Cows, sunburn, hand grenades and zinc

Have you ever had sunburnt nipples? If so, spare a thought for cows that need to be milked twice a day who succumb to the oddly-named “facial eczema”. This condition leaves the skin incredibly sensitive to light, to the point where whole sheets can burn and peel off.

We normally don’t get it in this part of the country but it’s been a problem for the Kiwis for decades and we’re lucky to be able to learn from our trans-Tasman dairying friends because it appeared in our part of Australia last summer and we are desperate to avoid it this year.

Dozens of our poor girls suffered burns to the white sections of their skin. It was hideous and we felt devastated. The only treatment is sunscreen, rest, shade and anti-inflammatories.  We also gave the cows extra drench to make sure their systems were as robust as possible.

The good news is that the New Zealand experience shows that we can help to prevent facial eczema. The key is to understand the cause: spores that look like hand grenades under a microscope.

Yesterday, the local pub was packed with dairyfarmers as we heard from a Dairy Australia project team that includes legendary dairy vets, Jacob Malmo and Jack Winterbottom, DA’s feed guru Steve Little,  and nutritionist, Andrew Debenham. In a nutshell, this is what they had to say:

Grass + humidity = fungus that generates spores

Cows eat grass and spores → spores release a potent mycotoxin called sporidesmin into the gut

Mycotoxin damages liver → liver cannot deal with chlorophyll properly → skin tissue sensitive to sun → sunburn

While the sunburn is the most obvious sign of facial eczema, the other symptoms can include diarrhoea, bloody urine, jaundice, a drop in milk production and even liver failure.

The Kiwis have found that zinc binds up the mycotoxin, inhibiting its ability to release free radicals and cause damage. We have to be quite careful with it though because too little is ineffective and too much zinc is very toxic indeed. It seems the best way to provide it to the cows is mixed into the feed, which we’ve been doing on our farm now for a month. The other downside is that it’s only known to be safe to feed for 100 days – not long enough to get through the summer/autumn danger period. After that, we will need to take regular blood samples and make sure zinc levels aren’t getting too high. I’ve arranged for the vet to come next week  to be sure our cows are getting just the right amount.

To learn more about facial eczema and how farmers are working to prevent it, check out this Dairy Australia fact sheet and booklet. It’s a must for anyone with cattle.

4 thoughts on “Cows, sunburn, hand grenades and zinc

  1. In all the years I have farmed we have only ever had one cow where the skin dried and peeled off its shoulders and udder and that was in one of the hottest and driest summers we had in UK. We had never seen it before or since, the vet was at a loss to know how to treat it. The cow was kept out of the sun, but it seemed it had got to follow its coarse, she did recover but lost a lot of condition and the loss of yield.


  2. I just learnt something new – I’d never heard of this condition before although I learnt from the Horse Whisperer that the reason they have black angus (the best beef cattle imo) in Montana is because they have black udders and therefore don’t get sunburnt from the sun reflecting off the snow.


  3. Pingback: Farm meets laboratory | The Milk Maid Marian

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