Abstract: To investigate the fat deposition mechanism of Hulun Buir sheep,twenty one Hulun Buir ewes at five months old were divided into two groups,Baerhu group(semi-ellipsoid tail,n=11) and short-tailed group(small-peach tail,n=10),and fed under the same management conditions.The carcass weight,body size and tail type indexes of two groups were measured.Adipose tissues from 8 body locations were used to analyze adipocyte morphology and triglyceride(TG) content.Moreover,the adipose metabolism related genes were detected by Real-time quantitative PCR.The result showed that two populations were significantly or extremely significantly differed in length,width and weight of tail as well as carcass weight and body length (P<0.05;P<0.01).Although the morphology of adipocytes in the same part of two populations were basically the same,the area and volume of adipocytes in the tail of Baerhu population were larger than that of short-tailed ewes (P<0.01).And TG content in adipose tissues including subcutaneous,omentum and tail tissues were significantly or extremely significantly different between two sheep groups (P<0.05;P<0.01).The mRNA levels of lipid-metabolism related genes,including ATGL,PPARγ,C/EBPα and SREBP,were higher in Baerhu population than that in short-tailed group (P<0.05; P<0.01).For the Baerhu ewes,the expression of ATGL and SREBP was negatively or positively associated with the TG content (r=-0.965,0.972),respectively.In summary,it was preliminarily revealed that it had significant differences of adipose deposition ability between two populations.The study was helpful for further exploring the molecular mechanism of fat tail formation in sheep and providing a theoretical basis.

Key words: Hulun Buir sheep; adipose tissue; adipocyte metabolism; gene expression