Our objective has been to determine the effect of supplementing selenized yeast to ewes kept on a poor diet, composed of fodder from periodically flooded meadows, on the reproductive results of ewes and the serum Se concentration in lambs, their body weight and daily weight gain. The study involved 25 ewes and 25 lambs, which were divided into two groups: experimental (12 ewes) and control (13 ewes). Their lambs were also assigned to different groups. Prior to supplementation, all the sheep from the two groups were analysed for selenium concentrations in the serum. The serum selenium concentrations were determined fluorometrically using a DAN and Shimadzu RF-5001 PC spectrofluorometer. The excitation wavelength was 376 nm, while the fluorescence emission wavelength was 518 nm. All sheep in the analysed flock were found to be selenium deficient. The supplementation of selenized yeast to the experimental group caused an almost 2.5-fold increase in the serum selenium concentration in the ewes. Lambs from the experimental group were characterized by a significantly higher concentration of selenium at 7 and 14 days of age (P≤0.05) compared to control lambs. Very high (P

22.4.2016