It could be a random feed change but I would expect those that are in the business of chicken feed knows what nutrients the chickens need.
This is great, with you we have our own FR chicken lab! Let us know about the hatchlings.
What do you do if you get a lot of boys?
If we get a lot of roosters, we usually butcher them for meat except one. It is not humane to have more than one rooster as they will fight to the death eventually. I have such a sweet rooster now, I will keep him for sure. I have never had a rooster who didn’t want to attack me, lol.
I choose a breed that is good for meat and/or eggs.