Abstract #M34

# M34
Effects of anti-inflammatory treatment and milking frequency on mRNA abundance of adipose tissue from early lactation cows.
Melissa Riley*1, Miriam Garcia1, Caroline Ylioja1, Laman K. Mamedova1, Barry J. Bradford1, 1Kansas State University, Manhattan, KS.

We hypothesized that at the onset of lactation, inflammation may contribute to a temporary adaptive insulin resistance to protect against hypoglycemia and to promote fatty acid mobilization, but infrequent milking may reduce nutrient demand to the extent that this adaptation is unnecessary. In this study, 33 multiparous Holstein cows were used to evaluate whether treatment with the anti-inflammatory drug sodium salicylate (SS) alters plasma nonesterified fatty acid (NEFA) concentrations and mRNA profile of adipose tissue. Cows were randomly assigned to frequent (3×/d) or infrequent milking (1×/d, decreasing milk yield by 24%), and SS (2.3 g/L in drinking water) or control treatments in a 2 × 2 factorial design, beginning ~24 h postpartum. Blood was drawn daily before the morning feeding, and on d 5 of treatment, ~1 h after the conclusion of a hyperinsulinemic-euglycemic clamp procedure, adipose tissue biopsy was performed. Data were analyzed as repeated (NEFA) or non-repeated (mRNA abundance, reported as fold change ± SEM) measures with mixed models. Plasma NEFA concentrations were greater in SS cows (605 vs. 476 ± 34 μM, P = 0.01) but did not differ with milking frequency. Regardless of milking frequency, SS tended to reduce the abundance of INSR (−1.92 ± 0.48, P = 0.06). For cows milked 1×, SS reduced the abundance of IRS1 (−2.98 ± 1.35, P = 0.05). Abundance of TNFA tended to decrease with SS (−2.03 ± 1.69, P = 0.08) but only for cows with ≥3 parities. The effect of milking frequency on mRNA abundance depended on parity. Within parity 2, cows milked 3 × had greater abundance of the inflammatory transcripts TNFA (6.52 ± 2.41, P < 0.01) and MCP1 (4.80 ± 2.50, P = 0.02), and the antioxidant regulator NFE2L2 (2.19 ± 0.464, P = 0.05). Within cows milked 3×, second-parity cows had greater abundance of IRS1 (3.20 ± 1.44, P = 0.04) and NFKB1 (1.70 ± 0.62, P = 0.03). Results suggest that SS promotes adipose tissue insulin resistance and NEFA mobilization in early lactation, and that second-parity cows milked 3 × may have exacerbated adipose inflammation, possibly due to greater metabolic requirements during early lactation.

Key Words: inflammation, transition cow, fatty acid