Predicting livestock productivity and methane emissions in northern Australia: development of a bio-economic modelling approach

Abstract

Enteric fermentation from livestock is a large source of methane, which has a global warming potential 23 times that of carbon dioxide. In Australia, enteric emissions from the livestock sector contribute 10% of Australia’s greenhouse gases. The northern Australian beef industry about 16 million animals is a major contributor to these emissions. However, relative to temperate systems, comparatively little research has been conducted on enteric methane emissions from tropical feeding systems. This paper describes a modelling approach that estimates cattle methane emissions for various bioregions of northern Australia. The approach incorporates a metabolisable energy based model of animal production linked to a property herd economic model. This provides a flexible tool to evaluate animal and property herd dynamics on regional methane yields and liveweight productivity, as well as to assess financial impacts. The model predicts that an important determinant of methane output per unit of product is reduced days to market. Reduced days to market may be achieved through a range of energy supplementation and marketing strategies.