I think I may have the wronge feed for my new chicks. These crumbles say starter grower and it tells me to add grit to it. I thought it was suppose to have grit already in it. also to continue this feed for 22 wks of age. its called nutrena country feeds. Is this ok to use? if so how much grit do I need to add. I will have layer hen. Do they require a different feed. I'm so confuseddddddddddddd