Understand Facial Eczema
Updated: Oct 7, 2018
Does Facial Eczema affect your flock? Have your scanning percentages decreased? Do you have issues with flock survivability? Learn what FE is and how you can prevent it.
Facial Eczema (FE) is a metabolic disease caused by the fungus Pithomyces chartarum which produces a toxin called sporidesmin. This fungus requires warm humid conditions to grow vast numbers of toxic spores. Animals ingest the toxin when grazing the pasture, particularly if eating into the base leaf litter.
The primary effect of sporidesmin is liver and bile duct injury which causes sub-clinical (non-visible) and clinical (visible) effects on the animal.
Sub-clinical effects:
Decreased scanning percentages (fewer multiples & more dry ewes)
Poor lactation
Death at lambing
Slow growing lambs
Clinical effects:
Avoiding direct sunlight
Drooping ears
Reddened facial features
Shaking & rubbing of faces against posts and gates
Scabby peeling skin with potential for infections or fly-strike
“If you get, say, 5 per cent clinicals, then at least 50 per cent of the flock has sub-clinical FE. With 20 per cent clinicals, the whole flock will be affected.”
-Former Whatawhata scientist Dr Clive Dalton (from Facing Up to Facial Eczema)
FE is manageable with several options available:
Purchasing proven FE-tolerant rams to breed a tolerant flock
Dosing stock and/or pasture with zinc variants
Applying fungicides to control numbers of spores
Growing a forage crop or alternate pasture species
Shortening stock rotations so the grass sward is not lowered to the leaf litter
Of these options, selecting FE tolerant rams has the best long term effect to the flock's health and farm profitability. There is also a degree of resistance towards mycotoxins such as Lolitrem B (grass staggers) and Ergovaline (heat stress) with FE tolerant sheep.
Zinc is a heavy metal, and whilst effective when administrated at the correct time, it requires intensive stock management with possible weekly drenching. This method is very costly and can create toxic levels in the soil over prolonged periods.
Fungicides are sprayed onto pasture which can be very expensive and need to be reapplied with constant monitoring of spore counts.
Breeding for a FE Tolerant Flock
The most effective and proven way to manage FE is to breed for tolerance. By choosing rams that can withstand high spore counts with no clinical effects you can begin to breed tolerance into your flock. Kirikau Coopworths has been FE Gold rated for 5 years, this means we are dosing minimum 10% of our stud rams to a rate of 0.6 mg sporidesmin/kg liveweight.
References:
Beef&Lamb booklet “Facing up to Facial Eczema”
https://beeflambnz.com/knowledge-hub/PDF/facing-facial-eczema
New Zealand Journal of Agricultural Research - Review of genetic studies of susceptibility to facial eczema in sheep and dairy cattle
https://www.tandfonline.com/doi/full/10.1080/00288233.2012.757240
Vet ENT - Facial Eczema
https://www.vetent.co.nz/sheep-beef-deer-disease-management/facial-eczema.html