Summer is just around the corner and with that comes the risk of facial eczema (FE).
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.
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 in 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.
You can take a couple of different approaches 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 over 15,000 is considered a risk, and over 60,000 a high risk. Aside from using zinc or fungicide, another good approach to protect your cows is to avoid grazing below 4cm pasture height using supplements when appropriate.
It's important to note, 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 more tolerant to FE is a long-term solution, and some farmers that 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.
New research shows facial eczema (FE) may be an even bigger problem than we first thought.
VetEnt veterinarian and researcher Emma Cuttance, who led the study, which involved eight dairy farms who had cows with evidence of liver damage across Taranaki, Waikato, Northland and Bay of Plenty in autumn this year, found there was a lot of unseen damage that farmers didn't know about.
Generally, it was thought not a lot of FE was seen last season. However, the study found there was substantial damage, even in herds attempting prevention.
Cuttance found 41 per cent 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 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 per cent of the 1050 heifer replacements at 17 various locations were found to have severe liver damage.
Another 21 per cent 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.
Steps to prevent FE
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 program. Do not stop your management program 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 program 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 4cm pasture height during summer months.
Chris Glassey is a farm systems specialist with DairyNZ