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Differential expression of genes in the jejunum of steers with extreme feed efficiency phenotypes
The small intestine is an important site of digestion and absorption of nutrients in cattle, and has the potential to significantly impact feed efficiency. We hypothesized that the differences in feed efficiency phenotypes of beef cattle can be partially explained by the differences in gene expression in the small intestine. The objective of this study was to determine whether cattle feed intake or growth phenotypes are related to the transcript abundance of genes expressed in the jejunum. Individual DM intake (DMI) and BW gain were measured on 248 steers for 84 d. BW gain was regressed on DMI and steers were assigned to 4 Cartesian quadrants. The four most extreme steers from each quadrant were identified and selected for jejunum sampling and analysis. RNA was extracted from the jejunum samples and the RNA samples were quantified and analyzed for integrity. The difference in RNA transcript abundance between the groups was measured using the Affymetrix GeneAtlas Microarray System with the Bovine Gene 1.1 ST Array Strips. The data were analyzed using the Affymetrix Transcriptome Analysis Console. Genes differentially expressed in steers with high intake/high gain phenotypes were in networks involved with lipid metabolism and small molecule biochemistry (CYSTM1, CRYAB, EDIL3). Genes with expression unique to animals with low intake/high gain phenotypes were related to proteolysis and hydrolase functions (USP18, MMP14, LYZ). Genes uniquely expressed in low intake/low gain animals were related to stress responses (HSPH1, HSPA6, DNAJB1), and genes differentially expressed in high intake/low gain animals were involved in cell-mediated immune response (IL1RN, CCL8). These results suggest that the differential expression of genes in the jejunum of steers may affect feed efficiency. USDA is an equal opportunity provider and employer.
Keywords:
beef cattle, feed efficiency, microarray