Characterization of selected nutrients and bacteria from anerobic swine manure lagoons on sow, nursery, and finisher farms in the Mid-South US

Authors: McLaughlin, Michael; Brooks, John; Adeli, Ardeshir

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2009
Publication Date: 11/1/2009
Citation: McLaughlin, M.R., Brooks, J.P., Adeli, A. 2009. Characterization of Selected Nutrients and Bacteria from Anerobic Swine Manure Lagoons on Sow, Nursery, and Finisher Farms in the Mid-South US. Journal of Environmental Quality. 38:2422-2430.

Interpretive Summary: This research documented the presence and levels of fecal indicator bacteria and human bacterial pathogens in swine lagoons in the mid south region of the USA. Researchers found little or no correlation between the presence of traditional fecal indicator bacteria and the presence of human pathogenic bacteria, suggesting the need for better indicators of these pathogens. Human pathogenic bacteria, Listeria and Salmonella, were detected in less than 70% of samples tested and were not detected in all lagoons. When these pathogens were detected, they were at relatively low concentrations. Findings from this work provide baseline data for future research in this region and that may also be applicable in other regions of the USA and North America. The fact that swine manure land applications have been regulated by nutrient management plans and not by bacterial pathogen levels, and the apparent absence of human health problems over the approximately 15-yr history of the industry is remarkable and suggests that swine manure management plans have been effective and appropriate in the region. Nevertheless, additional research is needed to monitor pathogen levels in lagoon effluents, to develop region-specific information on pathogen survival and transport at land application sites, and to find practical management solutions that further reduce or eliminate pathogens in swine manure impacted environments. Findings from this work will be of interest to microbiologists, agricultural waste management and other scientists, regulatory agencies, swine producers and the public.

Technical Abstract: Swine manure from confinement barns in the southeastern USA is flushed into anaerobic lagoons and the effluent land applied as fertilizer. Fertilizer qualities of effluents have been documented, but less is known of their microbiological quality. The present study assessed microbiological quality in samples collected from September 2007 through May 2008 from 37 lagoons, including at least 10 each on sow farms (breeding, gestation, farrowing), nurseries (21 days old to 18–kg feeders), and finisher farms (feeders grown to 113 kg). Cultural methods were combined with quantitative MPN (most probable number) PCR assays to identify bacteria and estimate levels of total and thermal–tolerant coliforms, Escherichia coli, enterococci, clostridia, Campylobacter, Listeria and Salmonella. Levels varied by farm type and bacterial group. Highest counts were from total coliforms (1.4 to 5.7 x105 cfu 100mL-1), which along with E. coli, Campylobacter, Clostridium and Enterococcus, occurred in every lagoon and virtually every sample. Lowest counts were from Listeria and Salmonella (=1.3 x102 MPN 100mL-1), which were detected in 81% and 89% of lagoons and 68% and 64% of samples, respectively. Levels were higher in sow farm lagoons for all groups except Listeria and Salmonella, which were relatively lower (1.4 x101 and 2.8 x101 MPN 100mL-1, respectively) and only slightly below their respective levels in nursery lagoons (1.1 x102 and 3.4 x101 MPN 100mL-1). Coliform group levels were positively correlated, but none of these or Enterococcus correlated with Campylobacter, Clostridium, Listeria or Salmonella levels.