engleski

Deposition of toltrazuril residues in eggs during and after treatment with dose over the therapeutic dose

The coccidiostat toltrazuril (TZ) is used for the prevention and treatment of coccidiosis in broilers and turkeys, but is prohibited for use in laying hens. In the present study, laying hens were treated with toltrazuril in doses of 125 mg l −1 in drinking water in three medication steps for 2 days every five days (days 1, 2, 7, 8, 13 and 14). Eggs were collected during treatment and over a 50-day post-treatment period. Residue levels of toltrazuril and its metabolite toltrazuril sulphone, also known as ponazuril (PZ), were determined in whole egg, yolk and albumen. Both analytes predominate in egg yolk samples with a a 10-times higher concentrations. During treatment, maximal residue concentrations of TZ 7, 571 mg kg−1 were reached on day 8 of treatment and for PZ 24, 743 mg kg−1 on 14-day of treatment. The highest level of TZ determined in yolk was 37, 297 mg kg−1 at 5 day of treatment and for PZ 46, 451 mg kg−1 at first day after last medication. Toltrazuril and ponazuril levels were detectable even on day 50 after the end of administration. Ponazuril half- life of elimination derived from period of 12 days after the treatment was 4.4 days, and 2.4 days for TZ. However, afterwards it is shown that a half- life of elimination to be slower. At the end of this study (64 day), 50 days after the end, PZ concentrations were: 294 μg kg−1 in whole egg, 998 μg kg−1 in yolk, 80.8 μg kg−1 in albumen.

toltrazuril; chicken; eggs

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