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In animal meat production,subcutaneous and visceral fat are unpopular constituents with consumers and are considered unhealthy.To investigate the effect of β-carotene(βC)on fat deposition,120 Simmental crossbred steers were assigned to four groups that received various βC supplementation for 90 days,after which 10 animals from each group were selected randomly for slaughter.Intramuscular fat content and back fat thickness were evaluated;βC content,vitamin A(VA)content,and the expression of ten genes involved in fat,α-carotene,and VA metabolism were analysed in both subcutaneous fat and omental fat tissues.Supplemental βC reduced back fat thickness but not intramuscular fat content;βC levels in subcutaneous fat were significantly higher than those in omental fat,but VA content remained unchanged in both adipose tissues.The two carotenoid oxidative cleavage genes,β-carotene-15,15-monooxygenase(BCMO1)and β-arotene-9,10-dioxygenase(BCO2)were up-regulated and three VA metabolic genes,RXRα,retinal reductases(RalR),and lecithin-retinol acyltransferase(LART),were down-regulated in subcutaneous fat and omental fat tissues.Genes involved in adipocyte differentiation and lipogenesis,including PPARy,acetyl-CoA carboxylase(ACC),and fatty acid synthase(FAS)were down-regulated,and the adipolysis related genes hormone-sensitive lipase(HSL)and adipose triglyceride lipase(ATGL)were up-regulated in subcutaneous fat tissue.In omental fat tissues,PPARy,FAS,HSL,and ATGL expression was down-regulated and ACC expression was up-regulated.Taken together,these data indicate that βC may repress subcutaneous fat deposition in its intact form when the animal bodies do not lack VA and effects differently on adipose tissues in different anatomical locations.