Effects of Time and Dietary Selenium Concentration as Sodium Selenite on Tissue Selenium Uptake by Sheep

Abstract

Thirty crossbred wethers (60 kg avg initial wt) were used to study the time-dose response to dietary Se as sodium selenite (Na2SeO3). Sheep were fed a basal diet (.20 mg/kg Se, M basis) for 10 d; three wethers were killed and tissues were collected for controls. The remaining 27 sheep were assigned randomly to diets supplemented with either 3, 6 or 9 mg/kg Se (as-fed basis) from reagent grade Na2SeO3 and fed for 10, 20 or 30 d. Feed offered was restricted to 1,200 g daily and tap water was available ad libitum. Sheep were stunned and killed by exsanguination and liver, kidney, muscle, heart and spleen were removed and frozen for Se analysis. No toxic effects were noted as expressed by feed intake or hemoglobin concentration. Added dietary Se increased Se linearly (P less than .01) in liver, kidney, and serum. Selenium in liver, kidney and serum also increased (P less than .01) as time advanced. Serum, liver and kidney were more sensitive to dietary Se than were muscle, heart and spleen. Ten days appeared to be an adequate length of time for further Se bioassay studies of this nature. Reagent grade Na2SeO3 was nontoxic when fed to sheep for 30 d at levels up to 90 times the Se requirement.

Effects of Dietary Selenium, Sulphur and Copper Levels on Selenium Concentration in the Serum and Liver of Lamb

“…This value is higher than the one obtained by Echevarria et al (1988), 4.5 mg/kg, using the same selenium values, although lower copper levels. By giving 5 mg/kg of selenium to lamb for 90 days, Brisola (2000), attained a selenium concentration of 40 mg/kg in the liver, higher to the 32 mg/kg obtained in this experiment.…”

“…Echevarria et al (1988) verified a lamb’s serum selenium concentration of 0.09 mg/L in the control group, using crossbred wethers with an average weight of 50 kg and diet contained 0.18 mg Se/kg (DM basis). In the group supplemented with 9 mg Se/kg DM, a concentration of 0.25 mg/L was obtained only 30 days after beginning with supplementation.…”

Subacute toxicity of nano‐selenium compared to other selenium species in mice

“…Selenium is a controversial nutrient for animals and people alike, and as a Janus-faced element exerts both beneficial and toxic biological effects. Selenium is present in all tissues, with the highest accumulation found in the liver, spleen, and pancreas [10][11][12][13][14][15]. Selenocysteine (SeCys) is present in the active site of approximately 25 selenoproteins including multiple families of antioxidant enzymes that help to prevent cellular damage from free radicals.…”

“…Seleniumcontaining enzymes are involved in thyroid hormone (T 3 , T 4 ) function, are efficient antioxidant peroxidases, and when in combination with antioxidant vitamins (C, E) help in the production of antibodies, aid in pancreatic function, and provide defense against oxidation [9]. Selenium is present in all tissues, with the highest accumulation found in the liver, spleen, and pancreas [10][11][12][13][14][15]. Excretion of Se takes place primarily through the kidneys (up to 15 mg/L); only a small amount has been traced in feces, sweat, and expired air [16].…”

Selenium

“…Selenium is generally utilized for syn thesis of selenoproteins, incorporated into tissue proteins or eliminated. Highest total selenium content is typically found in the kidney and liver, with lesser amounts in all other tissues (Muth et al, 1967;Levander, 1987;Echevarria et al, 1988;Davidson and Kennedy, 1993). The nonspecific incorporation of selenomethio nine effectively serves as a pool of selenium reserve with a long biological halflife (Schroeder and Mitchener, 1972a).…”