Moving Forward- Breeding for Resistance to Marek's Disease

[speckledhen]

Quote: Oh, Jen, you are so right (she says as she's landing from another Olympian jump).

 

[Nambroth]

I call it "personal acceptable risk". We must all decide at what point risks are acceptable either because we can't do anything about it, or doing something about it would take the enjoyment out of something permanently. It's one thing to occasionally do things we don't want to when it comes to the things we enjoy (I sure hate it with all my heart when I have to put a bird down because it is suffering) but if every day of your otherwise enjoyable thing becomes tedious and joyless... well.

So we must all, individually, access our personal acceptable risks. This comes by educating ourselves, and from this education deciding what parts are the most important to us. There isn't really any wrong answer as long as we are not knowingly harming others in our decisions.

This is inherently more complicated when dealing with the well-being of other creatures (compared to risks that are only risky to oneself), be it other people or, in our case here, the lives of our chickens (many of us really love our birds it seems!).

 

[speckledhen]

Found this misinformation online in an official-looking site re: Marek's vaccine. Unless I'm terribly misinformed, this is completely false.

If this were true, NO one would want to vaccinate their birds, ever.




Quote: http://www.poultryhub.org/physiology/body-systems/immune-system/

 

[ChicKat]

This is an interesting thread. It has a lot of interesting theories and ideas.

The conclusion that I came to is that breeding for resistance is not as clear cut as it sounds. Truly breeding for resistance involves intentional exposure (repeatedly) over generations. The pathogen would have to be the same strain etc. Then it would be necessary to test mate and "prove" the breeders. After all of that, you would find that often those that showed some tolerance and did not become symptomatic, would not pass the trait on to it's offspring. It has been found that a bird that did become symptomatic could possibly pass the ability to resist (tolerate), to the offspring.
Truly breeding for resistance requires a controlled setting, many generations, access to the pathogen, and test mating. This is not to say that a breed (or strain) would not be better off in the long run for this approach. I do think it is helpful to keep it in perspective. It is not as simple as some make it sound.
Generationally from one breeder to another, in a given area, real progress could be made. All bets are off when the bird is shipped across the country and is exposed to a different strain.

Instead I prefer to select for health and vigor. ........

I understand that the university level study - as described - with a very large number of chickens and an equal number of control chickens and the identical strain of Marek's given to each in the same dose at the same time -- would be more like a proof of breeding for resistance.

Some other studies have been cited subsequent to this post -- that perhaps followed those exact protocols - I admit I didn't follow all the valuable links going through. IMO what the original poster means - and what most of us that have back yard flocks mean is that we choose to by-pass the vaccination route - And that the flocks that we raise must develop and grow without the vaccine. They must obtain their own resistance or immunity to Merek's.

From what I've read, genetic resistance to MDV in chickens is similar to genetic resistance to AIDS in humans. Wired has a good (though older) article explaining genetic resistance with AIDS.

http://archive.wired.com/medtech/health/news/2005/01/66198?currentPage=all
It has been realized that people with two copies of the CCR5 mutation are more susceptible to fatal West Nile Virus disease.

Sigh, I've been thinking about this from more of a genetic based (breeding) point of view but looking at resistance from an environmentally acquired POV is also valid. While testing in a lab can separate the two, when living in the "real world" the two are inextricably intertwined. It is both a plus and a minus.

MDV affecting the eye *may* be related to the Harderian gland located near and connected with the structures involved with the eye. It's part of the immune system, disease may cause some reaction within the gland opening the door to MDV related changes.

IMO Genetic information lately has been changing at an exponential rate even faster than computer programs.

I agree, this has been a wonderful discussion. Multiple people with different focuses and experiences exchanging information.

tridentk9 - thanks for all the research and the good links. As tough as it is and as risky- I believe that flocks can thrive and survive if a chicken years ago in that flock died from Mareks.

I want to reiterate that my position is that you can breed for resistance. I have just wanted to communicate my position that it is easier said than done. Just the fact that some strains are more susceptible than others is proof that it is possible.

