The poultry barn at the fair is run by the NH Poultry Fanciers. You purchase any birds for sale through them. There is an "office" at the poultry barn, just go talk to them when you get there.
This list is from NOFA Mass. May help.
PROCESSING FACILITIES
Adams Farm
775 Bearsden Rd.
Athol, MA.
978-249-9441
EL Blood and Sons
94 West Main St
West Groton, MA 01472
978-448-6669
Valley View Farm
Matt LeClerk
179 Barre Rd
Templeton, MA 01468
978-833-1549
Limited livestock and poultry...
Actually they are still listed as critical by the ALBC.
http://albc-usa.org/cpl/wtchlist.html#chickens
We love our Dom's and Dorks... we have been working with multiple museums in MA and RI... I think I know which one you are referring to.
I have 3 different bloodlines (actually my son is raising them, as I am concentrating on Dominiques and Red Dorkings) and am always interested in diversifying the genetics with fresh genes. We love the Nankins, they are so docile.
I believe Joe doesn't bring in any new stock and birds that go out (shows or other wise), do not come back. So it is possible. We have a closed flock in that we don't bring in any new birds, and only occasionally hatching eggs from breeders we have been working with for years. Our one weak...
This is a nice little info packet on MS and MG, for anyone interested.
http://www.gapoultrylab.org/wp-content/uploads/2013/01/Mycoplasma%20handout%20for%20Backyard%20Flocks%204-12.pdf
According to the page it's MG... a bit of info is here:
https://www.backyardchickens.com/t/600566/mg-certified-hatcheries-breeders
What concerns me the most is that the Chicken Swap FB page is the ONLY place I am hearing about this. The Dept. of Ag has said nothing publicly, I haven't heard...