It is also one of the most misunderstood and most underdiagnosed. But now, a new test is set to help with earlier herd-wide identification, and lead to better conversations.
A costly disease
Facial Eczema (FE) costs the NZ dairy industry over $100M each year in lost production. The ability for individual farming operations to reach their productivity potential can be compromised by between 1kgMS to 2kgMS per cow per week as well as shortening the affected animal's productive season by up to 60 days due to having to dry off early.
Affected cows can then take up to 12 months to fully recover, but even once recovered, research has proven that production losses often continue in subsequent seasons.
A dangerously misleading name
One of the problems that prevents farmers coming to terms with this disease is its name. It would be easy to think that the disease is a skin disease; that it can be identified by its visual symptoms; and that it can therefore be treated in a timely fashion.
But FE is in fact a disease of the liver, and the most significant damage is being caused before any skin signs are apparent - if these occur at all. Because only a very small proportion of affected cows show physical (clinical) signs of the disease.
It is estimated that for every clinical case there will be 10 cows with subclinical effects.
The truth is, if you're noticing irritability, peeling skin, red udders or other external symptoms, then you're seeing signs of the disease long after it has taken hold and done much more serious damage to your animal. What matters most, is what is happening inside the cow.
The liver damage at a subclinical level - that is, before you notice it - is what has the most detrimental effect on the welfare of the animal and its short and long-term productivity.
The spores are the cause
FE is caused by ingestion of a toxin called sporidesmin, found in spores from a particular kind of fungus (called Pithomyces chartarum) that grows on the dead litter at the base of pasture.
The more litter present, the greater the potential for explosive fungal growth when periods of high humidity coincide with warmer grass minimum temperatures (over 12-13C). Most of the spores are situated within 5-6cm at the base of pastures.
For this reason, management of FE relies on proactive pasture and grazing management, as well as effective detection and measured preventative treatment.
Think how you zinc
There is no cure for FE, so prevention is the only way to protect animals.
Zinc is widely understood to be a reliable preventative measure against the disease - as a drench; as a slow release bolus; mixed with feed; or with limited effect, added to water troughs. But what is less well understood is the practice of optimising the levels of zinc in your herd based on current levels of risk - which vary by season and geographic region.
Veterinary researcher, Emma Cuttance of VetEnt, suggests that 60% of farmers using zinc are not getting enough zinc into their cattle to adequately counteract the toxins to ensure protection and reduce the risk of liver damage. So, monitoring zinc levels across the herd is critical to ensuring they're safe. Blood testing has been the most trusted means of testing, but testing costs are generally low due to costs and inconvenience. But it's about to become a lot easier with the introduction of a new herd-wide zinc test that will soon be available.
If you can measure it you can manage it
Fonterra's On-Farm Excellence Research and Development Group has developed a vat milk-based diagnostic test that identifies if a herd is receiving sufficient zinc to provide maximum risk mitigation against the disease. This diagnostic tool is called ZincCheck and will be available for the start of the FE season, from mid November.
Nuala Platts, GM of On-Farm Excellence Operations at Fonterra, believes that this is the first big step in not only providing faster, easier herd diagnostics of FE, but is also the means to improving awareness and opening up conversations about how kiwi dairy farmers can better manage the risk of FE across the country.
Emma Cuttance agrees. "This is the biggest step forward in FE management since the discovery of zinc supplementation in the 1970s."