Associations of breed, herd structure, and grazing system with the reproductive performance of Nguni and Boran cattle in South Africa

Abstract

Reproductive efficiency remains a major constraint limiting the productivity and sustainability of communal cattle production systems in sub-Saharan Africa. Although breed adaptation, herd structure, and grazing management influence cattle productivity, their combined effects on reproductive performance remain poorly understood. This study investigated the effects of breed adaptation, herd structure, and grazing system on the reproductive performance of Nguni and Boran cattle managed under communal rangelands in the Eastern Cape Province of South Africa. A total of 80 clinically healthy multiparous cows (40 Nguni and 40 Boran) were observed within a 2 × 2 × 2 factorial field design comprising two breeds, two herd structures evaluated as homogeneous (single-breed) or heterogeneous (mixed-breed) groups, and two grazing systems (cattle-only and mixed-species grazing). Reproductive traits, body weight, body condition score (BCS), and calf performance were monitored over a 12-month breeding cycle and analysed using mixed-effects models in R, with the herd/farm set as the primary experimental unit to reflect the herd-level application of treatments. Breed, herd structure, and grazing system were significantly associated with reproductive performance (p < 0.05). Nguni cattle achieved higher pregnancy (91.3%), conception (86.5%), calving (88.9%), and calf survival (96.2%) rates than Boran cattle. Heterogeneous herds and mixed-species grazing improved reproductive efficiency, body condition, and growth performance. Integrating adaptive indigenous breeds with improved grazing management can enhance reproductive performance and livestock productivity under communal rangelands.