Boletim Técnico No. 33
Facial
Eczema, it Should Scare You, but There is a Solution.
Edward
Dinger, Ceres Farm Ltd.
Member
N.Z. Ovine Reference Scheme
That
is too often to be a coincidence; it must mean that some scientists and the greenies are
right after all and that we are in a phase of global warming. Leaving other effects out of
the picture, it means that places you always thought of having cool enough nights, will be
now within reach of the fungus called Pithomyces chartarum.
In
other words, virtually the whole of the north islands and several coastal bits of the
south island, can at least expect some effects of a disease that for some is a total
unknown quantity. If this sounds serious, I think it is. Facial eczema is a serious
disease, which if you did not already know it, can be fatal for your sheep and may damage
the health of your cattle. It is estimated to cost the nation millions every year, in some
years tens of millions. In 1981 58.4 million dollars for 1999 the estimate is between 65
and 75 million.
Most
likely it will surface on your place as something you cannot see, sometimes have, without
you knowing or realising it, it is called sub-clinical facial eczema.
So
if you have more dry ewes than you can explain or a lambing percentage that you don't seem
to be able to improve on, too many ewes with dead lambs, ewes that run dry before you are
weaning, hoggets that don't seem to want to grow, even with plenty of feed about, it is
more than probable that sub clinical FE is at the root of your problems.
Here
is a pleasant surprise for you. There is a solution for this, you can do something about
it. It won't cost the earth either, but it will take a few years to solve...
You
will have to find a ram breeder that test his rams for his own use for tolerance to Facial
Eczema, it is as simple as that.
I
will give you a short description of what the test procedure entails. Out of the top 10%
of my 2th ram selection list I choose 15 to 20 rams. The vet comes and bleeds them and
their blood taken is tested for GGT levels.
GGT
is short for gamma glutamyl transferase, an enzyme that leaks from your liver. For sheep
this level is normally between 30 and 55. If there is something wrong with the sheep's
liver function, these levels can be much higher. So if there has been eczema about, and
liver damage occurred, it shows in the GGT levels. The rams with raised GGT levels are
taken out. The ones that looked OK are given a dose of sporidesmin, this is the toxic
substance that is produced by the FE causing fungus and which causes the liver damage
responsible for facial eczema.
Three
weeks later an other batch of blood samples is taken and the score of GGT levels, gives an
indication on how tolerant the animals have been, for that dose. If the breeder feels that
not enough animals have reacted, he can give the nil reactors another shot to separate the
men from the boys. Of course you don't want to kill the animals so Ramguard carefully
works out, how high your dose rate should be. They work that out from your past history,
the usage of the tested rams and whether you had FE that season.
Now
if the breeder has used FE survivability as its first priority, as I have, you can make
reasonably quick progress. Facial Eczema has a very high factor of inheritability, 40-42
%, compare that with fleece weight at 25%, fertility at 12%.
It
took me 15 years to increase the dose rate to 5 times than that I started out with. I
estimate that my flock can now handle up to 400.00 spores (the peak level last year)
without getting clinicals in a normal season.
If
the season is prolonged I still expect to get hit, but I won't have anything near the
devastating effects, that a non FE breeder will experience.
In
the meantime my lambing percentage increased from 135% to 180%, fleece weights per animal
increased by 1.2 kg, weaning weights of the lambs by 4.5kg.
The
steepest increases occurred over the last five years. My stocking rate did not change and
I did nothing different in overall breeding policy. But in order to feed my ewes better, I
had to lamb a few weeks later.
In
my opinion the above results have come about, purely because my sheep have become tolerant
for the average yearly toxic effect of FE and can now express their genetic ability,
without anything hampering their progress. For the first time it is now possible to
compete with sheep of the south island and match their profitability.
Besides
the visible effect, there is this hidden factor, sub-clinical facial eczema.
The
biggest impediment in the general acceptance that facial eczema is a problem, is its
haphazard occurrence over the past decades. Some of you might have seen it once or twice,
but then it disappeared for years. But without you realizing it, it was damaging your
stock almost every year. It has been the frustration of FE ram breeders to convince you,
that this was going on.
Few
farmers really want to believe it, but if there are any limitations in your production,
there is fair chance sub-clinical facial eczema is the problem.
Sub-clinical
facial eczema not only limits production (fertility, growth rate, fleece weight) it also
lowers the general immunity of sheep, so it gives you all sorts of what seems to be,
unrelated problems. Above all, it limits the life time production of your replacements ewe
hoggets, without you having a clue of what is going on.
People
hate change and farmers even more than most. Yet, if you want to stay in sheep farming you
will have to increase your profitability, which at the moments means more lambs for sale.
That will mean that you, rather then your stock and station agent, will have to make the
choice where you buy your rams. Think about it, you need rams anyhow, you might as well
buy from a ram breeder that breeds for FE tolerance.
They
won't be more expensive, although they should, it cost about 150 dollar to test each ram.
Over 15 years it has cost the ram breeder tens of thousands of dollars. Since it takes a
few generations to take effect, give him a chance, stick with him for a while.
