Stock Sense with Paul McKee Ravensdown Technical Manager

As ‘e friend’ zinc is an essential mineral required by stock for their health and wellbeing.

It plays important roles in a number of processes that affect growth, production, reproduction, immunity, hoof, skin and udder health of stock.

Generally, New Zealand pastures will contain adequate amounts of zinc meaning clinical deficiencies are unlikely to be seen. However, there may be times where reduced zinc intakes could result in sub-clinical effects including reduced appetite, growth and production, deterioration of hair and skin, and hoof health. Testing pasture and other feed sources will determine whether or not stock require zinc supplementation.

Rather than testing, many dairy farmers simply elect to regularly provide their stock with small amounts of zinc in a trace element supplement.

Additionally, zinc has a range of important non-nutritional benefits in animals including Facial Eczema prevention, foot rot control and dermatopholosis (lumpy wool) control in sheep.

Facial eczema prevention would be the most recognisable of these uses, where large doses of zinc are given in order to neutralise the FE toxin before it can damage the liver.

‘The foe’

Like most things in life, too much of a good thing can end up being a bad thing. Nowhere is this more so than in the use of zinc for the prevention of FE.

While zinc is very good at neutralising the FE toxin, the high rates required are getting close to being toxic for stock. Animals being treated with high rates of zinc for long periods of time will be at increased risk of milk fever, weight loss, reduced production and copper deficiency.

Preventing a copper deficiency by supplementing with copper at the same time as high rates of zinc is not encouraged.

Why? Copper can interfere with the zinc’s ability to neutralise the FE toxin, and may even amplify the toxins effect.

At the end of a long hard FE season, farmers are advised to check the copper status of their stock and where necessary consider some form of copper supplementation.