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.

The amount of herds experiencing the problem is quite staggering.

Has it something to do with the weather?

Is it due to the quality of the silage being fed?

Were animals carrying too much condition at drying off? Was this taken into consideration when calculating (or not calculating) how much feed to give to these animals over the dry period?

In 2004, an average case of milk fever in Ireland was calculated by Ryan & O’Grady at the UCD Veterinary School to cost the farmer €312.

Given inflation and increased prices, just imagine what that cost has risen to in 2021.

The cost to the farmer includes the reduction in milk yield.

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. Quite staggering!

Other things taken into the equation include values given to the time the farmer puts in to a case, and the veterinary fees involved.

Where we see cows in a herd with milk fever, we know that there are so many more in the herd with what is called sub-clinical milk fever.

These are animals that have a lower level of calcium in their blood, but not low enough to show clinical signs.

Research has shown that anything from 30% to 50% of cows suffer from sub-clinical milk fever.

These animals appear quite normal, but it is found that the motility of their rumen is reduced, and their food intake is much lower.

Because of this, their milk production is also going to be reduced.

These are “silent” losses that mostly go unnoticed, but nonetheless, they all add up to less income in the pocket at the end of the day.

Following a calving, the womb naturally contracts, bringing it back into a nice, neat shape, so that the cow is ready to go in calf again.

With milk fever and sub-clinical milk fever, the womb is much slower to contract, with the result that we see more retained afterbirths in these cases.

We also see more cases of womb infections, and less activity in the ovary, with significant delays to the first ovulation.

All of this, as research tells us, leads to a longer calving to conception interval. This is yet another cost.

Yet more research tells us that the immune system is badly affected by the reduction in blood calcium levels.

This brings more cases of disease, with the figures showing that milk fever cows are eight times more likely to experience mastitis than cows that do not have milk fever.

Personally, this year alone, I can testify to that being the case.

What can you do to prevent milk fever?

There are a lot of options given, like actually reducing the amount of dietary calcium in the lead up to calving, feeding extra magnesium, balancing the positive and negative mineral ions in the diet, giving Vitamin D in the run-up to calving, and others say to give calcium supplementation at the time of calving and shortly after.

All of them can genuinely give good results, but before you jump to any conclusions, you need to body condition score your stock at drying off and at calving.

You need to have all your feeding analysed in the autumn, and have your diet formulated properly.

Monitoring the blood calcium levels of those that are about to calve should also be carried out, especially to find out the level of sub-clinical milk fever in your herd.

In the long run, maybe this is a way to get more milk from your herd.

Paul Redmond, MVB, MRCVS, Cert DHH, works at Duntahane Veterinary Clinic, Fermoy.