Transcriptomics and Metabolomics Signatures of Fat Deposition Following Orchiectomy in Yak

Fat deposition plays an important role in yak metabolism, reproduction, and meat quality, and male yaks are often castrated to facilitate management and improve production performance. The effect of castration on the characteristics of fat deposition in male yaks and the molecular mechanisms of action was explored in this study. The subcutaneous fat thickness in castrated and common male yaks was measured, further the content of fatty acids in yak subcutaneous fat was detected using gas chromatography-mass spectrometer (GC-MS); the transcriptome, metabolome in the yak subcutaneous fat were detected using mRNA-Sequencing, ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), respectively; the integrative analyses of differentially expressed genes (DEGs), different metabolites (DMs), fatty acids and fat thickness were carried out. The results showed that castration can strengthen the ability of fat deposition and improve the content of fatty acids, especially PUFAs, in male yaks, and both transcriptome and metabolome were significantly different between castrated male yaks and common male yaks. The effect of castration on the male yak fat deposition was closely related to the PPAR signaling pathway, citrate cycle, and insulin resistance. Data suggests that FASN, ACACA, AGPAT2, ACLY, ACSL5, SCD, GSK3B, and SLC2A4 may be the crucial control genes for the fat amount in yaks, and that FADS2, LPL, and ACSL4 may be the crucial control genes for the polyunsaturated fatty acids (PUFAs) content in yak adipose tissue. Further functional studies will be conducted to determine the specific role of each gene in regulating fat deposition and fatty acid composition in yaks.