April 2, 2011

Facial eczema – NZ disease scourge for 100 years

By Dr Clive Dalton

Clinical cases of Facial Eczema showing typical lesions on ears
and around they eyes, and sometimes along the back.

Problem for 100 years
For over a century now, Facial eczema (FE) has caused massive animal suffering and economic loss to New Zealand flocks and herds, and every year it still takes its toll. It’s a fungal disease of the autumn, thriving in a combination of soils still warm from summer, dead pasture litter, and moisture from autumn rains and heavy dews.

Looking down a microscope, it’s hard to imagine how the tiny hand grenade shaped fungal spores can produce a toxin that can permanently damage an animal’s liver, leading to photosensitivity, great suffering and often death. When cases get really bad the animal has to be euthanased. Stock sent for meat processing end up being condemned, as their flesh is jaundiced and has an unacceptable 'off' smell.

The Fusarium fungus (Pythomyces chartarum) which produces the spores, is common in many other countries such as Australia, South America and South Africa, but for some unknown reason does not produce the ‘sporidesmin’ toxin. The toxin is most dangerous from young rapidly-growing spores like the ones in the picture below.

Spores of the fungus Pithomyces chartarum

Finding the cause

Facial eczema has been known in New Zealand since the importation of modern grasses in the 1870s, and it was certainly reported by J.A Gilruth in the Department of Agriculture's Annual Report in 1897.

Finding the cause and working out prevention measures took 40 years of solid research, (including many setbacks) by scientists at the New Zealand government’s, Ministry of Agriculture and Fisheries, Ruakura Animal Research station, working in close cooperation with local farmers desperate to find a solution, many of whom regularly lost more than half of their sheep flocks in bad years. It took them years to get over one bad FE year.

Farmer demands
In fact, it was farmer action led by a Waikato farmer, Mr F.C. (Togo) Johnstone in 1939, strongly supported by Waikato Federated Farmers, that got Ruakura under P S Smallfield to take a serious look at the problem. A long hard road of research was started and got a major boost in 1943 when Dr C.P. McMeekan was recruited from Massey College (later University) to develop the Ruakura Animal Research Station.

McMeekan recruited a team (many from overseas), to find the cause and then provide a prevention to the scourge causing massive economic losses on farms in the warmer northern parts of the North Island of New Zealand.

Today, with the climate warming and more dry summers, the disease is being found in many other areas of New Zealand.

When I arrived at the Whatawhata Hill Country Research Station in 1968, researchers had done most of the hard work. The fungus and its toxin had been identified, and treating animals with zinc salts was the accepted prevention.

Gladys Reid

Gladys Reid OBE

A famous part of the zinc research story was Mrs Gladys Reid who farmed at Te Aroha in the Waikato. There was always an argument, which continues to this day even after her death at age 92, as to who was first to ‘discover’ zinc to prevent FE. As a former dental nurse she knew about the qualities of zinc, and tried throwing zinc sulphate into water troughs with clear benefits to preventing the disease.

To her dying day, she declared that she told the scientists at Ruakura about the value of zinc, and that they needed to follow it up. She must have spent 30 years goading them on to do more, and they certainly didn’t like it, and to this day they claim to have discovered zinc before Gladys.

Things certainly got heated from time to time and much of it was played out in the local newspaper - the Waikato Times under farming editor Peter Bourke. I got involved in the cross fire at one stage when Scientific Liaison Officer at Ruakura and in the end, I and Dr Rex Munday were the only two scientists at Ruakura who Gladys would talk to, and who were in contact with her. We always listened to her, difficult though it was at times as she was so deep into biochemistry and certainly well ahead of my knowledge of the subject. Rex could certainly follow her theories and ideas. Scientists from all around the world kept in touch with her and used to visit her.

There was the famous letter from overseas addressed to ‘The zinc lady, Te Aroha, New Zealand’ that got to her with no problems!

Before she died, I managed to get most of her original papers and correspondence into the archives at the Hamilton City Council’s public library, where they are publically available. In my opinion, from reading all her original letters, she clearly was the first to see zinc as a practical preventative for FE.

But I don’t expect my former colleagues to ever agree with me, and even years after it was all over ( I thought !), I was reprimanded by the President of the Waikato branch of the NZ Institute of Agricultural Science, for some words I had written for a display in the Hamilton City Museum of Art and History on the history of FE research. My scolding was because I had ‘given overdue emphasis to the role of Mrs Reid in the story of FE research’. Certain scientists never gave up their pique.

What made things worse for them was that Gladys was awarded an OBE for ‘Services to Agriculture’, an honour she always felt was a ‘sop’ to compensate her for the years of insults and rebuffs she’d had from Ruakura scientists as well as MAF's Director General of Agriculture.

