I'm amazed you can get chick crumb over there anyway MAK. I heard chicken feedstuffs were expensive and very poor quality. Mashed boiled egg is a good chick starter with adult feed ground up. It's the extra protein they need as their digestive system isn't initially very efficient. However the first Mallard we reared was fed on ground up adult food from day two and thrived, flying off at 10 weeks!
Snails are bad news as they contain a lot of intestinal worms. you should avoid giving them to poultry, leave them to the hedgehogs.