Options for reducing methane emissions from ruminants in New Zealand and Australia

This paper outlines potential emission-reduction strategies for ruminant methane. The simple option for lowering ruminant methane emissions by substantially reducing livestock numbers is economically unacceptable as New Zealand and Australia depend upon ruminant products for income. Ruminant methane production in both countries and the digestive processes in the rumen leading to methane formation are outlined and two possible approaches for reducing methane emissions are presented. These approaches focus on dietary and microbiological factors to take into account the fact that the problem is a microbial one as well as an animal one. One option is to increase the efficiency of both feed utilisation and production by forage-fed animals in order to reduce the amount of methane produced per unit of product. This approach involves reducing animal numbers but maintaining production levels. The other option, which does not require a reduction in animal numbers, is to target directly the microbial processes which lead to methane formation in the rumen.