Management of Enteric Methanogenesis in Ruminants by Algal-Derived Feed Additives

PURPOSE OF REVIEW: In this paper, we critically review the current state of nutritional management strategies to reduce methane emissions resulting from enteric fermentation in livestock production. In this context, it highlights the novel strategy regarding the use of macroalgal- and microalgal-derived feed additives. RECENT FINDINGS: Several feed management strategies for ruminants focus on the inclusion of nutritional supplements, increasing proportion of starch, or supplementation with high-energy lipids. These strategies aim to improve animal productivity, whilst at the same time reduce methane emissions. Algae supplements are currently investigated as novel ingredients for decreasing methanogenesis, with the potential production of algal biomass also contributing to reducing greenhouse gas emissions. Thus, utilisation of algal biomass as a feed concentrate in dietary supplementation presents a sustainable and environmentally friendly strategy. This review summarises the current stage of research on dietary strategies and their influences on the metabolic processes during enteric fermentation. This information is essential for developing strategies to mitigate methane emissions in the livestock industry. We specifically present the opportunities that algae could offer as a feed additive for methanogenic reduction in cattle. The data compiled from the peer-reviewed literature revealed synergistic effects of algal biomass on methane reduction and animal productivity. However, the challenges regarding the mass cultivation of macro- and microalgae were noticed. Considering the diversity of algal species, future research should increase screening efforts to include more species and dosage evaluation, along with efforts to see if such effects are sustained over time.