Environmental Engineering Program


First Advisor

Tiffany Messer

Second Advisor

Shannon Bartlet-Hunt

Third Advisor

Daniel Snow

Date of this Version

Spring 4-2020


American Society of Civil Engineers


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Environmental Engineering, Under the Supervision of Professor Tiffany Messer and Shannon Bartelt-Hunt. Lincoln, NE: May 2019 [2020]

Copyright 2020 Brittany Nicole Trejo


The common practice of using therapeutic antibiotics in livestock farming is a worldwide phenomenon. Over the last decade, there has been a growing concern of antibiotics entering the environment via animal manure. Similar studies have focused on the occurrence and biological effects of antibiotics in land-applied animal feedlots; however, limited research has been conducted on the occurrence and persistence of antibiotics in animal feedlots. A study was conducted to investigate the occurrence and persistence of four injected antibiotics (ceftiofur enrofloxacin, florfenicol, and tulathromycin) and two continuously fed antibiotics (monensin and tylosin) in feedlot sediment, runoff, and sediment runoff. For antibiotics that were injected, concentrations were >20ng/g in feedlot sediment and >0.65 µg/L in runoff; there was no statistical significance found (p-value > 0.05). Monensin and tylosin were detected at the highest concentrations in both feedlot sediment and runoff, at 298 ng/g and 8.8 µg/L and at 129 ng/g and 2.68 µg/L, respectively. Statistical significance was detected with antibiotics continuously fed (p-value <0.01). Mean concentrations in feedlot sediment for monensin and tylosin were 5 and 33 times higher in pens; while, the mean concentrations in runoff were 3.5 and 1.2 times higher, respectively. This study suggests that the antibiotics that are continuously administered through animal feed will be persistent and remain in feedlot sediment and runoff, while those that are injected will be ingested by the animal and degrade more quickly.

Advisors: Tiffany Messer and Shannon Bartelt-Hunt