FUNCTIONAL FEED ADDITIVES FOR ANIMAL HEALTH

World population growth is leading to an increase of the of food from animal origin demand. For the future of the planet and food-production system sustainability some important issues required to be faced. Antimicrobial resistance is one of the most important global concerns cause of thousands of deaths per year and livestock can contribute to the antimicrobial resistance spreading. In livestock, the highest use of antibiotic treatments is recorded in young animals, due to their immature immune system, and the presence of several stress sources that predispose young animals to develop multifactorial diseases, particularly from gastrointestinal origin, that causes important economic losses and antibiotic use. Nutrition is no longer considered as science that only satisfies nutritional requirements but is considered fundamental for its functionality through the supplementation of ingredients and additives which contain bioactive molecules that positively impact on health. Functional feed ingredients and additives possess bioactive characteristics, such as antibacterial and antioxidant activities, capable of contrasting infections and improving animal health or a particular organic function. Preserving intestinal health decreases the incidence of pathologies, optimises digestive processes, and promotes animal performance thus resulting in higher profitability for the farmers. The aim of the following project was to evaluate innovative functional feed additives for animal nutrition, in order to increase animal health, performance and reduce the use of antibiotics in farm animals. The attention was focused on the evaluation of algae, tannins extract, leonardite, tributyrin and probiotics as functional feed additives alternative to antibiotics. For reaching this goal different in vitro, in vivo and ex vivo approaches have been used. In vitro methods allowed to characterize functional feed additives for their antimicrobial and antioxidants effects and cell culture was useful to predict their interaction with the intestinal epithelium. In vivo zootechnical trials were conducted on young animals to assess dietary supplementation of functional additives on growth performance, prevention of gastroenteric disorders, metabolic status and microbiota modulation. Obtained results highlighted that functional additives were characterized by bioactive properties such as antioxidant and antimicrobial effects. Their supplementation showed a plethora of positive impacts including higher zootechnical performance, decreased diarrhoea occurrence, improved health status and microbiota modulation. A combined effect was also assessed in order to evaluate a possible synergistic of different additives. The combination resulted in a positive effect for diarrhoea prevention with a slight modulation for the gut microbial environment. Even if feed additives displayed different bioactivities in vitro, they did not always reveal a boosting effect on growth performance in vivo resulting less evident for farmer perception. However, the reduction of gastrointestinal disorders incidence could be considered the most interesting characteristic of functional feed additives which have shown to possibly reduce pathologies occurrence thus improving farm profitability. Lastly, due to the needing to decrease animal for experimental purposes an innovative ex vivo intestinal perfusion model was developed in order to study nutrient bioaccessibility for obtaining reliable science-based data in line with the 3R principles. In conclusion, tested compounds can not substitute the therapeutic treatment of antibiotics. However, the utilization dietary approaches supplementing functional feed additives can significantly contribute for decreasing pathology occurrence, boosting animal health and performance thus the antibiotics use. In line with the One Health principles, antibiotics reduction is a key point for the future sustainable development on the planet. The use of functional feed additives can be considered as interesting alternative to antibiotics due to their ability to prevent multifactorial disorders and thus reducing the antibiotic treatments in livestock farming.