A very sound position - and among the particular chickens that I have heard that have greater resistance to the disease are those with a B21 gene that is resistant to Merek's -- A study I read years ago - and I'm sorry I haven't found it again since - so you can take it or leave it on my word - stated that White Leghorns were more resistant (B21 genetics) than many other breeds - and among the most susceptible breeds are Rhode Island Reds. -- My first loss was a black sex-link - the first year I had chickens - and it was a RIR X BPR.

For those who have rare breeds - like the Spitzhaubens - not only are they new to our envirionments, but resistance in their strains are to diseases in foreign countries...and the Merek's here in the USA (and the vaccines) are different from the ones in the UK, and also different from Australia's Merek's I believe.

"Likely" and "consistent with" is through out my personal medical records. For me it means that they aren't certain because there is not specific enough testing available to prove it one way or the other. My condition is poorly understood, and rare enough for there to be a lack of research.
Whenever "likely" and "consistent with" is used, it could certainly could be something else. For the subject that we are discussing, you can pretty safely assume it is what is implied. The likelihood of it being something else is pretty slim.

Thanks for these clarifications - I understand that to be scientific it is very difficult to be 100% - and so using the terms reinforces the integrity - but for a novice - it would be nice to have them be more 'blunt'. IMO.

I'm really new to chickens and am perhaps misinformed but I thought that there were several strains of mareks any of which could be present in the dirt itself and that in addition wild birds could have it..and I thought that a bird could be resistant to one strain and not others..so as a newbie if I am getting a basic understanding it would seem that mareks isn't something we can deal with by culling because, well, it's in the dirt? And dirt is..everywhere do wouldn't logic say to breed for resistance? I'm not trying to offend. I am simply here to learn and see if I am understanding the facts. And I'm really sorry to those of you who have lost birds.

This was addressed subsequent to this post-- but it was in my multi-quote collection - and I appreciate the viewpoint. Marek's is in the air, and on peoples shoes - and it would be more dynamic to be able to reduce the influence it has on our chickens than to try to provide a sterile environment for our chickens to my way of thinking. The resistant or even possibly immune chickens could thrive in their environment and they could survive. Infact isn't the turkey herpes virus a mild form - and perhaps the milder strains of Merek's could protect a chicken from the more virulent. Add to that the vaccine that we would get for home use is more incomplete than the one used in hatcheries -- the home-vaccinated chickens in a way have turkey Merek's don't they? or am I misunderstanding what Dr.Davis wrote to Speckled Hen about the two different levels of vaccination?

Well, I didn't start the thread, I just bulldozed my way in to sassybirds' thread and hung in there, trying to finally make sense of this disease, if that's really even possible. I'm beginning to wonder. If someone really does follow me here, maybe they'll learn along with me. I hope so.

Yep, that's how it worked, I followed you here - and learned a lot more about Merek's.

It is generally a good idea to discourage pigeons, starlings, house sparrows (etc) from hanging around your coop or barn if possible. It's not always possible, but if you can, you should. While they do not actually "get" Marek's disease, as mentioned above, they can physically carry it if they also visit other flocks of chickens.

They are genuine disease vectors for other problems though, most especially parasites such as mites and worms. Doves (this includes pigeons) are a vector for canker (Trichomonas gallinae), spread through shared drinking water, etc. There are many good reasons to discourage wild birds from sharing roosting, dust-bathing, drinking, and food sources with your chickens.

There was one year in the drought when the 'wild' birds were all over the feeders - and out ate the chickens... There can be a lot of wild bird visits - and who knows who's flock they last visited........I think it is a fairly real part of the puzzle. Perhaps wild birds were the source of the OPs introduction of the virus.

......................................................
The inheritance of resistance or immunity is a fascinating subject. I wish that I had the resources to have a few hundred extra birds, isolated facilities, and a reliable source for a given pathogen. Then I could actually breed for resistance to that pathogen, expect to make, and measure progress. Otherwise I am just operating under the assumption that my birds are or are not, and I would not even be certain of what (or how much) they are being exposed to. I would not know if I was gaining or losing ground.

Marek's is different because it has the ability to build up and "accumulate" on a piece of property.

