title: Aerobic degradation of tylosin in cattle, chicken, and swine excreta.
abstract: Tylosin, a fermentation-derived macrolide antibiotic, was tested to determine its aerobic degradation rate in cattle, chicken, and swine excreta. For chicken, excreta from a hen administered 14C-tylosin as part of a metabolism study were used. For cattle and swine, 14C-tylosin was added to control excreta. The formation of 14C volatile breakdown products and 14CO2 was not observed throughout the study. Material balance for the carbon-14 label ranged between 94% and 104%. Initial, day-0, concentrations of tylosin-A averaged 119.52+/-4.39, 35.01+/-1.34, and 62.82+/-2.11 microg/g (dry weight basis) for cattle, chicken, and swine excreta samples, respectively. After 30 days, samples averaged 4.16+/-0.69 and 4.11+/-0.69 microg/g tylosin-A in cattle and swine excreta, respectively. No residues of tylosin-A or its factors were apparent in the chicken excreta samples after 30 days of incubation. In each case, tylosin declined to less than 6.5% of the initial level after 30 days. Calculated first-order half-lives under the test conditions were 6.2 days, <7.6 days, and 7.6 days for cattle, chicken, and swine excreta, respectively. The results indicate that tylosin residues degrade rapidly in animal excreta. Therefore, tylosin residues should not persist in the environment.
authors.affiliation: Lilly Research Laboratories, A Division of Eli Lilly and Company, 2001 West Main Street, Drop Code GL45, Greenfield, IN 46140, USA. jsteeter@lilly.com
authors.forename: Jerold Scott
authors.initials: JS
authors.lastname: Teeter
authors.forename: Roger D
authors.initials: RD
authors.lastname: Meyerhoff
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000378:metabolism; D002417:Cattle; D002645:Chickens; D004350:Drug Residues / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D005260:Female; D012989:Soil Pollutants / Q000378:metabolism; D013552:Swine; D015645:Tylosin / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D002250:Carbon Radioisotopes; D012989:Soil Pollutants; D015645:Tylosin