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.