Wish that the resources were available to you as well -- you could probably find some answers that would be helpful.

Chooks and George. Breeding for resistance I would think is very difficult in that there are many many factors that come into play. Like we've said before, it's like fighting a ghost. I wonder how many times it's been tried by researchers and their results printed. Not just one experiment by one scientist.

Also, humans being humans, there is always room for unintentional mistakes. And a person can't be condemned for not caring or not knowing because they still have (had) the best of intentions.

Fern is not doing well. Is there any way to euthanize with a block or wood over her neck and a hammer? I know this is crude but I don't want her to bleed out since she'll be sent for a necropsy. Would it be cruel?

Seminolewind - I'm very sorry to hear about your loss of Fern,
on your point of researchers--- Most of the research is funded in part by the major companies, isn't it? For them it is a different ball game entirely - as you have noted - It's all in and all out -- and not a continuing process like a back yard flock.... It is kind of going to be up to individuals - like the people participating in this thread to work together to find what answers we can and what approaches seem to work and make sense and then share the results...

..............
Breeding for immunity is great, but I keep few birds--and breed Show and breeding birds. How do you know they are immune? And if Marek's appears, I could lose years of breeding successful lines of birds, if the ones that did not inherit immunity were the ones that became infected. Just wouldn't work for me.

There is a great deal of information, some conflicting, about Marek's on many websites. We just do our best and our own experience is our best guide. Just keep learning......

This is a good point--- I wonder to what degree a bird entered in a show is exposed to various diseases. Because you enter shows and continue to have healthy chickens, it could be that you have birds with a great deal of immunity.

.......

chooks4life, not something I'd like to contemplate, Marek's even possibly passing to humans, as if we don't already have enough disease troubles!

Speckled Hen -- interesting thought about cross species virus infection - but what if it is like the original 'cow pox' - that prevented people from dying of small pox? One a mild disease and the other one deadly - maybe it isn't all bad. Just wondering about the possibilities.

I call it "personal acceptable risk". We must all decide at what point risks are acceptable either because we can't do anything about it, or doing something about it would take the enjoyment out of something permanently. It's one thing to occasionally do things we don't want to when it comes to the things we enjoy (I sure hate it with all my heart when I have to put a bird down because it is suffering) but if every day of your otherwise enjoyable thing becomes tedious and joyless... well.

So we must all, individually, access our personal acceptable risks. This comes by educating ourselves, and from this education deciding what parts are the most important to us. There isn't really any wrong answer as long as we are not knowingly harming others in our decisions.

This is inherently more complicated when dealing with the well-being of other creatures (compared to risks that are only risky to oneself), be it other people or, in our case here, the lives of our chickens (many of us really love our birds it seems!).

Several years ago - someone from Europe was expressing the opposite view of many in the States...they were saying that they wished people wouldn't vaccinate for Merek's because then they take their vaccinated bird to a show, it sheds Merek's and infects the bird in the next cage - and Merek's is brought home from the show-- This may be extreme....and he may have been lamenting to prove a point. In the USA there is a tendency IMO to over medicate chickens - I see a lot of people asking for help on the forum and a large number of replys will go straight to the pharmaceuticals. I'm not sure that vaccination (except for the 18th day to the embryo) is the answer to solve the problem. I appreciate that many people will choose this - and that will give their own flock protection - from the tumors, and the worst symptoms - but I think it needs to be clearly understood that the virus can still be carried by a vaccinated chicken.

Thanks so much for all the contributions here - I hope it keeps up.

some years ago - I put together a Merek's fact site here on BYC...it is open to contributions by everyone - your approach, your experiences etc. -- just go to the site and click the edit button. I'm going out to update it now - and put a link to this thread---since there is a lot here that has surfaced since I first made the site. Please feel free to put things at the link that you feel may help others. Thanks

https://www.backyardchickens.com/a/mareks-disease-fact-site

 

[tridentk9]

Found this misinformation online in an official-looking site re: Marek's vaccine. Unless I'm terribly misinformed, this is completely false. If this were true, NO one would want to vaccinate their birds, ever.


http://www.poultryhub.org/physiology/body-systems/immune-system/

I think it's more a case of poor editing.

