Animal manure has widespread use as natural fertiliser to increase food production. However, manure application bears potential risks for human and animal health, and effects on the ecosystem. Wageningen University & Research assesses the ‘One Health’ risks of contaminants, such as pathogenic bacteria and viruses, resistant bacteria and residues of veterinary medicines. The research focuses on relevant reservoirs of contaminants, transmission routes, and related processes. This knowledge could contribute to the development of intervention strategies to assure safe food production.
Manure is widely used as a natural fertiliser and therefore constitutes a globally important resource for agriculture. However, manure application poses potential risks for human and animal health and may affect the ecosystem. To determine the risks involved and to be able to develop intervening measures, the fate, dissemination and the effects of antimicrobial resistant bacteria, resistance genes, veterinary medicines (among which antibiotics) and pathogens in all relevant reservoirs in the production chain and the environment must be understood.
Today, the number of undernourished people worldwide remains unacceptably high. Global food security issues are an increasing concern realising that the world population is expected to increase severely in future. To assure food security, a significant increase of agricultural output is crucial, which can, among others, be obtained by increasing food production on existing farmland. Fertilization is of vital importance to increase food production and animal manure constitutes an ever important nutrient source. Due to the extensive dissemination routes and different reservoirs, the use of animal manure as a fertilizer poses several risks. These risks are mainly related to ‘contaminants’ that may be present in manure:
- Pathogenic bacteria and viruses
- Resistant bacteria / resistance genes
- Residues of veterinary medicines (including antibiotics)
There are clear trade-offs between these ‘contaminants’. For example, antibiotics used to promote the health of livestock may cause undesired effects elsewhere such as in the human population (e.g. AMR) and in ecosystems by their toxic effects. Also transfer of resistant genes can affect the evolution of pathogens.
There are many different reservoirs that can contain contaminants, e.g. the animal, manure, soil, water and arable crops. Each of these reservoirs, the transfer from one to the other reservoir and the trade-offs among the mentioned contaminants is of relevance to understand the processes and potential health effects. As this is a comprehensive task, a multidisciplinary and multi-annual project is proposed. In the first year the focus will be on technical aspects like mechanisms of gene transfer mainly in the rhizosphere, the longitudinal effect of antibiotic residues and resistance determinants on the microbiome and resistome in faeces, and the bioactivity of antibiotic residues in manure and soil. In future years, the project will focus on other aspects, such as microbiome, resistome and mobilome analysis in the rizosphere and manure, manure processing, other transmission routes and the effects in the ecosystem and on human health.