Morrison's Feeds & Feeding is an old, out of print reference I find helpful when formulating feeds. You can find them used on eBay and other places.
I have a mix for my dairy cows that includes a lot of alfalfa (about 17% protein), corn, oats, wheat middlings (a decent protein source), sunflower seeds, a bit of soybean meal. I would like to eliminate the soy & corn as I know it is likely GMO. Need to work on that. The mix is 15-16% protein.
If your animals are not producing milk, they will not need such high levels of protein. The book I referenced above covers everything but goats.
So LinuxBoy, care to share your spreadsheet?