In Mediterranean-type environments, livestock productivity in mixed livestock and cropping enterprises often is limited by a period of feed scarcity that extends from late autumn, when dry residues of crops and pastures from the previous growing season are being exhausted, through to early winter when green feed is just commencing. Dual-purpose crops have been developed as a source of winter green feed, while still being a source of grain at harvest. These crops increase feed availability and boost livestock productivity. This study evaluates the role and value of dual-purpose wheat and canola crops, in combination with lucerne, in mixed-enterprise farming systems that experience a Mediterranean-type climate. Using bioeconomic modelling, the value of dual-purpose crops is assessed under a range of yield, price and technical assumptions. For an Australian study region, the robust finding is that the joint inclusion of dual-purpose crops and lucerne greatly increases the farming-system profits. Under standard assumptions when the farming system is operated to maximise profit, farm profit increases by AU$68 000 (or 88% over the base case) following the inclusion of both dual-purpose wheat and canola. The increase in profit is attributable to wool and sheep sales rising by 261%, yet the proportions of crop and pasture remain similar with or without the dual-purpose crops. Importantly, the proportion of the pasture area that is lucerne greatly increases to complement the increase in feed availability generated by the dual-purpose crops. The resultant large increase in feed availability in winter and summer allows the stocking rate to increase so sheep numbers and sheep turn-off become the main source of the increase in profit. Sensitivity analysis shows that even with significant commodity price fluctuations and further reduction in grain yield caused by grazing, and exclusion of lucerne, inclusion of dual-purpose crops in these farming systems still increases farm profit.