We don't have all that many options where we live. We take what shows up. To me the brand name is not as important as the % of protein and the mill date. You want what's fresh, as far as the date is concerned.* And as for protein, I'm probably going to confuse you and I'm NOT an expert!**. So consider this a general sorta-introduction by a very green newbie!
Most layer feed (this is the one with calcium) is going to be about 16% protein. You'll also find formulas with 18% and up to 22% protein. The higher protein formulas may variously be labeled something like "Feather Fixer," "Grower," or "Meat Bird." We will use different formulas at different times of the year, depending on what our birds need, as best we can tell.
Before I end I will see if some of our REAL experts will come take over for me before I make a, er, donkey of myself!
I'm glad you're giving your flock calcium and that they like it! But don't forget they need grit too.
@aart
@Ridgerunner