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Review Article
Inorganic Versus Organic Selenium Supplementation: A Review

Mahima , Amit Kumar Verma, Amit Kumar, Anu Rahal, Vinod Kumar and Debashis Roy

Selenium is an essential trace element in the diets which is required for maintenance of health, growth and biochemical-physiological functions. The area covered in this review has been rapidly unfolding in recent years and has already acquired a vast spread. This study presents a concise introductory overview of the effect of organic and inorganic selenium on growth performance, carcass traits, daily egg production, egg quality, Se uptake in various tissues and plasma and plasma glutathione peroxidase activity in animals.

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Mahima , Amit Kumar Verma, Amit Kumar, Anu Rahal, Vinod Kumar and Debashis Roy, 2012. Inorganic Versus Organic Selenium Supplementation: A Review. Pakistan Journal of Biological Sciences, 15: 418-425.

DOI: 10.3923/pjbs.2012.418.425

Received: May 09, 2012; Accepted: August 18, 2012; Published: September 07, 2012


For health, growth and biochemical and physiological functions, essential trace elements are necessary in diets of the animals (Scott et al., 1982). Among those essential trace elements is Selenium (Se), known to have important roles in a number of biochemical functions in human and animals, such as biological antioxidant, immune function, reproduction and thyroid hormone metabolism (Surai, 2006). Selenium (Se) is a one of the essential trace mineral (NRC, 1994). After its discovery in 1817 by the Swedish chemist, Jons Jakob Berzelius in the flue dust of iron pyrite burners, in Stockholm, Sweden (Levander, 1986; Sunde, 1997), it was thought to be toxic; direct cause of alkali disease and blind staggers (Franke, 1934a, b; Franke and Potter, 1935; Moxon, 1937) and as a carcinogen (Nelson et al., 1943) for many years. Since, selenium was identified in association with tellurium which was named after the Latin term, tellus, for earth; so Se was named Se after the Greek term, selene, for moon. However, Schwarz and Foltz (1957) first time reported that Se prevent liver necrosis (along with vitamin E and cystine) in rats, since then nutritionists around the world started studies to discover the metabolic function of this element and document the effects of its deficiency in the food of human and animals. In both the human and animals, its deficiency causes various diseases like necrosis of liver, exudative diathesis, nutritional muscular dystrophy, poor feathering, retention of placenta, mastitis, cystic ovaries, cancer, cardiovascular diseases, immunodeficiencies, poor fertility etc. (Shamberger, 1983).

It has been identified to be an integral part of more than 30 distinct selenoproteins, including the enzyme particularly glutathione peroxidases (Rotruck et al., 1973), a group of antioxidant enzymes that help in the protection of the body cells from the damage caused by free-radicals (Sunde, 1997; Arthur, 2000). Free radicals, being highly reactive, induce a series of events leading to pathogenesis of various diseases affecting cardiovascular system and aging process etc. (Puri, 2002). Although the dietary need for Se has been established but still it is considered to be the most toxic dietary essential trace mineral. Therefore, the FDA regulates supplementation of Se into diets (FDA, 2000). Therefore, it is very common practice to supplement diets with Se. Selenium occurs in both inorganic and organic form (Daniels, 1996). Among the inorganic forms (i.e., selenates, selenides and selenite), the selenide form is more frequently found in the food supply. The organic form includes selenomethionine and selenocysteine and is found in plants (Schrauzer, 2000) and animals respectively (Kincaid et al., 1999; Boldizarova et al., 2004). Free mineral ions released during the process of digestion may form complexes with other dietary substances and become difficult to absorb or, totally unabsorbable. Thus, the availability of the element may vary significantly. Because of these uncertainties, the levels provided in the diet are often kept on higher side than the required amount for optimum performance. This may sometimes result in excess of supply and wastage. Therefore, after the approval by FDA (2000), researchers are interested in the studies using organic forms, such as Selenomethionine (SeM) or Se-enriched Yeast (SeY), as supplemental sources of Se (Rayman, 2004).

Although, previous studies have reported about the use and benefits associated with inorganic and organic Se supplementation. The area covered in this review has been rapidly unfolding in recent years and has already acquired a vast spread. This study presented a concise introductory overview of the effect of organic and inorganic selenium on growth performance, carcass traits, daily egg production, egg quality, Se uptake in various tissues and plasma and plasma glutathione peroxidase activity in animals.


With the atomic number 34 and atomic weight 78.96, Se is a member of Group VIA along with oxygen, sulphur, tellurium and polonium (Sunde, 1997) in the periodic table of elements and classified as a metalloid element i.e., having the properties of both metal and non-metal. It has four common oxidative states: selenide (-2), Se (0), selenite or selenious acid (+4) and selenate or selenic acid (+6). These different states play significant role in the biochemistry of Se.


