Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 2003
Publication Date: November 15, 2003
Citation: Henderson, K.L., Phillips, T.A., Moorman, T.B., Coats, J.R. 2003. Persistence and movement of tylosin in a manure-soil matrix [abstract]. SETAC Abstract Book, 24th North American Annual Meeting. p. 48.
Antibiotics are widely used in food animal production in subtherapeutic doses for growth promotion, and in therapeutic doses for disease prevention. These compounds enter the environment via application of manure to soil, and have recently been detected in surface water bodies throughout the United States. There is additional concern for the development of microbial antibiotic-resistance related to such contamination. Tylosin is a veterinary antibiotic commonly used as a feed additive in swine production for both growth promotion and disease prevention. Swine excrete this drug in urine and feces, and tylosin enters the environment via manure application. Little is known about the fate of tylosin in a manure-soil matrix. In this study, the mobility and degradation of tylosin were investigated using intact soil columns. Soil columns (10-cm diameter and 25-cm length) were prepared and randomly assigned among manure treatment groups (e.g., manure without antibiotic, manure spiked with 5 ppm tylosin, manure spiked with 50 ppm tylosin) with four replicates per treatment. Manure, from hogs on an antibiotic-free diet, was uniformly applied and incorporated into the top 2 cm of soil. Columns were maintained at 20 deg C, and the equivalent of 3.8 cm of rainfall was applied dropwise over a period of 40-60 minutes weekly for four weeks. Waters leaching from intact soil columns were examined for tylosin; following the completion of leaching, the soil column was evaluated for the mobility of tylosin. Each column was divided into three 10-cm sections; two aliquots of soil from each section was homogenized and extracted with methanol. Tylosin was extracted from water using solid-phase extraction; concentrations of parent compound and major metabolites in leachate and soil were determined using LC/MS/MS. The results of this study provide data and methods that may be useful in risk assessment of antibiotics and manure management in the environment.