Screening for the coccidiostats halofuginone and nicarbazin in egg and chicken muscle: development of an ELISA

Abstract

Nicarbazin and halofuginone have been widely used as coccidiostats for the prevention and treatment of coccidiosis in poultry. It has been shown that accidental cross-contamination of feed can lead to residues of these compounds in eggs and/or muscle. This paper describes a direct competitive assay for detecting halofuginone and nicarbazin, developed as qualitative screening assay. In an optimized competitive ELISA, antibodies showed 50% binding inhibition at approximately 0.08 ng ml⁻¹ for halofuginone and 2.5 ng ml⁻¹ for dinitrocarbanilide (marker residue for nicarbazin). Extraction from the matrix was carried out with acetonitrile followed by a wash with hexane. The assay's detection capability (CCβ) for halofuginone was <0.5 µg kg⁻¹ in egg and <1 µg kg⁻¹ in muscle. For dinitrocarbanilide, the CCβ was estimated at <3 µg kg⁻¹ in egg and <10 µg kg⁻¹ in chicken muscle.

Keywords:

• Halofuginone
• nicarbazin
• egg
• muscle
• ELISA

Acknowledgements

Work was sponsored by the Belgian State, Services of the Prime Minister, Federal Office of Scientific, Technical and Cultural Affairs.