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Association between postpartum health and subsequent detection of spontaneous estrus by activity monitors in dairy cows.

T. C. Bruinjé



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Association between postpartum health and subsequent detection of spontaneous estrus by activity monitors in dairy cows.
T. C. Bruinjé*1, E. I. Morrison1, R. Couto Serrenho1, E. S. Ribeiro2, D. Renaud1, S. J. LeBlanc1. 1Department of Population Medicine, University of Guelph Guelph, ON, Canada, 2Department of Animal Biosciences, University of Guelph Guelph, ON, Canada.

Our objective was to investigate associations between postpartum health and the probability of detection of spontaneous estrus between 50 and 75 d in milk by automated activity monitors (AAM) in dairy cows. In this observational study, Holstein cows (n = 454) from 2 dairy farms in Ontario were enrolled at wk −3 relative to parturition. Body condition score (BCS) was assessed at wk −3 and 9, and lameness at wk −3, 3, and 7. Total calcium (Ca), haptoglobin (Hp), and nonesterified fatty acids (NEFA) were measured in serum at d 2 and 6 (±1; SD). At d 4, 8, 11, and 15 (±1), blood β-hydroxybutyrate (BHB) concentrations were measured and the occurrence of metritis (brown, watery, foul-smelling vaginal discharge with or without fever) assessed. Cows were examined for purulent vaginal discharge (PVD) and subclinical endometritis (≥6% polymorphonuclear cells in endometrial cytology and no PVD) at wk 5. Herds used detection of estrus by AAM with no hormonal intervention for first AI until d 75. Metabolites were categorized based on ROC curve cutpoints associated with PVD. Detection of estrus between d 50 and 75 was analyzed in a multivariable logistic regression model, including parity, health variables, interactions, and herd as a random effect. Common health disorders were hypocalcemia (Ca ≤2.1 mmol/L; 60% of cows) and high Hp (≥0.7 g/L; 37%) at d 2, high NEFA (≥0.5 mmol/L) at d 6 (47%), hyperketonemia (BHB ≥1.3 mmol/L) at any sample (25%), subclinical endometritis (24%), PVD (19%), and metritis (14%). Overall, 61% of cows were detected in estrus between d 50 and 75. The odds of estrus detection were reduced in cows with vs. without PVD (46 vs. 66%; P < 0.01), in cows with high Hp at both d 2 and 6 vs. at least one sample with low Hp (43 vs. 64%; P = 0.01), or in cows with BCS ≤2.75 vs. ≥ 3.00 at wk 9 (50 vs. 62%; P = 0.05). In the 32% of cows without these risk factors, 72% were detected in estrus vs. 56% in cows with all 3 risk factors (P < 0.01). Identifying variables associated with reduced odds of estrus detection by AAM will allow refinement of reproductive management decisions.

Keywords: activity monitoring, reproduction, postpartum health.

Biography: I was born and raised in Curitiba, Brazil, where I obtained my veterinary degree in 2014. I obtained my MSc in 2017 at the University of Alberta, Canada, where I investigated an in-line milk progesterone analysis sensor to monitor reproductive function and fertility in dairy cows. Since 2019, I am pursuing my PhD in Epidemiology at the University of Guelph, studying postpartum health, estrus expression, and reproductive physiology in dairy cows managed using precision technologies. My goal is to develop approaches for reproductive management that involve health monitoring and optimization of precision technologies, improving farm management, animal welfare, and sustainability.