Thanks for your response. As I mentioned above, it's not just AI. Opensanctuary.org and other websites also indicated that broad breasted turkeys and meat birds in general are not as cold tolerant because they are not bred to be around very long. I know for example, that the local animal sanctuary near me, which is quite well respected and works with a well-known local farm vet clinic, doesn't even let their meat birds outside the barn when it falls below 20°F. They have beautiful Cornish Cross birds over 6 years old, so it seems like they're doing something right.