Feeding just muscle meats to pets is a serious error since no carnivore in the wild eats such a diet. If they did, they would become diseased from doing so. (
Wysong Call of the Wild™ is a supplement designed to balance a fresh meat diet, and provide those vital food elements lacking in a strictly fresh meat diet.) In fact, carnivores often prefer the non-muscle meat parts of their prey that are labeled "by-products." Critics of by-products evidently feel food animals have no inherent merit and that they should be raised, slaughtered, and then everything but their "prime meat" should go to a landfill.