Zinc reacts with the sporidesmin toxin in the intestines creating a stable compound, preventing liver damage. It takes time for the zinc levels to become high enough in the animal to be able to protect it. However, zinc isn’t very palatable, so try masking the flavour with products like Grapple or molasses and starting with a low dose once pasture spore counts trend toward 30,000 and before they reach 60,000.
If you see the clinical signs like depressed milk production, skin blistering, or head shaking, it indicates the animals were exposed about 10 days ago. About 25 animals can be sub-clinically affected for every clinical animal.
Some of the fear about using zinc for too long is that was thought to strip copper from the liver. In fact zinc doesn’t interfere with animals’ use of copper.
Administering copper sulphate to animals will act as a catalyst for the oxidation of the sporidesmin toxin though, which will increase damage, so it is best to only use chelated copper products or remove it from your mineral mix over the FE season.
The FE risk this summer is as bad and in some areas worse than a “normal” season, which is unexpected in an El Nino. Visit your local rural merchant or veterinary practice to consult them on a FE plan for your livestock. There is no silver bullet or “one size fits all” answer but a multi-pronged, planned approach yields the best results for you and your livestock.
For more information visit www.nzagritrade.co.nz
