Sheep or beef cattle (cattle) share of total farm feed consumed, measured in stock units (SU) on New Zealand farms, is often adjusted depending on the profitability of each enterprise. The impact of these adjustments on whole‐farm productivity, profitability and predicted methane (CH 4) output has not been recently explored. A system dynamics model of a representative North Island Hill Country sheep and beef farm was parameterised to evaluate whole‐farm productivity, profitability and predicted CH 4 output simultaneously, while varying sheep and cattle SU. Five scenarios were considered: 80%: 20%, 60%: 40%, 50%: 50%, 40%: 60% and 20%: 80% sheep and cattle SU, respectively. For every 20% increase in cattle SU, on average, total liveweight and carcass weight equivalent (kg CWeq) sold increased by 0. 5% and 3. 3%, respectively, while cash operating surplus (COS) increased by 10%. However, predicted total enteric CH 4 emissions increased by 2. 2%, due to fewer lambs in the system, which have a lower emission factor, and farm economic emission efficiency (COS (NZ) /tCO 2 e) increased by 7. 5%. Overall, the results show that to increase COS, farmers should increase cattle SU. Although when considering a transition towards a higher proportion of cattle SU in the mixed system, they should also consider pasture management and environmental implications.
Adjabui et al. (2026) studied this question.