Abundance and fate of antibiotics and hormones in a vegetative treatment system receiving cattle feedlot runoff

Authors: McGhee, Ryan; Miller, Daniel; Durso, Lisa; SNOW, DANIEL - University Of Nebraska

Submitted to: Waste to Worth Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/23/2014
Publication Date: 3/30/2015
Citation: McGhee, R., Miller, D.N., Durso, L.M., Snow, D.D. 2015. Abundance and fate of antibiotics and hormones in a vegetative treatment system receiving cattle feedlot runoff. Waste to Worth Conference [abstract]. Available: http//www.extension.org/pages/72825/abundance-and-fate-of-antibiotics-and-hormones-in-a-vegetative-treatment-system-receiving-cattle-fee.

Interpretive Summary: Vegetative treatment systems (VTS) have been developed and built as an alternative to conventional holding pond systems for managing run-off from animal feeding operations. Initially developed to manage runoff nutrients via uptake by grasses, their effectiveness at removing other runoff contaminants (fecal microorganisms, pathogens, antibiotics, and hormones) needs to be evaluated. In a three-year project, wastewater and soil samples were collected at a beef cattle feedlot utilizing a VTS equipped with multiple treatment cells (grass paddocks). Clean rainfall runoff, feedlot runoff, and excess wastewater that accumulated after runoff application were samples. Soil samples were collected in four treatment cells and in a berm between treatment cells receiving no wastewater were also collected and analyzed for antibiotics and hormones. The antibiotics monensin, tetracycline, chlortetracycline, and lincomycin and the hormones 4-androstendione, estrone, progesterone, and testosterone were most frequently detected in feedlot runoff. Excess wastewater runoff from the treatment cells contained similar antibiotic concentrations, but hormone concentrations decreased markedly by passage across the treatment cells. ‘Clean’ cell water often contained monensin and trace lincomycin and tetracycline, but hormones were largely absent. Analysis of soils from the cells and from the berms indicated monensin was the primary antibiotic with some chlorotetracycline, tetracycline, and tylosin. The hormones 4-andorstenedione, 17a- and 17b-estradiol, and 17a- and 17b-trenbolone were also detected in soil samples. Analysis by soil depth, time, and comparisons with berm soil indicated no evidence that antibiotics and hormones were accumulating within the VTS. Monensin seemed to be the dominant compound and could serve as a sentinel compound here and at other sites since it was in greatest abundance and may be mobilized from the soil during rainfall events.

Technical Abstract: Vegetative treatment systems (VTS) have been developed and built as an alternative to conventional holding pond systems for managing run-off from animal feeding operations. Initially developed to manage runoff nutrients via uptake by grasses, their effectiveness at removing other runoff contaminants (fecal microorganisms, pathogens, antibiotics, and hormones) needs to be evaluated. In a three-year project, wastewater and soil samples were collected at a 1200-animal beef cattle feedlot utilizing a VTS. At this VTS, four replicate, 0.5 ha treatment cells received feedlot runoff. Control points enabled the collection of ‘clean’ cell water (cell rainfall runoff), feedlot runoff, and excess wastewater that accumulated after excess feedlot runoff application. Soil samples were collected to 50 cm depth along transects in each treatment cell and in berms receiving no wastewater. Antibiotics and hormones were determined in samples by LC-MS/MS. The antibiotics monensin, tetracycline, chlortetracycline, and lincomycin and the hormones 4-androstendione, estrone, progesterone, and testosterone were most frequently detected in feedlot runoff. Excess wastewater runoff from the treatment cells contained similar antibiotic concentrations, but hormone concentrations decreased markedly by passage across the treatment cells. ‘Clean’ cell water often contained monensin and trace lincomycin and tetracycline, but hormones were largely absent. Analysis of soils from the cells and from the berms indicated monensin was the primary antibiotic with some chlorotetracycline, tetracycline, and tylosin. The hormones 4-andorstenedione, 17a- and 17b-estradiol, and 17a- and 17b-trenbolone were also detected in soil samples. Analysis by soil depth, time, and comparisons with berm soil indicated no evidence that antibiotics and hormones were accumulating within the VTS. Monensin seemed to be the dominant compound and could serve as a sentinel compound here and at other sites since it was in greatest abundance and may be mobilized from the soil during rainfall events.