Prediction of methane emission from sheep based on data measured in vivo from open-circuit respiratory studies

OBJECTIVE: The current study analysed the relationships between methane (CH(4)) output from animal and dietary factors. METHODS: The dataset was obtained from 159 Dorper×thin-tailed Han lambs from our seven studies, and CH(4) production and energy metabolism data were measured in vivo by an open-circuit respiratory method. All lambs were confined indoors and fed pelleted diet during the whole experimental period in all studies. Data from two-thirds of lambs were used to develop linear and multiple regressions to describe the relationship between CH(4) emission and dietary variables, and data from the remaining one third of lambs were used to validate the established models. RESULTS: CH(4) emission (g/d) was positively related to dry matter intake (DMI) and gross energy intake (GEI) (p<0.001). CH(4) energy/GEI was negatively related to metabolizable energy/gross energy and metabolizable energy/digestible energy (p<0.001). Using DMI to predict CH(4) emission (g/d) resulted in a coefficient of determination (R(2)) of 0.80. Using GEI, digestible energy intake, and metabolizable energy intake predict CH(4) energy/GEI resulted in a R(2) of 0.92. CONCLUSION: the prediction equations established in the current study are useful to develop appropriate feeding and management strategies to mitigate CH(4) emissions from sheep.