PSI-11 Anti-inflammatory treatment modifies epigenetics changes to muscle tissue caused by altered nutrient demand in early lactation dairy cows

Abstract

Abstract Short-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) has been shown to alter whole-lactation milk yield; perhaps because epigenetic modifications are responsible for long-term effects, although mechanisms are unclear. Altered nutrient demand due to fasting or exercise in other species has been shown to affect DNA methylation in muscle tissue. Our objective was to determine if NSAID treatment or alterations to nutrient demand have epigenetic effects on muscle tissue in early lactation. In this study, 33 multiparous Holstein cows were enrolled at parturition and randomly assigned to milking frequency (MF; 1× or 3×/day), and either sodium salicylate (SS; 2.3 g/L administered via drinking water) or control (CTL; molasses carrier alone) treatment in a 2×2 factorial design, beginning ~24 h postpartum. Milking frequency treatments were designed to alter nutrient demand, and 3× milked increased milk yield by 24%. After 5 days of treatment, tissue biopsies were collected from the Longissimus dorsi muscle and snap-frozen. DNA was isolated and global methylation (GM) was assessed with a 5-methylcytosine enzyme-linked immunosorbent assay. An interaction between MF and SS treatment was detected (P = 0.02), with GM of muscle tissue decreased by more frequent milking only in the CTL cows (4.9 and 1.4 ± 1.0% of DNA methylated for 1× and 3×, respectively; P < 0.001). No effect of MF was detected in SS-treated cows (2.9 and 2.4 ± 1.0% of DNA methylated for 1× and 3×, respectively; P > 0.1). Observed changes to DNA methylation in muscle tissue due to altered nutrient supply are consistent with results reported after fasting and exercise. Additionally, increased demand for milk component precursors in 3×-milked cows may alter the availability of methyl donors for DNA methylation. Our data support a link between SS and epigenetic changes, but further research is needed to determine how SS may have altered the muscle DNA methylation response to nutrient demand.