Abstract The growing world population and rising income in developing countries create more demand for animal products. However, natural resources such as land, water, and nutrients are not boundless. As a consequence, competition of resources in food and feed production is an issue to be confronted with. One promising solution is relocating food losses into animal feeding, propelling the course of sustainability and circular economy in the livestock sector. Given this scenario, former food products (FFPs) represent great opportunities. Instead of ending up in landfill or compost, a better destination for FFPs is to be used as feedstuffs to replace traditional ingredients. FFPs are foodstuffs not accepted by the human market but have several advantages enabling them to enter swine feeding programs. FFPs are mainly composed of processed and ready-to-eat food products such as snacks and bakery goods. Thanks to industrial processing and their product type nature, FFPs are rich in easily digestible starch, simple sugars, fat, and energy contents comparable with cereal grains. 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. On fresh matter basis, FFPs can substitute conventional feed ingredients up to 30 % in the diets of pigs. Starting from post-weaning piglets, FFP-based diet is able to maintain piglet growth without substantial effects on hindgut microbiota. In growing-finishing pigs, FFP-based diets at a 30 % inclusion level support growth performance of pigs without altering their nutrient and energy deposition efficiency, live body and carcass composition, and general meat quality traits. When considering liver proteome and plasma peptidome of pigs fed such diets, minor modulation occurs. To sum up, while maintaining the performance and wellbeing of pigs, the use of FFPs up to 30 % to replace classic feedstuffs represents a great potential in: i) mitigating food-feed competition, ii) re-distributing valuable food losses to livestock sector to produce animal protein, and iii) reducing environmental footprints resulting from animal production. All these aspects point out important concepts under the principles of circular economy and resilience enhancement in livestock farming, namely, making the most of resources to build a regenerative food system.
Read full abstract