Facial eczema: Fake vs real news

By Claire Ashton.

Folklore and fake news abounds when it comes to facial eczema.

Facial eczema (FE) was first identified in 1897, but it wasn’t until 70 years later that the experts pinned the cause to a fungus. Facial eczema is a disease of the liver caused by a mycotoxin (sporidesmin) that affects all ruminants exposed to the fungus (Pithomyces chartarum).

At a recent SMASH field day, Emma Cuttance from Epivets said wide-ranging folklore and fake news abounds when it comes to facial eczema, and when to spore count, with some farfetched and downright superstitious theories.

“Just an amazing amount of bullshit has come out about FE, and that has made it harder for farmers.”

She cites a few examples taken from surveys of farmers of completely incorrect myths – or in modern terminology – fake news.

It’s rained so now there are not going to be any spores as the rain washes the spores away.
I put a jacket on today and there aren’t going to be any spores because it’s too cold.
I don’t need to spore count because I watch the mushrooms, and when they grow, I know I have facial eczema.
When the cows with FE die after the calf is born, it is because the cow was living off the calf’s liver, and once it is birthed the cow dies.
You don’t need to spore count because the white butterflies will tell me when I have facial eczema.

Another myth is around lime.

Some years back some students tested paddocks after applying lime and the spore count was low afterwards – but they never tested the paddocks beforehand. Emma conducted a research project that dispelled the myth that lime lowers spore count. It doesn’t.

Real news

Information can only have one source – your farm and what the pasture tells you. Stock can have facial eczema and not show any visible evidence we usually associate with FE; peeling skin, red udders, and irritable cows. These signs are only surface indicators.

“Everyone thinks of it as a skin disease. It is not a skin disease. “Only 5% of stock will show. This disease is all about the liver, so you won’t know if you have it. You cannot tell by looking at your cows,” Emma says. She goes on to explain that a third of farms in NZ have cows with significant liver damage. In 2014, data was taken from 105 farms across the country via blood tests, on an average year to below average year for spore counts. In 2020 they looked again – and again the statistics were the same – a third of cows showed liver damage.

“The liver is the powerhouse of the whole body, if they have a damaged liver the cow cannot get rid of built-up toxins, and ‘toxins’ is not some kind of airy-fairy word.”

The inability of the cow to process chlorophyll can cause phylloerythrin. Usually the animal processes phylloerythrin safely through the liver. Sometimes this is not possible if there is a lot of phylloerythrin or when the liver is damaged.

The main thing is that it drops milk production severely, the cows become low producers, may get dried off early and may even get culled from the herd. Lost production is a big deal of course, but also it is an animal welfare issue.

If you play the tape forward, the repercussions of a damaged liver on a cow in the herd lasts for years – 1000 stock were examined at six months of age, they had slower growth rates of up to 15kg difference up to the two-year-old, the damage is lost milk production for a couple of years even after they have recovered and been treated for FE.

“Bottom line. This disease is preventable if you treat it like a disease, fungus and how to prevent it.”

FE Likes:

temperatures of 18-24C, about 20C is perfect
Humidity
Rain (a bit)
Weather not too windy or exposed.

Prevention:

Look at pasture
Majority of fungus lives at the base
Spores can move up to two metres high
Spores are affected by water.

“The newly produced spores are the most toxic – trends in spore counts are that if they jump up from 10-50,000 in one week watch out as those spores are going to be highly toxic.”

Breeding

Emma predicts there could be pressure on zinc coming down the pipeline and says that while it hasn’t been flagged yet, with the amount of environmental and water quality issues it may come. Some work is going on in genetics around breeding FE-tolerant bulls, and genetic companies such as CRV and LIC are undertaking research. Some parts of the EU have banned zinc in feedstuffs and they are looking at waterways and aquatic life, and perhaps soil.

Prevention

Spore counting is the main prevention, but its limitations need to be understood and it is incredibly variable and reliant on micro environments.

“Your neighbour’s is not going to be the same as yours, and regional counts are unreliable so never rely on anyone else. And furthermore, paddocks are going to show variations, too, so it is recommended that four paddocks are tested and different grasses are tested.”

When farmers go ‘shopping’ for grass and pluck handfuls, what is in that handful is what is tested. Tests are only going to give accurate spore counts if they are tested onfarm with a variation of grasses, paddocks, and heights.

As soon as regional spore counts go up, it’s time to start testing. Once the management programme is started, you don’t reduce zinc until the spore counts are consistently low.

Safe feeds in pure swards have indicated that chicory, plantain, lotus, and brassicas as well as tall fescue are less prone to the fungal spores growing at the base as they sit higher above the ground.

Suppressing the toxin is a preventive, and while fungicides can be applied, they are less common, and they don’t actually get rid of the spore – they only stop the fungus growing. It is vital to spore test before applying a fungicide, and they don’t work if applied when pasture is poor.

Once the toxin is present, the chemical make-up of the spore, sporidesmin, is unstable and destabilises the rumen by creating free radicals, and it is the free radicals that cause the damage – a reaction to the toxin. Zinc binds to the sporidesmin and stabilises it and zinc is still the magic bullet for now, but it must be saturated. Copper is not helpful as it speeds up the reaction to free radicals, and while base copper from pasture is all right, elevated copper levels are not beneficial.

It appears most farmers feed zinc, but blood testing in 2013 revealed only 40% of farmers were giving enough zinc to combat the toxin issue in the rumen. Another test was run via bulk milk and 80% of farmers did not have enough zinc present.

Farmers can herd test for zinc in their bulk milk testing. If they are a Fonterra supplier, the free bulk milk zinc test may be a useful initial screening tool.

It can provide an idea as to whether the farm is achieving adequate or inadequate supplementation across the milking herd. Blood tests are more accurate.

The question has to be asked, if farmers are feeding zinc as part of a management plan, why are so many cows lacking in enough zinc to combat the problem?

One standout issue is that enough farmers don’t weigh their cattle so the dose given is incorrect. If you weigh then you can know the herd range and can cater for the greater weight. About half of farmers add zinc to the water. Not all cows like this as they can detect its taste.

During wet weather cows drink less trough water, and there is a large variability of water intake across the herd. Trough hierarchy is another issue and younger cows miss out, with evaporation being another water loss issue.

Dose rates suggested by feed companies can be inaccurate, however feed is the second most common method to get zinc into cows.

Mixing wagons are better for uptake of zinc than feed out wagons, but still some cows will get little, due to herd hierarchy and mixing. It is recommended to check the silos as the zinc can stick to the sides and not go through the feed.

Drench is the best way to get zinc into the animal, but it’s not popular any more, and needs to be done in conjunction with weighing.

Full doses should be delivered even at a low spore count to catch them on the up, and zinc needs to be delivered even in cows that are dried off. Zinc is a daily dose. It is not like copper which is stored in the liver.

“The guidelines are to not overdose. 2.5g/100kg is average, as some cows respond poorly to a high dose, 3.5g/100kg can get them up high, but only lift the dose if you can confirm they are very low,” Emma advises.

Following Regional Spore counts is essential but onfarm pasture testing will give a specific farms’ reading.

Alas, every way of delivering zinc can be partially ineffective across the herd.
There is caution against getting zinc via a multivitamin approach.
All zincs are not created equal.

And that’s the news – real and fake on FE.

An image from a postmortem showing the effects on the liver – scarred/cirrhosis vs normal

The one of the udder is the best visual of skin signs.