Perfect conditions for fly and FE
Warm wet weather in many areas of the country creates the perfect conditions for the production-limiting diseases flystrike and facial eczema (FE).
So says agricultural scientist Neale Towers, who warns that damp weather coupled with mild night and warm daytime temperatures are ideal for the FE-causing fungus. This fungus lives in dead and decaying grass in the base of a pasture sward.
The recent rise in FE spore counts in many North Island regions has coincided with upcoming ewe mating. Towers says if animals are exposed to the toxin, FE can impact negatively on fertility and scanning results.
“The number of dry ewes will increase and the number of multiples decrease.”
Towers says zinc – preferably in the form of a zinc oxide bullet – is the only direct FE treatment available for livestock when it is too late in the season to be spraying paddocks with fungicide.
As the FE-causing fungus only lives in pasture, feed crops can minimise livestock’s exposure to the disease -- although grassy headlands can be a source of contamination.
Towers urges farmers in FE risk areas to keep an eye on weather and regional FE spore count reports.
“If you see the district averages rising then it is highly likely that counts on your farm will be rising.”
FE affects the liver and Towers says by the time clinical symptoms appear – swollen ears and eyes caused by photosensitivity – the damage has already been done. “You are two weeks too late.”
He says while only a few animals would display clinical symptoms, a much greater proportion of a flock would be affected sub-clinically. However, while the symptoms of FE may not be visible, the disease would still affect productivity and fertility.
Towers says there is a large genetic component to FE susceptibility in sheep and he urges farmers in high FE risk areas to ensure their ram breeders are testing and selecting for FE tolerance. “It is the only long-term strategy.”
