The challenges and opportunities when integrating animal models into grazing system models for evaluating productivity and environmental impact.

The intensification of livestock production has highlighted the importance of balancing production and the environmental impact in grazing systems. With the advent of more distributed computing power we have seen more complex models being developed, capable of simulating most aspects of a livestock production system. Where the modelling objective includes prediction of both productivity and environmental impacts, it is imperative to include appropriate consideration of the grazing animal in the simulation. This raises numerous challenges with respect to environmental impact modelling, including explicit treatment of nutrients in dung and urine, the prediction of grazing behaviour, dry matter intake and associated enteric methane loss. This paper discusses these challenges and opportunities when integrating animal models into grazing system models for evaluating productivity and environmental impact.