How much protein is in the gamebird starter? Do you have any vitamins, baby vitamins, or some vitamin B Complex? Riboflavin deficiency can cause curled under toes and walking on the hock. Chopped beef liver, hamburger,and many other foods contain riboflavin (vitamin B2.) Do you know if he was vaccinated for Mareks? Does he put weight on the bad leg, hold it up, or drag it? Hopefully, it is not Mareks, a virus that can cause paralysis, tumors, and death. Injury could be a possibility, so I would place him close to food and water in a pen or large dog crate, to force him to rest it and to keep an eye on him.