title: Transformation kinetics of trenbolone acetate metabolites and estrogens in urine and feces of implanted steers.
abstract: Biotransformation of trenbolone acetate metabolites and estrogens derived from animal feeding operations in soils, waste storage systems, and in land applied manure has been well characterized. Yet recent data demonstrate potential for steroid transport into the environment directly from feedyard pens via runoff or airborne particulate matter. Therefore, the objective of this study was to determine steroid transformation rates in beef cattle excreta. Feces and urine were collected from steers recently treated with steroidal implants. Excreta were stored and periodically extracted over 112 d then analyzed for trenbolone acetate metabolites and estrogens by liquid chromatography mass spectrometry. Conjugated steroids were present primarily in urine, and conjugates quickly degraded to free steroid with a half-life of 0.6-1.0 d. The primary trenbolone acetate metabolite, 17α-trenbolone, had a half-life of 5.1-9.5 d. Likewise, 17α-estradiol was the predominant estrogen, with a half-life of 8.6-53 d. Secondary trenbolone metabolites formed from 17α-trenbolone biotransformation were observed at low concentrations less than 10% initial 17α-trenbolone concentrations. Estrone was the primary metabolite of 17α-estradiol and concentrations of estrone exceeded initial 17α-estradiol concentration in all sample types. These results suggest manure-borne steroids are more stable in excreta than in soil microcosms.
authors.affiliation: Texas Tech University, Department of Environmental Toxicology, 1207 Gilbert Dr, Lubbock, TX, USA.
authors.forename: Brett R
authors.initials: BR
authors.lastname: Blackwell
authors.affiliation: Texas Tech University, Department of Animal and Food Sciences, Box 42141, Lubbock, TX, USA.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Johnson
authors.affiliation: Oklahoma State University, Department of Biosystems and Agricultural Engineering, 111 Agricultural Hall, Stillwater, OK, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Buser
authors.affiliation: Baylor University, Department of Environmental Science, One Bear Place #97266, Waco, TX, USA.
authors.forename: George P
authors.initials: GP
authors.lastname: Cobb
authors.affiliation: Texas Tech University, Department of Environmental Toxicology, 1207 Gilbert Dr, Lubbock, TX, USA. Electronic address: phil.smith@ttu.edu.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Smith
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001711:Biotransformation; D002417:Cattle; D002853:Chromatography, Liquid; D004967:Estrogens / Q000378:metabolism* / Q000652:urine*; D005243:Feces / Q000737:chemistry*; D006207:Half-Life; D007700:Kinetics; D008297:Male; D008372:Manure / Q000032:analysis; D019736:Prostheses and Implants; D014204:Trenbolone Acetate / Q000378:metabolism* / Q000652:urine*
chemical_list: D004967:Estrogens; D008372:Manure; D014204:Trenbolone Acetate
keywords: Aerobic degradation; Biotransformation; Estrogens; Manure-borne steroids; Trenbolone