In short, it’s hard to predict. So far, spore counts in most areas have remained low, but we are seeing pockets of medium to high risk around the region.’ Therefore, all farmers should be ready to start their zinc supplementation programme for the season.
It’s important to remember that while every season has different patterns of warmth and wet; spores are always present on pasture, and given how quickly conditions can change, no season is free from facial eczema. Both short-term exposure to high spore counts (>40,000) and longer-term exposure to low–moderate spore counts (>10,000) can lead to liver damage and clinical signs in grazing animals.
The graph below, produced by Gribble’s laboratory, shows the highest weekly spore count from mid-January (week 1) in the Central Waikato for the past four seasons. It’s important to recognise that while some seasons are clearly worse than others (2016!), every season shows a similar pattern – spore counts climb rapidly in early February (week 3) and remain elevated until the end of May (week 20). Therefore, it’s critical to have a zinc supplementation plan in place ahead of the high risk period, to protect your animals against this devastating disease.
What are my options for zinc supplementation?
Zinc can be supplemented in four main ways: bolusing, oral drenching, in feed, or water treatment.
How do I know my zinc supplementation is protective?
Most of our farmers put zinc supplementation plans in place, but often, blood tests show that zinc levels in supplemented animals are not high enough to be protective against facial eczema. A 2014 study found that the majority (two-thirds) of farms were in this position. This is especially true of those who supplement solely with water treatment, as it relies heavily on individual animals drinking the required amount.
The best way we can confirm whether your animals are protected is by taking blood samples two weeks after the start of supplementation. We can then tweak your zinc dosing accordingly.
What should I do next?
- Discuss your zinc supplementation plan with your vet to determine which zinc product, or combination of products, will work best for you and confirm dosing levels.
- Check out our weekly spore count emails to identify the current risk for your area, and determine when zinc supplementation should begin. If you are aware of another farmer who would benefit from these emails, please encourage them to sign up at www.anexafvc.co.nz/newsletters
- If you have any questions, please contact your Anexa vet today.