136 Increased pre-weaning metabolizable energy supply affects the expression of genes related to adipogenesis and lipid metabolism in the skeletal muscle of prepubertal Holstein heifers.

摘要

It is unknown how dairy heifer skeletal muscle responds to increased pre-weaning ME intake. Therefore, the objective was to determine how elevated ME provision during the pre-weaning period affects the expression of the skeletal muscle transcriptome. Holstein heifers consumed either 5.9 (elevated, , n = 4) or 2.8 ± 0.2 Mcal ME (control, n = 6) per day in milk replacer (28% CP, 15% fat). Heifers were harvested at d 54 and muscle was snap-frozen in liquid N and stored at -80°C until analysis with Affymetrix Bovine Gene 1.1 ST arrays to profile transcriptome expression. A moderated t-test using a Bayesian model was used to generate the gene data set. Ingenuity Pathway Analysis software analyzed the fold change ( ; ELE/control) in expression of 18,811 genes, of which 577 met the threshold ( < 0.01) for analysis. These results reflect myocyte and intramuscular adipocyte contributions to the transcriptome expression. Decreased or increased activity was declared using a z-score ≤ -2 or ≥ 2, respectively, and trends were discussed when -2 < z < 0 or 0 < z < 2. was identified as the top affected ( < 0.001, 22 molecules) upstream regulator within the transcriptome. Based on FC of gene expression, triacylglycerol concentration was predicted to increase (z = 2.043, < 0.001, 26 molecules affected) while the quantity of lipid peroxide may decrease (z = -1.982, = 0.003) for ELE calves. As a result, lipid metabolism was the most affected ( ≤ 0.017, 96 molecules) cellular function, while the adipogenic pathway was determined to be the third top affected ( = 0.010, 118 molecules) canonical pathway. Gene results suggest that consumption of increased ME during the pre-weaning period affected adipogenesis and increased triacylglycerol storage while simultaneously reducing lipid peroxidation within skeletal muscle.