Some herbivores have evolved specialized teeth and digestive systems that allow them to break down tough plant material, such as grass. Like a connoisseur of fine wines, it will turn its nose up at low-quality leaves. Whether leaves meet a koala’s quality standards depends on the time of year, region and “mood” of the tree! Eucalyptus trees produce a horrible substance to prevent animals from eating its leaves. When ruminants are fed high-grain or concentrate rations, the digestion process is