A simple, inexpensive, and rapid method for measuring calcium concentrations in colostrum to predict postpartum milk fever in cows using a commercially available water quality test device

To diagnose milk fever (MF) in dairy cows under clinical practice, measurement of ionized calcium concentrations in blood using point-of-care (POC) devices is required. However, blood sampling poses a significant financial burden on farmers and increases the workload of veterinarians who must visit farms to perform the examinations. The present study aimed to evaluate whether the onset of MF could be predicted using colostrum samples, which can be collected by farmers themselves. Total calcium (tCa) concentrations in colostrum were measured using a commercially available water quality test device. The results showed that cows treated for MF had significantly higher tCa concentrations in colostrum (2,141.1 ± 623.7 mg/L) compared to cows without MF (1,546.3 ± 494.4 mg/L) (P=0.006). Receiver operating characteristic (ROC) curve analysis suggested that measuring tCa concentration in colostrum could be used to predict the onset of MF. When the cut-off value was set at >2,000 mg/L, the sensitivity and specificity were 66.7% and 88.9%, respectively. Results from these findings, measuring tCa concentration in colostrum using a water quality test device offers a simple, inexpensive, and rapid method for predicting the onset of MF in dairy cows.