A mixed day on the chook front!!!

14 years 9 months ago #293547 by Simkin

Sue;276243 wrote:

Then although all the batch may have been affected, around a quarter of them will show symptoms and die.

Birds from breeders who have never vaccinated against Marek's (and therefore breed from stock that has shown good resistance) shouldn't have a mortality rate of more than 10%. Although there are exceptions but then a reputable breeder should warn you.

I didn't have a single case of Marek's during my first years of breeding as I used stock from a VERY experienced breeder who rigorously selected for disease resistance (his contact details are available by pm). Only after I got in a rooster from an 'unrelated' strain I brought in some susceptibility.

Marek's can be bred out - and it can be bred in. The best way to insure that chicks are not susceptible to Marek's is to breed from older stock. The price you pay for this is lower fertility as older roosters aren't as fertile as cockerels.

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14 years 9 months ago #293556 by Sue

The best way to insure that chicks are not susceptible to Marek's is to breed from older stock.

Sorry Simkin, I can't quite agree with this last statement!

Young birds are susceptible to infection from the virus from day old until around 20 weeks of age. If you keep them away from contact with older birds (and contamination from their faeces, fluff and dust) until this time then they will not get Mareks disease.
You can hatch eggs from them and as long as you keep the chicks apart from adults from any source they too will be free of Mareks. The parents, having not had contact with Mareks should not be shedding the virus, so chicks 'should' be safe. However without blood tests you wouldn't know they hadn't had Mareks.

If you bring in a bird from a flock in which Mareks is present (just about every back yard flock) remembering the survivors, even 2nd and 3rd year birds may still shed the virus, then your young birds which have never been exposed will always be susceptible until 5 months of age.
It is not egg transmitted, so you don't bring the disease in with buying hatching eggs. The chicks which result may be from birds which have a genetic resistance or the may be totally susceptible to Mareks which exists in your flock, but keeping them isolated till 5 months of age helps protects them until old enough not to be affected.

Unless blood tests are done looking for antibodies against Mareks disease you wouldn't know whether a bird was positive or negative for Mareks disease.
Just by breeding from old birds does not guarantee Mareks resistance, it may just be a survivor!
So if a bird is genuinely genetically resistant (identified by blood typing)it can be bred from at any age.

Labrador lover for yonks, breeder of pedigree Murray Grey cattle for almost as long, and passionate poultry person for more years than I care to count.

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14 years 9 months ago #293568 by Jenny
Many thanks for the info Simkin and Sue.

I had 4 chicks hatch from the same batch as this rooster and the others (girls) seem fine. These eggs that I bought were put under a broody hen and that was what I was hoping to do with the next lot of eggs (from here) when one of my old chooks goes clucky. Is there much point in keeping them in a seperate area for 5 months or will they be susceptible to Mareks from the hen anyway?

Now that it has showed up is there anyway I can get rid of it or can I just hope the chicks that are born will establish a resistance?


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14 years 9 months ago #293570 by Simkin
Hi Sue,

you are - of course - right - but I'm not wrong, either.

In my situation (which probably is representative for the majority of backyard and small farmyard breeders) the chicks are exposed to Marek's at a very young age, especially the ones raised by a mother hen. In my experience hen raised chicks don't develop Marek's nearly as frequently as hand raised chicks. The early and the very late chicks spend their early days in our lounge to move into the garage at about 5 to 10 days old depending on weather. (With the exception of last year's buff chicks.)

I have for instance just put my wee chickies into a run on grass outside in our garden with adult hens peeking in.

The summer hatched chicks don't get Marek's any more often than the early and late ones although they are in the garage from day 1.

Many of my backyard chicks may well be survivors but if they never showed any symptons who cares? I don't. If their immune system is strong enough to get over it they'll produce chicks who are likely to fend off an infection, too.

If a chick is not strong enough to fend off the Marek's virus then it may well die as a young bird. However, Marek's sometimes only becomes apparent at the time a pullet starts to lay which is at the 'tender' age of 9 months in the case of most Orpingtons. If they get past this hurdle the next hurdle is their first moult. Some birds develop Mareks when they are over a year old. I've had one such case. She was the mother of dozens of my chicks[:(!] Had I waited with breeding from her until her second laying season this would never have happened.

That was the defining moment when I brought Marek's into my flock because I had no choice but to breed from her offspring and back then I was more soft than I'm now. But you need to get burnt hard to change attitudes. I think I have eliminated most of the susceptible birds but only next season will show.

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14 years 9 months ago #293571 by Simkin
Hi Jenny,

just do what you intend to do. It may just be bad luck that you had a case of Marek's. Some chicks get it but never show symptoms.

Hen raised chicks tend to be a lot healthier and resistant to diseases like Cocciodiosis so any disadvantage in exposure to Marek's is outweighed by advantages.

You'll never be able to get rid of Marek's - it's everywhere, you can only limit the exposure. Let your hen do the job for you and if you loose another one down the track just consider how much work your hen has spared you.

Also a bird that doesn't get Marek's because it hasn't been exposed to it at a young age (Sue's point in her post above) may very well produce susceptible chicks in the future. I honestly think that when you are breeding it is better if that bird never makes it as a breeder.

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