Preventing facial eczema in cows

Summer is just around the corner and with that comes the risk of facial eczema (FE) in cows

If you have treated cows for this disease, you will know how unpleasant it is. Unfortunately, the damage it causes to cows’ skin is just a symptom of what’s occurring internally to the animal’s liver.

Vet William Cuttance from VetEnt spore counting

Now is a good time to get a plan in place to make sure you’re prepared to mitigate the risk of FE. The disease is most prevalent from January to May when warm, moist conditions make it ideal to grow the fungus (Pithomyces chartarum), which produces the toxin in the pasture that causes FE.

With no cure, the best way to protect your herd is through prevention. There are a couple of different approaches you can take. Both include monitoring pasture spore counts and either dosing animals with zinc or spraying pastures with fungicide.

If you notice an upward trend in your own farm spore counts, that’s a clear sign you should begin using your preferred FE prevention method. Anything more than 15,000 is considered a risk, and more than 60,000 a high risk.

Aside from using zinc or fungicide, another good approach to protect your cows is to avoid grazing below four-centimetre pasture height using supplements when appropriate.

It’s important to note that FE is just like an infestation. If one cow has FE symptoms, it’s likely more are affected, even if they’re not showing signs. Some indicators to look for in your cows include restlessness, seeking shade, licking their udder, and reduced milk production.

Breeding cows that are more tolerant to FE is a long-term solution, and some farmers who have gone down this path are already reporting the benefits. This is probably our best strategy to manage this challenging disease in the long-term.

The sheep industry has been breeding for FE tolerance for the last 30 years with great success. I think it’s something for us to aim for.  Wouldn’t it be great if we could put an end to this nasty disease once and for all? Now that’s something I would love to see happen in my lifetime. 

For more information on facial eczema, how to prevent it, and treat it, visitdairynz.co.nz/facial-eczema.

Steps to prevent facial eczema

  • Monitor pasture spore count on your farm from the same four paddocks every week: When the spore counts start to rise to trend upwards to 30,000 spores/g pasture, start your management programme and continue until the spore counts are consistently low across those paddocks for at least three weeks. 
  • Zinc dosing: Weigh a representative sample of at least 20 cows from each mob to calculate the correct dose of zinc required, which can be administered as a drench, dose water, or in feed. Start your zinc dosing programme when the spore counts start to rise. After two weeks, check that your cows are receiving enough zinc by blood testing 15 cows and checking for zinc concentration. Work with your vet to tweak your management system if they are not receiving enough zinc. 
  • Pasture spraying: A fungicide will slow the development of the fungus and subsequent production of new spores. Apply only when you are sure that spore counts from multiple paddocks are below 20,000 on your farm and pasture is green and growing.
  • Pasture management: Avoid grazing below four-centimetre pasture height during summer months.

New facial eczema research

The study found there was substantial damage, even in herds attempting prevention

New research shows facial eczema (FE) may be an even bigger problem than first thought. VetEnt veterinarian and researcher Emma Cuttance led a study across eight dairy farms with cows with evidence of liver damage and found there was a lot of unseen damage that farmers didn’t know about. The farms were spread across Taranaki, Waikato, Northland, and Bay of Plenty.

Generally, it was thought that there wasn’t a lot of FE seen last season. However, the study found there was substantial damage, even in herds attempting prevention.

Emma found 41% of the cows studied were impacted by FE, despite only three percent showing symptoms. This goes to show that just because you can’t see it, doesn’t mean it’s not happening.

She also measured the impact this had on the loss of production by comparing the average amount of milk collected from healthy cows and cows with FE. She found cows with liver damage produced about eight percent less milk per day.

Another study also measured the impact of FE on young stock growth. It found 19% of the 1050 heifer replacements at 17 various locations were found to have severe liver damage. Another 21% had some liver damage. Damaged animals were 15kg lighter on average at first calving compared to their peers. This can have a long-lasting impact including lower in-calf rates, later calving and lower milk solid yields.

Farmer case study: Farmer faces FE challenge

Waikato dairy farmer Gavin Fleming and his family have battled FE on their Otorohanga farm for the past 50 years. Gavin says for as long as he can remember, FE has been a challenge on the farm his father bought 62 years ago, some years worse than others.

He puts this down to the farm’s north-facing position. North-facing areas tend to have higher spore counts than south facing. However, over the last five years, he and his son Paul have really managed to get on top of the disease.

Up until then, despite following best practice – closely monitoring pasture spore counts and regularly drenching zinc – the pair struggled to prevent the disease. Determined to get to the root of the problem, they did some research and worked with their local vets, who ran blood tests that revealed the issue. They discovered they had been under dosing zinc.

“It just goes to show it’s critical to get your levels right,” Gavin says. “We drench our milking herd daily to keep their zinc levels up.”

However, Gavin finds zinc bullets (which slowly release a consistent dose) a more practical option for their young stock. His key advice for farmers is to be vigilant about monitoring spore counts. The farm was one monitored in the FE study and found none of the cows sustained any liver damage.

Gavin says it was great to be a part of the study and get confirmation that everything they are doing is right. Like many farmers, he can’t wait to see what developments lie ahead to prevent the disease.

“I’d really love LIC to breed some FE resistant bulls. Over time, I’m sure it will happen. Until then, we’re stuck with trying to prevent it.”

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