Moving Forward- Breeding for Resistance to Marek's Disease

[welasharon]

I think the issue is a genetic weakness or susceptibility of the immune system. Obviously I have it on my property but the other birds are impervious to it. I am hoping that the ones I have left will pass on that ability to survive it.

 

[Northie]

I think the issue is a genetic weakness or susceptibility of the immune system. Obviously I have it on my property but the other birds are impervious to it. I am hoping that the ones I have left will pass on that ability to survive it.

I'm really hoping this as well.

 

[seminolewind]

I have heard that it takes several generations to breed resistance.

 

[Nambroth]

I have heard that it takes several generations to breed resistance.

For consistent resistance, yes. I read once that 7 years should be a minimum goal. I'll have to see if I can dig that up again. I think it was an article, but it may have been a scientific paper. I've read so many that I can't quite remember.

 

[Northie]

I'm asuming/hoping that you would lose fewer with each passing generation and I suspect how long it takes to achieve resistance depends on how resistant your birds were to start with. It could also reflect how hard you cull the ones who show signs of sickness. I have a hard time watching animals struggle so we'll probably cull pretty hard at first.

 

[seminolewind]

My silkies were my brooders until I found Marek's. I actually hatched 6 silkies following the time that "Typhoid Mary" was here. I didn't know. But all were fine. Then a year after that I hatched 10 Polish eggs under the silkies and they all died one by one.

I let her hatch 2 Polish eggs, I got 2 of the prettiest sweetest roosters. Both died (I culled). Then she hatched a Polish girl who's got to be about a year old now. These last 3 eggs were oops eggs. By the time I went to throw them out, there were viable chicks in there.

Sassy, is there any change in your hen?

 

[chooks4life]

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Apparently as far back as 1930's it was considered feasible to breed for resistance... Yet here we are. I don't know if these links will be helpful or not but they do clearly demonstrate success in breeding for resistance or breeding for susceptibility. The first two links cite studies which successfully bred for high levels of resistance.

This site linked below mentions breeding for resistance too and has a vaccine pros and cons debate linked to in the article I've linked to. At this stage the Marek's vaccine looks all con to me, no pro. At least for people with my objectives. I've never vaccinated for it though I have bought in vaccinated stock and they're always permanently sub-par, I won't bother with those immunologically compromised birds anymore, haven't for a few years now. I'm not sure how much if any of that is blameable on the vaccines as opposed to the usually quite degrading conventional rearing but I support backyard breeders 100% now, lol.
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Not sure what this source is worth but it mentions that Mareks goes in a 7 year cycle so breeding for resistance is a long term project. This one appears fairly anecdotal compared to the others but there's generally mixed bits of truth (and falsehoods, unintentional or otherwise) to be picked up from every source no matter how accredited and well-researched, or well-intentioned.
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This next link is from a vet with 30-odd years' experience who reckons breeding for resistance 'obviates any need to vaccinate against this significant disease'.
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Apparently this isn't the only vet of this opinion, various discussion boards contain references to people acting on their vets' advice and breeding for resistance and succeeding. I have had a very similar experience (minus vet advice, lol), and Mareks' is no longer something I worry about.

Best wishes with your endeavor.

 

[welasharon]

So once a bird survives mareks it is a carrier. I understand that. The ones I have that didn't contract it are supposedly resistant? Breed those and not the survivors? Does becoming a survivor make it a good candidate for passing on resistance? Have not read anything on this yet.

 

[chooks4life]

So once a bird survives mareks it is a carrier. I understand that. The ones I have that didn't contract it are supposedly resistant? Breed those and not the survivors? Does becoming a survivor make it a good candidate for passing on resistance? Have not read anything on this yet.

As far as I understand all birds are considered carriers until proven otherwise. Some people say it's so common all flocks should be considered to have Marek's until proven otherwise, even without any symptoms present.

Some say even resistant birds are carriers, others disagree... It's a fair bit of conflicting info.

