Depends on what sex and whether your milking or breeding, I give mine pasture in summer and a soft grass mix hay in the winter, some years I'll feed a sweet 16 if they are looking thin or the weather is bad or I'm growing some kids. I don't like feeding too much grain as goats can get digestive problems easy. Always make dietary changes slowly, and I give mine baking soda free choice as well as a goat mineral that contains copper..
Goats are ruminants, they are designed to extract nutrients out of roughage, grain can cause too much acidity to develop due to them not producing enough saliva during chewing as well as not need to chew their cud afterwards, too much acid in the stomach can crash the system. So small amounts. I stay away from alfalfa, especially in wethers, because I believe it's the cause of stones, I've never had one with stones, I keep mostly wethers.