Methane gas production and phenolic compound of two species in tropical brown seaweeds

Abstract

A study has indicated that the metabolites found in seaweed can lower methane emissions from ruminants, especially the phenolic compound. Indonesia is a tropical nation where seaweed variety is abundant, but it has not been widely reported to be used to reduce ruminant methane emissions. The research aims to measure the methane gas production and phenolic compound of two species in tropical brown seaweeds (Laminaria Sp. and Padina australis) from Tuban, East Java, in Kelapa Beach, Indonesia. The treatments were completely randomized with four replications and t test for the differences among treatment means. After a 24-hour incubation period, 10 mL samples used for the analysis of methane gas production were taken from the aliquot, preserved in a vacuum tube, and measured using gas chromatography (GC). The phenolic compound analysis included phenol, tannin, and flavonoid with a spectrophotometer according to Makkar (2003) and Arvouet-Grand et al. (1994) method. The result showed that Padina australis (2.47 mL and 13.00 mL/g DM) is lower in methane than Laminaria sp. (3.41 mL and 18.41 mL/g DM). Meanwhile, Padina australis is higher in flavonoid, phenol, and tannin (3.99, 0.88, 0.87 mg/g DM respectively) than Laminaria sp. (2.73, 0.63, 0.61 mg/g DM respectively). It was concluded that from two species of tropical brown seaweed, Padina australis had more potential to reduce methane emission than Laminaria sp. due to higher phenolic compounds (flavonoid, phenol, and tannin).