Facial eczema is a disease caused by ingesting the fungal toxin, sporidesmin, while grazing pasture, which damages the liver.
Zinc is an important tool on-farm for helping with facial eczema prevention as zinc forms a complex with the toxin reducing damage to the liver.
Providing animals with high rates of zinc is the best available option to help protect cows against the harmful effects of facial eczema over the high-risk period. However, the rates of zinc required to give protection are very close to toxic levels, especially when continued for over 100 days.
Below are some tips for delivering zinc to your animals for optimum animal health outcomes:
Pre Facial Eczema season
- 3-4 weeks before pasture spore counts start rising, weigh a representative sample of at least 20 animals from each mob to work out the average and range of weights to calculate the full dose of zinc required. This will ensure that the zinc rate you dose is relevant for your size of animal.
- Keep your eye on local spore counts and do spore counts on your farm to identify when spore counts are increasing so you don’t need to dose high levels of zinc when there is not a facial eczema risk on your farm.
Key indicators to trigger preventative treatment
- When regional spore counts reach 20,000 spores/g of pasture, begin to monitor spore counts on your farm.
- When spore counts on your farm reach 30,000 spores/g pasture, this is when zinc dosing should begin.
During the Facial Eczema season
- Delivering zinc via an animal feed is a very targeted and safe way of getting zinc into animals. It is more targeted than water dosing. Water intake can be very variable between animals, so it is not as reliable as dosing zinc via feed and water is not recommended for dosing young stock.
- Ensure you stick to the feeding rate of the supplementary feed ordered with zinc added as the addition rate of zinc is directly related to the daily feeding rate you stipulate when ordered.
- In-shed feeders should be checked to ensure they are delivering the expected weight of feed per milking.
- Multiple routes of zinc supplementation may be appropriate to deliver zinc in high-risk situations.
- Don’t dose high levels of zinc for over 100 days.
- It is advisable to discuss a facial eczema control programme with your veterinarian who will understand the local risks.
Key Indicators to check your zinc dosing program is working
- 10 animals should be tested for serum zinc 2-3 weeks after the full zinc programme has started to check zinc is being delivered at the correct rates.
- 10 animals should then be tested for serum Gamma-glutamyl Transferase (GGT) levels 6 weeks into the programme and repeated around 8 weeks later to check in on liver function. High levels of serum GGT indicate liver damage.
- Fonterra suppliers have access to zinc testing of bulk milk samples, which indicate if sufficient zinc is being consumed. This can be another useful tool to check your zinc dosing program.
When ordering your feed with added zinc for facial eczema prevention, your local SealesWinslow TSR will be able to help work out the correct addition rate given your animal size and daily feeding rate.
For those farms without in-shed feed systems, Zincmax+® is a water-soluble solution with organic copper and flavouring.
Talk to your TSR or visit your local Farm Source store to find out more.