Cumulative gas production of basal ration added with biochar (BC) during 24 hours incubation. BC0 (basal ration+0 mg/ml biochar), BC 1 (basal ration+0.1 mg/ml biochar), BC2 (basal ration+0.2 mg/ml biochar), BC3 (basal ration+0.3 mg/ml biochar), BC4 (basal ration+0.4 mg/ml biochar) 

Cumulative gas production of basal ration added with liquid smoke (LS) during 24 hours incubation. LS0 (basal ration+ 0 μl/ml liquid smoke) is added before LS1 (basal ration+ 0.25 μl/ml liquid smoke), LS2 (basal ration+0.5 µl/ml liquid smoke), LS3 (basal ration+0.75 µl/ml liquid smoke), LS4 (basal ration+1 µl/ml liquid smoke).