Moving Forward- Breeding for Resistance to Marek's Disease

[chooks4life]

To do what the phrase says accurately could require a lot of birds, many generations, multiple enclosures, identical conditions, uniform exposure, a control, and a reliable source of the same strain of pathogen for many years. There would be a lot of test mating to demonstrate the heritability of resistance.

Or, just a lot of birds in one flock over enough years and generations, living on the same soil, with disease exposure regularly occurring via exposure to new animals, and carriers who shed remaining present at all times, and all offspring being continually exposed to those birds. No need for 'test matings' per se, as every mating is a test mating under such conditions. (Note that what I've described there is the same sort of mongrel flock I was referring to before).

Resistance also is used interchangeably with immunity, which would be misleading. Just how resistant is resistant?

We're talking about resistant enough to not succumb to it, never mind die from it.

'Remains for all intents and purposes healthy despite infection' kind of resistance. You may have observed if you read earlier posts in this thread (don't know if you did) that we all agreed that birds who became sick but recovered were not really what we consider 'resistant'.

I don't think anyone on this thread intentionally referred to resistance and immunity as being the same thing; to my way of thinking, immunity would be the term used for a bird that never even carried the disease despite being exposed to potential infection, whereas resistant birds could carry it but wouldn't become ill with it.

I used land race breeds to your credit. They best illustrate your point.

I don't believe so. I'm referring to birds being exposed to new diseases regularly in ways that only birds under domesticity can be, whereas landrace birds are not the same thing as they are not domesticated... At least in my sense of the term. Perhaps it means other things to you.

A landrace bird is one completely left to its own devices, which includes not having new birds from other regions regularly introduced to its territory; a mongrel is a domestic bird whose environment is continually subject to human influence. Being left to choose its mates does not make a bird a landrace. Landrace animals are not being exposed regularly to the new strains of disease all domestic birds are, simply because in order to be truly landraces, they must be living outside of human interference, and pretty much as a rule they're found in remote areas.

Feral domestics are somewhat inbetween the two, but as with mongrels, they too must have greater overall resistance to withstand being exposed to the domestic hubs of continually evolving diseases.

They would be more uniformly tolerant of local conditions than other birds would be. I have Thai game fowl mixes in Thailand, birds in tropical Africa etc., in mind. Birds in tropical areas that are barely managed and disease pressures are high.

I believe when you refer to 'landraces' here, the term is actually being used to refer to feral domestics or mongrels, no?

Anyway, this conversation has derailed into confusion over the meaning of the term 'mongrel', which is not really constructive beyond a certain point given the thread topic. Probably not much more to be said here. Best wishes.

 

[chooks4life]

Hi and welcome! First off click on "Marek's the big FAQ" link at the bottom of my posts. It should help you understand it better. It would take me too long, LOL.

If you buy hatchery chicks, and request vaccination, the vaccine they use is a 3 in 1 which is better than we can get. To get Marek's , your chicken must have contact with another chicken that has it. Once they have it, it spreads quickly and the chickens spread the virus in their dander. It does not randomly live in the ground unless Marek's virus chickens lived there. Wild birds can spread it, but it's uncommon. The wild bird would have to hang out with one flock, then fly to your flock and hang out. I don't know how big a territory is for a wild bird.

The last bolded bits really are food for thought. I know a bit about birds overall, certainly wouldn't call myself an expert, but I do know some have territories ranging from a mere few hundred meters to those which have territories measuring many miles, to say nothing of migratory species.

Do they cross-infect one another with MDV? If so, how much 'random' soil really is clear of it?

Now I'm wondering whether wild birds are by and large immune to it, or whatever control method is occurring there to stop them all dropping dead from it. Exposure levels are a likely control point but that doesn't apply to a lot of species which tend to crowd in high density populations and spend a lot of time on the ground within given territories, i.e. pigeons, especially given how many wild birds will regularly visit farms where they can access feed. Why aren't they dying from it?

Makes me reconsider whether Australia really is overall free of the harsher strains of it, which I had previously thought might be the case simply due to far less dense population, with far greater geographical distance between the average populations, than many other countries...

 

[speckledhen]

All of this reading is making me feel hopeless and then, when I see supposedly respected breeders selling and showing birds from their MD-positive flocks, that makes me insanely angry, to think they are helping to cause all this heartache we are seeing on this thread and others. I'm going to have to find a way to feel about this, a philosophy about it, so I can stop obsessing over it. I don't feel as if I'm helping here. Quote speckledhen

Those people will be banned from the other side of Rainbow Bridge.

I know what you mean. It's hard to not obsess . Or not be angry. Bad things happen to animals all over the world. The abuse of helpless animals is unending.

Instead of causing myself depression-that I take lots of pills to prevent, I had to find a neutral ground in my mind. If I see something bad happening, I stop it. If someone needs help I help. The rest is to know that MY animals are well cared for and loved. I can control my own little Private Idaho (LOL). I stay home unless I go to see my horse or get feed. I spend hours in the back with all my chickens. Other people will have to live with themselves and their conscience. I will live with my conscience.

