MORPHOFUNCTIONAL EVALUATION OF THYMUS IN PEKIN DUCK DURING DIETARY INCORPORATION OF ORGANIC SELENIUM FEED ADDITIVE DAFS-25k

The histological study results of the thymus structure of Pekin ducks during administration of DAFS-25k feed additive are presented. It has been established that the thymus is  a  morphologically mature and actively functioning organ in  one-day-old Pekin ducklings. With age an  increase in the size of thymus lobules was observed in ducklings in the control and experimental groups but under the influence of selenium the cortical area increased more intensively. 45-day-old ducklings in the experimental group demonstrated a reliable increase in the ventricular-brain ratio mainly due to the expansion of the cortical area. The surface of the cortical substance did not change in intact ducklings, the tendency of extension in the surface of the brain substance was observed, which at that age is a sign of an accidental involution associated with the onset of a plumage change from juvenile down to primary feathers. Under the influence of selenium in the thymus of the ducklings of the experimental group the processes of accidental involution are leveled, the processes of synthesis of thymopoietins and proliferation of thymocytes are more active. Up to age of 75 days there is active proliferation of thymocytes in the thymus of ducklings of both groups; however reliably higher parameters of ventricularbrain ratio under the influence of selenium were observed in the experimental group, there was a clear boundary between them, as well as significantly higher quantity and size parameters of Hassal’s corpuscles were noted. From the age of 90 days signs of age involution in the organ were observed, and in the experimental group these processes were going more physiologically in accordance with the age of the birds. Introduction of the organic and selenium additive DAFS-25k in the diet of ducklings at a dose of 1.3 mg/kg of feed promoted the increase of the functional activity of the thymus that leveled the development of accidental involution and optimization of age involution.

thymus, Pekin duck, DAFS-25k, Hassal’s corpuscles, thymocytes

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