You can also reduce grain costs by feeding chopped veggies. Do you have room to grow them yourself? I am feeding mangels that I grew to my one lactating doe and she loves them. There was a learning curve to growing them. This was my third year, and my first real crop. They didn't do well in the two previous rainy years, but this past drought year, I watered.
I add the mangels to the sprouted grains to stretch them and to add variety to her diet. I also had a few squashes that I accidentally forgot in the garage that froze, and she loves those, too.
I cleaned up my garden and the neighbor's garden (organic, too) and got some overgrown kohlrabi, turnips, mis-shaped carrots, beets, and various holey greens. Makes great milk. Fed on the milking stand, I don't notice any off taste in the milk.
I have a client who eats a lot of organic fresh veggies purchased in the grocery store, and she saves all trimmings and unused veggies in the freezer for me and I bring them home in a cooler every two weeks. Mya's favorites are brussells sprouts trimmings and the big leafy stems from cauliflower. I get 2-4 days worth of trimmings just from this one trusted person. Some people just hate to see anything go to waste, just gotta find these people!