Moving Forward- Breeding for Resistance to Marek's Disease

[tridentk9]

Sigh, not to give you even more to worry about but Marek's and Lymphoid Leukosis both have liver tumors and can be almost impossible to differentiate. Marek's strain 2 is sometimes found in birds with Lymphoid Leukosis even though Strain 2 normally causes no problems.
http://www.thepoultrysite.com/publications/6/diseases-of-poultry/202/lymphoid-leukosis

FROM THE POINT OF VIEW OF DIFFERENTIAL DIAGNOSIS, THE FOLLOWING FEATURES DESERVE A SPECIAL EMPHASIS:

LYMPHOID LEUKOSIS
Usually, it is not seen in birds younger than 14 weeks.
The lethal issues occur mostly at the age between 24 and 40 weeks.
Distinct nodular tumours.
Tumours in the bursa of Fabricius.

MAREK'S DISEASE
Could be observed after the age of 4 weeks too.
The peak mortality is seen between the 10th and the 20th week, sometimes continues after the 20th week.
Paralysis.
"Grey eye".
In some birds, the bursa of Fabricius is atrophied, in others: neoplastic.

And then there's REV. Another problem that can be difficult to tell apart from Lymphoid Leukosis. http://www.poultrynews.com/New/Diseases/Merks/203704.htm

I'm wondering how many cases of Marek's are another disease or combination of diseases. Even with PCR and microscopic testing it can be hard, without testing extremely difficult.

 

[chooks4life]

Interesting info, tridentK9.

This bit made me laugh though:
Quote: Er... No... I'm pretty sure if your rooster is going around infecting all your hens via mating, then he IS fulfilling an important role in congenital infection of the progeny. A few steps removed from the hen, but you don't get progeny without a rooster, and if he's infected, and she's not, well, that's a rather important role right there.

The Leucosis I had in mine was easy to diagnose, the intestines were absolutely covered with hundreds upon hundreds of white tumors, and the stomach with black ones. But apparently there are a few forms of Leucosis too.

Best wishes.

 

[Nambroth]

Thank you so much, Karen. Yes, I am making myself crazy, you're right. Nothing I can do about any of it. And it was only by chance that I decided to open up that hen, who I thought had an early, unexpected case of egg yolk peritonitis or had been poisoned somehow. I almost didn't. But, you know me, I just had to know.

Ignorance is bliss, isn't it?


Golly, I hope I don't bore the membership with "broken fingernails"! Oh, my! LOL.

Sorry I haven't been around to answer questions, but Karen has given you great advice! Also I wanted to let you know that you share a state with one of the nation's best poultry labs, in Athens, GA.... they do Marek's sequencing and if you can get in touch with them you may get answers that we haven't been able to answer yet!

 

[speckledhen]

Sorry I haven't been around to answer questions, but Karen has given you great advice! Also I wanted to let you know that you share a state with one of the nation's best poultry labs, in Athens, GA.... they do Marek's sequencing and if you can get in touch with them you may get answers that we haven't been able to answer yet!

Thank you. Good to know. Athens is somewhat further from me than Oakwood. And they're almost finished with a state-of-the-art facility in Gainesville, which should be a tad closer than even Oakwood. I hope I'm worrying for nothing.

 

[sassybirds]

Sorry I haven't been around to answer questions, but Karen has given you great advice! Also I wanted to let you know that you share a state with one of the nation's best poultry labs, in Athens, GA.... they do Marek's sequencing and if you can get in touch with them you may get answers that we haven't been able to answer yet!

They will charge you an arm and leg at UGA. I looked into it. The Geoegia Poultry Lab is free. I think that I heard that the new lab off of 365 is supposed to be opened in October.

 

[speckledhen]

They will charge you an arm and leg at UGA. I looked into it. The Geoegia Poultry Lab is free. I think that I heard that the new lab off of 365 is supposed to be opened in October.

Fabulous resource for us Georgians, those free diagnostic necropsies. My friend in Ky had one done at the University of Kentucky just yesterday and it was still just $40. She found that her hen didn't have anything sinister, at least in the preliminary report, which she got within 25 minutes, other than egg coelomitis (which is another word for internal laying, caused by an ecoli infection, something very familiar to me, but unexpected in a bantam hen).

