Development of an independent forage-cultivar selection decision-support tool (DST) could transfer substantial benefits to sheep and beef (S&B) farmers. This study took a first step toward development of a S&B DST by describing and assessing one method of calculating S&B forage trait economic weightings. The ‘change in livestock production’ economic weighting method was applied to the Otago/Southland Breeding Finishing Farm Class in this study. The trait economic weightings for the seasonal dry matter (DM) production trait were applied to cultivar performance trial data using the DairyNZ Forage Value Index (FVI) framework. Analysis indicated the rankings of perennial ryegrass cultivars using the DST method varied from those calculated using the DairyNZ FVI when using the same seasonal DM production data. It was concluded the change in livestock production method is an option for calculating the economic value of traits for evaluation of perennial ryegrass cultivars that are more applicable to S&B farmers. However, this method should be applied to a wider range of S&B Farm Classes before a decision is made as to its suitability for the New Zealand S&B industry.