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Facial Eczema (FE) is a disease affecting cows, causing liver damage, skin irritation, production decrease, and sometimes death. It's caused by a toxin from a fungus in pasture. Signs of FE include milk production drop and skin reddening. Not all cows show clinical signs but might still have liver damage, reducing milk production by up to 50%. The fungus produces spores when grass minimum temperatures are above 12°C for two or three nights and humidity is high (usually January to May). You can prevent it using combinations of spore count monitoring in pasture, using zinc dosing, pasture spraying, or breeding for FE tolerance. For treatment, act quickly, using measures like moving affected cows to shade and removing pasture from their diet.
Facial Eczema (FE) is a disease that causes liver damage, lowered production, skin irritation and peeling, and sometimes death.
Facial eczema is caused by a toxin (sporidesmin) produced by the spores of the fungus Pithomyces chartarum growing on pasture. The fungus grows in the dead litter at the base of pasture in warm moist conditions.
Sporidesmin, when ingested by cattle, damages the liver and bile ducts.
The damaged liver cannot get rid of a breakdown product of chlorophyll that builds up in the blood causing sensitivity to sunlight, which in turn causes inflammation of the skin.
Not all animals affected with FE show physical signs (i.e. clinical FE) although liver damage (i.e. subclinical FE) may have occurred. It is estimated that for every clinical case there will be 10 cows with subclinical FE.
Milk production of animals with subclinical FE can be depressed by up to 50%. Blood tests can be used to monitor the extent of subclinical FE.
Badly damaged liver tissue will not regenerate. Chronic wasting and/or death may occur at the time of damage or months later when the animal is under stress (e.g. calving).
The fungus produces spores when grass minimum temperatures are above 12°C for two or three nights and humidity is high (usually January to May).
The fungus grows on soft litter at the base of the pasture so hard grazing during danger periods increases the risk of spore intake. Pasture management, which which increases the build-up of soft litter is a likely contributor to increased FE risk.
There is no cure for FE so prevention is the only way of protecting animals. To be effective, preventative measures need to be in place before eczema spores are found.
Preventative measures include monitoring pasture spore count and either dosing animals with zinc or spraying pastures with a fungicide.
Breeding cows that are more tolerant to facial eczema is a solution to reduce the impact from facial eczema in the long term.
Facial eczema tolerance is a heritable trait and the right breeding programme can reduce the severity of the disease over time.
Research and development completed by CRV Ambreed, AgResearch and DairyNZ resulted in the ability to identify facial eczema tolerant bulls. These sires will typically breed daughters that are 25% less reactive to a facial eczema challenge, compared to the average bull.
Cows resulting from FE tolerant sires will typically have:
For a herd starting a breeding programme with FE tolerant sires the first benefits (FE tolerance in young stock) are not available for 18 months after first insemination. Gains in FE tolerance will be made as each generation of daughters from FE sires enters the herd. A full herd with FE tolerance is achievable in 7-8 years.
Pasture spore counting is an excellent way to visualise spore count trends and to get a handle on the likely risk. It is highly variable between paddocks but as a guide:
|Low||Less than 15,000/g of pasture|
|Slight||15,000-30,000 (begin zinc treatment if trending to 30,000)|
|High||Greater than 60,000|
Choose 4 paddocks that are representative of the farm and monitor.
Tips for predicting the most susceptible paddocks for spore counting:
Start early – at least two to three weeks before the spore growth danger period.
Weigh a representative sample of at least 20 cows of each of the mobs to be treated to calculate the dose of zinc required.
Fully dose cows with zinc: drenching with zinc oxide, water dosing with zinc sulphate, administering in feed or as an intraruminal bolus (e.g. Time Capsule, Face-Guard).
The more control a farmer has over the amount of zinc a cow receives the more likely it is that the cows are receiving the correct daily dose. Zinc drenching and intraruminal bolus will, for this reason, provide more reliable protection than adding zinc sulphate to drinking water.
Zinc is toxic in high doses; care should be taken in calculating dose rates.
Spraying the pasture with a fungicide will slow the development of the fungus and subsequent production of spores.
Apply only when:
Spraying should cover all areas including fence lines and under hedges.
Check spore counts after spraying and before grazing, to ensure pastures are below acceptable levels. Pasture will be safe for 4-6 weeks after which they will need to be resprayed or monitored with spore counting.
Cows showing clinical signs of facial eczema can recover if prompt action is taken
In addition to the above, for very sick cows
Practical indicators of recovery include liveweight gain and improvement in body condition score (BCS). Be aware that animals can take up to 12 months to fully recover.
Animals with a previous history of clinical FE have a lower chance of recovery than previously unaffected animals.
When making decisions to cull cows act early before body condition score and the severity of the condition cause unnecessary distress and suffering. If sending cows for processing farmers need to be aware that animals will not be accepted if emaciated or with severe skin damage (sores, weeping wounds etc.).
Not all animals affected with facial eczema show physical signs (clinical), although liver damage (subclinical) has occurred. It is estimated that for every clinical case there will be 10 cows with subclinical FE.
Subclinical FE can result in up to a 50% loss in milk production.