Cows generally responded remarkably well to intravenous injections and hypocalcaemia was no longer the dreaded disease it once was.

Clinical cases are still common in over-conditioned older cows, but it is now recognised that sub-clinical hypocalcaemia is a major contributor to poor cow health and performance post-calving.

Slow calving and retained foetal membranes are the immediate consequences of sub-clinical milk fever and perhaps even more significant is the reduced feed intake and inhibited rumen function in the calving period that is caused by reduced blood calcium availability.

The cow that doesn’t eat and ruminate well around calving is prone to early lactation health issues and is less likely to perform well.

The cow’s rumen is prone to reduced activity when blood calcium levels are marginally reduced.

Every cow’s production ability is directly related to its stomach capacity and any digestive impairment around calving will leave the cow more prone to reduced performance and conditions, such as displaced abomasums and ketosis.

Good dry cow management is essential to keep calcium metabolism at optimum level in the critical transition period.

Having cows in optimum body condition score, feeding the right silage (low potassium) and keeping magnesium levels up in the pre-calving diet will help.

Blood sampling a group of cows around calving will give a good idea what is going on as regards calcium management in the herd (as well as yielding very useful information on energy and mineral status.)

Often there may be no clinical case of milk fever, but quite a few cows are hypocalcaemic.

Identifying and dealing with this hidden problem before it causes losses may be something you need to discuss with your vet.

Conor Kilcoyne owns and runs Kilcoyne Veterinary, Wolfe Tone Sq, Tubbercurry, Co Sligo, part of XLVets, a group of progressive practices working together to achieve a better future for agriculture and veterinary in Ireland. Visit www.xlvets.ie.