Emerging smallholder cattle farming from a One Health perspective: A system dynamics model of the highveld region of South Africa

Background: One Health is built on the concept that "human health and animal health are interdependent and bound to the health of the ecosystems in which they exist" (OIE, 2021). The zoonotic origins of the COVID-19 pandemic elevated the importance of the One Health concept while highlighting the complexities of human-animalenvironmental interfaces in public health management. The definition and purpose of One Health includes an applicability to cattle farming systems. One Health-awareness in livestock rearing is essential in ensuring animal, human, and environmental health and in limiting the spread and emergence of diseases that threaten the health of the three domains. Originality: This article identified a gap in One Health research in South Africa and its emerging smallholder cattle production systems. It presents the research problem of the impact of low on-farm productivity on One Health outputs in the emerging smallholder cattle farming sector, and addresses a gap in the academic literature to adopt modelling approaches as a comprehensive means of representing the dynamics of One Health with Systems Dynamic Modelling. Methodology: We adopt a One Health approach in presenting a system dynamics simulation model of the weanerrearing production system and the effect of nutrition and disease management on One Health production outputs. Results: The model is applied to the highveld region of South Africa and aims to identify the interventions that would most benefit the three One Health parameters of human, animal, and environmental health. The results suggest that increasing farmers' access to disease management training and on-farm infrastructure that aids in disease prevention activities (such as crushing pens) can improve One Health farming outputs (such as improving herd numbers, increasing income from weaner sales, and reducing the disease burden). However, these interventions do not have the desired significant positive impacts on cattle nutrition or feed density. Therefore, some well-intended interventions also have undesirable effects on One Health farming outputs. The results suggest One Health trade-offs within the production system and emphasizes that decision-makers across all levels must clearly define their individual and collective goals when adopting a One Health strategy.