Risk factors associated with postpartum subclinical hypocalcemia in dairy cows

Abstract

Our study objectives were to evaluate the association of prepartum plasma Mg concentrations with subclinical hypocalcemia (SCH) classification at parturition and to evaluate the association of other cow-level risk factors with SCH classification at calving or at 2 d in milk (DIM). A total of 301 animals from 2 dairy herds located in New York were enrolled in a cohort study. Blood samples were collected at approximately 1 wk before the expected calving date, within 4 h of calving, and at 2 DIM. Prepartum samples had plasma macromineral concentrations (Ca, K, Mg, P), albumin, and β-hydroxybutyrate analyzed. Samples collected at calving were analyzed for Ca only, and samples from 2 DIM had macromineral and albumin concentrations determined. Postpartum SCH was defined as Ca concentrations ≤2.1 mmol/L. The prevalence of SCH at calving was 2, 40, and 66% for first, second, and third or greater parities, respectively. Only 4% of cows could be classified with prepartum subclinical hypomagnesemia (Mg concentrations <0.8 mmol/L), which did not provide enough power to appropriately determine the association of plasma Mg with postpartum Ca concentrations and its effect on SCH classification. Multiparous cows with Ca concentrations ≤2.4 mmol/L in the prepartum period and third or greater parity cows had a higher risk of being categorized as SCH at calving [relative risk (RR) = 1.4 and 1.7, respectively]. The risk of SCH at 2 DIM was associated with the interaction of Ca status at calving and lameness score. Nonlame cows with Ca concentrations ≤2.1 mmol/L (RR = 3.2) and normocalcemic lame cows at parturition (RR = 3.4) were more likely to be SCH at 2 DIM compared with nonlame normocalcemic cows. In conclusion, we identified a prepartum Ca cut-point for identification of cows that are more likely to be classified as SCH at calving. Different risk factors were associated with SCH depending on the timing of diagnosis relative to parturition.

Epidemiology of subclinical hypocalcemia in early-lactation Holstein dairy cows: The temporal associations of plasma calcium concentration in the first 4 days in milk with disease and milk production

“…At 3 DIM, BCS following a 5-point scale with quarter-point increments (Ferguson et al, 1994) and locomotion score (LS) following a 5-point scale (Sprecher et al, 1997) were performed by the first author. Description of the herds and rations fed in the prepartum and postpartum periods can be found in Neves et al (2017).…”

“…To date, there is no consensus in the literature as to how (i.e., what cut point to use) and when to classify SCH in relation to parturition, as blood Ca testing is more likely to be applied by dairy producers and consultants if a specific time point relative to parturition can be better identified; this is further complicated by the fact that the appropriate cut point or DIM of blood Ca assessment could differ based on the outcome measured. In an earlier study, our group was able to demonstrate that the risk factors associated with a suboptimal Ca concentration state in the early postpartum period are different depending on the time of blood Ca assessment (i.e., within 4 h of parturition and at 2 DIM; Neves et al, 2017). This sug-gests that timing of blood sample collection relative to parturition for blood Ca assessment may be an important factor to take into account when determining the association between SCH and downstream outcomes.…”

Proteomics and metabolomics characterizing the pathophysiology of adaptive reactions to the metabolic challenges during the transition from late pregnancy to early lactation in dairy cows

“…Hypocalcaemia impacts health, future milk production, and reproductive performance and has been demonstrated to be linked with compromised immune function; cows with lower blood Ca concentrations within the first day after calving were more likely to have retained placenta and resulting metritis, and mastitis [50]. In addition, hypocalcaemia is also associated with metabolic diseases such as left displaced abomasum, ketosis and fatty liver [51,52].…”

Associations of subclinical hypocalcemia with fertility in a herd of grazing dairy cows

“…Some found negative associations with indicators of reproductive performance (Martinez et al, 2012(Martinez et al, , 2016Caixeta et al, 2017), whereas others reported no association (Chamberlin et al, 2013;Gild et al, 2015;Rodríguez et al, 2017). These discrepancies could partly be the result of differences in the study design (i.e., timing of diagnosis and cut-point used; Neves et al, 2017). No consensus exists as to when and how to objectively assess SCH, and this lack of standardization of SCH classification may affect our ability to establish associations between SCH and fertility (Neves et al, 2018).…”