Résumé
Eggs and tissue residues and the adverse effects of tilmicosin were investigated in laying hens after repeated oral administrations [25 mg/kg b.wt.] once daily for 5 consecutive days. Tilmicosin was completely cleared from blood, eggs and all tested tissue [lung, liver, kidney, thoracic muscles, ovary, oviduct] at 7 days after the last dose. The effect of the tested antibacterial on some enzymatic activities [ALT, AST and ALP], blood constituents [glucose, cholesterol, total proteins, urea, creatinine] and blood picture [Hb, PCV%, RBCs and WBCs counts] revealed significant alterations after discontinuation of drug regimen. It was concluded that the withdrawal time of tilmicosin in eggs and muscles and tissues of laying hens was 5, 6 days for lung and 7 days for liver. Thus, chicken must not be slaughtered for human consumption for a period of at least 7 days after the last treatment with tilmicosin. Moreover, our data suggest that repeated administration of tilmicosin could induce deleterious effects represented by hepatic and renal dysfunction as well as possible microcytic anaemia