Effect of Selenium Supplementation on Thyroid Hormone Levels and Selenoenzyme Activities in Growing Lambs

Abstract

The aim of the present study was to evaluate the effects of selenium supplementation on thyroid hormone metabolism and selenoenzyme activities in lambs. Twelve 20-d-old male lambs were assigned to one of two diets: A (0.11 ppm Se) and B (supplemented with 0.2 ppm selenium as sodium selenite). Blood samples were collected weekly for the determination of T3, T4, and selenium levels. The response to thyrotropin-releasing hormone (TRH) challenge was estimated at the 11th and 20th wk. Animals were slaughtered at wk 20 and tissues were collected for enzyme determination. Plasma selenium concentration was significantly higher in supplemented lambs (p<0.001). Plasma T3 and T4 levels remained similar in both groups. Type I deiodinase activity (ID-I) was decreased in the liver (p<0.05) and increased in the pituitary (p<0.01) of supplemented animals. No ID-I activity was detected in the thyroid. Pituitary type II deiodinase activity (ID-II) remained unchanged. The response to TRH challenge did not differ between the two groups for both challenges, but in group B, the second TRH challenge (20th wk) resulted in a significantly higher T3 response compared to the first one (11th wk) (p<0.05). In conclusion, the lack of effects of Se supplementation on thyroid hormone metabolism demonstrates that enzyme activity is homeostatically controlled and selenium is incorporated in that order to ensure the maintenance of thyroid hormone homeostasis.

Effect of Selenium and Copper Supplementation on Blood Metabolic Profile in Male Buffalo (Bubalus bubalis) Calves

“…On the contrary, basal diet in our experiment had much higher levels of Se (0.23 ppm), and probably for that reason, we did not observe any significant effect of Se supplementation on thyroid hormones in the buffalo calves. Similar to our observations, sheep (0.11 ppm Se in the basal diet) supplemented with 0.20 ppm of Se did not show any effect on thyroid (plasma T 3 and T 4 levels) metabolism [29].…”

“…However, there was an overall increasing tendency in the testosterone levels with increasing post-feeding period in all the groups, which may be associated with physiological changes that accompany male sexual maturation [30]. Similar to the present findings, Angus steers supplemented with 10 and 20 ppm Cu also did not show any effect on serum insulin values [29]. Se supplementation has been reported to increase T 3 and decrease T 4 concentrations [21,28]; but it was probably due to very low levels of Se being 0.015 [21] and 0.02-0.03 ppm [28] in the basal diets in these experiments.…”

Effect of different selenium sources (Selenium yeast and Sodium selenite) on haematology, blood chemistry and thyroid hormones in male goats (Capra hircus)

“…Similarly, Shinde et al (2009) Kumar et al (2009) observed that supplementation of 0.15 ppm Se both as organic and inorganic form to lambs for 90 days had no effect on serum concentration of T 3 , T 4 and T 4 : T 3 ratio. Increased T 3 in the blood due to nutritional factor is indicative of the better metabolic balance (Blum et al, 1980) and better enzyme activity thus to regulate the thyroid hormone homeostasis efficiently (Chadio et al, 2006).…”

Selenomethionine: an Effective Selenium Source for Sow to Improve Se Distribution, Antioxidant Status, and Growth Performance of Pig Offspring

“…Se requiring enzyme type І deiodinase was needed when T 4 was deiodinated to the active T 3 [36]. Se deficiency would cause an increased T 4 and decreased T 3 in animals [37].…”