Plant-based solutions to integrate livestock disease control, nutrition and environmental sustainability in Africa

Smallholder livestock production is crucial to the livelihoods of rural populations throughout Africa, but is experiencing many challenges. Climate change is making nutritional resources from grazing more unpredictable, and at the same time increasing threats from parasitic and other diseases. Investing in greater inputs to stave off these threats is out of the question for most subsistence farmers and is unsustainable. Better ways of running integrated animal-plant systems are urgently needed. To that end, this project seeks to build on successful previous work, in which targeted treatment of individual sheep and goats within a herd achieved substantial uplift in health and productivity with much lower input costs than standard whole-herd treatment. Further improvements to the system would be to replace chemical anthelmintics with plants shown to reduce parasite burdens, which grow locally and could be cultivated or sustainably harvested. Research on such plants shows a long list of candidates but evaluation of effects in the field under real farming conditions are very limited. These plants can help bridge the nutrition gap also by increasing protein availability, but assessments have rarely considered antiparasitic and nutritional benefits together, especially with native plants in Africa. We will train farmers to apply targeted selective antiparasitic treatment strategies based on established field guides for monitoring impacts of infection on health, and compare the need for treatment and the health and performance levels between herds using antiparasitic drugs only and those that integrate 'bioactive' plants species into their feeding practices. A key benefit of using plants to reduce parasite burdens is reduction of environmental contamination with infective parasite stages, and therefore general reduction in infection levels, benefitting all animals sharing grazing. Recent advances in epidemiological modelling enable rigorous evaluation of this indirect effect of plant use for the first time, as a function of climate and management, and we propose to apply those models to assess impacts under current and future climates. Models will be extended to consider where and in what seasons the evaluated interventions would be of most use, and how they should be configured to maximise resilience of smallholder production systems under current and future conditions. Finally, benefits of healthier livestock for household livelihoods are potentially immense but are hard to measure for subsistence farmers, in which improved productivity does not necessarily translate into cash profit, but has subtle effects on food and economic security. Integrated into the field trials, we plan to evaluate connections between livestock health and household wellbeing using socio-economic interviews. Outcomes will be a toolkit for application of targeted treatment approaches and nutritional intervention that makes the most of locally available plant resources, an improved evidence base for plant-focused interventions in these systems, measures of livelihood impacts within the study and potential when upscaled, and projections of epidemiological risks and benefits across Africa. As a result of this project, tools will be created for rapid evaluation of and adaptation to disease and nutrition threats throughout Africa, to support sustainable production and food security in the poorest areas.

Integration of plants with elevated antiparasitic and nutritional properties has the potential to increase resilience of livestock systems and their performance under the challenges of climate change and drug resistance. This will support food security among the rural poor in Africa, who depend on livestock for survival, and aid in the transition of subsistence agriculture to also support growing urban populations. Although plant secondary metabolites are known to have antiparasitic properties and also protect protein from degradation in the rumen, these have rarely been assessed together, nor in field settings in the context of sustainable interventions in integrated subsistence farming systems. Moreover, the indirect benefits of this integration for disease control under climate change through reduction of transmission has not been considered in quantitative terms. This project proposes to run field studies to evaluate and quantify the potential for locally grown plants to impact positively on nutrition and disease in smallholder livestock, by embedding them in existing targeted treatment approaches that have been shown already to have positive effects on health and productivity. The onward effects on transmission will be captured and predicted in well-calibrated mechanistic models of parasite population dynamics. Non-linear effects on livelihoods will be investigated by socio-economic questionnaire surveys. Outcomes will be an improved evidence base for integrated plant-animal interventions to support sustainable and resilience smallholder production in Africa.

The project directly addresses the RCUK Global Challenge Area "Equitable access to sustainable development", specifically by targeting its first sub-priority: secure and resilient food systems. Parasite infection, especially by gastrointestinal nematodes, is the dominant production-limiting disease of grazing livestock worldwide. Infections are endemic, difficult to control effectively, and disproportionately affect small farmers who have limited access to advice and drugs. Excessive reliance on chemical treatment has led to widespread drug resistance, while climate change makes infection increasingly hard to predict. We showed in previous work that targeted selective treatment of parasites can be applied by resource-poor smallholder farmers; predicting risk would help them further by focusing monitoring and treatment, while investigation of plant-based interventions in the current project would help to refine and apply local solutions that simultaneously improve nutrition, leading to better integration of plant and animal production on smallholder farms. Outcomes will be improved animal health and production, impacting directly on rural livelihoods; the project seeks also to map those positive livelihood impacts.

Given limited agricultural extension support, and little cash to spend on inputs, a clear need was expressed in previous co-creation meetings with partners in Botswana for targeted approaches to both parasite infections and nutritional supplementation. A workshop held with state and private veterinary and agriculture extension personnel in Botswana in 2017 ranked parasitic infections and access to feed as top priorities for intervention. The Department of Veterinary Services in Botswana has incorporated targeted treatment strategy into policy and training, and these links as well as those on existing projects in Malawi present an established path for transferring impact. Additional research is needed to increase self-sufficiency of the targeted approach through better integration with locally available plants, and mapping of risk in space and time so that farmers are able to put appropriate systems in place to respond to these risks using existing resources and hence increase their resilience to climate change. We seek to place such evidence-based tools into the hands of farmers while also engaging government in the process so that solutions align with rather than running against existing support structures. Previous data showed substantial improvements in animal health using targeted treatment approaches. Of 42 farms followed up after two years (>1,000 goats), anaemia scores and body condition improved just as much in herds using this method as in those treating the entire herd, but the number of treatments and therefore costs were on average 76% lower. We anticipate that farmers and household livelihoods will benefit directly from the interventions employed in the project and the evidence base and materials generated will support their dissemination and application on a much wider scale.

Farmers will benefit from much improved ability to meet the challenges of nutrition and disease under changing climates with plant resources that they have to hand and are affordable. Engagement with supporting governmental bodies and NGOs will inculcate them with the same integrated outlook and provide them with the tools to develop effective and sustainable interventions at a range of scales, from individual farm to regional agricultural policy. The project outcomes will represent an important step along the path to increased availability of precision approaches to support remote and poor rural communities engaged in farming and increase their ability to meet challenges in their own way.