Salinomycin concentration in eggs and tissues of laying hens

The objective of our study was to monitor the presence of salinomycin in eggs and tissues of laying hens fed with rations containing 60 mg.kg(-1) salinomycin sodium for five days. Residues of salinomycin were determined on the day of withdrawal from salinomycin treatment in the breast and thigh muscle, liver, abdominal fat and ovarian yolk. In eggs, residues of salinomycin were monitored in both yolk and albumen daily from the beginning of treatment until the tenth day after withdrawal. Salinomycin was first found in yolk 1 day after starting the treatment and persisted for 8 days after withdrawal. The highest average level, 480 mu g.kg(-1), was present on the third day after withdrawal. In albumen, levels of salinomycin residues were significantly lower, with a maximum level of 15 mu g.kg(-1) reached on the fifth day of the experiment; and they were only found up to one day after withdrawal. Salinomycin was found in all ovarian yolks present in the body of layer hens in a concentration range between 237 and 553 mu g.kg(-1) . It was also found in the abdominal fat (concentration range from 62 to 237 mu g.kg(-1)) and the liver (concentration <= 10 mu g.kg(-1)), but not in breast or thigh muscle tissues. No changes in salinomycin residues were observed after cooking and frying the eggs.