Assessing the methane mitigation potential of Canadian red seaweeds using in vitro batch culture

Abstract

Seven red Canadian seaweeds ( Callophyllis flabellulata, Graciliariopsis verrucosa, Mastocarpus papillatus, Mazzaella splendens, Mazzaella japonica, Palmaria mollis, and Prionitis lanceolata) and a positive control ( Asparagopsis taxiformis) were selected to evaluate their chemical and elemental composition and their effects on in vitro fermentation and methane (CH4) production in an alfalfa hay or barley straw diet. The in vitro batch culture was conducted as a completely randomised design with a control (alfalfa hay or barley straw) and seven increasing concentrations of seaweed. Chemical and elemental composition varied greatly across seaweed genera. Increasing supplementation of A. taxiformis linearly decreased ( P < 0.001) dry matter disappearance (DMD) and gas production (GP; mL, mL/g DMD) with CH4 production eliminated ( P < 0.001) at 1.0% inclusion of A. taxiformis in both diets. Inclusion of Mastocarpus papillatus, Mazzaella japonica, Mazzaella splendens, Palmaria mollis, and Prionitis lanceolata increased ( P ≤ 0.05) GP (mL/g DMD) at 0.5% and 1.0% in alfalfa diets. Graciliariopsis verrucosa linearly decreased ( P = 0.01) CH4 production (mL/g DMD) in the straw diet, but no doses were different compared to the control. In conclusion, the Canadian red seaweeds examined in this study did not exhibit anti-methanogenic potential when incubated with alfalfa hay or barley straw.