Selenium, thiobarbituric acid reactive substances, and thyroid hormone activation in broilers supplemented with selenium as selenized yeast or sodium selenite.

The objective of this experiment was to compare the efficiencies of sodium selenite (SS) and selenized yeast (SY) supplemented at different doses (0.05 and 0.30 mg Se/kg feed) with respect to plasma glutathione peroxidase (Gpx) activity, extent of oxidative lipid injury, and thyroid hormone activation in broilers during the first four weeks of growth. Results indicate a significant increase in plasma Gpx activity and reduction in thiobarbituric acid reactive substances (TBARS) in all supplemented groups at 4 weeks of age compared to 2-week-old chicks. Plasma thyronine activation was highest in SY supplemented broilers. It can be concluded that in the first 4 weeks of broiler life selenite has a more efficient antioxidative effect which is reflected in lower plasma and liver TBARS values. However, broiler feed supplementation with selenized yeast results in a more proficient conversion of T4 to T3.