Animal Health 1: Transition Cow

摘要

Monitoring of behavioral variables has been used to assess individualhealth and estrus presentation in dairy cows. The objective was to evaluatepopulation dynamics of behavioral variables during postpartum todetermine cut-off values associated with the subsequent occurrence ofhealth events up to 21 DIM. Cows (n = 1,350) in an organic certifiedherd in CO, were affixed with CowManager tags (AABV, the Netherlands)for monitoring of rumination, eating, and active times (min/d).Health events were retrieved from on-farm software (PCDart, Raleigh,NC). Cows were categorized as healthy (HT) or diagnosed with at leastone health event (DZ) within 21 DIM. Explanatory variables includedbehavioral variables summarized in 20 min intervals at 0, 1, and 2 DIM.Logistic regression and ROC curves analysis were used to calculate cutoffvalues maximizing sensitivity (Se, %) and specificity (Sp, %). Calvingseason, parity, and dystocia were included in the models as controllingvariables when P < 0.1. Overall, 17.2% of the cows were in the DZ category.Increments of the behavioral variables were associated with lowerodds of disease presentation. For each 20 min/d increment in ruminationat 0, 1, 2 DIM the odds of DZ decreased by 0.95 (95% CI: 0.92–0.98),0.92 (0.9–0.95), and 0.90 (0.87–0.92), respectively. For each 20 min/dincrement in eating time at 0, 1, 2 DIM the odds of DZ decreased by0.89 (0.86–0.92), 0.85 (0.82–0.89), and 0.84 (0.8–0.88), respectively.For active time, the odds of DZ decreased by 0.96 (0.93–0.99), 0.94(0.91–0.96), 0.95 (0.92–0.98), respectively. Eating time at 1 DIM hadthe greatest area under curve (AUC = 0.69), followed by eating (AUC= 0.68) and rumination time (AU = 0.64) at 2 DIM. The cut-off valuesthat optimized Se and Sp at these points were 233.5 (Se = 65; Sp = 61),285.9 (Se = 63.2; Sp = 61.3), and 438 (Se = 61.3; Sp = 52) min/d, respectively.AUC for active time was < 0.6 and Se and Sp < 50%. This studysuggests that rumination time and eating time have discriminative valueat early lactation for cows at risk of health disorders and these assessmentpoints could be used for developing targeted prophylaxis after calving.