Friday, July 8, 2022

Quantifying the cost of facial eczema

How much does facial eczema (FE) “cost” farmers? The Beef + Lamb New Zealand (B+LNZ) Waikato demonstration farm is four months into a three-year on-farm study that will compare different FE prevention treatments and ultimately put dollar figures around the cost of FE – clinical and sub-clinical. Demonstration farmers Steve and Sandra Parrott farm in partnership with Steve’s brother Alex and his wife Rika. The 800ha operation is a true family farm with parents John and Dot also still actively involved. The Parrotts farm over two properties – at Matira and Te Uku near Raglan.

Being a trading operation, stock numbers vary but March 2013 tallies were about 1700 head of cattle – made up of 575 rising two-year-old dairy heifers, 200 rising one-year-old dairy heifer calves, 450 rising one-year-old Friesian bulls, 200 Charolais weaners and 215 rising two-year-old Charolais bulls as well as 1100 Romney breeding ewes.

Replacement ewe lambs are normally bought in during summer or autumn but the dry spell might stop that happening this year.

As B+LNZ demonstration farmers the Parrotts were invited to nominate a topic for further investigation on their property. For Steve, it was an easy call.

“I’ve lived on the same farm my whole life and facial eczema has always been an issue. We’ve been down the track of genetics and buying in FE tolerant rams but these days we are running a trading system.”

Sandra is doing weekly pasture sampling to measure actual spores present in the grass. Different spore thresholds will trigger specific facial eczema treatments.

The Parrotts’ FE study involves 90 of the 215 rising two-year-old Charolais bulls because they are familiar with their history and they are a good even line of stock. What is less helpful, when it comes to administering the boluses, will be their sheer size.

Steve says the family is so mindful of the threat of FE that all dairy heifers are treated with boluses at the owner’s cost. Some of their own stock are also treated. 

No new research

Steve is frustrated that most of the research around FE is dated and nothing new appears to be happening.

“I’m hoping part of this study’s outcome will be to draw people out of the woodwork and stimulate some new interest in FE.

“Facial eczema is creeping down the country and I think it affects us a lot more than we realise – just because it’s not always visible. A lot of people do nothing about it. We’d rather do something than do nothing but are we treating when we don’t need to be? What are the implications of using zinc unnecessarily? Ultimately, we want to find out how much it actually costs us.”

As Country-Wide went to print, Waikato’s dry conditions continued and spore counts were sitting around 0-10,000 – below the 10,000 and 25,000 spores/gram of leaves trigger for any of the study treatments to kick in.

Steve was in an unusual position – almost willing the spores to take off so the study could begin.

“There’s some roughage there and the ground temperature is still good so rain could possibly trigger a lift in spore numbers.” 

Insidious disease

B+LNZ farm general manager Richard Wakelin says this project is an obvious project to support wholeheartedly.

“Facial eczema is an insidious disease that has been around for all of my career. While there are management practices and systems around, there have been few new farm system support projects developed.

“There has been good progress in the ram breeding arena and now we need to understand how these are applied on-farm and trial new practices. This demonstration study is important because it takes the knowledge and understanding that is already there and builds on it.

“Many farmers have been forced to farm around the threat of FE. From a B+LNZ perspective, improvement in the management of this disease has the potential to broaden farmers’ options around the classes of stock they can run.” 

Pinning down basics

The Parrotts’ veterinarian and FE study advisor Dr Kara Watson says she is looking forward to getting some base information recorded.

Watson and husband Geoff Tucker farm a 335ha sheep and beef farm only 30 minutes from the Parrotts’ property so her interest is twofold.

“Because of our own sheep and beef farm in the same area, it’s something I have a genuine interest in. We all lose money to it, including the sub-clinical effects.”

Watson says that zinc has been the only answer for so long that it’s great to have the opportunity to consider what other answers might be out there.

“When I sat down with Steve and Sandra we had so many ideas and realised we could take this in so many directions. But we decided we needed to get some basics down in the first year or two then branch out from there.

