Moving Forward- Breeding for Resistance to Marek's Disease

[speckledhen]

Hi seminolewind,

What I hadn't heard stated quite so directly before I read this is the idea that the vaccinations can be detrimental in the long run - or maybe chooks4life has said it -- but just not in a published article.

"The philosophy here is that vaccinating the entire flock masks the weaker individuals that succumb to the disease weakening your breeding program and the health and strength of your best birds in the process."

That statement is pretty much the way I've been feeling about the vaccination, though it is not for me to ever tell anyone what to do with their flocks as far as this disease goes, other than to avoid causing harm to another person's flock by knowingly passing it on. If I was starting fresh and only keeping a small group of penned layers, I might go the vaccination route as long as I was ordering direct from a hatchery myself, something I've never done. I'm convinced for myself that the consumer vaccine is not effective from speaking to the big time poultry vets.

 

[PetRock]

I'ld be interested in hearing what people are doing with their flocks if they have mareks?
- letting them dwindle and no more chickens eventually?
- bringing in chicks and keeping separate for 6 mo
-letting broodies sit and hatch, mixed with flock

whats the game plan?

so far, everyone seems/appears fine. Its been a month since the diagnosis of mareks in one 4 mo old rooster. waiting for the other shoe to drop.

I am interested in the answers to these questions, also. I lost a 28 week old Langshan cockerel mid September and the necropsy results said that based on the case history and some cellular evidence it was indicative of Merek's. He had no tumors or eye problems. He had problems with both hock joints and then got picked on by the other cockerels in the pen before I isolated him. My breeding stock is at a friend's farm 20 min away and I'm only out there every 7-10 days. They are farmers not chicken breeders so any sick chickens are usually culled or die then are buried before I am told about them. I had 2 other cockerels that were limping and each had problems with only 1 hock. We processed them and the joints were very much enlarged but all organs looked normal. I've been told that because Langshan are such big birds, they can have joint problems similar to what Cornish cross can have. So, I'm watching my flock and wondering if it is Merek's or growth problems. We lost one more of the Langshan cockerels a couple weeks ago but he was long buried before I knew about it. I've asked them to let me know the next time they see any of the birds limping or showing signs of illness so we can cull it and send it to UC Davis for a necropsy. Meanwhile, I have too many POL pullets here in town that I need to do something with. I hate to process pullets but without knowing if it is Merek's in my flock, I can't in good conscience sell them. I guess that I am waiting for the other shoe or shoes to drop, also!

Edited to add the actual comment from the necropsy: The histopathologic findings in the brain, heart, lung and skin in addition to the clinical history are suggestive of
Marek’s disease caused by gallid herpesvirus 1.

 

[speckledhen]

Hock issues could also be MS (Mycoplasma Synovaie). That can be passed through the egg. I believe a friend, an NPIP breeder, had to cull her entire flock due to contracting that through hatching eggs, Marans, I think.

Quote: http://www.thepoultrysite.com/publications/6/diseases-of-poultry/183/mycoplasma


The point is that lameness can be many things other than Marek's, including gout. I knew of someone who was experiencing lameness in Brahma males, only males. Turned out to be gout.

 

[chooks4life]

Thanks for sharing that. All common sense went out the window to me when she mentioned raising a few turkeys with a flock of chickens. I won't argue about it either.

The reason behind it is simple and commonsense; while they don't 'catch' Marek's from the turkeys per se, they do gain antibodies to it via some comparatively harmless exposure.

I've found people making all sorts of claims about raising them together on this forum despite the problems that also turn up on the forum, and the century long practice of raising different Avian species separate.

Yep, and I'm one of those people you've 'found' making such claims, lol, we did discuss this recently. What works for some does not work for all but it doesn't mean that there is only one 'proper' way to raise poultry.

Regardless of a given separatist practice being a century old, historically there's been far more centuries of raising them together.

A comparatively modern trend working in practice for some people does not equate to representing the only commonsense approach to managing a situation.

When science discovered turkeys don't get Marek's and a vaccine of non-infectious type was derived from the turkey virus which blocks Marek's from infecting turkeys. In simple terms I need to understand, the turkey virus in the vaccine does not put a case of Marek's in the chicken as some other vaccines do. In the case of the vaccine derived from turkeys, it must get into the chicken's system before the Marek's virus does.

So that does not even justify raising turkeys with chickens, in addition to the other reasons (Histomoniasis, bickering, injuries, increasing the odds of other viral mutation, etc.).

Turkeys do get Marek's as far as I understand, just not the same form and it's not anywhere near as much of a problem for them. Chickens exposed to them develop antibodies that assist them when they are later exposed to the chicken's form of MDV. Those statements have not been challenged on any scientific site I've seen, right now it appears to be accepted as the facts of the matter.

