It is no secret that Facial Eczema (FE) is spreading across more of the country than ever before. It is also becoming widely accepted that the last minute prevention approach does not save any money in the long run. A proactive and accurate approach is the best way to front foot FE risk, and keep cows healthy and milking through the summer.
Facial Eczema (FE) is caused by the ingestion of spores from a fungus called 'Pithomyces Chartarum'. This fungus lives mainly in the dead litter at the base of ryegrass, and thrives in the warm, wet conditions which we typically see in the humid summer months. Initial signs of FE can be symptoms such as diarrhoea, a drop in milk production or weight loss. It is estimated that even mild damage from FE can result in a milk production loss of 0.17 kilograms of milk solids per day (kgMS/day)1. For a 300 cow herd, that is a loss of $382.50/day on a $7.50 pay-out.
More serious signs of FE include skin sensitivity on the udder and insides of the hind legs. It may become as serious as photosensitivity, raw peeling skin, and potentially, even death. So, what is actually happening when a cow gets FE?
When the spores from the FE fungus are ingested, they release a compound known as sporidesmin. This compound is absorbed through the rumen wall, into the blood stream and moves into the liver. The sporidesmin causes cell damage to the liver and impacts the function of the bile ducts. Damaged bile ducts inhibit the ability of the liver to process phylloerythirn, the active compound of chlorophyll. This results in a build-up of phylloerythirn, and an overflow back into the blood stream, leading to the sensitivity symptoms mentioned above.
It is important to note that it can take up to two weeks of toxin exposure and poor liver function before physical signs of photosensitivity can be seen. Only 5% of animals with liver damage actually show any visual skin signs1. When physical signs are observed in one animal, damage is occurring in many others.
The best way to prevent FE is to supplement with Zinc (Zn). However, Zn supplementation is only a preventative measure; it cannot reverse any damage that has already been done. It is recommended that cattle receive 20 milligrams per kg (Mg/kg) of liveweight/day of elemental Zn2. Pasture spore count monitoring is essential to predict pasture spore levels. Supplementation should begin two to three weeks before pasture spore levels become toxic2.
Accuracy and practicality need to be front of mind when making decisions on how to supplement. SealesWinslow offers a range of options to meet your needs.
2 Dairy Australia Facial Eczema Working Group, 2013