I am always suspect to get any gov't agency involved in my business, but I also do not want contagions "loose" in my flock, either. Next odd one gets tested. Thankfully, I can drive to the lab in less than two hours.

 

[Nambroth]

They will charge you an arm and leg at UGA. I looked into it. The Geoegia Poultry Lab is free. I think that I heard that the new lab off of 365 is supposed to be opened in October.

I had Marek's and ALV (lymphoid leukosis) PCRs run at UGA and they weren't too out of line with what other places charge. They were a bit more than Texas A&M. It's awesome that the GA poultry lab is free though!

 

[speckledhen]

I had Marek's and ALV (lymphoid leukosis) PCRs run at UGA and they weren't too out of line with what other places charge. They were a bit more than Texas A&M. It's awesome that the GA poultry lab is free though!

Not all services are free but the necropsies are. The others seem quite reasonable. The link has more than just the fee schedule so here it is, but for your convenience and comparison, here is the schedule of tests and fees:

http://www.gapoultrylab.org/?page_id=21

$40.00

This may be a very stupid question, but they actually test the organs for Marek's in one of these necropsies, right? I mean, they don't do only a visual examination and say, "Ayup, looks like Marek's or LL and since this bird is X number of years old, we'll go with LL". As you said, Karen, there are so many reasons for a sorry looking liver and these labs see so much of this that day in and day out, if I had to have a bird tested, I would not want them to jump to any conclusion based on visual exam and not a real test of the tissues. For instance, Avian Vibrionic Hepatitis in the way it affects the liver could appear similar to both those diseases. Wouldn't be happy for them to have that, either, but it's preferable, IMO, to the alternatives, if you know what I mean.

 

[Northie]

Random thought... What's the chances the vaccine is enabling non-resistant, but not completely susceptible (middle of the road type) birds to pass on their semi-effective yet semi-apathetic immune response to Marek's by preventing the fatal symptoms in enough of them for non resistant birds to pass on their weak responses? Seems quite likely to me.

In which case vaccinating would be a further cause of problems, not the solution it's touted to be by some (lol at the 'experts' who call vaccination a preventative); I think it should be judiciously used in some flocks and not in the rest of them. Used right, the vaccine could help preserve rare breeds, but further controls would be necessary to somehow ascertain that we are in fact breeding towards resistance, should that be something the owners of such flocks choose to do. It seems futile, saddening, and not a little crazy, to spend one's time as a poultrykeeper living in fear of a disease which isn't even fatal to many.

There's other diseases which are fatal to susceptible individuals but which the vast majority of the rest of the species is infected with and passes on, all without harm; one day Marek's may be the same. But at this rate it'll be brought about at the expense of rare breeds unless we figure out a better way to manage it, or a complete cure for it.

I strongly agree with this. Vaccinating and doctoring a bird through the disease definitely allows "less resistant" birds to continue to exist, reach maturity and pass on their genetics to the next generations. In a wild population a disease like this would cause a bottle neck where only the most resistant would survive, others would be picked off by predators, and eventually the survivors would have a decent level of genetic resistance. The pressures of natural selection in a wild setting selects for a far different creature than most of us can find in our coops though.... We select for very different things, my super soft, fluffy and sweet cochin isn't exactly "as nature intended"....
But I don't really care for hunting wild grouse to replace my chicken dinner and good luck collecting wild eggs.... I'm not much of a wild hunter gatherer type human either...
Vaccinating absolutely has it's place, disease resistance isn't the only thing we are breeding for right. Sometimes to get a trait you want you may have to bring in less disease resistant (vacinated) birds, cross them with your disease resistant strain and allow the disease to bottle neck population again... With hopes that in some of the survivors you've managed to pick up the trait you wanted.... it's kinda like cheating the disease for one generation.
In an industrial situation like the hatcheries and egg industry they're pushing production not disease resistance. Vaccinating is hugely important for them. Egg barns want as many eggs as they can get so vaccinating and using the all in - all out closed flock method is the best way to achieve this. For hatcheries, the best way to protect your customers and the birds they purchase is to vaccinate them. If you wanted to preserve a breed that is naturally very weak to Marek's disease in particular you'd probably need to be committed to vaccinating...
For creating a solidly disease resistant strain, that must be the highest priority ranking over conformation, feathering and color, egg and meat production and tempermant... Meaning no babying and fussing over a chicken just because it's has the best ______ or is the sweetest of the bunch... I'm not sure if disease resistance is priority number one for me.... It's something I want for sure but again I still want eggs and meat from my birds and i won't keep something nasty either... Plus i'd like to keep up a couple different breeds... Maybe a line of custom mutts... So we'll see.... Its a project in motion

