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Mitigation Strategies for Antimicrobial Resistance and Nutrients at Critical Control Points in Livestock Manure Management Systems
Abstract
Livestock waste is regarded as an important source of antimicrobial resistance (AMR) and nutrients in the environment. This study focuses on developing novel manure management practices to mitigate the dissemination of AMR and nutrients at critical control points within the manure management system. The interventions tested include 1) lime amendment of pen floor surface materials in open feedlots for the reduction of AMR bacteria and genes, 2) heat treatment by conductive concrete slabs for the transformation of phosphorus P and nitrogen N in beef cattle manure stockpiles, and 3) setback distance, the distance between manured soil and surface water, as a means to reduce AMR genes in surface runoff following the land application of swine manure slurry. First, the application of lime to pen floor surface materials in open cattle feedlots significantly reduced the concentrations of AMR bacteria and genes. Stockpiles of lime-amended manure showed a significantly lower AMR bacteria and gene levels compared to stockpiled manure from control pens that received no lime. Beta diversity analysis showed that lime altered the microbial compositions in both pen floor surface materials and stockpiled manure. Second, bench-scale tests showed that the heat from a conductive concrete slab increased the fraction of the readily available NaHCO3-P in stockpiled manure. The concentrations of ammonium-N, total N, and total P were greater in runoff generated from the heat-treated manure after 10 days of stockpiling. Third, a high throughput quantitative polymerase chain reaction array was used to assess the resistome and mobilome in runoff and soil from field plots. The abundance of AMR genes and mobile genetic elements (MGEs) in runoff from manured plots decreased with increasing setback distance. A setback distance of ~40 m was estimated to reduce the total abundance of AMR genes and MGEs in runoff from manured plots to that of control runoff. SourceTracker analysis revealed that background soil gradually became the predominant source of AMR genes and MGEs in runoff as setback distance increased. These findings highlight potential mitigation strategies that stakeholders and farmers can use as best management practices to reduce AMR dissemination and nutrient loss from livestock manure.
Subject Area
Environmental engineering|Microbiology|Agriculture|Environmental management
Recommended Citation
Mware, Noelle Atieno, "Mitigation Strategies for Antimicrobial Resistance and Nutrients at Critical Control Points in Livestock Manure Management Systems" (2021). ETD collection for University of Nebraska-Lincoln. AAI28865768.
https://digitalcommons.unl.edu/dissertations/AAI28865768