Author(s)

Robert D. Kinley^1,2, Siong Tan¹, Jemima Turnbull^1,3, Shane Askew⁴, Jessica Harris¹, Breanna M. Roque¹

¹FutureFeed Pty Ltd., Townsville, Australia.
²Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Townsville, Australia.
³College of Public Health, Medical and Veterinary Sciences, Douglas Campus, James Cook University (JCU), Townsville, Australia.
⁴Advanced Analytical Centre (AAC), Douglas Campus, James Cook University (JCU), Townsville, Australia.

Asparagopsis oil products are of interest due to the stabilizing effects of the Asparagopsis-derived antimethanogenic bioactive compound bromoform (CHBr₃). The objective of this in vitro series is to characterize antimethanogenic efficacy of freeze-dried Asparagopsis (FD-Asp) and Asparagopsis oil (Asp-Oil) and compare relative antimethanogenic response over time at multiple levels of CHBr₃ delivery. Relative methane (CH₄) emissions (mL/g) are based on in vitro apparent feed digested dry matter (IVDDM) after 24, 48, and 72 h of fermentation. CHBr₃ contained in FD-Asp was included at 95, 191, and 286 mg/kg, and CHBr₃ contained in Asp-Oil was included at 78, 117, and 175 mg/kg, to produce the Low, Mid, and High inclusions, respectively. Low FD-Asp had no significant impact on CH₄ emissions, Mid FD-Asp demonstrated 91%, 44%, and 37% reductions, and the High FD-Asp demonstrated complete inhibition of CH₄, after 24, 48, and 72 h of fermentation, respectively. Comparatively, Low Asp-Oil demonstrated a 46%, 28%, and 18% CH₄ reduction, Mid Asp-Oil resulted in 99%, 92%, and 73% reductions, and the High Asp-Oil demonstrated complete inhibition of CH₄ after 24, 48, and 72 h of fermentation, respectively. IVDDM and total volatile fatty acid (tVFA) production were not changed by the inclusion of FD-Asp and Asp-Oil. The results from this study show that Asparagopsis is not only a compelling CH₄ mitigating feed supplement but is also able to be delivered in edible oil forms which will strengthen its applicability to on-farm use. This study is promising for the utility of Asp-Oil, and in vivo trials are essential to demonstrate the extent of efficacy of Asp-Oil in ruminant animals because FD-Asp has consistently demonstrated greater antimethanogenic efficacy in vivo compared to in vitro.

Asparagopsis, Edible Oil, Methane, Greenhouse Gas Mitigation, In Vitro

Kinley, R. , Tan, S. , Turnbull, J. , Askew, S. , Harris, J. and Roque, B. (2022) Exploration of Methane Mitigation Efficacy Using Asparagopsis-Derived Bioactives Stabilized in Edible Oil Compared to Freeze-Dried Asparagopsis in Vitro. American Journal of Plant Sciences, 13, 1023-1041. doi: 10.4236/ajps.2022.137068.