LAUSR

Abstract The objective of this study was to investigate the relative importance of key performance metrics for temperate grassland-based suckler calf-to-beef production systems on farm economics and greenhouse gas (GHG) emissions. The approach was to use data obtained from commercial farms participating in a farm improvement programme to parameterise a whole farm systems bioeconomic model. This model was then used to evaluate the biotechnical, financial and GHG emissions effects of variation in key performance metrics including calving rate, calving date, cow replacement rate, progeny live weight gain and age at slaughter. Age at slaughter and calving rate had the greatest effect on costs of production per kilogram of carcass weight. Calving rate was also the most influential parameter affecting net margin (NM) with a change of 10 percentage units (from 0.75 to 0.85 calves per cow per year) resulting in NM increasing by +€84 per hectare (ha). Age at slaughter had the greatest effect on GHG emissions; increasing slaughter age by eight months, resulted in GHG per farm increasing from 23.5 to 31.6 carbon dioxide equivalents (CO2e)/kg carcass. Although, combining high performance levels among all key performance metrics led to the greatest profitability and lowest emissions per kg carcass, the relative effects of individual parameters are not additive. This highlights interdependencies between production parameters for suckler calf-to-beef production systems.