The problem is that people in general regiment their animals diets so much that when change does occur, they cannot deal with it! If you gave your horse a different feed every day, their stomach would be in a position to deal with this diversity, but to make it simpler to understand, if you as a person, ate oatmeal for breakfast with milk, oatmeal for lunch with milk, and oatmeal for supper with milk, and did this straight for 2 months. Now one morning you wake up and you have bacon and eggs with coffee - for lunch you have perponi pizza and a coke, adn for supper you eat a peppered steak with french fries and a coke. Your stomach would be rolling. You might not even make it through the day without either vomiting, some pepto, or a trip to the doctor, yet this is exactly what we do to our animals. So we have to options, feed the same every day - easiest! Or change up every day (exactly the same way we as humans eat) Much harder!