We have 5 Speckled Sussex they are just over 9 weeks old. We have maybe 2 weeks worth of the medicated chick start left. Is it time to switch them to just a grower now? Also my chickens love crabgrass is it safe for them to eat or will it mess with their nutritional balance. They mainly eat their chick start. The crabgrass is a treat they get when I am weeding the garden.