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Selenium-biofortified alfalfa hay supplementation modulates liver and macrophage gene expression in periparturient dairy cows.

S. Busato




Selenium-biofortified alfalfa hay supplementation modulates liver and macrophage gene expression in periparturient dairy cows.
S. Busato*, M. Bionaz. Oregon State University Corvallis, OR.

Heightened oxidative stress is characteristic of the transition from pregnancy to lactation in dairy cows. Supplementation of selenium (Se) can boost the antioxidant response, improving overall oxidative status of transition cows. In a prior study, we demonstrated that feeding transition dairy cows a relatively low amount (1% BW) of Se-biofortified alfalfa hay increased Se concentrations in blood and liver, increased glutathione peroxidase activity in blood and improved the liver function. Se supplementation can also improve the response to mastitis. Thus, we hypothesized that the gene expression profiles in the liver and milk-derived macrophages would be modulated by Se supplementation to reflect these effects. We collected liver biopsies from 10 periparturient Jersey cows (5 supplemented with Se-biofortified hay, 5 fed control hay, for 54 d), at −10 and +10 DIM. Milk samples were collected from the same cows at +10 DIM, and macrophages were isolated using CD14 as a marker. RNA was extracted using RNAeasy (QIAGEN), integrity was measured using a 2100 Bioanalyzer (Agilent), and samples were sequenced using a HiSeq 3500 (Illumina). We detected approx. 10,000 transcripts in both type of samples. Using an FDR of 0.30 as cut-off with JMP genomics (SAS), we detected 247 and 148 DEG (237 and 129 downregulated by Se) in the transcriptome of macrophages and liver, respectively. Bioinformatic analysis was performed using the Dynamic Impact Approach and DAVID. Se conferred changes in metabolism- and replication and repair-related pathways in the liver, including downregulation of sphingolipid metabolism in the postpartum and mismatch repair in pre-partum. In macrophages, Se supplementation inhibited overall metabolic-related pathways, especially lipid and carbohydrate metabolisms (citric acid cycle) and inhibited cell cycle and cell redox homeostasis. Taken together, our results suggest a mild but inhibitory effect of organic Se supplementation on the transcriptome of liver and milk macrophages on transition dairy cows, affecting mostly lipid and carbohydrate metabolism and cell cycle.

Keywords: selenium, peripartum, dairy cow.

Biography: Sebastiano Busato is a doctoral student at Oregon State University. Under the guidance of Dr. Massimo Bionaz, his research focuses on the study of bioactive compounds with known or potential nutrigenomic effects in dairy cows, and their role in regulating gene expression.