3wk & 1 day old chicks ???

Im feeding my girls Chick mash and they have grit and water 24/7. They are getting fairly big now and have had the odd 10mins on the garden in a little run when it was warm.  They loved it and did the usual chicken stuff.

Can I give the chicks anything extra or should I just stick to the food/grit & water?

Oh... well they have chick grit if they want it... so it can't hurt.... its not the grit for full grown chickens