Abstract
Thyreostats are growth-promoters banned in Europe since 1981. The identification of thiouracil (TU) in animal biological matrices can, however, no longer be systematically interpreted as a consequence of illegal administration. Indeed, some experimental results have indicated a causal link between cruciferous-based diet and the presence of TU in urine of bovines. The present study aims at investigating, on a large scale (n > 1300), the natural occurrence of thiouracil in urine samples collected from different animal species. TU was identified in main breeding animal species: bovine, porcine and ovine. The natural distribution of TU allowed proposing threshold values to differentiate compliant from suspect urine samples. Suggested values are 5.7 and 9.1 µg l−1 in male adult bovines (6–24 months), 3.1 and 8.1 µg l−1 in female adult bovines (6–24 months), 7.3 and 17.7 µg l−1 in calves (<6 months), 3.9 and 8.8 µg l−1 in female bovines (>24 months), and 2.9 and 4.1 µg l−1 in porcines at a 95 and 99% confidence level, respectively.
Acknowledgements
The authors thank the French Ministry of Agriculture (General Directorate for Food, DGAl) for financial support as well as Laboratoire Départemental des Landes, Laboratoire Départemental d’Analyse d’Ille-et-Vilaine, and Laboratoire Départemental de la Côte d’Or for their involvement in data production.