“For a start, we want to find out what’s happening in the grass and what’s coming through the animals. Then, in the next few years as we learn more we can trial some different grasses and other possible prevention systems.”

– Supplied by Beef + Lamb New Zealand

How the cattle study will work

The study started in December and involves 90 animals across four treatment mobs. The bulls were recorded for weight, age, breed and any signs of eczema. Then all representative animals in the treatment mobs were blood-tested for GGT and zinc levels and six bulls were given a liver biopsy. (GGT is a specific enzyme that indicates damage to the liver.) All four mobs have access to a Dosatron system throughout the trial period which ends in May.

The four mobs are:

1 Receive a 400kg animal zinc bolus and zinc via a Dosatron;

2 Receive a 650kg animal zinc bolus and zinc via a Dosatron;

3 Receive zinc via a Dosatron only and;

4 Receive zinc via a Dosatron and grazed on paddocks sprayed with Mycotak and Mycowet.

Weekly pasture spore counts both began in December and will continue until May.

When pasture spore counts rise above zero, weekly faecal spore counting will start and the Dosatron system will begin. Zinc levels in troughs will be measured to ensure the system is working correctly.

When pasture spore counts reach 10,000, Mob 4’s paddocks will be sprayed with Mycotak and Mycowet. When pasture spores reach 25,000, Mobs 1 and 2 will receive their bolus treatments with follow up treatments as per manufacturer’s recommendations.

Additional recording will kick in when pasture spore counts exceed 25,000. Blood samples and weights will be taken at four-weekly intervals with visual signs of eczema also checked for. Final samples – around early May –will include liver biopsies and serum zinc levels.

How the sheep study will work

With the ongoing dry continuing, the sheep study is looking like it will be held over to next season. The Parrotts are unlikely to buy in their replacement ewe lambs – as a strategy to reduce on-farm feed demand.

However, it should be all go for the 2013/14 season. The plan is for the lambs to arrive February/March when they will be recorded for breed, level of eczema resistance and weight. They will then be split into two treatment mobs of 100-150 head with 20 lambs in each mob tagged as test animals for blood samples.

The two mobs are:

1 Lambs on rape crop only and;

2 Lamb on grass and treated with a zinc bolus

The grass-fed lambs (Mob 2) will be given the bolus when the FE spore count reaches or exceeds 25,000 spores/gram of leaves with new boluses given as per manufacturer’s recommendations.

Grass spore counts will be measured from one week before the lambs arrive. When counts are at or over 25,000 spores, faecal spore counts will also be collected from both mobs.

In early May – at the end of the risk period – the lambs will be recorded for weight and visual signs of eczema. Later in the year, pregnancy scanning results will also be recorded. The 20 tagged lambs in each mob will have follow-up blood samples taken.

Blood samples will be used to identify levels of GGT, selenium, vitamin B12, copper and zinc.

The treatments

Bolus = Face-Guard for cattle; Time Capsule for sheep.

Dosatron = technology which slots into the water supply line and “feeds” a concentrate – in this case, zinc – into the water stream at the appropriate ratio.

Mycotak and Mycowet = Mycotak is a commercial product designed to prevent FE. It is a concentrated granule containing carbendazim and works by eliminating spores in the pasture. Mycowet is a companion product described as a “super spreader” surfactant blend which enhances the uptake of Mycotak.

What is facial eczema?

Facial eczema is a photosensitive dermatitis, affecting sheep and cattle. It shows up as depressed animals, scabbing and swelling of the skin (especially light-coloured areas and the ears and head) and jaundice or yellowing of the skin and whites of the eyes. FE is caused when stock ingest a fungus which carries the sporidesmin toxin. The toxin causes severe inflammation of the liver and blocks the bile ducts. The fungus thrives on litter in leafy pasture, such as perennial ryegrass and white clover, in a warm and humid environment. 

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