Non-starch polysaccharides composition of 23 macroalgae and their potential as future feeds for ruminants

This study aimed to characterize the non-starch polysaccharides (NSP) content of 23 macroalgae and to evaluate how algal polysaccharides are degraded in the rumen to be able to evaluate their potential as feed for dairy cattle. Selected macroalgae species were incubated for 48 h in an in vitro system simulating rumen fermentation. The raw macroalgae and undegraded macroalgae residue (UDMR) were analyzed for NSP content. Chemometric analysis was performed on the data sets using principal component analysis. The UDMR clustered according to either their degradability or content in undegraded sugars rather than their phylogenetic group. The highest degradability was observed in Palmaria palmata with 78.1 % dry matter degradability which can be attributed to its high content in xylans. Macroalgae with lower degradability had higher contents of insoluble galactose, rhamnose and glucose, all present in less degradable algal polysaccharides such as κ-carrageenans and ulvans. In conclusion, algal polysaccharides determined with the NSP method were in accordance with the phylogenetic group and the literature which validates the use of the NSP method for macroalgae. P. palmata would be of interest as an ingredient for ruminant nutrition as well as other macroalgae with the help of exogenous enzymes to increase their degradability.