Ultimate methane yield from beef cattle manure: Effect of temperature, ration constituents, antibiotics and manure age

Abstract The effects of temperature, ration constituents, antibiotics and manure age on the ultimate methane yield B 0 , litre CH 4 /g volatile solids fed (VS f )) were investigated using 4-litre batch fermenters. The average B 0 for fermenters maintained at 30–60°C (at 5°C intervals) was 0·328 litre CH 4 /g VS f . The B 0 at 65°C averaged 0·118 litre CH 4 /g VS f , but this low yield was attributed to unstable fermentation rather than decreased substrate availability at that temperature. These results agreed well with B 0 values estimated from daily-fed fermenters. Chlortetracycline and monensin did not affect B 0 ; however, monensin did delay the start of active fermentation in batch fermenters. The average B 0 of manure from cattle fed 91·5, 40 and 7% corn silage were 0·173, 0·132 and 0·290 litre CH 4 /g VS f , respectively. The average B 0 for 6–8 week old manure from a dirt feedlot was 0·210 litre CH 4 /g VS f .