Moving Forward- Breeding for Resistance to Marek's Disease

[Nambroth]

Truly, it all comes down to goals. There are pets, then there are breeder birds, then The Industry. And sometimes it is not always clear cut when we do it ourselves. Many people breed but their birds are also pets, etc.
In the end, educating oneself and being smart about what you intentionally breed is a very solid start.

I have pet birds and do not breed, so my answer is to vaccinate and try to save the ones I love. The will not pass on their inferior resistance because they won't reproduce. This is acceptable to me as my use of the vaccine does not make the virus any stronger; unlike the use overuse of antibiotics creating antibiotic-resistant disease, Marek's disease is a herpesvirus, and interacts only with the immune system. Based on my understanding, the evolution of different strains and virulence of the virus has more to do with the fact that there are many more chickens on the earth than ever before (and more immune systems to combat), that are being transferred all over this earth in ways that were impossible before, and less to do with the vaccine. In the last century because of our ability to transport birds so easily (especially domestically! We can put them in the mail!), we have gone from chicken populations existing in isolated pockets (depending on the landmasses) to it being a global community for this disease. There's no one answer and it is an evolving science.

 

[seminolewind]

Truly, it all comes down to goals. There are pets, then there are breeder birds, then The Industry. And sometimes it is not always clear cut when we do it ourselves. Many people breed but their birds are also pets, etc.
In the end, educating oneself and being smart about what you intentionally breed is a very solid start.

I have pet birds and do not breed, so my answer is to vaccinate and try to save the ones I love. The will not pass on their inferior resistance because they won't reproduce. This is acceptable to me as my use of the vaccine does not make the virus any stronger; unlike the use overuse of antibiotics creating antibiotic-resistant disease, Marek's disease is a herpesvirus, and interacts only with the immune system. Based on my understanding, the evolution of different strains and virulence of the virus has more to do with the fact that there are many more chickens on the earth than ever before (and more immune systems to combat), that are being transferred all over this earth in ways that were impossible before, and less to do with the vaccine. In the last century because of our ability to transport birds so easily (especially domestically! We can put them in the mail!), we have gone from chicken populations existing in isolated pockets (depending on the landmasses) to it being a global community for this disease. There's no one answer and it is an evolving science.

In 100 years, the only thing that has been done about Marek's is inventing a vaccine that makes a chick resistant to the symptoms of the virus. That's the only tool we have at this time to prevent chickens from dying from Marek's. If Marek's is not passed from hen to egg to chick, how can resistance be passed on?

I wonder if there's anything to this: I had a roo and some chicks hatched here unvaccinated. They went to a farm at about 8 weeks old.
The hens stayed there fine, but the rooster came back to me at about 2 months later. He's now 1.5 year old and fine.

I had a hatch of 7 Polish that I vaccinated and quarantined. At 8 weeks old, one Pullet developed paralysis. I could not bring myself to do anything. So she lived in my bedroom for 6 weeks. In that time, she started to stand, then take a step , then enough steps and walk again. She started laying eggs at about 20 weeks and still does. I lost all but 1 other hatchmate from enteritis, no symptoms.

My next door neighbor has 1 three or four year old roo, and two 1.5 year old hens from me that are still there and were never vaccinated. I had taken one of his hens at 3-4 years old with a broken leg and after 6 weeks, she invited herself into my flock and is still with me 3 years later.

So , not enough evidence, but I do wonder if resistance can be built by way of being exposed , then kept away for a period of time and then reintroduced. Maybe the concentration of virus is an important factor in whether a chicken gets the symptoms or does not. I also think there may be times of different concentrations of virus and that may be an influence.

I have pets too, so I won't be experimenting with this.

Chooks, there are many viruses past and present that have not been controlled or eradicated by vaccine; HIV, Herpes, Smallpox was eradicated by vaccine due to almost everybody being vaccinated. But it was not "cured" The common cold is still an annoying virus. Children have been vaccinated for years and years against things like measles because there's no way to eradicate it or build resistance.

It's unfortunate but sometimes artificial means is the only way.

And it's pretty interesting to get input all the way from Australia!

 

[speckledhen]

My poor DH euthanized a young hen today who had been going downhill for over a week. That is so hard when they aren't really ready to let go of life, and I find that my birds generally are very strong, overall, so they hold on longer than many would, and fight to stay like tigers. She had generally the same outward symptoms as the other same-age hen who died with the abnormal liver and intestines so I decided I had to drive the two hours to the lab to have a necropsy done. Nasty, rainy day, not a pleasant drive but the lab was easy to find, at least.

Just got the preliminary report and a short email from Dr. Davis. Will have to wait for tests on organs to come back, but to quote the vet in his email, "She had an overwhelming bacterial infection in her ovaries and body cavity" The AIV (Avian Influenza?) was negative as was the ACIA (??), but other results are pending. Doesn't really say much on it, but if she ends up negative for contagions, then I'd say the other hen would have been as well since they were like two peas in a pod, sisters and pals, always together.

Quote:

 

[Northie]

No the disease isn't passed through the hen to the egg it's the genetic potential to be resistant. That potential plus environmental conditions gives the birds the chance to be resistant. The disease may still take them, even if they were more resistant, if their environment sucks and they're already stressed and sick or, oppositely if they're very healthy and happily stress free they may seem to be more resistant to disease. A cold always seems to hit you harder when your run down right.

