Việc sản xuất của lợn, gia súc, gia cầm tăng cho người đại diện một phần đáng kể của nền kinh tế nông nghiệp Mỹ. Để tối đa hóa sản xuất, nhà sản xuất thường xuyên sử dụng thuốc kháng sinh như bổ sung trong thức ăn chăn nuôi và nước tăng tăng cân và ngăn ngừa bệnh tật trong số các vật nuôi của họ. Lợn, Ví dụ, người ta ước tính rằng thuốc kháng sinh được sử dụng để phòng bệnh và tăng trưởng thúc đẩy hơn 90% thức ăn khởi động, 75% thức ăn trồng, 50% hoàn thiện thức ăn, và 20% thức. | 7 Mobility of Tylosin and Enteric Bacteria in Soil Columns Keri L. Henderson Thomas B. Moorman and Joel R. Coats Contents Enteric Materials and Preliminary Main Study. 171 Results and Preliminary Main Study. 172 INTRODUCTION The production of swine cattle and poultry raised for human consumption represents a significant portion of the . agricultural economy. To maximize production producers regularly use antibiotics as supplements in animal feed and water to increase weight gain and prevent diseases among their livestock. In swine for example it is estimated that antibiotics are used for disease prevention and growth promotion in more than 90 of starter feeds 75 of grower feeds 50 of finishing feeds and 20 of sow feeds and equally relevant numbers are seen in beef cattle production Hayes et al. 1999 USdA aPhIS Swine 2000 and COFE . It has been well documented that measurable quantities of these antibiotics are excreted often in original form in feces and urine of livestock FAO WHO 1991 . Livestock waste containing antibiotics is often used as fertilizer for farm fields or pastures and may result in nonpoint source pollution of ground or surface waters Loke et al. 2000 . Although antibiotic residues have been studied extensively in tissues and excrement we are only beginning to understand the environmental fate of antibiotics and their metabolites once the excreta reaches soil and water environments. 167 2008 by Taylor Francis Group LLC 168 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems Recently antibiotics including the veterinary antibiotic tylosin which is described in this study were found in 48 of 139 stream waters tested in 30 states according to the . Geological Survey Kolpin et al. 2002 . Antibiotics entering the environment could .