 

[chooks4life]

All true Northie, I know it's not an easy-answer situation, and once you start involving economics-driven livestock husbandry practices, particularly those in massive commercial operations, it's nigh-impossible a situation. They're one of the largest bastions of development of vaccine/ antibiotic/ drug resistant diseases. They're in large part responsible for the severity and virulence of so many modern diseases, as a byproduct of their modus operandi. (Though some backyard breeders and farmers are certainly doing their bit to contribute to those resistant strains of diseases... It's gobsmacking how heavily some folks medicate and vaccinate. Understandable though, especially when pets are involved.)

Over time, it seems these commercial operations will likely end up having to breed for resistance, judging by the past enormous losses they've sustained which even vaccination/antibiotics etc couldn't reliably prevent, and their past projects in breeding programs aimed at disease resistance. They know it can be done, though they'd have to accept lower production for a while to achieve it.

The final straw that looks poised to break the camel's back is the upcoming changes to regulations about antibiotic use due to the growing epidemic of antibiotic resistant diseases, not to mention the very antibiotics they depend on becoming obsolete due to that resistance; they are facing no longer having any option to do otherwise than breed for resistance, and if they don't start now they are going to lose their valuable genetic stock and have to start from scratch. That'd be a crippling blow for the industry. But they know that, they're aware of what they're facing and are scrambling to find ways to survive it. There's some fascinating research into organic methods going on, lots of testing and studies finally getting some serious funding and interest, and dare I say it, legitimacy. For too long it's been derided and ignored at the expense of total health.

It's still pretty quiet, but many commercial Australian poultry farms and breeders are already altering their keeping and breeding programs to achieve resistance rather than rely on artificial aids, shifting to organic practices and even free range farms etc, on a huge scale. It's only a matter of time before the rest of the breeders/growers are forced to follow suit, it seems. Looks like tumultuous times ahead, for everyone, and possibly some mass outbreaks involved.

I'm not sure it wouldn't be better for them to scrap purebreeding as a rule, only keeping it for some lines (i.e. cell breeding or staggered breeding programs) and bring in mongrels from outside which already have great resistance. Chances are they will have to do so, sooner or later.

I've always selected for productivity, temperament, and all the other desired traits at the same time, with greater importance placed on temperament, conformation and hardiness than most other traits. But I'm aware of how much easier my project has been by virtue of the fact that I've started with mongrels who contain many great genetic lines which have been often terribly neglected on various disease-riddled farms, until only the hardiest survived to breed. Who knows how many generations of disease resistance breeding they've got in them, lol!

I'm in a mild dilemma myself, because we've got pets, which makes things a bit more complicated, both in terms of breeding projects, and my decisions to risk lives to gain flock immunity to a new disease. Some of these pets are old, others 'special' i.e. survivors of injury or illness; almost none of them, however, would have been kept if they hadn't made pets of themselves. While I comprehend and respect the logic of not babying the weak I also value them as sources of greater education than culling the weak ever will be.

I've learned a heck of a lot from trying to save the ill or injured as compared to those who only ever treat illness or injury with an axe, and animal rehabilitation has always been a passion of mine, with a great success ratio, which of course only compels me to greater efforts lol... But beyond a certain point I'm not going to be willing to keep certain animals on the front line as it were.

Currently I'm planning to have several free range but separated flocks, to work on a few projects concurrently, and one of those flocks I expect is going to be a 'retirement flock' --- basically just a safer place where animals with no need to justify their continued feed/care expenditure can continue to live out their days. A pet flock, I guess you could call it. I would take greater steps to protect them from disease, but not to the point of attempting complete biosecurity, and not vaccinating them. That said I certainly don't disagree with anyone else's decision to vaccinate a pet.

Best wishes.