Unless you purchase a FRESH turkey your Thanksgiving Turkey is bound to have Lactose. Whey, whey products, and products like sodium lactate are in deli and processed meats to improve texture, emulsification, cook yield, and the finished product performance.
Lactose can be used to replace sugar, dextrose, and syrup so it keeps cost down and it looks healthier.
So, if you need a casein free or lactose free product chose a FRESH turkey.