Toward a criterion for suspect thiouracil administration in animal husbandry

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.

Keywords:

• LC/MS
• risk assessment
• screening assays
• statistical analysis
• veterinary drug residues
• animal

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.