I have two laying ducks and i'm concerned that they may not be getting the right amount of nutrients that they need. I feed them country roads layer crumbles and scratch grains with some roasted crushed eggshells. Their food is free-choice and always full but the layer crumbles is formulated for chickens. Does it make a difference? They do roam around the yard when its warm out but in the winter they solely eat the commercial food. I just want to make sure my girls get everything they need to be healthy and lay as many eggs as they can, especially in winter. Thanks!