SUMMARY

This study details the performance of Merino and Dohne Merino ewes and lambs over eight years in either a pure or a crossbreeding regime. Ewes were mated either to rams of their own breed or to Dormer or Suffolk rams as terminal sires. Dam breed affected birth weight and lamb survival, with lambs borne by Dohne ewes being heavier and having greater survival to weaning than those borne by Merinos. Progeny of Dohne ewes and progeny sired by terminal rams were heavier at weaning. Dohne Merino ewes were heavier at mating than Merinos, but produced less clean wool at a slightly lower fibre diameter. No ewe breed or breeding regime differences were found for number of lambs born or weaned per ewe lambed. Total weight of lamb weaned was higher in Dohne Merino ewes and in ewes mated to terminal rams. Crossbreeding may have a relative advantage to pure breeding in terms of lamb output per unit ewe body weight maintained. Further studies on breed differences and crossbreeding of the South African ovine genetic resource are warranted.