13/06/2026
Milk fever is quietly costing New Zealand dairy farmers hundreds of millions of dollars every season.
DairyNZ research found cows with clinical milk fever produce 14% less milk for the entire lactation, while sub-clinical milk fever costs 7% of seasonal production. With New Zealand now milking approximately 4.68 million cows averaging 414kgMS per cow, and DairyNZ reporting around 7% clinical and 33% sub-clinical hypocalcaemia, the lost milk revenue alone equates to approximately $621 million every year at a $9.80 payout.
That's before accounting for vet costs, extra labour, cow deaths, retained membranes, mastitis, ketosis, poorer fertility and increased culling risk.
This makes transition cow management and post calving supplementation one of the highest-return investments available.