Cynthia, when I discovered Marek's, like others here, I became obsessed with learning and educating others. And being careful to listen rather than jump in and diagnose everything with Marek's. You really have to think about all your posts (65,000 or so) and how many have helped someone. How many people trust what you say. How many people you have made feel welcome. Your reputation has made you someone people listen to. Which is a great thing considering the subject of Marek's.

You have oh so unknowingly helped or saved many from anguish just by starting this thread. And I know what I'm talking about!

The thing that hurts me the most on BYC is when some new first time owner of chickens is just so full of joy and love for their chickens, then they start to lose them, and don't know why. They did everything right, they feed them well, their new coop cost them a small fortune. With Marek's, nothing compares with the devastation of losing chickens and the symptoms are so broad that it doesn't give you any clue as to what illness they have. Then there are those who give false hope because they have the Cure for Marek's.

Many many members are learning this Marek's stuff right along with you and save themselves a lot of pain. So maybe find some peace in who you are and the good you've done whether you're aware of it or not.

It's after midnight and I tend to get philosophical and type! Night.

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.

This you said:
Quote:
Of course, everyone here knows I do not bring in birds. I got old Hawkeye about 8 years ago and he was 10 months old and healthy other than a few mismanagement issues from his former owner (lice, favus, malnutrition). Then, not long after, my friend Kate gifted me my now 6 1/2 yr old EE, June, as an 8 week old pullet, hatched from breeder eggs, also healthy, who was quarantined for two months. Let me tell you, it was very hard to accept her, knowing what I know, but I did know her flock and took a calculated risk, asking her all the pointed questions before accepting June.
All others here over the years were either direct from hatchery shipments via local feed store brooder, hatching eggs from excellent breeders or hatched here from those birds. So, if I get a MD-positive result with the final report, how would I know where it came from? Would I have to assume it was a freak wild bird transmission occurrence? Everyone sprays shoes when they come, but no one really ever comes here other than the mailman and he certainly doesn't go near my coops. Ladyhawk visits once or twice a year and she buys brand new shoes to use here. It would be one of those life mysteries whose ending I would be just stuck with, I suppose. No chickens have been near mine that haven't always been here unless they've been partying with the locals behind my back.

Stupid old woman across the street "free ranges" two young Golden Comets that I have no idea where she got them. I keep my gate closed, but they have gotten in the other day when it had to be open for awhile. Thankfully, my driveway is 200' long and they didn't make it far before DH herded them out and locked the gate, just inside the gate and started scratching around in the leaves. With this nasty disease and Ebola here now and everything else going on in the world, I'm contemplating that huge dome for my property, lol.
Is the Zombie Apocalypse here already?

ETA: I don't call her "stupid" for nothing. She really is a sandwich short of a picnic, trust me. I won't even try to explain biosecurity and disease to her-she thinks coyotes don't eat chickens so she probably thinks chickens cannot become ill, either.

 

[Nambroth]

The last bolded bits really are food for thought. I know a bit about birds overall, certainly wouldn't call myself an expert, but I do know some have territories ranging from a mere few hundred meters to those which have territories measuring many miles, to say nothing of migratory species.

Do they cross-infect one another with MDV? If so, how much 'random' soil really is clear of it?

Now I'm wondering whether wild birds are by and large immune to it, or whatever control method is occurring there to stop them all dropping dead from it. Exposure levels are a likely control point but that doesn't apply to a lot of species which tend to crowd in high density populations and spend a lot of time on the ground within given territories, i.e. pigeons, especially given how many wild birds will regularly visit farms where they can access feed. Why aren't they dying from it?

Makes me reconsider whether Australia really is overall free of the harsher strains of it, which I had previously thought might be the case simply due to far less dense population, with far greater geographical distance between the average populations, than many other countries...

Respectfully, Marek's disease is a virus of galliformes. MDV1, which is the virus we all hate as it is the virus that kills or causes symptoms in our chickens, is not known to be zoonotic to other bird species outside of the family phasianidae. Songbirds, pigeons, etc... Do not "catch" Marek's disease any more than you or I do. Our species is too different. Songbirds (passerines) act a physical vehicles to transport dander over distance, hence "carrying the virus". Very similar to us picking it up on our shoes or hair and accidentally moving it around.

