As I've not seen a post from Morena, I though I'd better chip in with a vet's view.
Scraps are fine as the odd bit here and there, but I'd be very wary of raw meat as the main basis of a pup's diet, especially the large, faster growing breeds like Labs. The problem is that the Calcium to Phosphorus ratio in meat is not balanced. It is one of the factors behind in cartilage damage and potential arthritis in a young dog. There were loads of cases like this when the rottweiler was popular in the mid 80s and fed exclusively on raw meat. The natural diet for a dog would be the whole animal, hide, bone, intestines etc which is then correctly balanced.
Personally, I like the simplicity that comes with a bag of dried kibble. Pick a quality food (ie not an own brand) stick to it, keep the pup slim and it should be fine.
As a chewing aid, the legs etc are great, just avoid her trying to break them up to much, so remove them before the cracking starts! Cooking makes them more likely to be crunched up and this can lead to constipation as Mac states.
Have fun training!