Potential of Alaria esculenta Silages as Ruminant Feed: Ruminal Fermentation, Methane Production, and Nutritive Value

Abstract

Brown seaweed Alaria esculenta has potential as a sustainable feed for ruminants, but it deteriorates quickly after harvesting. This study evaluated silage as a preservation method and analyzed its effects on nutritive value and anti-methanogenic properties. Four treatments were tested: no additive, formic acid, lactic acid bacteria (LAB), and pre-wilting at 30% dry matter plus LAB (PLAB). Chemical composition and in vitro fermentation using sheep rumen fluid were analyzed. Ensiling reduced fiber components and polyphenols but did not affect gross energy, and increased gas production and total volatile fatty acids, indicating improved fermentability, especially in PLAB treatment. However, overall nutritive value remained lower than that of alfalfa hay and concentrate. Methane production increased after ensiling due to higher fermentation levels. Despite this, the methane-to-VFA ratio in all the seaweed samples was about one-third of that of conventional feeds, indicating anti-methanogenic properties. No differences in this ratio were found between fresh and ensiled seaweed, indicating that these anti-methanogenic properties were preserved. Overall, ensiling is a viable method to stabilize A. esculenta, improving its fermentability and maintaining its capacity to reduce methane emissions, although its nutritional value remains relatively low compared to traditional ruminant feeds.