The short answer is, yes, to an extent. Dairy cattle can present hypocalcemia in a clinical (milk fever) or subclinical form. At calving, the cow’s priority is to provide substantial amounts of calcium to colostrum and milk production. The body’s response to the high calcium demand is not fast enough to maintain blood calcium concentration. Consequently, blood calcium concentration suddenly drops. Cows with subclinical hypocalcemia might take up to 3 days to restore blood calcium concentrations. However, recumbent cows with milk fever urgently need intravenous calcium administration (followed by an oral calcium bolus, or calcium under the skin).

A cow’s individual characteristics (e.g. parity, milk production), as well as farm management factors (e.g. maximize dry matter intake around parturition, hypocalcemia control strategies), affect the ability to respond to lack of calcium and the magnitude of this reduction. When using preventative strategies, e.g. pre-partum negative DCAD diet, cows experience a smaller decrease in blood calcium around calving. If the management changes are applied to all cows at risk of milk fever, it is expected that the herd average blood calcium concentration increases. Thus, both the number of milk fever cases and the proportion of cows with subclinical hypocalcemia postpartum will be reduced.

– Dr. Rita Couto Serrenho

University of Guelph, Ontario Veterinary College