Effect of supplement type and grass silage:concentrate ratio on methane production by sheep

Abstract

Methane production by ruminant animals is an important anthropogenic source of methane to the atmosphere and is considered an important source to more accurately estimate and to control. It has been known for some time that, in ruminants, diet type and composition can influence methane production, yet there is little quantitative information for contemporary diets used 1n the UK. Attempts to predict methane production from either diet chemical composition or digestibility have not been successful (Moss and Givens, 1990; Johnson et al., 1991). In order to estimate more accurately the amount of methane produced by a ruminant on a given diet, it is essential to establish whether there are interactions of various substrates with forage and to relate this to the rumen environment. Previous work showing interactions has used mainly hay-based diets (Blaxter and Wainman, 1964); as grass silage is now the major forage in the UK, work with this forage was needed.