pips&peeps :
From the Merck Veterinary Manual:
most commercial chicken strains are resistant, and lymphoid leukosis virus infection has been largely eradicated from susceptible stocks
Have a look at the publishing date. Mine says the same thing.
Avian sarcoma leukosis virus -there are different forms of it. I'm just really getting a handle on it myself.
Again, if you've had the leukosis virus show up in your slower growing broilers this thread is for you.
I know there's a bunch of you out there. To date, the only people I've heard from have poultry as a side venture in their larger farm production- largely beef, milk, pork producers- not backyard hobbyists. But I know that there is a wide cross over of peeps that purchase these slower growing birds and have them processed at USDA processing facilities. They'll have learned about it themselves. I'd not heard of it before in any flocks until this year. According to what I've learned subsequently, it's a new strain and not necessarily lymphoid. Traditionally, the birds were vaccinated against it in commercial flocks but there are so many different strains of each of the three different forms of the virus it is now nearly impossible to vaccinate for. Being proactive - treating all meat birds before it becomes a problem seems to be the way to go.
One of the things worth wrapping the old brain around is the sheer numbers of people raising chickens these days. it grows exponentially every year. Hatcheries simply can't keep up. The meat birds raised by Cargill or Hubbard Hill or what have you- they have a different management-so much goes into their protocols= that protocol is not in place for birds sold to the general public. I spoke with a woman that had kept a solid business going for many years selling these slower growing strains about this and she told me it was one of the reasons they couldn't afford to continue -they went out of business once a strain became systemic and they couldn't vaccinate for it any longer. AS Their customer base grew so too did their problems- just too many birds and too many factors to keep their arms around. They sold their breeding stock of uninfected birds to another party and destroyed the rest. That was eye opening. I'd never thought about that before.
This leukosis situation has always been present in the Cornish crosses- it's erythroblastic, and osteopetrotic forms of the virus that have been impossible to eradicate.
The pathologist told me we just don't keep those birds around long enough for the symptoms to appear. It's not something that's going to hurt any human being or necessarily move from even one breed to another. It's vertically transmitted from parent to egg.
It is much more systematic in other countries.
