If I understand correctly, chicken scratch is mostly corn and oats - really, not much nutrition, mostly calories. Go with a starter crumble and add poultry vitamins to their water once a week if they are younger than 3 weeks old. In this case, I would say younger than 4 weeks, because they need to catch up, nutritionally. Then switch to a grower-maintenance, and a month before the girls start laying (they will start trying to mate about a month before laying), set out free choice crushed oyster shell.