This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the October 2019 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.
The rumen allows cattle to digest fiber that chickens, pigs and humans can’t, and produce high quality beef protein from feed and land that otherwise wouldn’t produce food. Understanding the rumen better is the key to improving feed efficiency and improving cattle’s ability to convert fiber to protein.
There’s as much energy in straw as grain – burning a ton of either straw or grain generates the same amount of heat. But cattle can’t access all the energy in straw.
Grain is mostly starch. Starch is a long chain of identical sugar (glucose) molecules connected by simple links that rumen microbes can easily break using a few enzymes. That’s why feedlot cattle digest and convert grain-based diets so rapidly and efficiently. In contrast, straw contains cellulose, hemicellulose, pectin and lignin fibers. These contain many different molecules (not just glucose) connected by complex links that are much tougher (and require many more enzymes) for microbes to break. That’s why cows can’t be wintered on straw alone.