Facial eczema (FE) occurs when sheep, deer and cattle graze spores from the fungus Pithomyces chartarum containing the toxin sporidesmin. The toxin damages the liver leading to a secondary photosensitivity. Underlying liver damage is often subclinical leading to reduced lifetime performance and profitability.
The fungus grows on dead matter at the base of the pasture sward and takes off under favourable environmental conditions, such as high humidity, warmth, and moisture. These conditions are most commonly seen early in wet summers and autumn. When grass minimum temperatures are above 14 degrees and night-time temperatures exceed 12 degrees then spore numbers can climb extremely fast.
Animals showing symptoms of FE (photosensitivity) are usually the tip of the iceberg. For every clinical case there can be five to ten or more animals with underlying subclinical disease. Longer term effects over subsequent months and years include - poor scanning percentages, weight loss or poor weight gain in young stock, wet/dry ewes poor weaning weights and prelamb deaths in ewes. In clinical outbreaks you can have deaths in severe cases, and animals with a range of levels of photosensitivity. Affected animals are often a welfare issue and you can have trouble sending animals to the works with clinical signs and subsequent condemning of carcasses.
There is no effective treatment for facial eczema! Despite what snake oil salesman may say.
Prevention is multifactorial! Breeding for resistance, grazing management, spore counting, and preventative treatments are all important in reducing the impact of FE.
Spore monitoring – Eastland Vets FE Monitor Farms
Limiting the impact of FE on your farm is multi-factorial. A good place to start is by watching what spore counts are doing on our monitor farms. Monitoring will start in mid-January and run through to April or longer if necessary. We have five monitor farms located in:
Results will be in the Gisborne Herald on Saturdays and on our website www.evs.co.nz . Alternatively call the clinic for results. When counts begin to rise – it is time to start spore counting on your own property to establish safer areas to graze and when to start preventative treatments. Monitoring shows there can be extreme differences between neighbouring paddocks within farms and between farms. The best information is your own information.
Grazing management is crucial. Maintaining pasture quality is important as the fungus grows on dead matter at the base of the pasture rather than on green leaf. The lower your feed levels the more animals will graze in the high spore zone. Find out where your safe paddocks are by spore counting. Consider using safe feeds such as crops or new grass in your plan. Making good decisions about which stock classes to graze where or even selling stock in some instances, can reduce the longterm impact of this disease.
It is also important to understand that grazing on low spore counts of 20-30,000 over a long period can result in as much damage as short-term grazing on a paddock with a high spore count of say 70-80,000.
Fungicide spraying theoretically is a good tool but timing is really crucial and it is not fool proof - talk to one of our large animal vets before using products such as Mycotak.
Breeding is the long term goal. Being a high risk region you could expect a reasonable level of natural selection for tolerance in local bloodlines. However, seeking out FE tolerant breeders should be your longterm goal, as breeders are challenging animals with high doses of toxin to identify tolerant sires. Do your homework on FE tolerance and the 5 star grading system as not all FE tolerant breeders/rams are the same. A good place to start is ww.sil.co.nz or the FEGold website www.fegold.co.nz
Zinc supplementation. Zinc provides some protection to the liver from sporidesmin damage. Dairy and intensive farming operations have the option of using zinc sulphate either orally or by water trough treatments. Zinc oxide slurries are an option requiring repeated drenching at up to 2 weekly intervals but are time consuming and labour intensive. A more practical way to administer zinc is by using boluses such as Time Capsules. Boluses give you 6 weeks protection in sheep and 4 weeks in cattle. It is important to start supplementation early before spore counts rise too high. Be aware that with when facing extreme levels of spores that liver damage can still occur.
The answer to minimising FE is to be proactive. We will be living with this production limiting disease for years to come. Be proactive and talk to one of our vets soon about your options.
Cleo Rothschild (BVSc)