I cut my inferior (yet best available) coturnix feed with ground up dry cat food. The feed is 21% protein, the cat food is 30%. I do a 50/50 mix by weight, not volume. Doing the math, (so that you can figure out what you'd end up with), add the feed percentage of protein with the cat food percentage of protein then divide by 2 (because it's a 50/50 blend). So, I'm getting a boost up to 26.5% protein [(21+30)/2]. The feed stores here do not offer soymeal or other forms of protein supplement, pretty much have to make do with whatever they're offering at any given time. (I live in a third-world nation) I do not go higher than 50/50 mix because their feed contains specific vitamins, minerals, amino acids that I am already messing with by adding cat food; I'm trying to limit how much I mess with THOSE figures, while ensuring that they get enough protein.