One of the wonderful switchboard staff at Ruakura - Ruth Utting, told me that she was told by certain scientists and the Director that if 'that woman phoned', she was to tell her the person she wanted was not available. Ruth told me that Gladys got wise to this, and once got her daughter to phone the Director who then handed the phone to Gladys!

Google ‘Gladys Reid’ for her obituary.

Easy for dairy farmers
Daily drenching dairy cattle with zinc oxide was easy for farmers, as for most of the year cows had to be dosed for bloat and were well used to being handled – almost opening their mouths when approached with a drench gun. And when technology advanced, zinc sulphate could be applied via drinking water systems which circulated around the farm.

Messy chore
However, for sheep farmers where prevention involved weekly drenching with zinc oxide, it was just not practical, which was good because it got them determined to find an alternative solution.

I well remember seeing the mess in many woolsheds, as old washing machines were being used to mix the powder and water. You would think the shed and the sheep yards had been whitewashed – which was in stark contrast the shepherds’ blue language over their weekly mustering and drenching chore. The stress on sheep, dogs and staff was too much.

Why did some sheep survive?
Some smart farmers noticed that there were individual sheep that survived whatever the season (based on the survival of the fittest), so Ruakura researchers picked this up and started a flock selected for high and low FE resistance along with a randomly selected control group, and it continued for many years.

This was possible as the toxin (sporidesmin) had been isolated from the fungus (Pythomyces chartarum) grown in the lab at Ruakura, so sheep could be dosed with it to measure their liver reaction. As this was a very nasty toxin, handling and dosing animals with it had to be done by veterinarians, or under their supervision.

FE resistance heritable
These selection flocks soon showed that FE resistance was heritable and quite strongly too with heritability around 45%. This was similar to wool production, so it allowed farmers to start selecting for it along with their other important production traits. And they did – with great enthusiasm and success, working closely with Ruakura staff.

Colin Southey
A major driving force in this was the late Colin Southey who was a Farm Adviser at MAF Pukekohe, along with former Farm Advisor Andy Dalton. In their Raglan coastal hill country area in the early 1970s, FE was killing off over 40% of flock replacements causing enormous economic loss to hill country farmers. Many farms were losing 1000 sheep every year, and the losses in their replacement hoggets were particularly devastating.

It was Colin who drove the FE testing from the Ruakura labs into woolsheds and sheep yards for vets to administer the toxin and measure the response in blood tests using the enzyme GGT (gammglutylthiamase) which had been developed for measuring liver damage in human alcoholics.

Colin was a great driving force to get groups of breeders working together to select for FE resistance, and share the genetic gain made between their own flocks before passing it on to commercial ram buyers.

Two-tooth rams tested
Farmers put up the best of their top two-tooth rams for testing, and only kept those that survived the increasing levels of toxin as the years went on. In theory, if the flock had been achieving overall genetic gain over time, the two-tooths were the best genetics so were the obvious age group to test.

It’s a pity that the test was so expensive, around $300/ram, as it prevented stud breeders testing females, and hence speeding up overall genetic gain in their flock to pass on to commercial buyers. Selection on the female side had to come through survival of the fittest.

Dose rates
Dose rates were based on weight, so when farmers started, this was 0.1-0.2mg of sporidesmin/kg of body weight. Today most Waikato sheep breeders have sheep that will now take 0.6 mg/kg. In today’s flocks even in severe years, they never see a clinical case of FE so the programme has been a massive success.

Disappointing uptake
But the disappointing feature to me was that after 40 years of hard work and investment, none of the Romney, Coopworth or Perendale breeders who put large amounts of time and money into their flocks, got rich selling their FE-resistant rams to committed commercial sheep farmers.

The main reason was farmer complacency – as FE was never severe every year. Farmers seemed to believe that like lightning, it never strikes twice in the same place. So after a bad year, panic many drive farmers to buy FE resistant rams, but it may not based on the 'lightning logic'. But if they did buy the progeny of tested rams from stud breeders as they didn’t see the impact for some years which may not be bad seasons, they concluded that nothing had worked.

Genetic change takes time
Commercial sheep farmers didn’t seem to understand that genetic change took time, especially as new genes were only entering the flock on the ram side. So it took many sheep generations (average 3 years) to see any dramatic change, and it needed a few bad FE seasons to show this.

Buying rams locally
The other frustration was that even after massive losses, too many sheep farmers were loathe to buy rams from their local area. There seemed to be something wired into farmers that made them assume that you had to travel well out of the district to get ‘good rams’!

