Histopathological and biochemical changes associated with selenium and vitamin E deficiency in chicks.

One day old unsexed White Leghorn chicks obtained either from commercial hens fed adequate levels of selenium (Se) and vitamin E (VE) (Comm. chicks), or from hens depleted in both nutrients (Depl. chicks), were fed a low Se-VE semi-synthetic basal diet. The dietary Se content was kept constantly low, while graded levels of VE as dl-alpha-tocopheryl acetate (dl-alpha Ta), (0, 5, 10 or 15 mg VE/kg diet) were fed for six weeks. An efficient carry-over of Se and VE from hens to their progeny was observed by a significant increase in their muscle Se, liver Se-glutathione peroxidase (Se-GSH-Px), and VE content at hatching. In the Depl. chicks, signs of Se-VE deficiency, i.e. exudative diathesis (ED) were observed at hatching, indicating that the deficiency lesions had developed during the embryonic period, whereas these signs were not observed in Comm. chicks on the depletion diets until they were 2 weeks old. The VE supplemental level of 15 mg/kg was not adequate to provide a complete protection against ED. Exudative diathesis was associated with low levels of muscle Se, liver Se-GSH-Px and VE and was also accompanied by a simultaneous increase in the liver non-Se-GSH-Px. Autopsy findings and histopathological lesions were observed only in subcutaneous tissue and skeletal muscle. The subcutaneous tissue was edematous with hyaline vascular lesions and hemorrhages. The thigh muscles were more susceptible to deficiency lesions than were the breast muscles, and showed in acute stages degenerative processes of the muscle fibers including calcium deposits, vascular lesions and hemorrhages. In subacute and chronic cases, reparative changes and muscle damage may develop independently of the hyaline vasculosis. To prevent ED, adequate Se and VE in chick diet is essential after hatching, irrespective of their tissue reserves of both nutrients at 1 day of age.