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The major goals of this project are to: (1) evaluate and test conditions for effective and sustainable strategies that mitigate the spread and persistence of ARB and ARG within the agricultural ecosystem, from farm to food crops, and (2) design training, education, and outreach resources (including web-based resources) that can be used by farmers, operators, and policy makers to prevent spread of antimicrobial resistance from farm to fork. The objectives of this project are: Evaluate the fate and removal rates of antimicrobials, ARB, and ARG in conventional and advanced manure treatment systems at 11 dairy farms and in manure-amended soil. Through coordinated bench-scale and pilot-scale AD experiments, identify the driving manure characteristics and AD operating parameters for maximizing removal of antimicrobials, ARB, and ARG from manure. Quantify the amounts of antimicrobials, ARB and ARG that can be transferred from manure-amended soil to human food crops, using different crops and manure treatment. Utilize a watershed-scale hydraulic model to determine antimicrobial transfer from cow to manure to fields, crops and end of field (i.e. streams and ditches) with the three different manure management strategies to ascertain which management strategies have the largest effect and should be the focus of extension activities. Develop accessible extension and education activities to convey the importance of manure management strategies, food system interactions, antimicrobial use, and farm cleanliness in order to mitigate antimicrobial resistance to specific target audiences.
The dairy industry is one of the most important agricultural businesses in the United States and is the number one agricultural business in California, Wisconsin and New York. In modern dairy farms, antimicrobials are commonly used for both therapeutic (disease treatment) and prophylactic (prevention) purposes. However, the use of antimicrobials in animal agriculture has been associated with increased occurrence of antimicrobial resistant bacteria (ARB) and the presence of antimicrobial resistant genes (ARG) in dairy manure, which enter the human food chain when manure is used to fertilize croplands. This proposed integrated research and extension project seeks to evaluate critical control points in dairy farm operations that can prevent the spread of antimicrobial resistance from "farm to fork". Our study is based on 11 participating dairy farms that include small, medium, and large animal feeding operations employing various manure management strategies such as anaerobic digesters (with and without composting or pasteurization), solid-liquid separation, and long-term or short-term lagoon storage systems. The effectiveness of advanced manure treatment systems in reducing the spread of antimicrobial resistance will be evaluated through coordinated bench-scale and pilot-scale experiments to identify important manure characteristics and digester operating parameters for optimum removal of antimicrobials, ARB, and ARG. Plant-uptake experiments will be conducted to determine if certain types of manure treatment systems, combined with appropriate manure application in crop fertilization, can prevent the spread of antimicrobial resistance from "farm to fork". We will also evaluate whether general farm hygienic measures can potentially reduce the use of antimicrobials. Results from the different aspects of this study will be incorporated into a predictive model to simulate the proliferation of ARB and ARG at the watershed-scale.Our research and extension efforts are unique in that they are based on a strong partnership between academic researchers, extension specialists, and commercial dairy operations implementing varying manure treatment systems, which will allow us to directly relate laboratory studies with farm-scale conditions. The knowledge gained from this research will improve the scientific understanding of the role of anaerobic digestion technology and manure composting on mitigating the spread of antimicrobial resistance. Improvements in manure treatment and farming practices (e.g. antimicrobial use, cleanliness of farms, animal health management, manure application) will result from our planned extension and education activities that will include field days and workshops. Ultimately, specific abatement strategies and best management practices (e.g. type of manure treatment and applications, selection of crops grown in specific manure-amended fields) will result in the reduction of antimicrobial use in the animal industry, and ultimately spread of antimicrobial resistance in agricultural environment.