So farmers should treat any dairy and beef cattle, sheep, deer or goats with zinc from now to May, it said.
They should not wait to see clinical signs like appetite decline and a sharp fall in milk yield or sheep and deer becoming more restless, irritable and shade-seeking.
FE could have a significant impact on animals, particularly cows where it can result in an immediate drop in milk production, before any physical signs, Ballance product manager Jackie Aveling said.
“It’s possible that farmers will not be aware of the full extent of a facial eczema problem until it’s too late,” she said.
“If as little as 3% of the herd show clinical signs of facial eczema then subclinical cases can affect up to 70% of the herd.”
Sub-clinical FE is the result of exposure to the toxin sporidesmin, which grows in pasture.
Spores increase where grass temperatures are above 12 degrees for three consecutive nights.
FE makes animals sensitive to sunlight and causes extremely intense sunburn.
Stock can die from FE as a result of liver failure.
Most affected animals will survive but bodyweight and production will be seriously reduced in the short term.
