![]() To the best of our knowledge, AT is not yet cultivated on a commercial scale and wild harvest cannot be sustainable or meet the demand of the global or even U.S. Reduced animal performance would decrease the effect of AT on a CH 4 intensity (CH 4 g/kg milk or meat produced) basis and would likely limit industry adoption of AT. While these results are promising, some studies indicated that DMI and milk yield were negatively affected by AT supplementation 9, 10. Among these, macroalgae, specifically Asparagopsis taxiformis (AT), have been identified as a potential candidate to mitigate enteric CH 4 emission from livestock.Īsparagopsis taxiformis was shown to almost eliminate enteric CH 4 emission in vitro 6, whereas in vivo research in both cattle and sheep have reported decreases of 0 to 98%, depending on diet and AT inclusion rates 7, 8, 9, 10. Beyond feed management and formulation, several diet additives that act as CH 4 inhibitors have been identified 3, 4, 5. Being a downstream product, the quantity of CH 4 produced is greatly dependent on the initial fermentation substrate and rumen conditions. ![]() Enteric methanogenesis is a process by which various end-products of anerobic microbial fermentation in the rumen, mainly CO 2 and H 2, are metabolized by archaea for energy, creating CH 4 2. Within the United States, dairy and beef cattle contributed approximately 169 million metric tons (MMT) of CH 4 (43.6 and 125.3 MMT, respectively) on a CO 2e basis in 2020 through enteric fermentation 1. (on a CO 2 equivalent basis, CO 2e) with approximately 30% of these emissions being enteric methane (CH 4) 1. No other macroalgae were identified as potential mitigants of enteric methane.Īccording to the United States Environmental Protection Agency (USEPA), in 2020 agriculture was responsible for 11% of the total greenhouse gas (GHG) emissions in the U.S. In this in vitro study, Asparagopsis taxiformis was most effective in decreasing methane concentration and yield, but also decreased total gas production and VFA concentration which indicates overall inhibition of ruminal fermentation. Specific gene activities for Methanosphaera stadtmane and Methanobrevibacter ruminantium were decreased by AT inclusion. Inclusion of AT decreased relative abundance of Prevotella, Bacteroidales, Firmicutes and Methanobacteriaceae, whereas Clostridium, Anaerovibrio and Methanobrevibacter were increased. Vertebrata lanosa increased ammonia concentration, whereas 3 other species decreased it. Asparagopsis taxiformis also increased butyrate and valerate molar proportions by 7 and 24%, respectively, whereas 3 macroalgae species decreased molar proportion of butyrate 3 to 5%. Molar proportion of acetate was decreased 9% by AT, along with an increase in propionate by 14%. Total volatile fatty acid (VFA) concentration was decreased between 5 and 8% by 3 macroalgae, whereas AT reduced it by 10%. Total gas production was decreased 14 and 10% by AT and Sargassum horneri compared with control, respectively. Colpomenia peregrina also decreased methane yield 14% compared with control no other species influenced methane yield. Methane yield was decreased 99% by Asparagopsis taxiformis (AT) when compared with the control. ![]() Incubations were carried out in an automated gas production system for 24-h and macroalgae were tested at 2% (feed dry matter basis) inclusion rate. Specimens were analyzed for their effect on ruminal fermentation and microbial community profiles. This study investigated the effects of 67 species of macroalgae on methanogenesis and rumen fermentation in vitro.
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