Expression of cytokine genes and receptors in white blood cells associated with divergent body weight gain in beef steers

Previous work examining the transcriptome of steer tissue samples from animals with divergent gain have shown a relationship with the expression of genes with functions in immune and inflammatory pathways. The process of mounting an immune or inflammatory response is energetically expensive and variation in cytokine responses may affect cattle production traits. In addition, a previous study has identified variation in the transcript abundance of numerous genes, including the cytokine gene IL6ST, in the circulating white blood cells of pigs associated with high and low residual feed intake (RFI) lines. The aim of this study was to determine whether changes in cytokine expression in the circulating white blood cells (WBC) could also be associated with body weight gain in beef steers. Crossbred steers (n =12) with average feed intake (10.9 kg/d), but divergent body weight gain (Low =1.92 kg/d; High =2.25 kg/d), were selected for the study. The genes CCR3, IL9R, PF4, NAMPT and TNF were associated with gain (P≤0.05); and CSF1, IL2RG, IL6ST, CCL3, and TNFSF13B displayed a trend towards association with gain (P \u3c 0.1). The expression of cytokine genes in circulating WBCs may be useful indicators of production traits in cattle