As for the bickering etc, that doesn't happen in all flocks, and blackhead isn't a problem for all flocks either, and none of those potential issues are enough of a risk to be worth writing off everyone who keeps inclusive/mixed flocks as being improper poultry keepers. Not saying you're doing that, obviously. Just making a case for the many and varied ways one can 'properly' raise a healthy flock, mixed or otherwise.

Statistically speaking, there's far greater risk of viral mutations occurring in even non mixed flocks where combination vaccines are used, and/or strong chemical/artificial treatments, than from species mixing as they naturally do. No species naturally lives in isolation and no matter your security attempts you cannot guarantee them isolation from the greater ecosystem.

I'ld be interested in hearing what people are doing with their flocks if they have mareks?

- letting them dwindle and no more chickens eventually?
This will not occur unless 100% of your birds are 100% susceptible.

- bringing in chicks and keeping separate for 6 mo
Unnecessary unless you have the aforementioned extreme susceptibility scenario.

-letting broodies sit and hatch, mixed with flock
It's what I do, and it's what I've seen others with verified Marek's do, and it does seem to be the best solution if one includes breeding those chicks from the survivors.

whats the game plan?
The game plan will necessarily vary between owners, with their different environments, differing levels of susceptibility, and the differing strains of Marek's. What's right for you is what you should do, not just follow (for example) my game plan which would be detrimental for the wrong person with extremely susceptible birds.

so far, everyone seems/appears fine. Its been a month since the diagnosis of mareks in one 4 mo old rooster. waiting for the other shoe to drop.

Sounds like there's hope then, as far as I know if you had very susceptible birds or a very virulent strain you would be in the midst of a massacre right now. It may be incubating, or it may be developing somewhat atypically, but you're already in a better off position than some other unfortunate people. Hope it works out for you.

Best wishes.

 

[PetRock]

Hock issues could also be MS (Mycoplasma Synovaie). That can be passed through the egg. I believe a friend, an NPIP breeder, had to cull her entire flock due to contracting that through hatching eggs, Marans, I think.

http://www.thepoultrysite.com/publications/6/diseases-of-poultry/183/mycoplasma


The point is that lameness can be many things other than Marek's, including gout. I knew of someone who was experiencing lameness in Brahma males, only males. Turned out to be gout.

Thank you for this info! I requested that they test for MS and MG when I submitted the cockerel and they didn't report back on either of them. I guess that I was just assuming that they did the tests and they were negative. Maybe they assumed at the start that it was Merek's and didn't do the other tests that I requested. That is interesting about the lameness in Brahma males since they are a large Asiatic breed also. My boys are huge and maybe I'm not meeting their dietary requirements. Off to research gout in chickens...

 

[speckledhen]

Thank you for this info! I requested that they test for MS and MG when I submitted the cockerel and they didn't report back on either of them. I guess that I was just assuming that they did the tests and they were negative. Maybe they assumed at the start that it was Merek's and didn't do the other tests that I requested. That is interesting about the lameness in Brahma males since they are a large Asiatic breed also. My boys are huge and maybe I'm not meeting their dietary requirements. Off to research gout in chickens...

The bolded part of your statement has always concerned me. Statements like "there are two kinds of chickens, those that have Marek's and those that will get it" bug the heck out of me.That is the attitude that makes them go right to a Marek's diagnosis when they see a tumor. Unless there is definitive tissue testing, no one can say that for sure. There are numerous tumors that are not Marek's and not even cancerous as well as many reasons for lameness in chickens. After a conversation with a fine vet in Kentucky, and hearing his issues with them, I am more adamant in my lack of trust in labs now than ever. You'd have to go with your gut about whether you trust the test results. Question them if you are not satisfied.

I think our experience tends to color our opinions with chickens quite a bit. Folks with extensive Marek's experience tend to go to that direction when they see a lame chicken or one wasting away. I know experience warped my own perception for a long time after losing so many to internal laying and egg yolk peritonitis. Bird after bird showed the same cheesy masses, but finally, one had the same outward symptoms as the others, but when I looked inside, shocker, ZERO sign of internal laying/EYP. She had reproductive cancer, but for all outward appearance, she was laying internally. Symptoms can fool you, being similar in many different malfunctions/ailments.

 

[chooks4life]

The bolded part of your statement has always concerned me. Statements like "there are two kinds of chickens, those that have Marek's and those that will get it" bug the heck out of me.That is the attitude that makes them go right to a Marek's diagnosis when they see a tumor....

....Symptoms can fool you, being similar in many different malfunctions/ailments.

