RESUMEN
Among the multiple mechanisms of cadmium toxicity proposed, the most common is the disruption of the cellular antioxidant system, which may be limited by pre- or co-treatment with zinc. The aim of this study was to determine if simultaneous zinc supplementation of hen's egg could reduce embryotoxic effect of cadmium. Egg albumen was injected on day 4 of incubation with cadmium alone (50 nmol per egg) or in combination with zinc (100 and 500 nmol). Hatching results and antioxidant activity in plasma of newly hatched chicks were determined by photochemiluminescence (PCL) and FRAP methods. Administration of cadmium markedly reduced hatchabilty (30.2 %), while both zinc doses used were embryotoxic (43.2 and 48.9 %) as compared to the control group (61.9 %). This adverse effect was reduced by simultaneous zinc administration (completely at 10-fold higher molar concentration). This observation was confirmed by examination of the antioxidant capacity in plasma of Cd-treated chicks. A slight decrease in the hydrophilic and lipophilic antioxidant capacity induced by cadmium was compensated by a co-treatment with higher zinc dose administration, whereas the exposure of hen embryos to zinc caused an increase in antioxidant potential in the plasma of chicks. It is concluded that Zn supply in conditions of exposure to Cd can protect against Cd-induced oxidative stress in chicken embryos.