Milk fever (hypocalcemia)

Milk fever is low blood calcium at or soon after calving, when the sudden demand of colostrum and milk outruns the cow’s ability to draw calcium from bone and gut. Affected cows are weak, cold to the touch and may go down. Low blood calcium without visible signs is more widespread and is linked to retained placenta, displaced abomasum and metritis.

Prevention is done through the close-up ration: limiting potassium, lowering the dietary cation-anion difference, or restricting the calcium available before calving.

Written for the 2026 edition of the library.