X2. I think they go to the worst case scenario as a sort of habitual damage control mechanism, e.g. 'I'm going to assume it's the worst thing it can be, and act/treat accordingly, just in case'. In fact I've heard of doctors and vets being given that sort of advice from more experienced colleagues as a sort of 'cover all the bases'/reduce chances of worst case outcomes sort of measure.

Best wishes.

Re: my earlier comment about risks of using combined vaccines, with them being more likely to cause mutated viruses than merely mixing species, here's a little info on that... While it speaks of 'experimental conditions' this actually refers to an accidental fatal outcome in Australian flocks where a combined vaccine resulted in a virus mutation that decimated flocks.
Quote:

 

[Michael Apple]

"Chickens are the most important natural host for Marek's disease virus, a highly cell-associated but readily transmitted alphaherpesvirus with lymphotropic properties of gammaherpesviruses. Quail can be naturally infected, and turkeys can be infected experimentally. However, severe clinical outbreaks of Marek's disease in commercial turkey flocks, with mortality from tumors reaching 40%–80% between 8 and 17 wk of age, were reported in France, Israel, and Germany. In some of these cases, the affected turkey flocks were raised in proximity to broilers. Turkeys are also commonly infected with turkey herpesvirus (HVT), an avirulent strain related to Marek's disease virus that is commonly used as a Marek's disease vaccine in chickens. Other birds and mammals appear to be refractory to the disease or infection."
http://www.merckmanuals.com/vet/poultry/neoplasms/mareks_disease_in_poultry.html

"We know that early immunisation of breeder chicks is a key factor in the control of the disease, and in ovo vaccination is a very important tool for this control.
"Classical vaccination programmes are based in the application of a bivalent vaccine in day-old chicks via subcutaneous injection, but in some cases subcutaneous administration has not been proven to produce the best immunity level – particularly when there is significant disease challenge. In-ovo typically produces better protection in early challenges."

http://www.thepoultrysite.com/articles/1885/prevention-is-key-to-controlling-mareks-disease

 

[seminolewind]

I'ld be interested in hearing what people are doing with their flocks if they have mareks?
- letting them dwindle and no more chickens eventually?
- bringing in chicks and keeping separate for 6 mo
-letting broodies sit and hatch, mixed with flock

whats the game plan?

so far, everyone seems/appears fine. Its been a month since the diagnosis of mareks in one 4 mo old rooster. waiting for the other shoe to drop.

My personal game plan is to let my flock reduce itself by old age, etc, and I would like no more than 15 chickens. I have 29 right now, but because of Marek's I still have 5 roosters so I have 5 flocks. Too much for me. If I get new chicks it will be vaccinated hatchery chicks because if I hatch chicks, I'll have all those roos again. I can't give them away, and by the time I can give them to someone to eat them, I get too attached to them.

I had a broody hatch 2 and they developed paralysis at 8 months old. Then she brooded one egg and that pullet lived for 8 months and just looked sick and died. I tried to treat her but it was too late.

If you've had a positive Marek's, and want to continue to increase your flock, I would think about what you can deal with afterwards, or do what's necessary to have them not die. I'll vaccinate, since they are pets. I don't have the means to separate them for 6 months.

Hopefully, you won't lose anymore, it's a sad thing.

 

[speckledhen]

My personal game plan is to let my flock reduce itself by old age, etc, and I would like no more than 15 chickens. I have 29 right now, but because of Marek's I still have 5 roosters so I have 5 flocks. Too much for me. If I get new chicks it will be vaccinated hatchery chicks because if I hatch chicks, I'll have all those roos again. I can't give them away, and by the time I can give them to someone to eat them, I get too attached to them.

I had a broody hatch 2 and they developed paralysis at 8 months old. Then she brooded one egg and that pullet lived for 8 months and just looked sick and died. I tried to treat her but it was too late.

If you've had a positive Marek's, and want to continue to increase your flock, I would think about what you can deal with afterwards, or do what's necessary to have them not die. I'll vaccinate, since they are pets. I don't have the means to separate them for 6 months.

Hopefully, you won't lose anymore, it's a sad thing.

I completely understand Karen's plan. And if I was down to zero and was starting at Square One, I'd probably order vaccinated hatchery pullets. I am not 100% sure about it, but I could see doing that, if I wanted just a small coop of egg layers and did not want to breed again. If you are not breeding up a self perpetuating population that you want to be naturally resistant, which of course, is the subject of this thread, that to me would be the way I'd vaccinate my flock, at least at this point in time, from all I've been reading on this disease. Hope that makes sense.

Of course, then, I'm back to dealing with reproductive issues and they'll be dying from that mess again. So, I feel like I'm between a rock and a hard place, with my history with hatchery stock. At least, internal laying and egg yolk peritonitis are not contagious.