This study was carried out on 90 broiler chicks which divided into three groups. The first group has been given 0.75 g/L potassium nitrate and the second group was given 1 g/L potassium nitrate with drinking water for 30 days, While the third group w
as regarded as a control.
The birds were reared in same keeping house and feeded with the same ration without any additives and no vaccinations were applied.
All birds were sacrificed and examined by naked eye. Then the thymus gland was fixed by formalin and stained microscopic sections were examined by microscope.
The histological changes in the birds which dosed by 1 g/L and 0.75 g/L of nitrate were similar and the observed changes were the small size of cortex in some lobules, and the cortex were separated from bulb with increase the number of Hassall bodies in the bulb region, also there were vacuoles and reticular cells in different stages of degeneration and edema in the connective tissues in comparison with control group.
These results confirmed that nitrate had toxic effects on the tissues of thymus, and as a sequence reduced the number of T cells which lead to decrease the resistance and Immune response of the birds and retarded the growth rate.
