Abstract

More efficient farming practices will increase livestock production without increasing greenhouse gas (GHG) emissions. GHG emissions of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) have always been part of agriculture, but national and international concern about global warming has focused research towards their mitigation. CH4 production represents a loss of about 9% of metabolisable energy in feed, whilst N2O production represents a loss from excessive nitrogen (N) application. Mitigation should therefore provide benefits for farming by conserving dietary energy and reducing fertiliser costs. Unfortunately there are limited options for reducing CH4 loss. Nevertheless, by ensuring animals are productive and fertile and adopting management systems that ensure a high utilisation of feed grown, it is possible to lower CH4 emissions per unit of product. There are more opportunities for reducing N2O emissions, because these originate in large part from N fertiliser application, and more prudent use will lower costs, minimise nitrate leaching into waterways as well as lowering GHG emissions. Emissions per unit of product are termed emissions intensity. Application of current and new knowledge to agricultural systems will increase livestock production and lower emissions intensity whilst sustaining our ecosystem, but farmers will always need to address environmental issues.

GC, Waghorn

Proceedings of the New Zealand Society of Animal Production, Volume 71, Invercargill, 156-162, 2011