The plant based (Burk, 1976) and meat based (Levander, 1986; Cai et al., 1995) primary and natural sources of selenium are selenoamino acids such as selenomethionine, selenocysteine and selenocystine. The selenoamino acids are bound in protein, mainly as selenomethionine and selenocysteine and constitute 50-80% of the total selenium present in plants and grains (Butler and Peterson, 1967). These foods differ tremendously in concentration of Se depending upon the concentration of selenium in the soil of that region in which they are found. Longnecker et al. (1991) reported the low amount of selenium and dietary selenium deficiency has been reported in selenium deficient regions of China and Russia. Similarly, animals that take fodder that were grown in selenium rich soil have higher levels of selenium.


Selenium can be found in all the cells and tissues of the body but its level in blood and tissues are very much influenced by dietary selenium form and intake. Behne and Wolters (1983) and Behne and Hofer-Bosse (1984) conducted a study on rats with the diets supplemented with 0.3 ppm of Se and found its highest concentration in the kidneys, followed by testes, liver, adrenals, erythrocytes, plasma, spleen, pancreas, lungs, heart, thymus, gastrointestinal tract, skeleton, brain and muscles. Based on the data provided by Behne and Wolters (1983) and Behne and Hofer-Bosse (1984) in 1997, Sunde (1997) calculated total amounts of Se and reported that the largest total amount of Se was in muscle followed by the liver, plasma, erythrocytes and kidneys. Similar distribution of Se was reported by Schroeder et al. (1970) from the samples taken from autopsies of North Americans.


Selenium plays a vital role in a most of the physiological processes in the body. The metabolism of Se depends on its chemical state and on the amount supplemented in diet. Selenium is assimilated more effectively from plant food than animal products but some dietary contents viz., vitamin C and vitamin E affect its absorption. The majority of Se is absorbed in the duodenum (Wright and Bell, 1966; Whanger et al., 1976) followed by jejunum and ileum but practically none from the stomach (Whanger et al., 1976) and is transported across the intestinal brush border actively or passively. The type of absorption depends on the source of selenium in diet. It was found that inorganic sources such as such as SS or selenates are absorbed by simple diffusion process, while organic sources like as SY or Selenomethionine (SeM) are actively absorbed via amino acid transport mechanisms (Combs Jr. and Combs, 1986).

Due to reducing nature of rumen, absorbing ability for inorganic Se is poor in ruminants. Wright and Bell (1966) reported that rumen microbes reduce most of dietary inorganic selenium to unabsorbable inorganic selenide forms. So the selenite selenium availability to ruminants is 25-30%.

First of all selenate is converted to selenite (Axley and Stadtman, 1989). Then, selenite is non-enzymically reduced via., formation of selenodiglutathione (GS-Se-SG) to selenide (Ganther, 1966; Hsieh and Ganther, 1977; Foster and Sumar, 1997). Now, selenide may have several different options. Selenides plays an important role in the mixed function oxidase system of microsomal and other cellular membranes (Chatterjea and Shinde, 2002). Methylation of Selenide form methylselenol (CH3SeH) which then form dimethylselenide or trimethylselenonium ion ((CH3)xSeH) (Hsieh and Ganther, 1977). Selenide can also bind to the Se-binding proteins or it can be a substrate for selenophosphate synthetase for the tRNA-mediated synthesis of selenoproteins (Sunde, 1997). This last step converts inorganic Se into the organic forms of Se that are found in tissues of mammals.

Sunde (1997) found that the metabolism of organic Se is different than inorganic Se. Initially, all the dietary selenomethionine is incorporated into protein. Hoffman et al. (1970) and McConnell and Hoffman (1972). Selenomethionine can be metabolized to Se-adenosyl methionine (SeAM) and further to Se-adenosyl homocysteine (SeAH) (Markham et al., 1980). Then the SeAH is converted to selenocysteine by the enzymatic activity of cystathionine β-synthase and cystathionine γ-lyase. Subsequently, selenocysteine can be incorporated into proteins or degraded, releasing the selenite or it can be degraded by selenocysteine lyase enzyme, releasing elemental Se which can be reduced to selenide (Esaki et al., 1982). Another fate for selenomethionine is to be transaminated to methylselenol (Steele and Benevenga, 1979) and then methylselenol can be transformed to selenide via Smethyltransferase (Sunde, 1997). At this point, selenide would be metabolized as discussed above.


