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Association between haptoglobin concentrations and disease incidence, milk production, and reproductive performance at the cow and herd level.

A. L. Kerwin

Abstract:

M27
Association between haptoglobin concentrations and disease incidence, milk production, and reproductive performance at the cow and herd level.
A. L. Kerwin*1, D. V. Nydam2, W. S. Burhans3, S. K. Wall4, K. M. Schoenberg4, K. L. Perfield4, T. R. Overton1. 1Department of Animal Science, Cornell University Ithaca, NY, 2Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University Ithaca, NY, 3Dairy-Tech Group South Albany, VT, 4Elanco US Inc Greenfield, IN.

The objectives of this prospective observational study were to: 1) evaluate the association between elevated haptoglobin (HP) on 305 d mature equivalent milk at 120 DIM (ME305), conception within 150 DIM and conception at first service and 2) identify the HP herd-alarm level that is associated with herd-level changes in disease incidence (DI; displaced abomasum or ketosis), ME305, 21-d pregnancy rate (PR) and conception rate (CR) at first service. Plasma samples were collected from 868 cows, 0 to 12 DIM, across 72 herds, and were analyzed for HP (University of Guelph Animal Health Laboratory). Haptoglobin was dichotomized based on thresholds associated with increased DI (range: 0.55 to 1.52 g/L). Mixed effects models were used for the ME305 and herd-alarm level outcomes (PROC MIXED, SAS 9.4). Conception within 150 DIM was analyzed by a Cox proportional hazards model (PROC PHREG). Conception at first service was analyzed with a mixed effects Poisson regression (PROC GENMOD). The herd-alarm level with the smallest proportion of cows with elevated HP and the lowest HP threshold that resulted in the lowest P-value and largest change in the outcome of interest was kept in the final model. The initial proportion evaluated was 30% and it was lowered by 5% increments. Cows with HP ≥ 0.55 g/L produced 898 kg less ME305 (P < 0.01) and had a 25% (hazard ratio = 0.75; P < 0.01) decreased risk of conception by 150 DIM. Cows with HP ≥ 1.52 g/L were 0.60 times as likely to conceive at first service (risk ratio = 0.60; P = 0.01). The herd-alarm level associated with DI was defined as ≥ 20% of cows having HP ≥ 0.55 g/L, resulting in a 5.8% increase in DI (P = 0.01). The herd-alarm level associated with PR was defined as ≥ 10% of cows having HP ≥ 1.52 g/L, resulting in a 2.5% decrease in 21-d PR (P = 0.09). The herd-alarm level associated with CR at first service was defined as ≥ 20% of cows having HP ≥ 1.52 g/L, resulting in a 6.4% decrease in CR at first service (P = 0.09). There was not a herd-alarm level associated with ME305. These results indicate that HP can be used as a herd health-monitoring tool at the cow and herd-level.

Keywords: inflammation, haptoglobin, transition cow.