Morphological Changes in the Liver and the Response of Antioxidant Enzymes after Turkeys' Chronic Exposure to Cadmium

We observed the effect of cadmium (Cd group) and cadmium+zinc (Cd/Zn group) in the liver of turkeys after a 71-day exposure. The experimental birds were divided to three groups; control group (Control), group exposed to cadmium (group Cd) as CdCl2 (aqueous solution, 0.5 mg/kg feed); and group Cd/Zn exposed to the same dose of cadmium as Cd group plus zinc as ZnSO4 (aqueous solution, 90 mg/kg feed). Light and electron microscopy revealed pronounced changes in the liver of turkeys from the Cd group, such as hyperaemia, dilatation of sinusoids and accumulation of inflammatory cells, including macrophages, heterophils, and lymphocytes in sinusoids. Necrotizing hepatocytes were observed sporadically. The ultrastructural changes included swollen mitochondria with injured cristae, dilated cisternae of rough endoplasmic reticulum, and damaged intercellular contacts between hepatocytes. In the Cd/Zn group, Zn was not able to completely protect the liver, but the changes were less pronounced. The specific activity of superoxide dismutase was significantly increased in the Cd group. Glutathione peroxidase was significantly increased in all experimental groups. In the Cd/Zn group, zinc co-administration had a protective effect on the activity of antioxidant enzymes. Exposure of turkeys to cadmium did not affect the content of TBARS in the liver.