EFFECTS OF SELENIUM ENRICHED YEAST ON ANTIOXIDATIVE ACTIVITIES AND IMMUNE FUNCTIONS IN PREGNANT DAIRY COWS

Objective: To investigate the effects of selenium enriched yeast on antioxidative activities and immune functions in pregnant dairy cows. Methods: Twenty-four healthy Holstein-Friesian dairy cows were used for the experiment. All of them were pregnant as comfirmed by rectal palpation and divided into 4 groups, of which 3 were assigned for test groups(TI, T2, T3) and one served as control (C). Three different selenium (Se) sources namely Se-yeast (Sel Plex50, from Alltech ), mixture of Se compounds (70% Sel Plex 50 + 30% Na selenite ) and Na selenite were respectively supplemented to 3 test groups. Whole feeding experiment lasted for 168 days. During the experiment, the blood GSH-Px activity, serum Se concentration, erythrocyte superoxide dismutase(SOD) activity, malonaldehyde(MDA) level in serum, lymphocyte transformation rate and T cell count were determined. Results: Blood GSH-Px ,serum Se concentration and erythrocyte SOD activity,T1, T2 and T3 were higher (P0.0l) than control after 125 days of Se supplementation. MDA concentration in serum was markedly or very markedly lower than control group. At the same time, the lymphocyte transformation rates and T cell counts in T1 and T2 were much higher (P0.0l) and in T3 was higher (P0.05) than control. T1 was higher(P0.05) than T2 and T3 . Conclusion: Organic Se supplementation could significantly enhance animal's immune function , promote lymphocyte proliferation , phagocytosis of neutrophils and antioxidative activities as well.