Abstract #M88

# M88
Relationships between test-day fatty acid concentrations and early lactation survival.
Isaac W. Haagen*1, Chad D. Dechow1, 1The Pennsylvania State University, University Park, PA.

The purpose of this study was to quantify early lactation test-day fatty acid concentrations and their associations with survival during the first 90 DIM. Test-day fatty acid concentrations (g / 100 g milk) were available from 2,059 Holsteins located on 19 Pennsylvania herds during the spring of 2014. Concentrations of test-day BHB and acetone were also available and were natural log-transformed. Each cow was restricted to the earliest test-day fatty acid observation available during the first 90 DIM. Test-day yields and reasons for leaving herd were obtained from Dairy Records Management Systems. Cows were recorded as left herd if culled for involuntary reasons or died on farm within 90 DIM. Cows were stratified into quartiles based on concentrations for each fatty acid category, log BHB, and log acetone. Logistic regression models were used to test the effect of fatty acid, log acetone, or log BHB concentration quartiles on the odds of leaving the herd within 90 DIM. The model included lactation group (1, ≥ 2), test day yield, and either a single fatty acid, log BHB, or log acetone. The mean concentrations were 3.84, 1.57, 1.39, 0.31, 1.21, and 2.29 for total fat, long-chain fatty acid (LCFA), medium-chain fatty acid (MCFA), short-chain fatty acid (SCFA), unsaturated fatty acid (UFA), and saturated fatty acid (SFA), respectively. Means for log acetone and log BHB were 0.07 and 0.04, respectively. When evaluating odds ratios between trait quartiles, cows with intermediate concentrations had lower odds (P < 0.05) of leaving the herd within 90 DIM than cows in the top quartile for total fat, LCFA, MCFA, SCFA, UFA, SFA, and acetone. For BHB, cows in the lowest quartile had reduced odds of leaving the herd compared with cows in the highest quartile. The measure most strongly related to survival was SCFA, with an odds ratio of 0.26:1 for the third to the fourth quartile. These results suggest that cows with intermediate concentrations of fatty acids had greater odds of survival than cows with higher concentrations of fatty acids, and cows with smaller concentrations of BHB were favored over large concentrations.

Key Words: fatty acid, culling