Moving Forward- Breeding for Resistance to Marek's Disease

[Poop Cleaner]

I am sure there are outliers. My information is from the avian epidemiology department of UC Davis. It is true for the vast majority of cases.

Just to clarify, the vaccine needs to be administered either in the developing egg or at day one. Any later is ineffective. The age range is 8-20 weeks for birds that can get the disease. Birds that are exposed but not diseased can still be carriers.

Again, vaccinating after day one is NOT effective. It has nothing to do with time of exposure to Marek's. It has to do with immune development.

 

[ochochicas]

Some of the research out there regarding vaccine efficacy is old, but I often refer to the research done by Spencer et al.

"Therefore, chickens immunized with an MD vaccine develop stronger immunity at 7 days of age than 18-day-old embryos or 1-day-old chickens. This has been demonstrated by Spencer et al. (35), who showed that vaccination for MD at 23 days of age provides better protection than vaccination at 2 days of age."

They have also shown that re-vaccinating chicks at 7 or 21 days gives better immunity than only giving one vaccine at 1 day old.

I believe the virus and the vaccine have both evolved since the initial research was done in the 1970s to 1990s. New research would be beneficial to clear up many of the uncertainties that are out there.


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2643530/

 

[Poop Cleaner]

I took the time to read that article. You have misinterpreted the results. It is about revaccination at day 7, not vaccination at day 7. Here is the actual quote you mention but reword a bit heh:

"(iii) the immune system of chicks 7 days of age or older is more competent than that of 18-day-old embryos or 1-day-old chicks."

Of course immunity is stronger at day 7 than day 1. This is the reason why we vaccinate early, actually.

Here is what the study is actually about:

"This study was designed to determine (i) whether or not revaccinated viruses infect chicks in a manner similar to that of viruses given by single vaccination or natural MDV infection, (ii) how the host birds respond to revaccinated viruses following the establishment of specific immunity by primary immunization, and (iii) if revaccination induces superior immunity against MD."

Once again, revaccination is not to be equated to vaccination.

Thank you for the interesting read, regardless.

 

[Tropit]

I'm dealing with Marek's once again. I've just lost a polish hen yesterday and our main rooster has been in an isolation ward for the last 2 weeks, fighting for his life. We've lost quite few other birds from this flock due to Marek's over the last couple of years, even though they were all immunized for it at day 1 and are all over 2 years old.

I'm from Northern California and lately, we've seen a huge increase in Marek's here. I've raised chickens all of my life and I'd never even seen Marek's until just a few years ago. It's become a serious threat around our area and was a big topic of discussion at the local feed store last week. There is one story going around about the large-scale, poultry producers in Petaluma. Many years ago, they had to destroy whole houses of birds due to Marek's. Most of these poultry houses are gone now, but the disease is still around and more prevalent than ever. I can't say it's their fault, but we should look into the possible causes more carefully. I'm curious about doing the back-up immunization at day 7. Perhaps it could help. I'm also all for breeding for disease resistance.

I know that someone has already posted a reference about the disease and its symptoms. https://www.backyardchickens.com/a/the-great-big-giant-mareks-disease-faq Perhaps we can update the current sheet on the latest developments on this topic, instead of putting it in a long thread, so it is easier to find the information needed.

~C

 

[lalaland]

I'm doing two experiments this spring - mareks in the flock in the fall of 2014 - the broody-hatched chicks from that spring survived, but chicks from a breeder that I was brooding died over a couple of months .. I've brought in 6 month old pullets twice and they have been fine. I do not know if they were vaccinated or not becuse the family that bought them as chicks and wanted to rehome them by fall didn't know.

I didn't let any of the broodies hatch last spring. I haven't lost anyone in the past 12 months except to a predator.

I am letting two broodies set now, and I'm bringing in 25 chicks vacinated at day 1 in June to raise as meat birds. I won't vacinate the broody hatched chicks, there will be at most a dozen.

Am encouraged by others who have had broody hatches. The flock clearly has a less virulent strain of mareks. Keeping my fingers crossed.

 

[rebrascora]

Like you my first outbreak was Autumn 2014. Of the chicks that I broody hatched last year (28 of them) only one showed obvious symptoms (undersized and had a dropped wing) and they have all made it to adulthood and are laying including her, with no further problems although the cockerels have now almost all been butchered for meat, but they were strong healthy boys.

I have my first broody of the season, as of last night, so I will be setting more eggs but these will be hatching eggs from outside my flock. It will be interesting to see if they show the same results as that will indicate if my flock is becoming resistant to the strain I have or if being reared in that flock with exposure from day one gives them the resistance.

 

[ochochicas]

Last June I let a broody hen raise 7 chicks. None of them died from Marek's I grew the cockerels out for food until they were 6 months old and still have the pullets. All completely healthy and they are a year old now. The chicks were hatched in an incubator, vaccinated at hatch, and then put with the broody when they were less than 12 hours old.

Currently I have two more batches of chicks that are broody raised. They aren't old enough yet to determine if they will succumb to the affects of Marek's, but I am hopeful that they will be healthy. Part of me thinks the amount of virus on my property has to be less now than it was in the past since all my sick birds have died. Part of me also thinks that if my chicks can have gradual exposure to the virus over the period of several weeks that perhaps they can build immunity to it. It has been really hard since I lost a whole line of project birds with the exception of one rooster. I cannot find any suitable replacement stock. It is frustrating. I might just have to start a new project and scrap the old one.

 

[lalaland]

oh, it is good to hear from you both, and also to hear your good results. I am optimistic, and expect to have an ok outcome.

will keep you posted. 20 days to hatch!

 

[IACraig]

Another season of raising chicks has begun, and I wanted to update my Marek's situation. I got 14 chicks in March, three weeks in I had lost 2 and had another one that was going lame. Falling back onto its hocks, just the same thing I delt with all last year.

I started the birds on B12 Rooster Boaster and the lame bird got better. I have kept the birds on their vitamins and at 2.5 months they have all been OK.

I am sure this is not a cure all for everyone, but thought I would share. Good Luck.

 

[ochochicas]

My sick birds were also started on Rooster Booster vitamins. It bought them a couple more months, but they died later from Marek's anyway. I hope your strain isn't as virulent and that some of your chicks make it.