Why is there an explosion in milk fever cases?

Is it the weather, the quality of silage being fed or too much condition? 

Figures show that the 305-day milk yield from a cow that has suffered from milk fever can be reduced as much as 1,000 kg per cow.

For the last number of years, we had a serious amount of calls to one of our clients with milk fever, quite often involving a calving as well.

This current year, however, has seen an explosion in the number of cases throughout the countryside.