 

[Northie]

The vet I talked to said to be sure to keep pigeons (someone else mentioned starlings) a way from your birds. They'll come into your coop for the food mingle around with your birds then fly away to the next coop and do the same. She figured they're fairly common vector for the spread of different diseases. Could be in their droppings or carried along as dust/poop on their feet maybe they aren't affected by it the same... Haven't been able to find anything that speaks of wild birds being infected and getting sick with Marek's... That was one question I have been looking for an answer to. We have lots of wild birds on our land I would hate to see them dissapear because my chickens carry disease.
Edit to add...
Thanks for the answer above nambroth

 

[Nambroth]

The vet I talked to said to be sure to keep pigeons (someone else mentioned starlings) a way from your birds. They'll come into your coop for the food mingle around with your birds then fly away to the next coop and do the same. She figured they're fairly common vector for the spread of different diseases. Could be in their droppings or carried along as dust/poop on their feet maybe they aren't affected by it the same... Haven't been able to find anything that speaks of wild birds being infected and getting sick with Marek's... That was one question I have been looking for an answer to. We have lots of wild birds on our land I would hate to see them dissapear because my chickens carry disease.
Edit to add...
Thanks for the answer above nambroth

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.

 

[speckledhen]

I finally reported a local feed store that I used to go to (used to for very good reasons, you'll see) to the State Poultry lab. Here is my letter rather than rewrite an explanation:

Quote: The conditions have deteriorated tremendously since I got my first hatchery pullets about 9 years ago in her Ideal shipment. I've been meaning to report this woman for a couple of years now, but I didn't know how and finally asked William. With this discussion with Dr. Davis I've been having, it was the perfect time to do so. I regret waiting so long to get it done.

 

[gjensen]

You are still not getting what I am saying. All is well though. I wish that you could have, because I think it would go along well with your view.

One more comment on the breeding for resistance. You need proof. That they are not getting sick is not proof. Too many variables. You can't get anywhere operating with assumptions or on impression. You need proof to make progress. ALL of the offspring are proven and as a result, the dam and sire is proven. Just because a bird has something does not mean the offspring necessarily inherit it. Some of us are equally concerned with phenotype and genotype.

I went 15 years without having a disease problem. I have not had any concerns now for 6-7 years. Does that mean that my birds are resistant to anything in particular? No. I would not make that claim until I had actual evidence. That would require a purposeful and directly administered measured amount of the pathogen in question. Until we can and are willing to do that, I do not think we have any claims to make.
Until we can prove the offspring, sire, and dam - we cannot measure progress. Until you can measure progress we can't assume that we are in fact making progress. If we are not making or do not know whether or not we are making progress it is not safe to assume that we are. Within any flock there is variation. It would be extraordinary rare for any flock be universally resistant to anything. We do not know who is having the most influence or not, necessarily.

We already discussed a flock's tendency to lose ground. How do we know the specifics of what our flock is currently being exposed to until there is an outbreak and we take them to a lab? We don't.

The best that a private breeder can do is eliminate symptomatic birds from the gene pool and show preference for especially vigorous birds. That is not breeding for resistance. We cannot measure exposure and we cannot measure or prove the inheritance.
Yes. I agree that from generation to generation and from breeder to breeder resistance to localized pressures is gained as a result.

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.

 

[seminolewind]

Cynthia, there are very very few laws for chicken protection.. They are expendable or mostly worthless to most people. We here, our "Marek's" group, have been way ahead of most chicken owners in how bad things are. It's so important to get the information out there. For most hobby owners they don't want their chickens to die .

Unfortunately, the only method so far is to keep a closed flock, and vaccinate and quarantine any chick that comes in, or hatch, vaccinate, and quarantine for at least 3 weeks. Or more.

I believe that a chicken who carries Marek's can live it's whole life without one symptom meanwhile spewing dander everywhere. They never have symptoms until they die of old age.

I live in pigeon-ville. This neighborhood is packed with owners of expensive racing pigeons who look like they have taken a 2nd mortgage out to build their coops. They mark their own birds, and hold meetings at the local pigeon feed store, and do vaccinate their pigeons for pigeon illness . A few pigeons around here end up at some people's houses never to leave again. 2 very young pigeons lost their way home and never left my property. I could take them anywhere and they will come right back. If they had landed at other chicken flocks, they would have stayed there.

The pigeons, most of them, fly back to where they live. They will rest on my roof at times on their way home.

I know that birds can carry Marek's from one flock to another, but I take into consideration a few birds may carry Marek's, but possibly in a small enough amount that just gives a flock a small enough exposure to become resistant. Unless 100 birds or so land at your property every day.

Any adult bird or bird that had contact with a flock can carry Marek's and expose your flock. If the flock is pristine unexposed, you would generally see some deaths a few months later. I don't think it's just one. A flock history may pinpoint the carrier for some. Like me.

The Only way to prevent Your Own flock from dying is to vaccinate prior to exposure (day olds) and quarantine for 3+ weeks to give the vaccine time to build resistance. Or only hatch eggs into a clean flock or buy day old hatchery chicks or eggs from another person to hatch. Vaccinate them all and eventually you will have a vaccinated flock. There is no other way to prevent Marek's deaths at this time.

Most people that have a small flock do not have or want the number of chickens needed to breed for resistance. It takes quite a few generations. The only way now is to protect your own flock.

Cynthia, if a Marek's carrier came into your flock, you would most likely have symptomatic bird(s) within a few months. It would not wait a few years before you see your first victim.

 

[seminolewind]

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?