An examination of the transcriptional control of energetic efficiency in cattle divergent for RFI

The selection of cattle with high feed efficiency is of paramount importance with regard to reducing feed costs in the beef industry. Global gene expression patterns in metabolically important tissues can be used to identify genes that are potentially involved in regulating feed efficiency. We identified 5 genes (p<0.001;FDR <0.1) to be differentially expressed in skeletal skeletal muscle between high and low residual feed intake heifers with all 5 transcripts being upregulated in the low residual feed intake phenotype. Among these differentially expressed genes, all transcripts were related to oxidative phosphorylation and mitochondrial homeostasis. A total of 11 genes (p<0.001;FDR <0.1) were differentially expressed in hepatic tissue tissue between high and low residual feed intake bulls with 8 transcripts being upregulated and 3 being downregulated in the low residual feed intake phenotype. These differentially expressed genes were related to oxidative response, protein mediation and cell signalling. Pathway analysis on the RNAseq data indicates a relationship between oxidative phosphorylation and residual feed intake in skeletal muscle and aldosterone signalling and NRF2 mediated oxidative stress in hepatic tissue. Overall design: Residual feed intake was calculated in heifers (n= 20) and bulls (n=20) under ad libitum feeding conditions which were subsequently ranked, within gender, as high (n=5) or low (n=5) residual feed intake. RNA sequencing was performed on liver and skeletal skeletal muscle biopsies from high and low residual feed intake animals in order to identify differentially expressed genes that may be associated with this trait.

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