Coming out of the chicken industry, I was unprepared to feed an animal equipped with a 50-gallon bioreactor (i.e. a rumen). I quickly learned, “Happy rumen, happy calf. Unhappy rumen, unhappy calf.” What Buck helped me understand is that the rumen is primarily designed to digest grass. The result is that many common feed ingredients go straight through the rumen—undigested—and into the manure pile. This is how feed conversions wind up at an astronomical 7:1 and your finances start seeing red!