Be
sure that he has a FE certificate issued by Ramguard, which tells you how long he has been
at it, what dose rate he uses (it should have risen), numbers of rams tested, and how many
passed the test.
There
are some hidden benefits to a change as well. Because tolerant sheep don't sustain the
same liver damage, the improved ovulation rate does limit the damage caused by another
group of fungi called "Zearalanone" (of which Fusarium is one). This is strictly
my opinion and Dr. Neale Towers warned me that there is no data to support this theory.
If
you have not heard of the oestrogenic effect of Fusarium, read the article in another
section on this site..
All
this plus the advantage of a possible better functioning immune system, give a compelling
reason to change to a FE tolerant ram breeder.
To
alleviate some myth's I would like to make the following general comments and they are my
observations only, I don't think there is any scientific data to back me up. Put it down
to my gut feeling, experience and common sense.
The
obvious question, I have got clinical cases, what do I do now?
The
answer is simple: bugger all. The only thing you can do, is avoid stress to the animal,
give a low protein diet with no chlorophyll in it (hay, silage etc.), as much shade as you
have, water and keep the zinc dosing up as long as there are spores about. Keep monitoring
spores by sending grass samples to your vet (learn to spore count yourself).
There
is a strong correlation between copper deficiency and FE, which is one explanation why the
Finn seems to have a reasonable tolerance(it is chronically copper deficient) and the
Texel is so prone(there is no copper in the soil island of Texel ). Avoid copper
supplements as the plague if you expects FE to be a problem. Copper activates sporodesmin
toxin in the process of metabolism in the liver. Even the minute quantities in mineralised
drenches are enough to be harmful.
Supplements
of liver stimulants like vitamin B especially B12 could help.
It
is a myth that high rainfall eliminates FE spores. Although spore counts usually go down
after heavy rain, they can build up again very quickly afterwards. Same after a few cool
nights or even frosts. In some seasons spore counts can remain high well into month of
May.
Another
nuisance is the use of the word "resistance" even by scientist, when talking
about facial eczema. Webb's dictionary explains: "resistance is the ability of an
organism to ward off disease" whereas "tolerance is the natural or developed
ability to endure or resist the harmful effect of or the continued use of a drug." I
have always insisted on "tolerance" for facial eczema for the reason that
"resistance" creates the wrong impression. Given a high enough dose by natural
or artificial means, even a highly tolerant sheep will get FE.
Rye
grasses are the worst amongst grasses for FE, grass species, brown top, dantonia, tall
fescue, kikuyu, paspallum have less spores. Clovers, lotus, chicory and brassica's are
relatively safe.
So
there is a strong case to be made to have part of your farm (approx. 10%) in rye grass
free pasture. My advice would be a chicory clover mixture. Read about it in the sheep
feeding section. One last remark, FE should be tackled on different fronts. Dosing with
zinc should be a last resort, not the only solution.
P.S.
The following comments from an article by Mrs. Gladys Reid of Te Aroha:
The
liver metabolises products by using enzymes to oxidise these products. It is a very
complicated process. Metal catalysts are necessary for auto oxidation of sporodesmin.
Sporodesmin
is an inert pre-toxin till subjected to oxidation in the liver. Even small traces of
copper will trigger spontaneous auto oxidation of sporodesmin. It acts like throwing
petrol on a smoldering fire.
Low
protein diet reduced liver activity and works as a detoxifying agent and also reduces the
incidence of fibrosis and cirrhosis of the liver.
Zinc
and high carbohydrate diet work well together in the presence of sporodesmin.
Copper
and high protein diet or starvation stimulate more toxic liver products from the liver.
Facial
Eczema Fact Summary
·
Farmers
judge FE by the number of animals with clinical (visible) symptoms. But the grater concern
is the number of sub-clinical, since this is liver damage that is not visible.
·
Sub
clinical Facial Eczema suppresses the immune system, reduces fertility and growth rate and
increases the number of barren ewes.
·
With
global warming, Facial Eczema will be a recurring problem, but most of the time farmers
won't be aware of it. Low spore counts will cause non-visible liver damage and threaten
animal health.
·
Breeding
for increased tolerance to FE should be the first line of defense. Consistently buying of
rams from FE tolerant flocks, will in only a few years, reduce liver damage and protect
your stock.
·
Facial
Eczema outbreaks in the North Island are most severe on pasture, where rye grasses are
dominant and have been closely grazed after a dry period and then flushed after rain.
·
Having
an area set aside with clover/chicory, clover/tall fescue, or sort like mixtures will not
only be an excellent second line of defense for FE, but could also boost lamb growth in a
crucial time of the year and protect ewes from zearalenone when the rams go out.
·
Zinc
products should be your last resort, not the only one.
By
special and kind authorization of:
Edward Dinger.
128 Baker Road,
Whitehall, R.D.4,
Cambridge, New Zealand.
Phone/Fax:
(07) 827-8784
Email:
aedinger@ceresfarm.co.nz
