Characteristics and Sodium Pentobarbital Concentrations of Equine Mortality Compost Piles in the Upper Midwest.
Abstract: Recent changes in rendering availability for chemically-euthanized animals have created a need to explore composting as an equine mortality management method. The objectives of this study were to evaluate equine mortality composting in the Upper Midwest during fall and spring, document sodium pentobarbital concentrations throughout the process, and determine nutrient content of finished compost. During each season, four horses were euthanized by intravenous administration of sodium pentobarbital. Carcasses were positioned at the center of a woodchip and shavings base and covered with a 2:1 mixture of horse stall waste and cattle feedlot waste. Data loggers were placed at 46- and 91cm depths to record pile temperatures every 8 hours. At turning (44-50 days) and trial conclusion (181-216 days), compost piles were sampled for sodium pentobarbital and nutrient composition. Piles contained large bones after 6 months of composting. Sodium pentobarbital remained detectable at trial conclusion (<0.002-1.49 mg kg dry matter); however, composting reduced the estimated quantities of sodium pentobarbital by ≥94% (P ≤ .001). Compost from each season met ideal land application values for organic matter (45%-48%), pH (7.3-7.6), and electrical conductivity (3.3-3.4 mm hos cm). Low NPK and high C:N ratio (20-30) indicate compost could partially replace synthetic fertilizers when land applied. These findings suggest equine mortality composting is an effective management practice during fall and spring in the Upper Midwest. While remaining sodium pentobarbital residues were minimal, further research is needed to determine environmental implications of composting chemically-euthanized equines.
Copyright © 2022. Published by Elsevier Inc.
Publication Date: 2022-04-29 PubMed ID: 35490974DOI: 10.1016/j.jevs.2022.104000Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research evaluates composting as a solution for chemically-euthanized horses in the Upper Midwest due to the recent difficulty of obtaining rendering services for these animals. The study conducts the compost process during fall and spring, examines the residues of euthanasia drug sodium pentobarbital, and analyses the nutrient content of the resulting compost.
Methods of the Study
- The study was conducted in two seasons, each time involving four horses that were euthanized using sodium pentobarbital injections.
- The dead horses were laid at the center of a blend of wood chip and shavings and then covered with a mixture of stall waste from a horse and waste from a cattle feedlot.
- To monitor temperatures inside the compost pile, data loggers were placed at depths of 46cm and 91cm, set to record temperature every 8 hours.
- The compost piles were examined after 44 – 50 days and at the end of the trials 181 – 216 days later, specifically looking at sodium pentobarbital residues and the nutrient content.
Findings from the Study
- Large bones remained in the compost piles after half a year of composting.
- Residues of sodium pentobarbital were still detected at the end of the trials, but composting reduced the quantity of the drug by at least 94%.
- The compost formed was found to have optimum organic matter (between 45% and 48%), a desirable degree of acidity (pH between 7.3 – 7.6), and suitable electrical conductivity (between 3.3 – 3.4 mm hos cm).
- The compost had low nitrogen, phosphorus, and potassium (NPK) and a fairly high carbon-to-nitrogen ratio (between 20 and 30), indicating it could be used as an alternative to synthetic fertilizers.
Interpretation of the Findings
- The findings suggest that composting can be an efficient solution to manage equine mortality during fall and spring in the Upper Midwest.
- The remained sodium pentobarbital residues, even if minimal, prompts the need for additional research to understand the environmental implications of composting chemically-euthanized horses.
Cite This Article
APA
Lochner HL, Hutchinson ML, Wilson ML, Bianco AW, Johnston LJ, Prigge JL, Martinson KL.
(2022).
Characteristics and Sodium Pentobarbital Concentrations of Equine Mortality Compost Piles in the Upper Midwest.
J Equine Vet Sci, 114, 104000.
https://doi.org/10.1016/j.jevs.2022.104000 Publication
Researcher Affiliations
- Department of Animal Science, University of Minnesota, Saint Paul, MN.
- Cooperative Extension, University of Maine, Waldoboro, ME.
- Department of Soil, Water and Climate, University of Minnesota, Saint Paul, MN.
- College of Veterinary Medicine, University of Minnesota, Saint Paul, MN.
- Department of Animal Science, University of Minnesota, Saint Paul, MN.
- Department of Animal Science, University of Minnesota, Saint Paul, MN.
- Department of Animal Science, University of Minnesota, Saint Paul, MN. Electronic address: krishona@umn.edu.
MeSH Terms
- Animals
- Composting
- Euthanasia, Animal
- Horses
- Midwestern United States
- Pentobarbital / analysis
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