Project description:Steer mesenteric fat transcriptome. Evaluation of the naturally occurring transcriptome variation in mesenteric fat among beef steers with divergent gain and feed intake phenotypes.
Project description:Steer small intestine transcriptome Evaluation of the naturally occurring transcriptome variation among beef steers with divergent gain and feed intake phenotypes.
Project description:Steer liver transcriptome Evaluation of the naturally occurring transcriptome variation in liver among beef steers with divergent gain and feed intake phenotypes.
Project description:Steer spleen transcriptome Evaluation of the naturally occurring transcriptome variation in the spleen among beef steers with divergent gain and feed intake phenotypes.
Project description:Differential gene expression in the duodenum, jejunum, and ileum among crossbred beef steers with divergent gain and feed intake phenotypes.
Project description:The biological mechanisms associated with the residual feed intake in ruminants have been harnessed immensely via transcriptome analysis of liver and ruminal epithelium, however, this concept has not been fully explored using whole blood. We applied whole blood transcriptome analysis and gene set enrichment analysis to identify key pathways associated with divergent selection for low or high RFI in beef cattle. A group of 56 crossbred beef steers (average BW = 261.3 ± 18.5 kg) were adapted to a high-forage total mixed ration in a confinement dry lot equipped with GrowSafe intake nodes for period of 49 d to determine their residual feed intake (RFI). After RFI determination, weekly whole blood samples were collected three times from beef steers with the lowest RFI (most efficient; low-RFI; n = 8) and highest RFI (least efficient; high-RFI; n = 8). Prior to RNA extraction, whole blood samples collected were composited for each steer. Sequencing was performed on an Illumina NextSeq2000 equipped with a P3 flow. Gene set enrichment analysis (GSEA) was used to analyze differentially expressed gene sets and pathways between the two groups of steers. Results of GSEA revealed pathways associated with metabolism of proteins, cellular responses to external stimuli, stress, and heat stress were differentially inhibited (false discovery rate (FDR) < 0.05) in high-RFI compared to low-RFI beef cattle, while pathways associated with binding and uptake of ligands by scavenger receptors, scavenging of heme from plasma, and erythrocytes release/take up oxygen were differentially enriched (FDR < 0.05) in high-RFI, relative to low-RFI beef cattle. Taken together, our results revealed that beef steers divergently selected for low or high RFI revealed differential expressions of genes related to protein metabolism and stress responsiveness.
Project description:The aim of this study was to measure the effect of contrasting breed and dietary source on the skeletal muscle miRNA profile of beef cattle divergent for feed efficiency (RFI). Charolais (n=90) and Holstein-Fresian (N=77) steers) were offered two consecutive diets; namely a zero-grazed grass diet followed by a high concentrate diet. Dietary intakes were recorded for all steers throughout each dietary phase and residual feed intake values dertermined for each steer. At the end of each dietary phase the most efficient (Low-RFI; n=8) and least efficient (High-RFI; n=8) steers were selected across each breed for longissmus dorsi biopsy collection. RNA was isolated from all muscle tissue samples and subsequently used for small RNA sequencing. Ten miRNA were differentially expressed between the steers divergent for RFI across each diet and breed contrast. Biological pathway analyssi revealed enrichment of pathways related to both metabolic and growth processes.
