 d including a 14-d adaptation period and a 90-d data and sample collection period.Results No interactions were observed between dietary FA and lysophospholipids supplementation for growth and meat quality parameters.A greater dietary ratio of unsaturated FA(UFA)to saturated FA(SFA)from 1∶2 to 1∶1 led to lower DM intake and backfat thickness,but did not affect growth performance and other carcass traits.Compared with HSFA,bulls fed HUFA had greater shear force in Longissimus thoracis(LT)muscle,but had lower intramuscular fat(IMF)content and SOD content in LT muscle.Compared with HUFA,feeding the HSFA diet up-regulated expression of ACC,FAS,PPARγ,and SCD1,but down-regulated expression ofCPT1B.Compared with feeding HSFA,the HUFA diet led to greater concentrations of c9-C18∶1 and other monounsaturated FA in LT muscle.Feeding HUFA also led to lower plasma concentrations of cholesterol,but there were no interactions between FA and lysophospholipids detected.Feeding lysophospholipids improved growth and feed conversion ratio and altered meat quality by increasing muscle pH24h,redness values(24 h),IMF content,and con-centrations of C1 8∶3,C20∶5 and total polyunsaturated fatty acids.Furthermore,lysophospholipids supplementation led to lower malondialdehyde content and up-regulated the expression of ACC,FAS,and LPL in LT muscle.Conclusions Results indicated that supplementing a high-concentrate diet with lysophospholipids to beef bulls can enhance growth rate,feed efficiency,meat quality,and beneficial FA.Increasing the dietary ratio of UFA to SFA reduced DM intake and backfat thickness without compromising growth,suggesting potential improvements in feed efficiency.