Influence of Dairy Cattle Diet on Manure's Methanogenic Potential for Biogas Generation

Dairy cattle manure is commonly used as an inoculum for biogas production via anaerobic digestion. The methanogenic potential of manure can vary based on the cattle's diet. This study examines the impact of two different diets on biogas yield and methane content of dairy cattle manure. Manure samples were obtained from two groups of cattle: one grazing and hay-fed, and the other fodder (silage/concentrate mixture) fed. The anaerobic digestion process was conducted over 54 days in a 350 mL bioreactor at 37°C. Biogas production and methane (CH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>) and carbon dioxide (CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) content were monitored and modeled using the Gompertz kinetic model. Results showed that manure from silage-fed cattle produced 20% more biogas and had 45% higher methane content compared to hay-fed cattle. Methane production began on the 8<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> day for the silage-fed group, while it started only after the 23<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> day for the hay-fed group. These findings emphasize the significant influence of dairy cattle diet on the methanogenic potential of their manure, crucial for optimizing biogas production.