Milk fever (hypocalcaemia) occurs when dairy cows cannot mobilise calcium fast enough at calving. It causes weakness, collapse, and death if untreated, but is largely preventable through transition cow management.
Milk fever causes progressive muscle weakness culminating in inability to rise, which is frightening and physically harmful. A downer cow that cannot rise faces secondary complications including nerve damage and pressure sores from prolonged recumbency. Subclinical hypocalcaemia, affecting far more cows than clinical disease, causes immune suppression that predisposes to mastitis, metritis, and retained placenta — all painful conditions. Better transition management prevents substantial aggregate suffering across the dairy industry.