Your birds are looking good.
I worry about nutrition for my penned peas for the same reason. The constant recalls on commercial feeds also worries me. I'm old enough to remember the PBB problem in the 70's. I was at MSU when they were doing research on feeding commercial flocks of poultry...
1. Its sold as zoo food, that doesn't necessarily mean that's what zoos feed.
2. Its recommended to be fed as 1/8 of their diet., i.e. as a supplement.