Tools for decreasing enteric methane production by ruminants

Abstract

This paper reviews the strategies to reduce methanogenesis in ruminants and their applicability on farm. It is known that increasingthe percentage of concentrate decreases the production of methane per kg of dry matter intake. This effect is especially important athigh levels of concentrate. Cereals decrease more methane emission than concentrates rich in fibre. Lipid inclusion in diets significantlydecreases methane emission. Among forages, maize silage diets result in lower emissions than hay or grass silage diets, butdifferences in vegetation stages or between grasses and legumes are low and sometimes controversial. Alarge number of plant extractsand additives with different modes of action have been assayed. Plants rich in tannins or tannin extracts result in methane mitigation,but the risk of impairing diet digestibility has to be considered. The long term efficacy of many of these additives still needs tobe evaluated. Biotechnologies that reduce dihydrogen available for methanogenesis are promising but need further testing. Increasingthe level of production of animals results in a decrease in methane production, which is especially significant when methane isexpressed per kg of milk or meat. There are also differences between animals in their global productive efficiency, evaluated throughthe residual feed intake. The most efficient animals produce less methane per kg of milk or meat. This paper stresses the need to lookbeyond enteric methane mitigation, and to evaluate the efficacy of mitigation strategies on all greenhouse gases associated to ruminantproduction.