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Title: Composting swine manure from high rise finishing facilities

Author
item RITCHEY, EDWIN - University Of Kentucky
item Cook, Kimberly - Kim

Submitted to: University of Kentucky Cooperative Extension Bulletin
Publication Type: Trade Journal
Publication Acceptance Date: 8/4/2016
Publication Date: 8/6/2016
Citation: Ritchey, E., Cook, K.L. 2016. Composting swine manure from high rise finishing facilities. University of Kentucky Cooperative Extension Bulletin. 5:14. Available: http://uknowledge.uky.edu/pss_reports/8/.

Interpretive Summary: This research investigated how the physical and chemical properties of finished compost were influenced by turning frequency and environmental conditions of partially decomposed swine manure-woodchip mixtures from a swine HRFF. Further, recommendations are provided to maximize composting efficiency based on the results of this research.

Technical Abstract: Over the last twenty years there have been considerable increases in the incidence of human infections with bacteria that are resistant to commonly used antibiotics. This has precipitated concerns about the use of antibiotics in livestock production. Composting of swine manure has several advantages, liquid slurries are converted to solid, the total volume of material is reduced and the stabilized product is more easily transported off-site. The goal of this study was to determine if composting can also be used to reduce the concentration of indicators and bacteria containing genes for antibiotic resistance (AR) in swine manure. Compost trials were conducted in either fall (FT) or spring (ST) and piles were turned once, three times or upon reaching 65 ºC. Microbial indicators and populations with AR genes for tetracycline, erythromycin and sulfonamide resistance were quantified by culture and/or quantitative, real-time (qPCR) analysis. In the FT, concentrations of enterococci decreased below culturable detection within 21 days, corresponding with a 99% decrease in detection by qPCR. Similar decreases in qPCR detection in the ST took longer (day 49 or day 77 of composting). Changes in the concentration of bacteria with AR genes varied by antibiotic type (erythromycin (36% - 97%), tetracycline (94% to 99%) and sulfonamide (53% to 84%)) and compost season (greater decreases in ST). There were few differences based on turning regime. These results suggest that composting effectively decreases the concentration of indicators and AR genes in swine manure.