zinc oxide to prevent the effects of the disease,” he says. The system did not completely protect the herd of the farm where Hans was milking. “One year we had three or four cows with facial eczema,” he says. “They had sunburnt teeth and some skin falling off. So that was really bad. The best option is to prevent it, of course.”


Liver damage When Hans arrived in Australia, farmers were not really wor- ried about facial eczema, he recalls. “They did not see it here then. Over the years we have had some high spore counts but we never had any problems with our dairy cows, thanks to using zinc oxide. We did have a problem with about 15 calves getting facial eczema. It was impossible to get rid of the toxin, so we minimised the intake of grass. We in- creased the uptake of supplements and also found some pastures with low spore counts.” The calves with facial eczema ended up having liver damage and sunburn marks on their skin. “They recovered but seemed to be more prone to other problems a year later. Their liver was compromised. After that they did better,” Hans says.


He points out that farmers in New Zealand often give their cattle zinc bullets, one per animal. The bullets release a con- sistent daily dose of zinc oxide to protect animals against fa- cial eczema for up to four weeks. “But we can’t use them in Australia,” Hans says. “They have not been passed by the Aus- tralian Veterinary Association.” Hans explains that monitoring spore counts and weather conditions is an important tool for predicting periods of


toxicity. “We usually get a warning if the spore counts are at a dangerous level. Then you can take action. We feed a zinc pellet in with the grain. We have done that for up to 120 days. In the last few years high spore counts occurred about every second year, usually late summer, early autumn.” After 100 days of feeding zinc pellets, cows have to be test- ed. “We take blood samples and check the zinc levels, so we don’t get up to toxic levels,” Hans says. “Farmers have to be very careful and do their sums right. It is important to make sure of what the actual dose rate has to be in the feed. There are no short cuts.”


Critical dose Hans says there have been too many stories of things going wrong. “Farmers can give too little or too much. If you over- dose you get very sick cows. If you don’t give enough, it does not work. There is a critical dose that cows need to make it work. You have to do it properly or there could be effects for a whole generation of youngstock or young cows.” Zinc is not expensive for farmers, Hans says. “And the dam- age to cows of facial eczema is horrendous. They lose skin, they don’t eat; some of them die. I have seen it and it is an animal nightmare to look at.” Hans is very vigilant in protect- ing his animals, by keeping a good eye on the spore counts. According to the review by Dairy Australia, the prevalence of facial eczema in New Zealand and in Gippsland and other southern dairying regions of Australia may increase in the years to come as the effects of global warming may provide suitable conditions for more widespread outbreaks of the disease over longer periods.


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The fungus grows in the dead litter at the base of pasture and prefers warm, moist conditions. When ingested by cattle, spo- ridesmin dam- ages the liver and bile ducts.


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