As we head into the FE season, characterised by periods of warm and wet weather, it’s important to make sure that everyone knows the facts about this disease, which at its worst, can be devastating for livestock and farmers.
Facial eczema is primarily a skin disease.
The peeling skin seen on animals with facial eczema is a consequence of severe liver damage, caused by the sporidesmin toxin ingested from pasture. It is the liver’s inability to function properly that results in the skin becoming susceptible to UV damage. While the liver is amazing in regenerating itself after damage, in severe cases of FE, animals end up with permanent liver damage.
There are no animals with obvious skin problems or other signs of FE, therefore, none of the animals have FE.
It is common to have a significant FE problem without animals showing any obvious clinical signs like skin lesions. In cattle, it has been shown that it is the 80% of animals that have no skin lesions, but do have liver damage, that cause the major economic impact. While it is more likely to see skin lesions on unpigmented (white) skin, black skinned animals can get FE too. All animals have a liver!
Zinc supplementation can be introduced once signs of FE are apparent in livestock.
Zinc works by preventing the sporidesmin toxin from causing liver damage in the first place, therefore, animals should be supplemented before exposure to dangerous levels of spores (spore counts over 30 – 40k). Zinc can only help to prevent FE, it cannot reverse liver damage once it has occurred.
How to manage your FE risk: monitor, avoid, suppress, protect, and plan for the future
- Monitor – sign up for our weekly spore count emails at www.anexa.co.nz/newsletters. They will help you decide when to start supplementing your animals with Zinc. Alternatively, we provide spore count testing services so you can monitor spore counts on your farm.
- Avoid – a key part of reducing FE in your livestock is by helping animals avoid ingestion of the toxin. This involves managing pre and post-grazing heights (FE spores are at the base of the sward), moving animals to safer ryegrass pasture (spore counted), use of alternative pasture e.g. chicory, clover, plantain, and feeding low-risk conserved forage or supplements.
- Suppress – fungicide spraying will help to suppress the P. chartarum fungus that is responsible for producing the sporidesmin toxin and can be a useful way to control FE. However, it is not always economical or practical on many sheep and beef farms.
- Protect with Zinc supplementation – Zinc can be supplemented in several ways; Zinc sulphate through the drinking water, or Zinc oxide in boluses, feed or via oral drenching. Zinc should be supplemented throughout the risk period, which can be up to 100 days in ideal weather conditions. Remember, Zinc can be toxic if given at too high a dose rate but can easily be monitored by blood sampling two to three weeks after supplementation begins.
- Plan for the future – genetically selecting for FE tolerance in sheep, by buying FE-tolerant rams, is one of the most important methods of FE control in sheep. It is a highly heritable trait (0.42), meaning that 42% of his lambs will receive half of his tolerance genes in one season. Therefore, while effective, it will take a number of years to lift the overall FE tolerance of the flock.
FE is a complex and serious disease and requires multiple management approaches to ensure prevention and control. Although last season was a relatively kind one for FE, all indications are that FE is likely to become worse and more widespread in the face of global warming.If you would like help or advice on FE prevention on your farm, please contact your Anexa Vet.