Abstract
Sulfamonomethoxine (SMM) was fed to laying hens for 5 days at the dietary level of 400ppm, and thereafter, dietary SMM was withdrawn by changing the diet to SMM free diet for another 14 days. Contents of SMM in eggs laid after the withdrawal were determined by highperformance liquid chromatography.
Disappearance pattern of SMM from whole egg could be well described by following equation applied to onecompartment model, y=A•e-0.7834t where, y is SMM content (ppm) in whole egg, t days after the withdrawal of SMM and A the initial value of SMM content, which showed the SMM content in whole egg laid at 0 day of the withdrawal of dietary SMM. The coefficient, -0.7834, is a characteristic value indicating the speed of disappearance of SMM from whole egg. Biological half life of SMM in whole egg was estimated to be 0.88 (=loge2/0.7834) days with 95% confidence interval from 0.81 to 0.98 days. This value was equaled that of sulfadimethoxine, and was much shorter than that of 2 antibiotics and 4 synthetic antibacterials.
