With the diminishing availability of farming land, climatic changes and the threat of declining water resources, the challenge in agriculture is to how to meet the growing demand for food, feed, fiber, fuel, and industrial products using fewer resources. This will involve the reduced use and redistribution of resources by applying the principles of the circular economy, in other words, ‘Do more with less!’. These aspects, together with the increase in the cost of traditional feed for food producing animals over the last few years, have motivated feed researchers and producers to search for sustainable solutions for feeding animals. Insects, algae, ex-food (also termed former food products) as well as duckweed are regarded as interesting alternative protein/energy sources for feed and are expected to be increasingly used around the globe as replacers for conventional nutrient sources. The use of non-human-edible by/ co-products, such as former food products (FFPs) or ex-food, by the feed industry is evidence of the potential of this sector to make the best of the nutritional and economic added value of by-co-products by applying circular economy principles. As omnivorous animals, pigs are ideally the most suited species to convert several kinds of alternative ingredients into high-quality animal protein, thus keeping nutrients in the food chain. However, it is essential to thoroughly examine the compositional/safety/dietary features in order to provide new and fundamental insights aimed at efficiently reusing these ex-foods as value-added products for animal nutrition. Firstly this involves a nutritional and functional evaluation of these materials, followed by examining the impact of ex food on pigs’ performance, wellbeing and ultimately product quality. In this scenario the present work will address these aspects in pig nutrition.
