Effect of Gender and Residual Feed Intake Phenotype on the Transcriptome of Liver and Skeletal Muscle Tissue in Purebred Simmental Beef Cattle

Abstract

Background: The selection of cattle with enhanced feed efficiency is of paramount importance with regard to reducing feed costs in the beef industry. However the role, if any, of gender to the underlying molecular control of feed efficiency in cattle is not currently known. Global transcriptome profiling was undertaken on liver and skeletal muscle biopsies from Simmental heifers and bulls divergent in residual feed intake (RFI) feed efficiency phenotype, in order to identify differentially expressed genes that may be associated with this trait. Results: We identified 5 genes (p<0.001; false discovery rate (FDR) <0.1) to be differentially expressed in skeletal muscle between high and low RFI heifers with all 5 transcripts being up-regulated in the low RFI phenotype. Among these differentially expressed genes, all transcripts were involved in oxidative phosphorylation and mitochondrial homeostasis. A total of 11 genes (p<0.001;FDR <0.1) were differentially expressed in hepatic tissue between high and low RFI bulls with 8 transcripts being up-regulated and 3 being down-regulated in the low RFI phenotype. These differentially expressed genes were related to oxidative response, protein mediation and cell signalling. No genes were identified as differentially expressed in both heifer liver and bull muscle analyses. Conclusions: Results from this study show a clear effect of gender to the underlying molecular control of RFI in cattle, which may be attributable to differences in the physiological age between heifers and bulls. Despite this we have highlighted a number of genes that may hold potential as molecular biomarkers for RFI cattle.