Depletion study on nicarbazin and narasin in tissues and eggs of hens housed in deep litter

The experiment was performed to define the depletion of dinitrocarbanilide (DNC, marker of nicarbazin residue) and narasin residues in hen tissues and eggs after administration of Maxiban (nicarbazin and narasin, 80 mg kg⁻¹). A flock of 50 hens were kept in deep litter and fed coccidiostats for 14 d following 22 d of withdrawal. Randomly selected birds were slaughtered after the withdrawal of anticoccidial-containing feed. Samples of eggs, liver, and breast muscles were collected and analysed using validated LC-MS/MS method. The concentration of dinitrocarbanilide in the liver on day 0 of the withdrawal was 4,440 ±569 µg kg⁻¹ and quickly dropped to reach plateau level after 5 d. Long persistence of dinitrocarbanilide at plateau level and its presence in gastric contents during the withdrawal suggest the recycling of DNC with litter. The concentration of narasin in tissues and eggs was low even at the beginning of withdrawal period, which confirms the low probability of occurrence of narasin residues in food, even in the case of off-label use of this coccidiostat.

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