|Thurston Enriquez, Jeanette|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 18, 2007
Publication Date: October 3, 2007
Citation: Berry, E.D., Woodbury, B.L., Nienaber, J.A., Eigenberg, R.A., Thurston Enriquez, J.A., Wells, J. 2007. Incidence and persistence of zoonotic bacterial and protozoan pathogens in a beef cattle feedlot runoff control - vegetative treatment system. Journal of Environmental Quality 36:1873-1882. Interpretive Summary: Runoff water from cattle feedlots or from manure storage contains nutrients and pathogens that can contaminate surface and ground waters, so it must be contained and treated to reduce these risks. In this work, we examined the occurrence and persistence of manure pathogens in an alternative feedlot runoff control system that utilizes a shallow basin to collect liquid runoff and accumulate solids, and an area of bromegrass to utilize the nutrients from the runoff. After runoff events the pathogens E. coli O157 and Campylobacter were detected in the soil, but without additional runoff, prevalence of both pathogens decreased over time. However, low numbers of the generic nonpathogenic E. coli persisted in the soil. In this system, there is some risk of pathogen contamination of the grass hay, which could be transmitted back to cattle when feeding the hay. The grass runoff control system was effective for reducing environmental risk by containing and removing pathogens from feedlot runoff.
Technical Abstract: Determining the survival of zoonotic pathogens in livestock manure and runoff is critical for understanding the environmental and public health risks associated with these wastes. The occurrence and persistence of the bacterial pathogens Escherichia coli O157:H7 and Campylobacter spp. in a passive beef cattle feedlot runoff control-vegetative treatment system were examined over a twenty-six month period. Incidence of the protozoans Cryptosporidium spp. and Giardia spp. was also assessed. The control system utilizes a shallow basin to collect liquid runoff and accumulate eroded solids from the pen surfaces; when an adequate liquid volume is attained, the liquid is discharged from the basin onto a 4.5-ha vegetative treatment area (VTA) of bromegrass which is harvested as hay. Basin discharge transported E. coli O157, Campylobacter spp., and generic E. coli into the VTA soil, but without additional discharge from the basin, the pathogen prevalences decreased over time. Similarly, the VTA soil concentrations of generic E. coli initially decreased rapidly, but lower residual populations persisted. Isolation of Cryptosporidium oocysts and Giardia cysts from VTA samples was infrequent, indicating differences in sedimentation and/or transport in comparison to bacteria. Isolation of generic E. coli from freshly cut hay from VTA regions that received basin discharge (twelve of 30 vs. one of 30 control samples) provided evidence for the risk of contamination; however, neither E. coli O157 nor Campylobacter spp. were recovered from the hay following baling. This work indicates that the runoff control system is effective for reducing environmental risk by containing and removing pathogens from feedlot runoff.