Corn in low amounts is not a problem. The problem can be yellow corn in high amounts. The fruit content does not necessarily pose any risk factor: again type and amount, as well as size of the pieces. Dried carrots and some other firm dried foods have been known to blockages. Protein content can be higher. Can't recall fiber content offhand. Some fiber is needed to have foods hold together in kibbles, though some new types of equipment are letting that number be reduced, ditto using starch molecules which are larger. One ingredient will affect another. For instance, a highly mineralized meat source combined with low starch levels can rest in the runs. It becomes a balancing act: fitting the pieces together to get them to work out right. When a meat source is changed it may be need that the mineral levels, fiber type and amount, and starch type and amount all need adjusting. Meat is a very limited food source and is not necessarily better than meat by products. It depends on the sources of the by-products and on the supplementation in the food. Remember that organ meats are good sources of many nutrients, esp minerals. (There are cautions for certain organs. For instance, even though Mink Spongiform Encephalopathy (which ferrets get) is incredibly rare I really would like to see the same food stuffs removed from ferret food as have been removed from human food for prion reasons: things like mechanically separated beef, beef central nervous system tissue, beef small intestine, chicken crops (Chickens don't get prion disease but the prions remain contagious from eaten chicken crops of chicken fed infected beef meal for over 2 months.), etc. [Posted in FML issue 4442]