Personally, I think resistant birds are not carriers, but, that's just my opinion and may be wrong. As for whether survivors can pass on resistance, I would expect so, after all their immune system mounted a successful defense, hence their survival. Those very weak cases may not be worth breeding though.

I bred for blackhead resistance in my turkeys, it was so successful it's basically immunity really, and a few generations into that program I learned not to breed any who required help to overcome the disease.

At first, yes, they can be worth breeding as they are the very beginning of resistance when you're talking about diseases with up to 100% kill rates, but once you've begun breeding against it I reckon you need to get more and more strict about resistance levels with each generation, as they have resistance breeding behind them so any who are 'back at square one' i.e. showing the same degree of affliction that their forebear showed are not a step forwards and though they appear to be in stasis they may actually be a step backwards.

Just my 2 cents' worth. Best wishes.

 

[sassybirds]

Welcome new faces to this thread! Thanks for sharing your info, though I am sorry for the circumstance. Sorry I have been away... I have been on vacation!

Sassy, seems like your flock would be not getting Marek's with that flock history.  And even with those chicken houses, the chickens are vaccinated and deaths from Marek's is less than 5%.  I'm not saying that your flock can't get it or didn't get it.  Having chicken houses in the area is a risk.

I just lost a hen a few months ago who has supposedly been surrounded by Marek's for 3-4 years, and tested negative!!!  + for Aspergillosis.  I don't believe she could be negative.  So I will send the next one as well.  I wonder if you should send another for a necropsy?

Nutrition.  I think I've read and compared every chicken feed out there, and no matter how pricey, or whatever they promise, instead of beating my head against the wall, I just make sure they have some healthy food from me to compensate, and free range.  I've also added Nutritional yeast fortified with all the B vitamins-just to see.

With feed it seems the most important thing to me is buying it from a feed store that has a really high turnover and the bags don't sit there for months.  Purina even puts the date of manufacture on the bag.

Upon returning home, I noticed a couple more birds that are symptomatic- weak in the legs, lethargic. I have those separated out to take to the lab tomorrow to be tested. My poor little sacrificial lambs! At this point, I would be relieved if it's "just" Aspergillosis!
Although the commercial feed I buy is undoubtedly of inferior quality and of minimal nutrition (Purina), I do check the bags to get the freshest stuff on the shelves. It's usually within a week or two of manufacture.
I don't think it's a vitamin deficiency...I supplement with those as well as free range my birds.

My silkies were my brooders until I found Marek's.  I actually hatched 6 silkies following the time that "Typhoid Mary" was here.  I didn't know.  But all were fine.  Then a year after that I hatched 10 Polish eggs under the silkies and they all died one by one.

I let her hatch 2 Polish eggs, I got 2 of the prettiest sweetest roosters.  Both died (I culled).  Then she hatched a Polish girl who's got to be about a year old now.  These last 3 eggs were oops eggs.  By the time I went to throw them out, there were viable chicks in there.

Sassy, is there any change in your hen?

Well, I had to cull her. She was declining rapidly. Just wasting away. So far I have not had much luck with survivors...only one out of about 20. The most affected were the speckled sussex... I ended up having to cull ALL of them. About 12 birds. Pullets went first, cockerels were trying, but not thriving. 2 of 3 black australorp pullets (the line survivor is almost 5 months. FINGERS CROSSED!!). And now out of 5 splash marans, two pullets. One that I culled last week and the other is going for necropsy along with a Dixie rainbow. The last splash marans pullet seems okay as of right now. Date of hatch 3/8/14. I have some ameraucana and silver laced wyandotte chicks coming along right now...they are 8-10 weeks old. Hoping they will be more resistant and I'll have some birds left to breed from.

So once a bird survives mareks it is a carrier. I understand that. The ones I have that didn't contract it are supposedly resistant? Breed those and not the survivors? Does becoming a survivor make it a good candidate for passing on resistance? Have not read anything on this yet.

I am not an expert, by any means, but from what I understand- birds that have sickened but recovered will be carriers. Birds that remain asymptotic are either resistant or "silent" carriers. If that makes sense. I have been culling ALL birds that have shown themselves to be susceptible.