Project description:8 animals of high feed efficiency and 8 animals of low feed efficiency, selected by the measure of residual intake and body weight gain at the end of a feeding trial, had their liver samples collected by biopsy and sequenced in a Illumina HiSeq2500 plataform
Project description:We functionally analyzed the rumen epithelial transcriptomes from low- and high- feed efficient beef steers to identify differences that might contribute to variation in feed efficiency.
Project description:The transcriptome of 189 samples across four tissues from 48 beef steers with varied feed efficiency were generated using Illumina HiSeq4000
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.
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 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.
Project description:BackgroundReference genomes are essential in the analysis of genomic data. As the cost of sequencing decreases, multiple reference genomes are being produced within species to alleviate problems such as low mapping accuracy and reference allele bias in variant calling that can be associated with the alignment of divergent samples to a single reference individual. The latest reference sequence adopted by the scientific community for the analysis of cattle data is ARS_UCD1.2, built from the DNA of a Hereford cow (Bos taurus taurus-B. taurus). A complementary genome assembly, UOA_Brahman_1, was recently built to represent the other cattle subspecies (Bos taurus indicus-B. indicus) from a Brahman cow haplotype to further support analysis of B. indicus data. In this study, we aligned the sequence data of 15 B. taurus and B. indicus breeds to each of these references.ResultsThe alignment of B. taurus individuals against UOA_Brahman_1 detected up to five million more single-nucleotide variants (SNVs) compared to that against ARS_UCD1.2. Similarly, the alignment of B. indicus individuals against ARS_UCD1.2 resulted in one and a half million more SNVs than that against UOA_Brahman_1. The number of SNVs with nearly fixed alternative alleles also increased in the alignments with cross-subspecies. Interestingly, the alignment of B. taurus cattle against UOA_Brahman_1 revealed regions with a smaller than expected number of counts of SNVs with nearly fixed alternative alleles. Since B. taurus introgression represents on average 10% of the genome of Brahman cattle, we suggest that these regions comprise taurine DNA as opposed to indicine DNA in the UOA_Brahman_1 reference genome. Principal component and admixture analyses using genotypes inferred from this region support these taurine-introgressed loci. Overall, the flagged taurine segments represent 13.7% of the UOA_Brahman_1 assembly. The genes located within these segments were previously reported to be under positive selection in Brahman cattle, and include functional candidate genes implicated in feed efficiency, development and immunity.ConclusionsWe report a list of taurine segments that are in the UOA_Brahman_1 assembly, which will be useful for the interpretation of interesting genomic features (e.g., signatures of selection, runs of homozygosity, increased mutation rate, etc.) that could appear in future re-sequencing analysis of indicine cattle.