Feedlot Manure Management Considerations Including Anaerobic Digestion Potential and Mineral Retention

Cattle diet can impact manure quality and quantity, but has minimal impact on methane production from anaerobic digestion of manure. Quality of manure, measured as organic matter (OM) content, does affect methane production and is largely impacted by the environment cattle are housed in and methods used to collect manure. In three anaerobic digestion trials, as the amount of ash contamination of manure increased, or OM content of manure decreased, OM degradation and methane production decreased. The OM within beef cattle manure was 51-66% degraded within digesters. Methane production from beef cattle manure was 0.112-0.187 L CH4/g OM fed to digesters. Less than 10% of the ash within high-ash manure (85% ash), representative of open lot feedlot cattle manure, remained in digesters when a cone-bottom tank was used for digestion. With adequate daily cleanout of ash from digesters, open-lot beef cattle manure can be used for anaerobic digestion.