In vitro five brown algae extracts for efficiency of ruminal fermentation and methane yield

Abstract

This study aimed to evaluate the effects of extracts of five species of brown algae (Ecklonia stolonifera, ESA; Eisenia bicyclis, EBS; Sargarssum fulvellum, SFM; Undaria pinnatifida, UPA; Sargassum fusiforme, SFS) on in vitro ruminal fermentation characteristics, total gas and methane production, and rumen microbial populations when incubated with grass (timothy, Phleum pratense) as the primary substrate. Rumen fluid donors were two rumen-fistulated Holstein cows with free access to water and mineralized salt block. An in vitro trial was carried out using 6, 12, 24, 48, and 72 h incubation with brown algae extracts added at concentration of 5% of timothy. Digestibility of dry matter (DM) was highest for SFS compared with control (Ctrl), with the remaining treatments being intermediate and similar. Ammonia nitrogen concentration was significantly higher at ESA and SFS than Ctrl. The concentrations of total VFA, acetate, and propionate were higher in all treatments compared with Ctrl, except for the propionate concentration at 48 h incubation. Total gas production of all treatments significantly increased with incubation time compared with Ctrl, whereas methane production was significantly decreased after 48 h incubation. As determined by relative quantification of specific ruminal microbes, brown algae extracts significantly affected the abundance of cellulolytic bacteria (i.e., Ruminococcus albus, Fibrobacter succinogenes, Ruminococcus flavefaciens), methanogenic archaea, and ciliate-associated methanogens. These results suggest that supplementation of brown algae extracts can modify ruminal fermentation to increase VFA concentration and total gas production and alter ammonia nitrogen and methane production.