Graduate Student Literature Review: Limitations in feeding red seaweed Asparagopsis species for enteric methane mitigation in ruminants.

Enteric methane (CH₄) emission from ruminant livestock results in a loss of digestible feed energy, which has significant implications for animal production and contributes to global warming. Digestible feed energy losses and GHG emissions are sufficient justifications for devising strategies that reduce enteric CH₄ emissions from ruminants. Of the available and horizon GHG mitigation strategies for ruminants, there is currently considerable enthusiasm in the use of feed additive methanogenesis inhibitors. Asparagopsis, as a feed additive, is very effective at mitigating enteric CH₄ emissions from ruminants. Although research has focused on the potential of this feed additive to mitigate enteric CH₄, Asparagopsis supplementation has frequently been accompanied by a noticeable decline in DMI. This review summarizes the current literature on challenges and implications that persist in Asparagopsis feeding trials in ruminants. These include constraints in the experimental design and effects of the novel ingredient on dihydrogen (H₂) metabolism, which could affect rumen functions and, consequently, DMI. Concerns have been also raised regarding the cost, potential side effects on animal health, and the safety of Asparagopsis feed additives. Antimethanogenic activity must be reconciled with other nutritional considerations, including a reduction in rumen fermentation efficiency, which could contribute to a decrease in feed intake and indirectly affect animal health and productivity. Therefore, this synthesis provides essential information for the livestock industry to develop standardized protocols that could minimize the negative effects of dietary Asparagopsis on feed intake and productivity.