Comparative study of DL-selenomethionine vs sodium selenite and seleno-yeast on antioxidant activity and selenium status in laying hens

Selenium functions within mammalian systems primarily in the form of selenoproteins. Selenoproteins contain selenium as selenocysteine and perform a variety of physiological roles. Eleven selenoproteins have been identified: cellular or classical glutathione peroxidase; plasma (or extracellular) glutathione peroxidase; phospholipid hydroperoxide glutathione peroxidase; gastrointestinal glutathione peroxidase; selenoprotein P; types 1, 2, and 3 iodothyronine deiodinase; selenoprotein W; thioredoxin reductase; and selenophosphate synthetase. Of these, cellular and plasma glutathione peroxidase are the functional parameters used for the assessment of selenium status. Glutathione peroxidases catalyze the reduction of peroxides that can cause cellular damage. Thioredoxin reductase provides reducing power for several biochemical processes and defends against oxidative stress. Selenoprotein P appears to play a role in oxidant defense. Selenoprotein W may play a role in oxidant defense and be involved with muscle metabolism. Thyroid deiodinases function in the formation and regulation of active thyroid hormone. Selenophosphate synthetase is an enzyme required for the incorporation of selenocysteine into selenoproteins. In addition, a protein in the sperm mitochondrial capsule, which is vital to the integrity of sperm flagella, may be a unique selenoprotein. Recommended intakes, food sources, and status assessment of selenium, as well as selenium's role in health and disease processes, are reviewed.

An experiment was conducted to compare the effects of organic and inorganic sources of Se on growth performance, carcass traits, breast and plasma Se concentrations, and plasma glutathione peroxidase (pGPX3) activity in broilers. Broiler chicks were sexed on d 0 and within sex, randomly allotted to dietary treatment. Average initial and final BW of the broilers were 47 and 2,684 g, and the experiment lasted 49 d. A 3-phase feeding program similar to industry recommendations was used, and the basal diets for each phase were corn-soybean meal based. For each growth phase, the basal diet was supplemented with 0 (control) or 0.30 ppm Se from sodium selenite (SS) or Se-enriched yeast (SY). Each treatment was replicated 7 times (4 pens of males and 3 pens of females) with 50 male or 55 female broilers per replicate. Daily gain, feed intake, gain:feed, eviscerated and chill weights, carcass yield, breast weight, and moisture loss from the breast were not affected (P > 0.05) by Se supplementation. Dietary supplementation with SY increased (P 0.05) by Se source or concentration. The results from this experiment indicate that organic Se increases tissue Se concentration, but it does not affect growth performance, carcass traits, or pGPX3 activity compared with inorganic Se.