Effect of fit-for-purpose biochars on rumen fermentation, microbial communities, and methane production in cattle.

Introduction: Biochar has gained significant attention as a possible anti-methanogenic supplement for ruminants due to its potential to reduce methane (CH₄) emissions from enteric fermentation. However, its effects on rumen methanogenesis have been inconsistent and, in some cases, contradictory. These variations are likely influenced by factors such as the type of biochar used, its source material, and how it is administered, including the form in which it is provided and the dosage needed to achieve desired outcomes. This study aimed to examine the effects of two fit-for-purpose biochars on rumen fermentation, CH Experiment 1: This was a controlled pen trial conducted over 56 days, involving 12 steers that were fed Rhodes grass hay Experiment 2: In this trial, 45 heifers were selected and grazed together in a single paddock for 60 days to assess the effects of biochar on productivity and CH Results: In the controlled pen trial (Experiment 1), biochar supplementation resulted in a reduction of CH₄ emissions by 8.8-12.9% without any negative effects on rumen fermentation or dry matter intake (DMI). Minor changes were observed in the rumen bacterial community, particularly in the Conclusion: While the results from controlled feeding conditions suggest that biochar has the potential to reduce enteric CH₄ emissions, the lack of significant findings under grazing conditions highlights the need for further research. Future studies should focus on identifying biochar types, doses, and delivery methods that are effective in reducing CH₄ emissions in grazing systems without compromising cattle productivity.