Effect Of Energy Levels On Fat Metabolism In Altay Lamb

In order to meet people's demand for healthy and high-quality mutton,the aim of this experiment was to investigate the effects of different energy levels on serum lipid index,fat deposition distribution,fat cell size,and mRNA expression of fat metabolism-related genes in Altay lamb,and further use iTRAQ proteomics technology to screen proteins and pathways,which related to fat metabolism to provide data reference for the regulation of fat metabolism.Thirty Altay female lambs were selected base on similar age?3 to 3.5 months?,similar weight?19.16±0.54kg?,consistent hip shape,and good health,all lambs were randomly divided into3 groups with 10 sheep in each group,which were fed at the Maintain metabolism energy of50%(0.25 MJ/W^0.75×d^-1)?50%metabolic energy group?,100%(0.5 MJ/W^0.75×d^-1)?100%metabolic energy group?,and 150%(0.75 MJ/W^0.75×d^-1)?150%metabolic energy group?for 30 days,respectively.The results are showed as below.?1?The energy level had a significant effect on the serum lipid index and fat deposition in all parts of Altay sheep.In the different energy levels,the contents of serum glucose,free fatty acids and low density lipoprotein in the 50%metabolized energy group were significantly decreased?P<0.05?,while the contents of serum high density lipoprotein were significantly increased?P<0.05?.?2?The energy level had a significant effect on fat deposition and fat cell size in all parts of Altay sheep.The ratio of tail fat,kidney fat,epiploon fat and total fat to carcass weight of Altay sheep in the 50%metabolic energy group was significantly lower than that in100%metabolized energy group and 150%metabolized energy group?P<0.05?.The ratio of fat around the pericardial and subcutaneous fat to carcass weight differences between the three groups were not significant?P>0.05?;and the diameter,circumference,and area of fat cells in the 150%metabolized energy group were significantly greater than that of 100%metabolized energy group and 50%metabolized energy group?P<0.05?,but the number of cells was significantly lower than other two groups?P<0.05?.?3?There were significant differences on the expression of PPAR?,ACC,LPL and LEPR mRNAs in all groups of Altay sheep.Among tail fat,subcutaneous fat and epiploon fat,the mRNA expression of PPAR?,ACC and LPL genes in 50%metabolic energy group was significantly lower than that in 150%metabolic energy group?P<0.05?;The mRNA expression of LEPR gene in 50%metabolizable energy group was significantly higher than that in 150%metabolizable energy group in tail fat,subcutaneous fat and greater epiploon fat?P<0.05?.PPAR?,ACC and LPL showed site specificity,and the expression of each gene in the longest dorsal muscle was significantly lower than that in the adipose tissue?P<0.05?.?4?A tolal of 1866 differential proteins were screened by iTRAQ proteomics analysis.Among the GO annotation results,there were 205 protein related to the peroxisome,and 130protein were related to the metabolic process.In the KEGG annotation results,there were 151protein related to the fat metabolism,and 104 protein were related to the energy metabolism.In the differential protein analysis,there were 380 differential proteins in the 50%metabolized energy group compared to 150%metabolized energy group.Subsequently,there were several differential proteins related to fat metabolism were selected by GO and KEGG enrichment analysis for interaction analysis,and EHHADH,ACOX3 and ACAA1 were participated in the three pathways of PPAR signal,fatty acid metabolism and peroxisome,while,SCP2 was involved in PPAR signaling and peroxisome pathway,and ECI2 was involved in fatty acid metabolism and peroxisome pathway.In the fatty acid metabolism pathway,HADHA,HADH,ACAA2,HADHB and ACADS proteins interact more with other proteins.In the peroxisome pathway,HSD17?4 and HACL1 proteins interact more with other proteins.In the PPAR signaling pathway,SCP2 proteins interact more with other protein.The results indicate that energy levels have significant effects on serum lipid indicators,fat deposition in various parts,and fat metabolism-related genes at the transcription level and protein pathways in Altay lamb,providing data support for the regulation of fat deposition by energy level and provide molecular basis for the study of biological function and genetic evolution of fat metabolication-related genes in Altay lamb.