Insects and gut health in food-producing animals

Insect meals, oils and live larvae can represent valuable innovative dietary ingredients for animal nutrition. In particular, Hermetia illucens and Tenebrio molitor are the most promising insect species for animal's feed. This chapter will focus on the effects of insect-derived feed ingredients on gut health of food-producing animals. In poultry low dietary inclusion levels of insect meal (< 15%) are recommended, as they maintain diet digestibility, gut health, and, adequate growth performance. In fish and pigs, both low and high inclusion levels of insect-based products (fish: from 3 to 60% pigs: from 1.5 to 33%), can efficiently be used. Insect oils rich in lauric acid with antibacterial activities, seem to be a promising alternative fat source in rabbit nutrition as they do not impair diet digestibility and growth performance of the animals, also improving their intestinal microbiota. Less information is available on ruminants due to the European ban on the use of processed animal proteins in this species to avoid the spreading of the bovine spongiform encephalopathy. The available preliminary studies have been mainly performed in vitro using 7.5 to 25% of insects in substitution of soybean meal, suggesting that insects may represent a suitable protein and fat source also for ruminants, especially considering the ability of chitosan to reduce ruminal biohydrogenation and methane production without impairing diet digestibility. However, further studies are needed to confirm the potential effects of insect meals and oils on gut health of rabbit and ruminants and to better know the prebiotic/probiotic activity in different food producing animals.