Prediction of methane emissions from fattening cattle using the methane-to-carbon dioxide ratio

This study aimed to develop a prediction equation for methane (CH₄ ) emissions from fattening cattle based on the CH₄ /carbon dioxide (CO₂ ) ratio and validate the predictive ability of the developed equation. The prediction equation was developed using the CH₄ /CO₂ ratio combined with oxygen consumption and respiratory quotient estimations that were theoretically calculated from the relation between gas emissions and energy metabolism. To validate the prediction equation, gas measurements in the headboxes were conducted using eight Japanese Black steers. The predictive ability of the developed equation was compared with that of two previously reported equations. As a result, the developed and reported equations had significant (P < 0.01) linear relationships between the observed and predicted CH₄ emissions. Notably, only the developed equation had a significant (P < 0.01) linear relationship between the observed and predicted CH₄ emissions when expressed per unit of dry matter intake. The results suggest that the developed prediction equation has a higher predictive ability than previously reported equations, particularly in evaluating the efficiency of CH₄ emissions. Although further validation is required, the equation developed in this study can be a valuable tool for on-farm estimations of individual CH₄ emissions from fattening cattle.