Absorption and bioavailability of trace minerals including Se is generally one of the most important issue in their utilization. Most of the times, term absorption is coined with availability because selenium must be absorbed before its utilization. During the process of digestion in the gastrointestinal tract the Se from inorganic sources are released and may re-combine with other components of feed and fodder or we can say digesta in the intestine making insoluble complexes and excreted, thus reducing its absorption across the small intestine whereas, the organic minerals absorbs actively utilizing peptide and/or amino acid uptake mechanisms in the intestine (Ashmead, 1993; Power and Horgan, 2000; Schweizer et al., 2004). Within the complex, selenium is chemically inert due to the coordinate covalent and ionic bonding by the amino ligands thus, more stable and less prone to interactions. The mineral is also protected from physicochemical factors with dietary components such as phytate (Fairweather-Tait, 1996), remained electrically neutral. Bioavailability could be affected by any of the factor such as species, sex, age, physiological stage of the animals like growth, pregnancy, lactation, nutritional status, health, gastrointestinal secretions and microflora (Johnson, 1989; Fairweather-Tait, 1996).

In terms of bioavailability of dietary inorganic versus organic Se supplementation, many comparisons have been made in the last two decades using a variety of domestic animal species chicken (Collins et al., 1993), cattle (Ortman and Pehrson, 1999; Surai, 2006; Peters and Mahan, 2008), goat (Pavlata et al., 2011). Researchers have proved that organic Se is having 120-200% more bioavailability in comparison to sodium selenite (Pagan et al., 1999; Hall et al., 2011; Mansoub, 2011) in cattle (Pehrson et al., 1989; Nicholson et al., 1991; Gunter et al., 2003; Juniper et al., 2008; Liao et al., 2011), pig (Mahan and Kim, 1996) and guinea pig (Mahima, 2006; Chaudhary et al., 2010; Mahima et al., 2011). However, in contrast there were no significant differences in absorption and subsequent metabolism following supplementation with the two different forms of selenium i.e., inorganic and organic (Parsons et al., 1985; Pavlata et al., 2011) even higher in sheep fed inorganic selenium (Koenig et al., 1997).


Selenium is very important for the proper development of the newly born animal and its deficiency adversely affect the growth, health and fertility (Schwarz and Foltz, 1957). During pregnancy, Se passes through the placental barrier and the newborn receives a sufficient Se supply even if the animal is moderately Se deficient (Gunter et al., 2003). In the first weeks of life, milk is the only dietary source of selenium for newborn animals (Ortman and Pehrson, 1997, 1999). Selenium status of animals at birth and weaning can be affected by the dam’s body Se reserves, dietary Se concentration and source of Se (Mahan, 2000; Mahan and Peters, 2004). There are studies in pigs (Acda and Chae, 2002; Mahan and Peters, 2004; Yoon and McMillan, 2006; Svoboda et al., 2008), cattle (Knowles et al., 1999; Givens et al., 2004; Slavik et al., 2008; Ceballos et al., 2009) that clear that concentration of selenium in milk or colostrum increases in both the inorganic and organic supplementation but were significantly greater when dams were fed organic Se (Mahan, 1994; Mahan and Kim, 1996; Mateo et al., 2007). The increase has ranged from 34% (Juniper et al., 2006) to 90% (Ortman and Pehrson, 1997).


As far as the growth and production performance in terms of average daily gain, average daily feed intake or gain: feed ratio is concerned, the majority of studies in cattle (Nicholson et al., 1991; Gunter et al., 2003; Richards and Loveday, 2004; Davis et al., 2008), chicken (Spears et al., 2003; Payne and Southern, 2005; Ryu et al., 2005) did not detect any difference between inorganic and organic selenium supplementation. However, a significant improvement in feed intake (Cantor et al., 1982) and FCR (Naylor et al., 2000; Sevcikova et al., 2006; Wang and Xu, 2008) in chicken, Guinea pig (Mahima, 2006; Chaudhary et al., 2010), average daily gain in cattle (Clyburn et al., 2001) fed with organic Se were observed.

Studies on chicken (Payne and Southern, 2005), turkey (Niedzwiedzka et al., 2008), pigs (Mahan, 1996; Mahan and Parret, 1996) have shown that organic selenium is deposited more effectively in muscles than inorganic selenium. This increased tissue concentrations of selenium not only decrease oxidative stress, including protection of unsaturated fatty acids from peroxidation damage (Tapiero et al., 2003; Korniluk et al., 2007) but can also reduce drip loss from meat and the incidence of pale soft, exudative meat (Downs et al., 2000; Naylor et al., 2000) and improves the shelf life during refrigeration (Yoon et al., 2007; Smet et al., 2008; Skrivan et al., 2008). This indicates that supplementation of selenium, particularly organic selenium, improves meat quality and shelf life of poultry meat (Sevcikova et al., 2006).


