I have six female ducks that are 12 weeks old. What is the progression for feed (protein) requirements as they get older and approach laying age? They were on a high protein chick starter than moved to an 16-18 % protein. I am using organic non GMO Mash. There seem to be several options but not sure what would be the best choices? They do free range during the day so there are other options for them too during the day.