They need a higher protein content than what you get in chick crumbs, so if you can't get game bird then try for turkey starter crumbs. Either of these 2 would normally have an anti blackhead medication as well which is a good idea for peafowl.
I would be surprised if your supplier can't get turkey starter crumbs. They should be able to order it if they don't stock it. If not then try elsewhere.
In the meantime, if they're free range, give them wild bird seed with some mealworms (for added protein), or poultry food, again with some mealworms.