Determination of methane yield in cattle fed tropical grasses as measured in open-circuit respiration chambers

Abstract The objective of this study was to determine methane (CH 4 ) yield by crossbred cattle fed tropical grasses. A total of 66 individual determinations of dry matter intake (DMI) and 42 determinations of organic matter intake (OMI) in relation to the production of enteric CH 4 were carried out. Methane measurements in heifers were performed in open-circuit respiration chambers. Heifers ( Bos indicus × B. taurus ) with an average live weight of 288.5 ± 55.7 kg fed tropical grasses as basal ration were used. An average intake of 8.22 and 7.80 kg of DM and OM per day were recorded. An average enteric CH 4 production of 88.0 g/heifer/day was determined. It was found that DMI and OMI in relation to CH 4 production have a coefficient of determination ( R 2 ) of 0.73 and 0.70 respectively, to predict CH 4 emissions. It is concluded that the methane yield (18.07 g CH 4 /kg DM intake) predicted by regressing DM intake against methane production represents a reliable value to be used for the estimation of enteric CH 4 inventories for cattle grazing in the tropical regions of Mexico.