Methane emissions from sheep fed fresh pasture

Abstract

Methane emissions from ruminants are the major single source of greenhouse gases in New Zealand and considerable effort has gone into the measurement and prediction of these emissions. This paper analyses methane emissions measured in respiration chambers from adult sheep and lambs fed fresh-cut pasture of different quality. Results show that the major driver of methane production (pCH4, g/d) is dry matter intake (DMI, kg/d). Pasture quality affected methane emissions only in animals less than 1 year of age. A single equation to be used for all sheep based on DMI alone (ln(pCH4) = 0.792(0.0275) ln(DMI) + 3.1(0.03)) or a two-equation approach with an equation for sheep >1 year based on DMI (ln(pCH4) = 0.826(0.0438) ln(DMI) + 3.15(0.017)) and one for sheep <1 year based on DMI and the metabolisable energy content (ME, MJ/kg) of the diet (ln(pCH4) = 0.749(0.0190)ln(DMI) + 0.051(0.0064)ME + 2.45(0.069)) is proposed.