Consider adding Maize and Kitchen Wastes (Meat/Cheese etc) to your Chicken Feeds. Maize contains all the Seven Essential Chemicals in Food except Animal Protein and certain Vitamins. It also protect them from Disease because of its Zinc Content.
Here is a little help! A full bag of 100% Corn and easy to swallow by chickens of all ages, for only £7.50 or a Kilogram measured to your face for 38p a.