FE harder to spot in beef bulls

Ruminants contract liver-damaging facial eczema when they eat pasture containing spores of the Pithomyces chartarum fungus.

I recently helped out at the inaugural field day at Steve and Sandra Parrott's farm. The property at Matira is home to a Beef + Lamb New Zealand Demonstration Farm project on facial eczema (FE) in beef bulls.

There has been little trial work on FE's effect on this class of stock. FE is a disease of ruminants, which occurs when they eat pasture containing large numbers of spores from a fungus called Pithomyces chartarum.

The spores' toxin damages the liver and bile duct. Treatment with zinc offers some protection. Breeding FE-resilient animals is another avenue, but is not practical in a trading operation. So, with B+LNZ's support, the Parrotts set up a trial about a year ago to answer three main questions:

Does FE cause decreased live-weight gains in beef animals?

What is the best treatment to prevent FE in beef animals?

What is the most cost-efficient treatment to prevent FE and maintain live-weight gains in beef animals?

Rises in spore counts are unpredictable, so forecasting when to act is tricky. Using rising 2-year-old bulls, the Parrotts looked at three control methods: treating bulls with a Face-Guard bolus; putting zinc in the water via dosatron; and spraying paddocks with Mycoyak and Mycowet.

Conclusions so far are still reasonably broad. 1) Increases in GGT levels (an indicator of FE exposure) result in lower live-weight gains. 2) Bulls treated with zinc had lower increases in GGT levels and higher live-weight gains. 3) Bulls treated with Face-guard boluses had the greatest increase in zinc.

Each treatment has pros and cons. Not every farm has reticulated water so a dosatron may not be an option. But the key lesson is that beef bulls are affected by this disease - even though it may not be visible.

The impact on live-weight gains supported the suspicion that bulls are affected "subclinically". The analogy used at the field day was the "tip of an iceberg": what you see is only a small part of what is actually there.

Monitoring spore counts is crucial. Given there is no real cure, proactivity is the best approach.

Beef + Lamb New Zealand publishes spore counts on its website every Friday from mid-January to May.

Andrew Jolly is the Beef + Lamb New Zealand Northern North Island extension manager. For more info, email andrew.jolly@beeflambnz.com or call him on 027 489 734.