This scientific exchange aims at a long-term collaboration between Agroscope and KU Leuven while strengthening the methods in the field of monogastric gut health and animal nutrition. It implements and optimises advanced in vitro fermentation using feed samples from both institutes and investigates how alternative feed ingredients influence intestinal microbial activity and fermentation patterns. While previous studies have mainly investigated dried microalgae, this project focuses on fermentation characteristics of liquid microalgae, a novel feed ingredient that could be used as a sustainable alternative in pig nutrition. Feed substrates undergo simulated gastrointestinal digestion and are subsequently subjected to in vitro colonic fermentation using pig faecal inocula. Fermentation kinetics are assessed through measurements of gas production and short-chain fatty acid formation. The project involves reciprocal transfer of expertise, shared experiments, joint data interpretation and peer-reviewed publication. The outcomes include novel data on the fermentability of liquid microalgae, harmonised fermentation protocols and the implementation of the 3Rs principles in animal research.