Utilizzo di fonti proteiche alternative e probiotici nella dieta di specie ittiche allevate: effetti sul microbioma e salute intestinale.

In a scenario of growing food demand due to the rapid increase in the world’s population, which is estimated to reach 9.7 billion people by the end of 2050, agriculture is facing an enormous challenge. In this context, aquaculture represents the fastest growing food provider industry, but also one which only has a minor impact in terms of environmental footprint. However, a limitation to expanding the sector lies in the need for advancing technology, management, regulations, and, to the largest degree, in the necessity to reduce or eliminate the dependence of the sector on marine ingredients. Conventional ingredients, FM and FO, although they represent the best nutritional source for fish are finite and no longer sustainable, as their use still requires a large amount of wild marine resources. Hence, for the continuation and further development of the sector, it is essential to replace them. The number of possible alternatives has increased in the past few decades. The most widespread alternatives include vegetable feedstuffs, both meals and oils, that are currently used as partial or total replacement of marine-based ingredients. Insects, single-cell proteins, and feed additives, such as probiotics represent other possibilities that are attracting more and more interest in aquaculture nutrition owing to their balanced profile, availability, and promising results. Despite the advantages of these alternatives, a single substitute ingredient cannot satisfy all the nutritional and physiological requirements of fish; therefore, different application approaches and, consequently, numerous studies will have to be conducted to obtain the best feed formula for the numerous fish species now being farmed in aquaculture. One of the strategies to assess the effects of an innovative diet on the physiology and growth parameters of the fish is to investigate changes in the microbiota community that inhabit the intestine of the animal, as it represents the main factor in digestion and fermentation processes. Interpretations of the molecular mechanisms underlying the interaction between host, microbial populations, and fish feed represent the keystone to modulating fish gut microbiota and future, more sustainable diets, in order to enhance the digestive capacity and performance of these animals. Hence, the aim of the present PhD research project was to study how the composition of the intestinal microbiota is affected by using alternative protein sources and probiotics in the diet of freshwater and marine fish.