Of all of my chickens I only have a few that are heavy. Most of mine are small and thin. they have calcuim, grit and grower finish at all times. they are given sunflower seeds, bird seed, cracked corn, any type of greens, pasta, veggies, fruits, even cereal, meal worms and probably lots of other things for treats. I have also started adding Flock Raiser with their regular food to add some more protein. although my girls range in age from 1 year and older I choose not to force them to lay eggs. I have tons of eggs and I just supplement extra protein and calcuim. I want them to live out their lives not having to just lay eggs constantly and they seem just fine. I worm them twice a year and plan on using DE this year.
So if anyone has any other ideas about adding weight to my girls that would be greatly appreciated.