TITLE:
In Vitro Evaluation of the Antimethanogenic Potency and Effects on Fermentation of Individual and Combinations of Marine Macroalgae
AUTHORS:
Robert D. Kinley, Matthew J. Vucko, Lorenna Machado, Nigel W. Tomkins
KEYWORDS:
Asparagopsis, Methane, Rumen, Seaweed, Algae
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.7 No.14,
October
19,
2016
ABSTRACT: Contribution of ruminants to
total greenhouse gas emissions in Australia is approximately 10% and likely to
increase with demand for livestock products, thus an efficient method of
mitigation must be implemented. The red marine macroalgae Asparagopsis taxiformis reduces enteric methane production by up to
99% in vitro. Other macroalgae with
less potent antimethanogenic properties may complement inclusion of Asparagopsis in livestock feeds.
Adoption of environmental based changes in livestock systems must provide
benefits to producers if change in management is to be adopted. This study used
72 h in vitro fermentations with
rumen inoculum to characterize and rank seven species of macroalgae at low
inclusion that previously demonstrated some degree of antimethanogenesis at
higher inclusion concentration. The seven were assessed at 5% inclusion (OM
basis) and in combination with Asparagopsis to evaluate beneficial effects on fermentation. When tested individually,
improvements in volatile fatty acids were generally observed, however, minimal effect on gas production and no clear
justification for a ranking order were demonstrated. When tested
in combination with Asparagopsis, the
effects on fermentation were dominated by presence of Asparagopsis at 2% and no further benefits demonstrated. Therefore, Asparagopsis remains the only
macroalga inducing near elimination of methane in vitro and benefit of combinations with other macroalgae
evaluated in this study was not demonstrated. However, combination with high
protein macroalgae is proposed to provide productivity enhancement during
seasonal lows in grass quality and thus reduce methane emissions intensity
providing a stronger conduit for environmental responsibility while increasing
productivity.