I started responding to this a few days ago, got called away from the computer, and just re-opened to see an awesome post from
@GC-Raptor - couldn't say it better myself.
Of course I can't help but add to it. Nutrition is a much debated topic – and one I'm a little obsessed with. After starting with chickens 1.5 years ago, I fell down a deep chicken-nutrition rabbit hole. Mainly because with poultry vets being so scarce, disease prevention is paramount, and nutrition is a major piece of that.
Roosters barely rank when it comes to feed. In the big picture, many boys are eaten before you'd see the effects of excess calcium. However, we like a calm, protective rooster with each flock, and a good man is hard to find, so we want ours to live long, healthy lives. As such, we avoid the calcium.
You can't even find an all-flock in our area – just a bunch of layer or game feeds – so we drive to the next county or order an 18% grower online, with separate cups of oyster shell and adult grit on the side. Many people seem to skip grit, but it's a cheap way to prevent some sketchy health issues. There's also evidence (I won't find it right now) that easy access to grit reduces the amount of feed they eat, so I mix it right into their feed in case some birds don't think to visit the grit cup. If they don't need it, it's left at the bottom of the feeder. No harm no foul.
One note that the caloric content of a grower feed can lead to obesity, especially with breeds prone to it (Orpingtons, Brahmas, etc.). If this is a concern, the feed can be cut with high-nutrient ingredients like alfalfa meal. Cutting/mixing feed is a whole other rabbit hole.
How you ultimately do things will depend on your individual chicken-tending style and goals, like whether you're raising boys for meat or longevity, how much your flock forages, what breeds you have, yada yada yada. Thanks for posting a good question!