Milk Fever in Dairy Cattle: Welfare and Prevention
What Is Milk Fever?
Milk fever (parturient paresis) occurs when blood calcium falls rapidly at calving as lactation begins. It primarily affects high-yielding dairy cows, especially older cows in their third or later lactation. Subclinical hypocalcaemia (no obvious signs but low blood calcium) is far more common than clinical cases and impairs immune function, fertility, and milk production.
Welfare Consequences
Clinical milk fever causes muscle weakness, inability to rise, hypothermia, and depression. Affected cows cannot feed, drink, or escape danger, creating severe welfare compromise. Downer cow syndrome (failure to rise after treatment) is a serious sequel. Subclinical cases suffer increased susceptibility to mastitis, metritis, displaced abomasum, and ketosis.
Prevention Strategies
Dietary management in the dry period is the primary prevention tool. Feeding low-DCAD (dietary cation-anion difference) rations acidifies urine, stimulating calcium mobilisation before calving. Adequate magnesium supplementation (magnesium is needed for calcium mobilisation) is essential. Avoiding over-conditioning in late lactation reduces risk. Prophylactic oral calcium drenches at calving are effective in high-risk cows.
Treatment
Intravenous calcium borogluconate (typically 400ml of 40% solution) is the standard treatment for clinical cases. Response is usually rapid but re-lapse rates are high; subcutaneous supplementary calcium is often given. Cows that do not rise within 24 hours require intensive nursing: rolling, bedding, water, and food. Prognosis for downer cows worsens with each day down.
Farm-Level Welfare Monitoring
Recording and tracking milk fever cases allows identification of high-risk cows. Transition cow management programmes, body condition scoring, and regular blood sampling during the dry period improve prevention. Farms should have clear protocols for identifying and treating cases rapidly, minimising time spent recumbent.