Hit eczema hard before it starts

A ewe showing clinical signs of facial eczema.

01-02-2009 | Not Specified

High summer temperatures pose hidden risks for cows and sheep so farmers need to start monitoring for facial eczema.

While a long Indian summer may be enjoyable for humans, hot days and humid nights put cows and sheep at serious risk of contracting facial eczema.

Facial eczema is caused by sporidesmin, a toxin produced by the microscopic fungus Pithomyces chartarum which grows in the base of pasture during moist, humid conditions found during summer. Animals continuously exposed to sporidesmin, even at low levels, will experience liver damage, production losses and in the worst-case scenario, death.

Agri-feeds technical manager Andrew Oakley says significant liver damage will occur in unprotected animals grazing "hot" pastures when minimum soil temperatures start to rise above 12-13°C in summer.

"When climatic conditions become favourable, dead or dying leaf matter in predominantly ryegrass pastures will trigger fungal growth," says Oakley.

He warns district spore counts are indicative only and should not be relied upon; he advises farmers to do their own on-farm monitoring, remembering that the highest concentration of spores will be in the bottom 5cm of the pasture.

Oakley says significant liver damage can occur in animals continuously exposed to pasture spore counts of around 40,000 or less.

Not all animals show physical symptoms. It's estimated that for every 3% of cows exhibiting clinical signs of facial eczema (exposed unpigmented or peeling skin), 60% of the herd may be experiencing sub clinical effects (restlessness, seeking shade and licking their flanks or udders).

Prevention is the only recognised method of dealing with facial eczema, however it is important to remember no one method is 100% effective.

"Pasture and animal management combined with zinc treatments can reduce the risk significantly.

"For example, avoid topping pastures in summer months, regularly monitor pasture and/or faecal spore counts.

"Dosing sheep with oral zinc drenches is not always practical as it is necessary to dose once a day or twice a week to get good protection.

"Water treatments are effective only in dairy cattle systems because sheep and beef cattle don't drink enough water or drink from multiple sources."

Oakley says the zinc Time Capsule bolus is the best proven alternative method of preventing facial eczema for sheep and cattle.

It slowly but continuously releases a controlled amount of zinc oxide to the rumen providing protection in cattle up to 400kg LW for up to five weeks and for up to six weeks in sheep, using a single bolus.

"Single boluses are available for lambs and ewes up to 80kg LW and for cattle from 90kg to 400kg. For dosing larger cattle, up to 800kg, use two of the larger boluses in combination," says Oakley.

More? Andrew Oakley, Agri-feeds, (027) 600 4231.

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