Recipient Organization
UNIVERSITY OF MAINE
(N/A)
ORONO,ME 04469
Performing Department
School of Food and Agriculture
Non Technical Summary
Most medically important antibiotics in the US are sold for large animal use. The potential therefore exists for contamination of the food supply by antibiotic resistant enteric bacteria found in animal manure. However, knowledge is lacking regarding the prevalence of antibiotic resistant bacteria in equine manure, in spite of widespread use of horse manure and compost in organic food production. This problem is significant in the Northeast: of the ten US states with the largest number of organic farms, four are in the Northeast (NY, PA, VT, ME); of states with the most horses per acre the top three (MD, NJ, CT) are in the Northeast while PA is in the top ten. We therefore wish to determine the prevalence of antibiotic resistant bacteria in equine stall waste, and to investigate whether these bacteria can be eliminated through composting. In addition, with extramural funding, we would like to determine the impact of administration of antibiotics on the prevalence of antibiotic resistance organisms.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Goals / Objectives
Manure Disposal Objective #2 Improve manure disposal and composting techniques and promote their adoption on equine farms by:
1) Continue the study of different bedding types and effects upon on absorptive capacity, airborne particulate matter distribution, composting characteristics, and final disposition and use.
2) Determine the levels of ammonia emitted on horse farms, especially in stalls, and develop methods for reducing ammonia emissions.
3) Determine the effects of antibiotic use and resistance on the presence of antibiotics in manure piles. Objective 3 also deals with the subject of antibiotic use.
Carcass Disposal and Management Objective #3 Improve carcass disposal and management by surveying the industry for more information about current practices and developing composting management protocols.
1) Determine the methods of carcass disposal used in the industry. Objective 4 will also deal with a survey.
2) Determine the effects of antibiotic use and resistance on the presence of antibiotics in manure piles.
3) Determine the presence of antibiotic resistant bacteria at equine facilities across the state (ME) and evaluate potential risk factors.
4) Determine the level of barbiturate use in euthanized horses and determine whether compost management will result in the destruction of barbiturates.
5) Develop and promote compost systems that will best meet horse industry needs.
Outreach Objective #4 1) Undertake a survey about equine environmental management that can be given in any of the participating states.
2) Educate agency personnel (USDA-NRCS, county Conservation Districts, etc.) about the horse industry, horse farm management, and recommended practices for horse farms to empower them to work more comfortably and effectively with farm owners.
3) Increase access to environmental stewardship information and recommendations from research for horse farm owners and managers through online content and face-to-face trainings and demonstrations.
Project Methods
1. Detection of antibiotic resistance in stall waste, manure, and compost - For objectives 1, 2, and 3 we will use quantitative culture on Tryptic Soy Agar (TSA) and MacKonkey's (MAC) agar, (with and without the antibiotics ampicillin, gentamicin, and enterofloxacin), to estimate the prevalence of antibiotic resistant organisms. Using the differences in colony counts on TSA and MAC agar it will be possible to reveal broad trends between gram positive and gram negative organisms. We hypothesize that there will be a background of antibiotic resistant organisms in waste of normal horses, with Gram negative organisms accounting for the majority. The selected antibiotics are used heavily in equine practice and represent 3 distinct classes of antibiotics commonly used in human medicine.2. Composting of equine stall waste - For objective 2, we will compare stall waste composted at UMaine's Witter center with the waste from the same horses also composted at Highmoor farm. It is hypothesized that composting will reduce the prevalence of antibiotic resistant organisms, and will reduce the number of coliform bacteria in compost, possibly to the point of complete eradication.3. Analysis of stall waste from horses receiving therapeutic doses of antibiotics - Objective 3 will include analysis of stall waste from healthy horses treated with intrauterine antibiotics at UMaine's Witter Center, using experimental procedures mimicking typical administration by veterinarians during equine breeding. In addition, stall waste from horses receiving high levels of antibiotics in a hospital setting (e.g. post abdominal surgery at LSU or UF) will be compared to animals not receiving antibiotics, but are stalled at the same location.4. Biochemical analyses of compost and antibiotic metabolites - This will be conducted by the Soil Chemistry (PSE) and the Analytical Chemistry (FSN) laboratories.5. Survey of antibiotic use in Equine Hospitals and Facilities - Using surveys employing a semi - quantitative Likert scale, potential risk factors to developing antibiotic resistant bacteria in stall waste will be identified. It is hypothesized that certain signalments (age, breed, sex), disease, industry sector, or other potential factors will be associated with increased risk of promoting antibiotic resistant bacteria in stall waste.6. Development of database for surveillance of antibiotic resistant bacteria from equine hospitals - Building out from initial collaborations with veterinary epidemiologists and diagnostic laboratories, we will explore the feasibility of developing a nationwide database to track areas of emerging antibiotic resistance in equine bacterial pathogens.