Since I'm feeding the same feed to both bucks and does, I want the cal : phos ratio to be about 2:1. Mine is about 14% or 15% protein. If I need more protein, I can mix something in for specific goats. The does generally get alfalfa pellets mixed with their feed during late pregnancy/ when they're in milk. That ups their protein and the extra calcium boosts milk production. If I'm feeding good hay, I don't have to do nearly as much grain or alfalfa pellets.
There is more info out there about mineral ratios, etc., to look for in feed. I'm sure others will chime in.
I always ask other goat people what they're feeding. I know a lot of people who mix their own feed, and I have toyed with the idea of doing that, but the feed I can get from my local feed mill is cheap, my goats do well on it, and I like the simplicity of just dumping it into the barrel, and not messing around with different bags, etc. It's NOT the highest quality...there are grain by products in there...but I'm also not relying on it as the main source of nutrients, either. In summer, my goats mainly eat brush, and in the winter, they have good hay. So far, I am quite pleased. Ask me in 10 years, and I might have more to share.