for people who love the littlest dairy goats
If you're talking about mixing your own grain, I don't recommend it. It's much more complicated to feed goats than cattle or horses. We tried mixing our own using organic grain and Fertrell's goat feed additive, and the results were pretty terrible.
The other thing to think about is that if you're going for a more natural diet, grain is not natural for goats or any ruminant. Giving them oat hay would be healthier for them than oats. I know there's grain in goat feeds, but there is also a fair amount of grass products (labeled as roughage or forage products) in those pellets.
I've seen 1 pound of grain per 3 pounds of milk produced.