Magnesium and milk fever

There is clinical, experimental and theoretical evidence for a connection between the occurrence of subclinical hypomagnesaemia and the incidence of milk fever. Clinically, pregnant dry cows in dairy herds with a high incidence of milk fever have often been observed to have subnormal blood magnesium concentrations. Experimentally, it has recently been shown that subclinical hypomagnesaemia reduced the ability of cows to mobilise calcium in response to hypocalcaemia; a response which is essential if cows are to avoid milk fever. And theoretically there are several points in the biochemical pathways for calcium where a need for magnesium has been demonstrated in laboratory rodents. These connections between subclinical hypomagnesaemia and milk fever are explored and their consequences for the prevention of milk fever are considered.