Élisabeth Chassé1, Mihai Victor Curtasu1, Marco Battelli2, Annette Bruhn3,4 and Mette Olaf Nielsen1
1Department of Animal Science, Aarhus University, Foulum, Denmark
2Dipartimento di Scienze Agrarie e Ambientali – Produzione, Territorio, Agroenergia, Università degli Studi di Milano, Milano, Italy
3Department of Ecoscience, Aarhus University, Aarhus, Denmark
4Center for Circular Bioeconomy, Aarhus University, Foulum, Denmark
Macroalgae have attracted significant attention in recent years as potential feeds or feed additives, since their cultivation is not associated with use of arable land suitable for human food production, and because of the ability of some species to reduce methane formation during enteric fermentation in ruminants. However, most macroalgae species have a low digestibility, even for ruminants, due to the unique and complex carbohydrate (CHO) structure in cell membranes. This represents an obstacle to be overcome in order to implement macroalgae as future feeds in livestock diets. There is only limited information available on rumen degradability of the individual CHOs, including simple sugars, oligosaccharides and non-starch polysaccharides (NSP). It is the aim of this project to establish, how individual CHOs in seaweed are degraded in the rumen to be able to develop methods to increase their digestibility. In this experiment, presently in progress, we use 22 macroalgae species (brown, red and green species) for in vitro experiments simulating rumen fermentation. CHO composition of the intact macroalgae and the undigested remains after fermentation in rumen inoculum are analysed for contents of NSP as monomeric sugars, simple sugars and oligosaccharides. Gas production during the simulated rumen fermentation, and pH and volatile fatty acid (VFA) produced during the fermented are also measured in the fermented fluid after 48 hours of in vitro fermentation. Data will be available for presentation at the symposium.