These 'good rams' were inevitably massive animals, covered in wool and usually very fat, as they’d come from very good farming areas. Some had even been on ‘hard feed’ and regularly drenched before buyer inspection time. Inevitably, these rams came from areas where FE did not occur!

Buying replacement ewes
After a devastating season, farmers never bought replacement sheep in their own area – they always went well away south to sales, which was the very worst thing genetically that they could do, as this diluted any genetic gain made by resistant rams that they had been using.

Stock agents
Stock agents who still have a big effect on farmers' decisions
on where they buy their rams.

Stock agents had a major part to play in this misguided practice, and I battled with many of them over the years about their role in improving hill country sheep flocks in the Whatawhata Research Station (Raglan) area, where lambing percentages were the lowest in the country.

Agents always reckoned that rams from Raglan breeders were ‘too blardy small’, assuming size was a major indicator of genetic merit for sheep to survive and perform on hard hill country. They could never understand that most of a ram’s size was caused by the environment (feeding) and not genetics.

The visual look of a ram always took pride of place in ram selection by agents in those days and any records were a mystery that only held up the 'ram picking' job and delayed the time spent by the drinks cabinet in the front room of the house!

I always suspected there were Company deals going on to move surplus big fat rams from, the classical ram breeding areas (we called them ram alley) in theWairarapa and Manawatu up to the Waikato, as a sort of clearing house for their surplus.

Agents would take off with a car load of buyers at crack of dawn, pick the rams for the client, empty a whiskey bottle or two, and be home after the last pub closed on the way. It was great business as the rams didn’t live long, and the agents got regular business each season and the ram buyers had their ‘ram picking trip’ to look forward to as an annual feature!

I once met a very tired farm manager at 6pm, who had just been dropped off at a friends house where he’d left his car at 4am to be picked up by his agent. He was proud to tell me he’d been ‘to pick the rams’. I asked him where he had been, and he wasn’t sure – other than it was somewhere in the Manawatu and it had taken over 5 hours to get there. I then asked about selecting the rams and he said the agent had done this for his boss, and he just looked on to give them a final approval. I asked if the Sheeplan performance records had been used to pick the rams but he didn’t know what I was talking about. He had not seen any paper sheets around.

Dalton’s 13-pub rule for genetic gain
Once in a farmers’ meeting discussing this issue, I formulated a ‘natural law’ which said that if any sheep farmer wanted to be sure of getting genetic gain through his or her Stock agent, then they had to go past at least 13 pubs in the agent’s car, listening to all the agent’s wisdom and war stories, before genetic progress could be guaranteed from anything they bought! I sometimes still meet many farmers who can remember this – but nothing else I said!

Things have changed
But things have changed, and especially in the last five years, with this year seeing a total clearance of breeders’ rams selected for FE resistance. This is mainly due to increasing dry seasons (climate change or not) and the appearance of FE in new areas of the North Island.

What’s good for stud breeders selecting for resistance, is that seeing FE every year and enough losses to show on the bank balance, has made commercial farmers concentrate on finding a solution – which is through genetics and not their veterinarians. This has never been helped by veterinarians as they are not strong on genetics – and in any case genetics do not sell the farmer anything off their shelves.

Zinc boluses
Zinc oxide boluses for lambs showing the zinc inside
the wax protective cover

Veterinarians do sell zinc boluses for both sheep and cattle. When Ruakura scientists recognised the difficulty of regularly drenching sheep with zinc oxide, they developed these to stay in the rumen and be effective for a month. This delivers a slow rate of zinc as the exposed end of the bolus dissolves.

The bolus is used by farmers who see it, and the costs and work involved in inserting it, as a basic protection. The problem is that it does not provide enough zinc when spores rise rapidly and dangers of toxicity are high. The sheep in the picture at the top of this post were all given a bolus which clearly was not enough zinc to protect them from the 'natural challenge' they got on the farm.

All the past years of research at The Ruakura Agricultural Research Centre has been built into a programme called ‘Ramguard Facial Eczema Tolerance Testing Service’. Here sheep breeders can get information on how to test for FE tolerance and how to build this information into an overall breeding programme. Google ‘Ramguard’ for details.

Tolerance and resistance
I have been involved in many academic arguments about which is the correct term to use. I don’t really think it’s important – I use resistance.

Breeders need thanks
The sheep industry should be grateful to these Waikato breeders of FE-resistant sheep who never gave up, and were prepared to invest in on-farm R & D to deal to a major animal scourge. They have also proved conclusively that to farm sustainably in today’s world, genetics will have a better long-term outcome than chemotherapy.

Further reading
John D.J. Scott (1989). Ruakura - 50 Years of Research and Recreation.
Facial Eczema. Page 29. Chapter by John Scott and Archie Campbell
ISBN 0-477-08021-9.

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