We have 18 pullets that are 26 weeks old. They lay nearly a dozen eggs a day and everybody seems very happy and healthy. When I check vents and handle them they all seem to have very little muscle mass. The keel bone is easy to feel as there isn't much muscle tissue, it's the same with the legs also. Ever since they would eat stuff from the garden they got some everyday. Mostly summer squash, cucumbers and greens. How old do they need to be before their bodies start to fill out?