Evaluating the efficacy of red, brown, and green seaweeds in reducing in vitro methane production from cattle

Two in vitro batch culture experiments were conducted to evaluate the effect of 30 different species of seaweeds found along the Canadian coast and Asparagopsis taxiformis on in vitro degradability, gas production (GP), methane (CH 4 ), and volatile fatty acids (VFA) production in an alfalfa hay diet. Experiment 1 examined the inclusion of 5% dry matter (DM) of 26 seaweeds and A. taxiformis as a positive control. Experiment 2 examined five seaweed species and a seaweed blend at increasing inclusion rates (0%, 0.5%, 1.0%, 2.0%, and 5.0% DM). The composition of seaweeds varied greatly. Asparagopsis taxiformis decreased ( P < 0.01) GP (mL/g DM disappearance (DMD)) and completely inhibited ( P < 0.01) CH 4 production (mL), leading to modifications ( P < 0.01) in the VFA production profile. Shoreblend ( Chondrus crispus, Fucus vesiculosus, Furcellaria lumbricalis, Laminaria longicruris) included at 5% decreased ( P < 0.01) CH 4 yield (mL/g DMI, mL/g DMD) by 12.2% without altering VFA production. In conclusion, A. taxiformis exhibited strong anti-methanogenic potential, and incorporating 5% DM of Shoreblend in high forage diets could potentially mitigate CH 4 emissions from ruminants. The Shoreblend was the only seaweed that showed potential within an in vitro batch culture to inhibit CH 4 production.