Ex-Food: promoting a novel and sustainable pig production by using food leftovers as feedstuff

The use of alternative feed ingredients in farm animal diets is interesting from several perspectives. Ex-foods, also known as Former Food Products (FFPs), are one way of converting losses from the food industry into ingredients for the animal feed industry, thereby keeping nutrients in the food chain. Based on their nutritional features, these materials are extremely rich in carbohydrates, free sugars and, depending on their origin, also in fats. In addition, FFPs are often characterized by a high degree of processing including technological and heat treatments which can affect not only the availability of nutrients and the kinetics of digestion, but also gastro intestinal health and animal response. This review integrates some of the most recent published works about the chemical composition, nutritional value, digestibility and glycemic index of ex-foods. In addition, a view on the relationship between the use of FFPs and safety issues and their effects on intestinal microbiota are also given.