Breed and crossbreeding effects on growth, fitness and reproduction of commercial sheep in South Africa

The study aimed to assess additive breed effects for growth (birth, weaning and ewe adult weight), fitness (lamb survival tick count under natural challenge) reproduction traits per mated in Dorpers, the most common meat South Africa (SA), SA Mutton Merino (SAMM) a prominent dual-purpose extensive environments. Additionally, reciprocal crosses between two breeds were used estimate dam heterosis. No conclusive differences found lamb weight traits, or counts. There was suggestion that of Dorpers higher than their SAMM contemporaries, but significance could not be demonstrated. Crossbred progeny outperformed midparent value by 7.1% weight. As far as mature ewes concerned, mating affected combination with weights purebred well crossbred exceeding Dorpers. Number lambs born lambed independent genetic group. x Dorper group pure number weaned (NLW). Contrasts maternal heterosis significant NLW, direct amounted 32.5%. performed better total lambed, amounting 38.4%. other contrasts significant. A lack barring suggested similarly conditions study. Significant suggest role SAMMs commercial production enterprises.