Graphical AbstractSummary:Intergovernmental Panel on Climate Change (IPCC) equations were evaluated to study the precision and accuracy in predicting methane (CH4) emission from lactating dairy cows. The predicted values were compared with in vivo values obtained from experimental studies conducted using cows fed diets based on hay or silage forages in the Mediterranean region. Hay-based diets differed significantly from silage-based diets having lower energy digestibility (DE). The IPCC 2019 equations predicted CH4emission well and hence may be used for the computation of greenhouse gas inventories. However, specific equations are proposed to predict CH4emission by dairy cows in the Mediterranean region.