...And yes if a survivor is re-exposed to the exact same strain of disease a second time they should be immune, those of us who had chickenpox as kids usually only got it once right

Not many disease are 100℅ fatal to the entire population. It will be fatal to a percentage, another percent will be strongly affected but survive, some will only be mildly affected and others would appear to be completely immune.

 

[speckledhen]

My premise, though I never gave Marek's that much thought in the scheme of things back then, has always been that the most important thing is to manage your birds in such a way as to boost their natural immune systems so that germs will "pass them by".

You know that exposure does not necessarily mean infection or no one could go to a doctor's office waiting room for fear of catching every disease carried by every person in there. Your immune system being a force field is what keeps you going and I believe it's the same with chickens. So, if they are very strong and healthy and non-stressed birds, "happy" birds, they might walk among the Marek's germs and be safe from them. It's really overly simplistic but isn't that what an immune system does? That to me is what you call breeding for resistance, but not just to Marek's but to all contagions.

 

[seminolewind]

Cynthia, I would think if your hen at anything to do with Marek's , she would have tumors-lots of them-enough to be on a necropsy. (Right , Nambroth?)

Valerie and my silkie both went for necropsies a few months apart. Neither had Marek's. Neither died from it. So we obsessed people are still looking for an answer to why we can get negatives from positive chickens.

My silkie necropsy (I thought it would be Marek's) was a Capillaria infestation that damaged her small intestines and coccidia waltzed in and caused Enteritis. The histologies on all her organs including brain, lungs, heart, liver, etc, were all within normal limits. No tumors? I will keep sending demised chickens as long as I can.

"She had an overwhelming bacterial infection in her ovaries and body cavity"

I'm not sure what would cause this. Sounds almost like peritonitis without egg yolk. And to have 2? This one only 16 months old. I'm glad you are getting this necropsy. With all the past hens you lost with egg yolk peritonitis, I wonder if it ties in . I'm just thinking out loud. I'm not educated in these things. Thanks for posting the initial report, I am very interested to see the rest.

 

[welasharon]

I'm only having an issue with only certain birds...sptizhauben and tolbunt polish. All my other birds....the golden laced polish, cuckoo marans, french copper marans, barred rock, breda, white faced black Spanish, serama, modern game, some silkies and some o shamo all live on the same ground around and about these others and have not had problems with marek symptoms.

 

[speckledhen]

Cynthia, I would think if your hen at anything to do with Marek's , she would have tumors-lots of them-enough to be on a necropsy. (Right , Nambroth?)

Valerie and my silkie both went for necropsies a few months apart. Neither had Marek's. Neither died from it. So we obsessed people are still looking for an answer to why we can get negatives from positive chickens.

My silkie necropsy (I thought it would be Marek's) was a Capillaria infestation that damaged her small intestines and coccidia waltzed in and caused Enteritis. The histologies on all her organs including brain, lungs, heart, liver, etc, were all within normal limits. No tumors? I will keep sending demised chickens as long as I can.

"She had an overwhelming bacterial infection in her ovaries and body cavity"

I'm not sure what would cause this. Sounds almost like peritonitis without egg yolk. And to have 2? This one only 16 months old. I'm glad you are getting this necropsy. With all the past hens you lost with egg yolk peritonitis, I wonder if it ties in . I'm just thinking out loud. I'm not educated in these things. Thanks for posting the initial report, I am very interested to see the rest.

What is odd is her age and that she is not hatchery stock, but a cross of two heritage lines. That is very unusual and surprising. And she was laying probably three weeks prior to me noticing she was ill. What is also odd is that someone knowledgeable (has had chickens as long as I've been alive, a breeder and tester for the state) who saw pictures of the first hen's liver and intestines said he thought it looked remarkably like histomoniasis (blackhead). Now, that would make sense if that first hen ate worms like the one I just necropsied did. She slurped them like spaghetti. Many of my birds won't touch worms at all, I've noticed. They might have picked up the parasite that causes blackhead in some high concentration, foraging together, but then again, as you said, there are numerous reasons for a sorry looking liver. The vet at UK that Ladyhawk spoke to, after hearing the description from her about my hen, said he can think of a dozen things that would cause a liver like that and only two are contagious, so here's hoping I get one of the other ten- I'm on pins and needles to see what the cultures show. Of course, I'd prefer blackhead to Mareks or LL!

I'm only having an issue with only certain birds...sptizhauben and tolbunt polish. All my other birds....the golden laced polish, cuckoo marans, french copper marans, barred rock, breda, white faced black Spanish, serama, modern game, some silkies and some o shamo all live on the same ground around and about these others and have not had problems with marek symptoms.

That is interesting. Maybe certain breeds are just weaker overall? I've always thought of Silkies as not that hardy.

 

[tridentk9]

That is interesting. Maybe certain breeds are just weaker overall? I've always thought of Silkies as not that hardy.

Yes. It can be a breed difference (fe LH and RIR respond differently to some meds/vaccines), a genetic strain difference within the same breed (MDV resistant and susceptible strains exist), a family difference or an individual's difference.

 

[drumstick diva]

Northie, in regard to your comparison to chicken pox. You don't get it a second time but, it can later be reactivated as SHINGLES. Would Mareks possibility return in a different form?

As kids two of us (my brother and I ) both got chicken pox as youngsters. I shared a room with my sister, she never got chicken pox. My brother has had shingles twice. Brother and I have had shingles shot within past couple of years - hope it helps.