Methane yield from cattle, sheep, and goats housing with emphasis on emission factors: a review

Abstract

Global methane (CH4 ) concentrations are increasing in all parts of the world. This review study intends to provide an integrative approach to the complex relationships between environmental systems of farm animals. It reveals that more data are needed to better quantify CH4 emissions from farms. Methanogenic microbial functional groups play an important role in total methane flux from agroecosystems. The factors that regulate the activity of these organisms (temperature, diet composition, feeding technique, manure management) have been documented. The research based on the literature available presented was conducted under extensive and intensive management conditions. In principle, the approaches discussed can be applied to any dairy, beef or sheep production system because their aim is increasing productivity at the herd level. Recent studies on the effects of environmental temperature, feeding, internal and genetic factors, and emission from excrements on CH4 production are discussed. Finally, emission factors for dairy and beef cattle, as well as goats and sheep, are listed in tables.