In Vivo Study of Combining Asparagopsis taxiformis and Phloroglucinol to Reduce Methane Production and Improve Rumen Fermentation Efficiency in Goats
Abstract
Most CH4 mitigation strategies based on feed additives result in excess ruminal H2 being expelled and consequently
not accompanied by improved rumen fermentation efficiency that could benefit animal productivity. The present
study aimed to confirm previous in vitro results and evaluated the combined treatment of Asparagopsis taxiformis
(AT), a potent methanogenesis inhibitor, and phloroglucinol, an organic compound that can be degraded by rumen
bacteria using H2 as electron donor, yielding acetate as the terminal product. Eight Murciano-Granadina adult goats
were used in a replicated 4x4 Latin square design. Four treatments were considered: i) control; ii) AT at 0.5% DM; iii)
phloroglucinol at 20 g/kg DM diet (PHL) and iv) combination of AT and phloroglucinol (AT-PH). Each experimental
period consisted of 10 days of adaptation to the treatments, followed by 3 days for CH4 and H2 measurements in
open-circuit respiration chambers and 1 day for rumen fluid collection at 3h post-feeding for VFA analysis and rumen
microbial community characterization. Results showed that PH treatment did not affect CH4 production, while AT and
AT-PH significantly (P<0.001) reduced CH4 production by 30-40 %. The AT treatment increased H2 expelled, which was
reduced by 74 % when AT was combined with PHL (P<0.001). Total VFA and acetate concentrations were significantly
increased by AT-PHL compared to AT. Moreover, PHL supplementation decreased the concentrations of archaea,
protozoa and anaerobic fungi. This study demonstrated that phloroglucinol could be used as means to capture
ruminal H2 produced in excess in a methanogenesis inhibition scenario and redirect it towards acetate production,
which could potentially lead to improvements in animal productivity.