Association between hyperketonemia and automated body condition score at nadir in Holstein cows

The objective was to test the association between hyperketonemia (HYK) and automated BCS at nadir in Holstein cows. This retrospective observational study used data from 12,042 lactations in 7,626 Holstein cows calving between 2019 and 2022 in a commercial dairy in Colorado. Cows were tested for HYK at 6 ± 3 DIM (PortaCheck Inc.) and were considered positive when blood BHB ≥1.2 mmol/L. Scores generated after each milking by an automated BCS camera system (DeLaval, Sweden) at calving (BCSc) and at nadir (BCSn; lowest daily BCS from calving to 100 DIM) were selected. Nadir BCS were categorized into 2 groups using the median (low = 50% lowest nBCS), separately for primiparous and multiparous cows. Health events (dystocia, retained fetal membranes, metritis, pyometra, clinical hypocalcemia, left displaced abomasum, lameness, clinical mastitis, digestive problem, injury, and respiratory disease) occurring before BCSn were considered to classify the lactations as affected by one disorder, multiple disorders, or unaffected. Data were examined in primiparous and multiparous cows separately using ANOVA and logistic regression. Multivariable models considered calving season, BCSc, health status, and milk yield during the first 30 DIM as covariables. Least squares means (SE) for nBCS and ΔBCS by presentation of HYK are presented in Table 1. The adjusted odds ratios (95% CI) of being in the low nBCS category for cows with HYK compared with healthy cows were 4.16 (2.72–6.37) and 1.48 (1.27–1.73) in primiparous and multiparous cows, respectively. Presentation of HYK was associated with lower nadir BCS and greater loss of BCS from calving to nadir.