Use of sulfadimethoxine in intensive calf farming: evaluation of transfer to stable manure and soil

After prophylactic treatment of 50 calves with 62 mg kg −1 day −1 of sulfadimethoxine (SDM) for five days, the levels of the drug over time were followed in feces, bedding and stable manure, and then in the soil of a manured field and surrounding drainage courses. Analysis were done by HPLC after applying to the different matrices a quick and simple extraction procedure. The half-life of the drug in bedding was very short (24 h). In stable manure the degradation rate of the drug slowed down and the calculated half-life was 64 days, with 390 μg kg −1 of SDM still detectable after three months maturation. However, in a five months matured stable manure obtained from other groups of calves subjected to the same prophylactic treatment, levels of SDM were 1000.