Producing higher value wool through a transition from Romney to Merino crossbred ii: Cashflow and profit

•Bio-economic system-dynamics modelling of a Romney flock bred with Merino sires for whole flock breed transition.•Profit decreased during transition, but was greater post-transition than for Romney flock.•Economic benefit of transition ranged from zero to an increase of up to 26 %.•Greatest economic benefit with higher lamb selection intensity and longer transition.•With higher selection intensity, post-transition wool had lower fibre diameter and higher value. Data suggests crossbreeding a Romney ewe flock with Merino sires to achieve a second cross ¾ Merino ¼ Romney (¾M¼R) flock would reduce wool fibre diameter and increase income from wool sales. It is not known how cashflow would vary during such a breed transition and which factors would affect the profitability of such a strategy. A bio-economic system-dynamics modelling study was conducted to simulate the breed transition with low or high selection intensity (24 % vs. 35 % of crossbred ewe lambs not retained at each of two selection events) and either consistent lambing rate (132 % for all flocks) or breed specific lambing rate (lower for Merino-Romney crossbred flocks). Although sheep enterprise profit was always greater post-transition compared with the base Romney flock, during transition annual profit was reduced below that of the base Romney flock. The total cashflow of the breed transition (i.e. twelve years) ranged from relatively small or no economic benefit, to up to 26 % greater than maintenance of the base Romney flock. The most profitable breed transition strategies modelled had higher Merino-Romney ewe lamb selection intensity, achieved greater wool fibre diameter reductions, and occurred over a longer breed transition period.