The Deposition and Clearance of Rofenaid® in Chicken and Turkey Eggs

Rofenaid® is a coccidiostat and antibacterial for poultry. The active ingredients are a combination of sulfadimethoxine and ormetoprim in a ratio of 5 to 3. The deposition and clearance of Rofenaid® in chicken and turkey eggs were studied in order to establish a clearance time for replacement pullets and young breeder hens. Rofenaid®, labelled with radioactive carbon-14 either in the sulfadimethoxine or in the ormetoprim portion was administered to laying chicken hens at a level of 0.02% in the feed, and to laying turkey hens at 0.01% in the feed. Eggs were collected daily, separated into yolk, albumen and shell fractions, and assayed for radioactivity by liquid scintillation counting. When the radioactivity had reached a plateau, feeding of the drug was discontinued and an analysis of the eggs was continued until no more radioactivity could be detected. In the chicken, 0.59% of the daily intake of sulfadimethoxine and 0.83% of the daily intake of ormetoprim were transferred to the whole egg at the plateau level. The time required for the whole egg to clear to the 0.01 p.p.m. level was estimated at 9 days for sulfadimethoxine and 7 days for ormetoprim. In the turkey, 0.71% of the daily intake of sulfadimethoxine and 0.17% of the daily intake of ormetoprim were transferred to the whole egg at the plateau level. The time required for the whole egg to clear to the 0.01 p.p.m. level was estimated at 14 days for sulfadimethoxine and 12 days for ormetoprim.