The Livestock and Poultry Environmental Learning Center (LPELC) of eXtension says a new study focuses on the use and occurrence of antibiotics on dairy farms and in forage fields that receive manure. A team of researchers determined that compounds differed in their occurrence throughout the farm, but that most were constrained to farm boundaries. The article is published in the Journal of Environmental Science & Technology.

Four seasonal sampling campaigns were conducted on two dairies. A variety of antibiotics were used at both farms, leading to antibiotics excretion of several hundred grams per farm per day. Sulfonamides, tetracyclines, and their epimers/isomers, and lincomycin were most frequently detected by the researchers. The most frequent antibiotic detections were associated with lagoons, hospital pens and calf hutches. When detected below ground, tetracyclines were mainly found in soils, whereas sulfonamides were found in shallow groundwater reflecting key differences in their physicochemical properties, according to the researchers.

In manure lagoons, 10 compounds were detected, including tetracyclines and trimethoprim. Of these 10, sulfadimethoxine, sulfamethazine and lincomycin were found in shallow groundwater directly under the lagoons. Antibiotics were sporadically detected in field surface samples on fields with manure applications, but not in underlying sandy soils. Sulfadimethoxine and sulfamethazine were detected in shallow groundwater near field flood irrigation gates, but at highly attenuated levels.

Read about the study online at pubs.acs.org/doi/full/10.1021/es100834s.