Previous Lactation Risk Factors Associated with Hyperketonemia in the First Week Postpartum in Dairy Cows: A Retrospective Analysis

Hyperketonemia (HYK) is a common disorder in high-producing dairy cows, resulting in significant economic losses. Defined by elevated beta-hydroxybutyrate (BHB; ≥1.2 mmol/L) without clinical signs, HYK is often considered a gateway disease, predisposing cows to other metabolic and infectious problems. Our objective was to investigate the association between previous lactation risk factors and both BHB concentration and HYK status during the first week postpartum in the subsequent lactation. A retrospective study was conducted using previously collected blood samples from 2336 Holstein multiparous dairy cows from 7 dairy herds, where BHB concentration was measured during the first week postpartum. Data from the previous lactation were extracted from electronic farm records. Log-transformed BHB concentrations and HYK status were each modeled using separate linear mixed models. Both models included the same set of risk factors—lactation, previous lactation total times bred, dry length period, previous lactation days in milk, previous lactation days open, previous lactation days carried calf, previous lactation peak milk production, previous lactation total milk production, previous lactation total milk fat, and previous lactation total milk protein—to investigate their association with these outcomes. Potential confounding variables were offered to the models, and stepwise backward elimination was used to determine which covariates to retain. Significant associations were detected between BHB concentration and dry period length (DDRY), lactation number (LACT), previous lactation total milk protein (TOTP), and previous lactation days open (PDOPN). Inclusive, significant associations were detected between HYK status and previous lactation total milk production (PTOTM), DDRY, LACT, TOTP, and PDOPN. Our results suggest that a dry period longer than 60 days, days open exceeding 130 days, being in their third or greater lactation, and each additional 1000 kg of milk produced in the previous lactation are associated with an increased risk of having high BHB and HYK in the first week postpartum in the subsequent lactation.