The sometimes silent threat…
Facial Eczema (FE) is a topic that almost everyone has heard off and many know very well. It has been covered off time and time again BUT we continue to see animals being clinically affected and suffering as a result of this disease.
So, with the risk of “milking the same old cow”, here’s a brief FE summary as a refresher:
ALL stock that eat pasture can be affected.
FE is caused by a mycotoxin (sporidesmin) that is produced by the spores of the fungus Pithomyces chartarum that grows in dead litter at the pasture base (bottom 15cm of sward is riskiest part).
Humid warm wet weather conditions (three nights with minimum night-time temperatures of greater than 12.5⁰C plus 4mm of rain in 48 hours) put stock at risk.
When eaten sporidesmin enters the bloodstream → travels to the liver → damages liver and bile ducts → liver doesn’t function properly to rid the body of “wastes”, one of which is phylloerythrin (a breakdown product of chlorophyll in grass) → phylloerythrin builds up in the bloodstream causing sensitivity to sunlight and inflammation of the skin.
Affected stock are restless/irritated, seek shade, have inflammation of exposed skin (commonly around eyes, ears, nose and lips) causing it to look swollen/thickened and it may peel off. Production (milk and meat) loss (estimated at $200 million annually!) and decreased fertility can also result.
Liver damage from FE is cumulative so long-term consumption of low levels of spores (20,000 spores per gram) can potentially be just as harmful as a single large dose (levels greater than 45,000 spores per gram). Liver tissue does have some capacity to regenerate however severely/extensively damaged liver tissue will not and chronic wasting and/or death can result. This may occur at the time of the FE insult or months later when stock are under stress such as at calving.
Stock showing symptoms are generally only the “tip of the iceberg” and, if you are seeing these, there will likely be a significant number of other animals affected also.
There is NO cure so PREVENTION is the best. Plan your defence, which will depend on a number of things (stock type, stock location, farm type and facilities etc), so you are ready BEFORE spore counts rise! Options include:
Zinc dosing - in water (in-line/PETA dispenser), in/on feed or oral drenching (zinc oxide), or by zinc bolus administration. Ensure you dose according to weight and get bloods done (sample 10 cows three to six weeks after start) to check that serum zinc levels (and ideally GGT levels for any indication of liver damage) are adequate.
Fungicide spraying of pasture – must be done counts rise above 20,000 spores per gram of pasture. Spray does NOT kill spores that are already present.
Pasture management - reduce amount of dead matter in sward and avoid topping.
Spore counting – assess level of risk prior to putting stock in to graze. Be aware though that, due to differing microclimates, there can be HUGE variability between neighbouring farms, between paddocks on the same farm and even within the same paddock! At very least, keeping an eye on regional counts is prudent.
Breeding of resistant stock – longer term approach using genetics to increase tolerance to FE.
For further information and/or support don’t hesitate to contact us and keep an eye on spore counts at www.gribblesvets.co.nz , who publish weekly national and regional spore count data, and consider getting some counts done on your own paddocks too!