I have not seen organic meats at Henry Meats.
You can search organic producers listings here:
http://www.cog.ca/our-services/Directory/
You can also contact OPAM for current organic producers:
http://www.opam-mb.com/
John Finney of Crocusview Farms (by Kenton) should be able to help you as well. They have organic fully pasture grass fed (not livestock yard fed organic) bison and did have beef at one point. I am not sure if they still do beef but should be able to direct you to someone who does this and the other animals as well.
If you search eBrandon, you will be able to find his and other's contact information from past discussions about local organic food producers.
Welcome to the area!