I've been using (and am happy with it thus far) gameFISH pellets to increase protein. They are animal protein-based, 32%. I do have some pens that are fussy about it & will pick it out of their feed (I feel a pelled layer/breeder pellet that's 22%), so for those pens, I put the fish pellets right into their water (it floats...for awhile). That attracts the chickens & they peck it right out of the water.