2019 Volume 32 Issue 3 Pages 83-90
In recent years, livestock in Japan have consumed large amounts of veterinary antibiotics. Some of the antibiotics administered to livestock are discharged through their excrement. The use of antibiotic-containing excrement as farmland manure becomes concern, because bacteria in the farmland can develop resistance to the antibiotics. Antibiotics can also contaminate aquatic environments. However, the amount of administered veterinary antibiotics excreted by livestock into the environment has been rarely reported. In this study, the excretion ratio of sulfamonomethoxine (SMM) administered to livestock was investigated using sheep as a model animal of cows.
SMM extracted from sheep excrement with McIlvaine buffer solution was analyzed by LC-MS/MS after solid phase extraction. The developed analysis method achieved a high recovery rate of 85.9％ for urine and 93.2％ for feces. In the result, maximum SMM concentration was 45.6 mg/kg in feces at 16 hours and 532 mg/kg in urine at 2 hours after SMM was spiked. The average excretion ratios were 10.6％ in urine, 2.0％ in feces, and 12.6％ in total.
