A Pine Enhanced Biochar Does Not Decrease Enteric CH₄ Emissions, but Alters the Rumen Microbiota.

Area of Science:

• Animal Science
• Ruminant Nutrition
• Microbiome Research

Background:

• Enteric methane (CH4) emissions from cattle contribute to greenhouse gases.
• Biochar, a charcoal-like substance, is explored as a feed additive to mitigate CH4.
• Pine enhanced biochar (EB) effects on cattle digestion and microbiome require further investigation.

Purpose of the Study:

• To evaluate the impact of pine enhanced biochar (EB) on rumen fermentation, nutrient digestibility, CH4 emissions, and the rumen and fecal microbiome in heifers.
• To determine the optimal inclusion level of EB for improving cattle production and environmental outcomes.

Main Methods:

• A replicated 4x4 Latin square design with 8 Angus x Hereford heifers was used.
• Heifers were fed a barley silage-based diet supplemented with EB at 0%, 0.5%, 1.0%, or 2.0% on a dry matter basis.
• Measurements included rumen fermentation, total tract digestibility, CH4 emissions in respiratory chambers, and microbiome profiling (16S rRNA gene sequencing).

Main Results:

• Dry matter intake, total tract digestibility, and N balance were unaffected by EB inclusion.
• Ammonia N and protozoa counts decreased quadratically with EB at 0.5% and 1.0%, while minimum ruminal pH increased with 2.0% EB.
• EB did not affect CH4 production but altered rumen microbial composition, decreasing Fibrobacter and Tenericutes while increasing Spirochaetaes, Verrucomicrobia, and Elusimicrobia.

Conclusions:

• Pine enhanced biochar, at the tested concentrations, did not reduce enteric CH4 emissions in heifers fed a barley silage-based diet.
• EB influenced rumen fermentation parameters and modified specific rumen microbial populations, suggesting potential but limited efficacy for methane mitigation.