In my heart of hearts, I think the Ca is too high.
SO, I just called the manufacturer and talked to one of the managers whose name is Kevin and expressed my concern. He clearly didn't know a lot about nutrition other than the fact that this feed contains higher niacin for ducklings. I recommended they change their label and remove the reference to chicks. It is way too high for chicks. They didn't have a poultry nutritionist available to speak with me but he said he would look into it.
I also offered to have their nutritionist call me to discuss the matter.
I definitely wouldn't feed it as the sole ration more than 2 or 3 days. You have several options. The inclusion of grain into the diet to extend the time you can use the feed. Find another brand of organic feed or go back to scratch and peck and ferment it so the goodies in the fines will be bound up with the larger particles.