Abstract
The red macroalgae (seaweed) Asparagopsis spp. has shown to reduce ruminant enteric methane (CH4) production up to 99% in vitro. The objective of this study was to determine the effect of Asparagopsis taxiformis on CH4 production (g/day per animal), yield (g CH4/kg dry matter intake (DMI)), and intensity (g CH4/kg ADG); average daily gain (ADG; kg gain/day), feed conversion efficiency (FCE; kg ADG/kg DMI), and carcass and meat quality in growing beef steers. Twenty-one Angus-Hereford beef steers were randomly allocated to one of three treatment groups: 0% (Control), 0.25% (Low), and 0.5% (High) A. taxiformis inclusion based on organic matter intake. Steers were fed 3 diets: high, medium, and low forage total mixed ration (TMR) representing life-stage diets of growing beef steers. The Low and High treatments over 147 days reduced enteric CH4 yield 45 and 68%, respectively. However, there was an interaction between TMR type and the magnitude of CH4 yield reduction. Supplementing low forage TMR reduced CH4 yield 69.8% (P <0.01) for Low and 80% (P <0.01) for High treatments. Hydrogen (H2) yield (g H2/DMI) increased (P <0.01) 336 and 590% compared to Control for the Low and High treatments, respectively. Carbon dioxide (CO2) yield (g CO2/DMI) increased 13.7% between Control and High treatments (P = 0.03). No differences were found in ADG, carcass quality, strip loin proximate analysis and shear force, or consumer taste preferences. DMI tended to decrease 8% (P = 0.08) in the Low treatment and DMI decreased 14% (P <0.01) in the High treatment. Conversely, FCE tended to increase 7% in Low (P = 0.06) and increased 14% in High (P <0.01) treatment compared to Control. The persistent reduction of CH4 by A. taxiformis supplementation suggests that this is a viable feed additive to significantly decrease the carbon footprint of ruminant livestock and potentially increase production efficiency.
Highlights
Livestock production, ruminants, contributes to anthropogenic greenhouse gas (GHG) emissions globally
Carbon dioxide (CO2) production and intensity factors were not affected by either Low or High treatments, CO2 yield was significantly greater in High treatment compared to Control (P = 0.03)
Significant reductions in CH4 yield, which is standardized by Dry matter intake (DMI), when Asparagopsis is supplemented to beef cattle diets has been established in this study and are similar to the reductions found in previous studies [6,29,35]
Summary
Ruminants, contributes to anthropogenic greenhouse gas (GHG) emissions globally. These emissions are estimated to be 7.1 Gt carbon dioxide (CO2) equivalents annually which accounts for approximately 14.5% of the global anthropogenic GHG emissions [1]. Enteric CH4 emissions contribute to total agricultural GHG emissions and represent an energy loss amounting up to 11% of dietary energy consumption [2]. Reducing enteric CH4 emissions decreases the total agricultural contribution to climate change and can improve productivity through conservation of feed energy. There is potential for mitigation of enteric CH4 emissions through a variety of approaches with a focus on the use of feed additives, dietary manipulation and forage quality [3]
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