Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers

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.

Fig 1. Experimental timeline including covariate period, Asparagopsis taxiformis implementation, dietary regime, and greenhouse gas measurement intervals.

Fig 2. Asparagopsis taxiformis inclusion effects on methane, hydrogen and carbon dioxide emissions over a 147-day period.

Means, standard deviations, and statistical differences of methane, hydrogen, and carbon dioxide production (g/d) (A1,B1,C1), yield (g/kg dry matter intake (DMI)) (A2,B2,C2), and intensity (g/kg average daily gain) (A3,B3,C3) for 0%, 0.25% (Low), and 0.50% (High) Asparagopsis taxiformis inclusion. Means within a graph with different alphabets differ (P < 0.05).

Fig 3. Asparagopsis taxiformis inclusion effects on methane emissions during the 21 week experimental period.

Methane production [g CH₄/day] (A) and methane yield [g CH₄/kg DMI] (B) from beef steers supplemented with Asparagopsis taxiformis at 0%, 0.25%, and 0.5% of basal total mixed ration on an organic matter basis during the 21 week experimental period. Data points are treatment means for each gas collection timepoint and error bars represent standard errors.

Fig 4. Asparagopsis taxiformis inclusion effects on hydrogen emissions during the 21-week experimental period.

Hydrogen production [g H₂/day] (A) and Hydrogen yield [g H₂/kg DMI] (B) from beef steers supplemented with Asparagopsis taxiformis at 0%, 0.25%, and 0.5% of basal total mixed ration on an organic matter basis during the 21 week experimental period. Data points are treatment means for each gas collection timepoint and error bars represent standard errors.