RNA-seq analysis of differential gene expression in rumen papillae from Holstein Friesian bulls undergoing diet restriction and compensatory growth

The objective of this study was to examine the effect of dietary restriction and subsequent re-alimentation induced compensatory growth on the global gene expression profile of ruminal epithelial papillae. Holstein Friesian bulls (n=38) were assigned to one of two groups: restricted feed allowance (RES; n=19) for 125 days (Period 1) followed by ad libitum access to feed for 55 days (Period 2) or (ii) ad libitum access to feed throughout (ADLIB; n=19). All bulls received the same diet of 70% concentrate 30% grass silage through out the experimental trial,with the amount of feed provided different dependent on each treatment group. At the end of Period 1, 9 animals from each treatment group were slaughtered, with 10 animals from each treatment slaughtered at the end of Period 2. Rumen epithelium was collected from all animals within thirty minutes of slaughter. RNA was extracted and rumen epithelium gene expression was examined using RNAseq technology on all samles collected (end of Period 1: 9 samples each from ADLIB and RES groups; end of Period 2: 10 samples each from ADLIB and RES groups). Genes identified as differentially expressed in response to both dietary restriction and subsequent compensatory growth included those involved in processes such as cellular interactions and transport, protein folding and gene expression, as well as immune response. This information can be exploited in genomic breeding programmes to assist selection of cattle with a greater ability to compensate following a period dietary restriction. Overall design: 38 rumen epithelium RNA samples were analyzed in total. Purebred Holstein Friesian bulls were assigned to one of two feeding treatments (i) restricted feed allowance for 125 days (n=9) followed by ad libitum access to feed for a further 55 days (n=10) or (ii) a control group with ad libitum access to feed through out the 180 days trial (n=19). The first 125 days of the trial were denoted as Period 1, during which treatment groups were fed differentially. The subsequent 55 days, denoted as Period 2 during which all bulls were fed ad libitum. All bulls received the same diet of 70% concentrate 30% grass silage through out the experimental trial, with the amount of feed provided different dependent on each treatment group. Restricted fed animals were fed to grow at 0.6 kg /day during Period 1, with ad libitum animals expected to gain in excess of 1.5 to 2 kg/day.

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Keogh K, Kenny DA, Waters SM