I'm finding big differences in the bags of scratch I buy for my girls. Mostly made up of cracked corn,milo, some millet, some wheat. Some bags just label it as "grains," and some label the actual ingredients. At our MFA you can buy alot of grains in bulk and cheaper than if I buy the pre-mixed product. So I'm mixing my own scratch/bird feed to make it a more complete treat. I bought cracked corn, milo, black oiled sunflower seeds and a bag of oyster shell. I give oatmeal as a seperate treat. What would be the ratios?