 

[speckledhen]

I think it's more a case of poor editing.

I hope so, but I've heard this from many people on BYC over the years and on other boards I used to cruise through. I hope they fix that error.

 

[seminolewind]

Interesting read. Thanks for all information.

One bit about Marek's Disease often forgotten. Vaccine is made from a Turkey herpes virus, not from the Marek's virus. And it causes chickens to become immune to Marek's (most forms commonly suffered) if vaccinated at hatch. Marek's is world wide and sometimes losses are great. I had never heard of it, never had a bird infected until a "friend" sent me a pullet that started the limping on one leg, then the wing droop on the same side--progression and death. Had a few more infected from time to time,, but did not know what it was until the computer search some years later.

Another bit of info: . IF YOU KEEP TURKEYS with your chickens, you will not have Marek's Disease in your flock. The Turkeys are not sick, and I have poultry breeder friends who do not keep Turkeys, but collect Turkey poop from their friends, dry it,and sprinkle in the coop litter, even a bit in the poultry feeders~ and they do not ever have Marek's, believe their chickens become immune. I keep bantams and do not have room for Turkeys, so vaccinate every chick. And I do not have friends who have Turkeys and could collect a sack of poop for me to use. Although I have Wild Turkeys on my farm, they are not helpful~

Breeding for immunity is great, but I keep few birds--and breed Show and breeding birds. How do you know they are immune? And if Marek's appears, I could lose years of breeding successful lines of birds, if the ones that did not inherit immunity were the ones that became infected. Just wouldn't work for me.

There is a great deal of information, some conflicting, about Marek's on many websites. We just do our best and our own experience is our best guide. Just keep learning......

Keeping turkeys does not give your chickens immunity. Nothing gives chickens immunity from Marek's. Research has not found turkey ownership to cause resistance in chickens CONsistantly. Chicks can get resistant antibodies from a hen but it only lasts a few weeks.
Marek's virus does not travel with an egg. A hatched chick would have to be exposed to a carrier.

 

[seminolewind]

On the subject of MD being a disease of only (or is it mainly) chickens, if someone depopulated their MD-positive flock, did the usual disinfecting with Virkon, then waited, what do you think the chances are that repopulating with guineas would be a way to never see this disease again? Just thinking here because, way back, I originally wanted guineas and only got chickens because they are not just seasonal layers and they were available before the guineas were.

I had that thought, that if I had to, I might end up going back to guineas, though we all know even tame guineas like I had years ago are not the same as the personable birds I have now. I've considered having them again when I had room for them, though, but are they resistant to this disease? Dr. Peter Brown once joked, when speaking of disease among guineas, that you couldn't kill a guinea with a .22, LOL.



chooks4life, not something I'd like to contemplate, Marek's even possibly passing to humans, as if we don't already have enough disease troubles!

The ground and leaves, and trees can not be disinfected. So it will remain with you but I don't know how long.
I don't know if guineas are enough of a chicken breed to get Marek's. Someone else must know.

 

[Suzie]

This thread is fascinating to read...one of the very best I have ever seen on BYC...so much information from those of you who have knowledge you impart to us lay people...the powerful messages speak volumes...thank you everyone who contributes!

Seminolewind....I am so very sorry to hear of yet another you have lost....RIP Fern....I cannot imagine how you are feeling but the loving support of everyone who has the privilege to know of you will be feeling your loss with you...our hearts share your sadness...

Love

Suzie

 

[speckledhen]

The ground and leaves, and trees can not be disinfected. So it will remain with you but I don't know how long.
I don't know if guineas are enough of a chicken breed to get Marek's. Someone else must know.

Yes, I do know that, so really, I guess I'm just asking if guineas would be fine and not at risk on property where a chicken flock was MD-positive. Of course, knowing me, I'd still disinfect the coop and lime and till pens, etc, before adding new birds of any species if I had this issue and was starting over, though I realize no one can disinfect acreage. Hopefully, someone else might know this.