The old school cottonseed cake that was the forerunner of the modern range cube is going the way of the dodo bird. The original product was a byproduct of the cottonseed oil industry. They would mechanically press the whole cottonseed to harvest the oil and the "cake" or cottonseed meal was the remainder of the whole cottonseed. The reason it made such good cattle feed and fish bait was that the mechanical extraction process was inherently inefficient and left a significant amount of oil behind on the magnitude of about 6-8%.
As with most industries, the cottonseed oil industry got more efficient and switched to a solvent or chemical extraction process instead of the mechanical. It made the cottonseed oil extraction process much less expensive and more cost effective, but it forever changed the cottonseed meal that was left behind. The fat content of the new process cottonseed meal rarely exceeds 3%.
We used to get in mechanically extracted meal from the Wolf City plant that was so fresh it was still warm when it got there. That stuff smelled like fresh baked cookies and the cattle loved it. The newer solvent extracted product is still fine for cattle feed and works well as a protein supplement, but lacks a lot of the fat that made the old process cottonseed meal such a good all around feed. There are very few mechanical extraction mills left in the U.S. and that's going to make the real deal hard to find.
Making your own "cake" is going to be difficult if you're trying to mimic the hardness and almost time release nature of range cubes underwater. The pellet mills that are used to form those range cubes are usually in the realm of 250-300 horsepower. You need that kind of pressure to form those pretty cubes and get that kind of hardness.
I hope you've enjoyed our two hour special on everything you never wanted to know about cattle feed and fish bait. smile