Tylosin depletion in edible tissues of turkeys

The depletion of tylosin residues in edible turkey tissues was followed aft er 3 days of administration of tylosin tartrate at 500 mg l(-1) in drinking water, to 30 turkeys. Immediately after the end of the treatment (day 0) a nd at day 1, 3, 5 and 10 of withdrawal, six turkeys (three males and three females) per time were sacrificed and samples of edible tissues were collec ted. Tissue homogenates were extracted purified and analysed by HPLC accord ing to a method previously published for the analysis of tylosin residues i n pig tissues. In all tissues, tylosin residues were already below the dete ction limits of 50 mu g kg(-1) at time zero. However, in several samples of tissues (skin + fat, liver, kidney, muscle), from the six turkeys sacrific ed at that rime, one peak corresponding to an unknown tylosin equivalent wa s detected at measurable concentrations. The identification of this unknown compound was performed by LC-MS/MS analysis of the extracts from incurred samples. The mass fragmentation of the compound was consistent with the str ucture of tylosin D (the alcoholic derivative of tylosin A), the major meta bolite of tylosin previously recovered and identified in tissues and/or exc reta from treated chickens, cattle and pigs.