Facial Eczema is a disease that affects the liver. Whilst the most commonly associated symptom of FE (Facial Eczema) is photosensitisation, there are many other impacts of the disease such as drop in milk production, development of scours, liver damage, weight loss, infertility and even death in more severe cases.
The only way to positively identify FE is to have a blood test performed and the serum GGT (a liver enzyme) levels checked. Cattle develop FE after first consuming toxic levels of sporidesmin, a toxin produced by a fungus commonly found at the base of grasses, especially ryegrass. Under normal seasonal conditions, the amount of toxin produced is not significant to impact cow health. In some circumstances however, the conditions are such that the fungus sporulates and a high number of highly concentrated spores are deposited towards the base of the host plant. When the cow consumes these spores the sporidesmin toxin can then threaten the cow’s liver and cause facial eczema.
In the past, FE has been rarely seen in Victoria outside of the Macalister Irrigation District, however in the past 2 seasons FE cases have been reported throughout Gippsland. It is thought that the combination of weather conditions (heat, moisture, humidity) and the surplus pasture (creating dead, or dying litter on the ground) have presented ideal conditions for the fungus to sporulate and hence an increased number of FE cases and in a wider area.
Risk factors include: dead or dying leaf litter, grazing close to the ground, cattle already under immune stress, high rainfall followed by a period of heat and humidity.
Prevention strategies: a number of prevention strategies have been hypothesised, some of which are currently available in other countries. Various management strategies are possible, such as not grazing hard, or avoiding paddocks with high spore counts, however many of these are not viable long term. Here in Australia we are currently unable to use options such as fungicides, and instead zinc supplementation to the cow is the most commonly used prevention strategy. Studies have shown that the provision of elemental zinc to cattle can protect them against development of FE. Unfortunately, the level of zinc to be fed to protect the cows is very close to the toxic level, and as such, much care must be taken to correctly dose the zinc in order to be both protective, and yet still safe from toxicity. At this time, it is recommended not to supplement zinc for more than 100 days without seeking veterinary advice.
Supplementation of zinc as zinc sulphate in the drinking water is one option, however controlling and regulating intake is extremely difficult. Daily drenching with zinc oxide is an option utilised in New Zealand, however not well suited to most Australian dairy systems. Zinc boluses are not currently registered in Australia, but are currently going through the registration process. Zinc oxide powder or pellets are used in the grain ration to help prevent facial eczema. Zinc dosage must be calculated taking into account the liveweight of the herd and the feed rate. Advice from your veterinarian or nutritionist is imperative prior to adding zinc oxide to the feed.
Dairy Australia has set up a spore monitoring program where farmers can take pasture samples and send them to Maffra Veterinary Centre to have the spore numbers counted. Some farms that have seen Facial Eczema outbreaks in the past have been selected to be part of the spore monitoring program, where two paddocks are sampled weekly and results are posted on the Dairy Australia website, to allow farmers in the region to watch trends in spore counts and provide some sort of indication as to what is going on in terms of FE risk level in their local area.
Facial Eczema is particularly seen early on in the calendar year (esp Feb-April), however new cases were seen as late as June last year. A booklet on FE is available from the Dairy Australia website, or feel free to contact your Reid Stockfeeds Technical Services representative to discuss your concerns and your FE prevention plan.
To view affected areas and access more information please visit Dairy Australia.