For our body, the oxidation and reduction processes are very necessary and this gaining and loosing of an electron keeps our body processes in proper function. During the respiration, various peroxides, including hydrogen peroxide are produced in the body which can be harmful to the body as they can lead to generation of free radicals which can damage or destroy cells (Arthur, 2000). A group of enzymes, the glutathione peroxidases (GSH-Px), help to protect the body from these harmful peroxides (Arthur, 2000). Till now, four structurally and genetically different forms of selenium-containing GSH-Px have been functionally described (Ursini et al., 1999) and exist in different tissues or parts of the cell. These enzymes catalyze a reaction that removes hydrogen peroxide from erythrocytes via reduced glutathione. The reduced glutathione is made via the enzyme, glutathione reductase, from oxidized glutathione. Se is the integral part of glutathione peroxidases (Rotruck et al., 1973; Tapiero et al., 2003). Glutathione and glutathione peroxidase protect the unsaturated bonds of membrane phospholipids from the attack of free radicals(Korniluk et al., 2007; Rayman, 2004). Besides the glutathione peroxidase family of enzymes, there are 20 different selenoproteins (Table 1) have been identified, though estimates of the existence of 30-50 such selenoproteins have been made based on electrophoretic separation (Kohrle et al., 2000).

Table 1: Selenium containing proteins and their role

Being a component of GSH-Px, Selenium also acts as a second line of defence against cellular peroxide damage due to the inability of vitamin E to destroy all metabolic peroxides. Most of the times, selenium and vitamin E are mutually replaceable and each acts as a sparing mechanism for the other (Combs Jr., 1981). Wang and Xu (2008) reported that Se supplementation increased plasma GPx activity and further told that this increase is less pronounced with the supplementation of inorganic selenium in comparison to organic selenium. However, in contrast, several studies. (Acda and Chae, 2002; Mahan and Peters, 2004; Payne and Southern, 2005; Yoon and McMillan, 2006; Svoboda et al., 2008) reported that GPx activity was not affected by Se source or concentration or GSH-Px activity increase much faster with selenite in comparison to organic selenium (Pavlata et al., 2011).


The practical use of organic selenium will depend on the performance response, health status of animals and environmental impact. These responses will determine the cost effectiveness of organic selenium. Positive responses to organic Se have been reported in relation to bioavailability, secretion in colostrums and milk thus improving neonatal health, improved carcass quality, shelf life and can also prevent drain losses. However, reviews presented revealed no consistent effect of organic sources for Se on growth, performance variables and glutathione peroxidase activity.

Acda, S.P. and B.J. Chae, 2002. A review on the applications of organic trace minerals in pig nutrition. Pak. J. Nutr., 1: 25-30.
CrossRef  |  Direct Link  |  

Arthur, J.R., 2000. The glutathione peroxidases. Cell. Mol. Life Sci., 57: 1825-1835.
CrossRef  |  Direct Link  |  

Ashmead, H.D., 1993. Comparative Intestinal Absorption and Subsequent Metabolism of Metal Amino Acid Chelates and Inorganic Metal Salts. In: The Roles of Amino Acid Chelates in Animal Nutrition, Ashmead, H.D. (Ed.). Noyes Publishers, New Jersey, pp: 306-319.

Axley, M.J. and T.C. Stadtman, 1989. Selenium metabolism and selenium dependent enzymes in microorganisms. Annu. Rev. Nutr., 9: 127-137.
CrossRef  |  

Behne, D. and T. Hofer-Bosse, 1984. Effects of a low selenium status on the distribution and retention of selenium in the rat. J. Nutr., 114: 1289-1296.
PubMed  |  

Behne, D. and W. Wolters, 1983. Distribution of selenium and glutathione peroxidase in the rat. J. Nutr., 113: 456-461.
PubMed  |  

Boldizarova, K., L. Gresakova, S. Faix and L. Leng, 2004. Antioxidant status of lambs fed on diets supplemented with selenite or se-yeast. J. Anim.Feed Sci., 14: 245-253.
Direct Link  |  

Burk, R.F. and K.E. Hill, 1993. Regulation of selenoproteins. Ann. Rev. Nutr., 13: 65-81.
CrossRef  |  PubMed  |  Direct Link  |  

Burk, R.F., 1976. Selenium in Man. In: Trace Elements in Human Health and Disease, Prasad, A.S. and D. Oberleas (Eds.). Academic Press, New York, pp: 105-133.

Butler, G.W. and P.J. Peterson, 1967. Uptake and metabolism of inorganic forms of selenium-75 by spiroldela oligorrhiza. Aust. J. Biol. Sci., 20: 77-86.
Direct Link  |  

Cai, X.J., E. Block, P.C. Uden, X. Zhang, B.D. Quimby and J.J. Sullivan, 1995. Allium Chemistry: Identification of selenoamino acids in ordinary and selenium-enriched garlic, onion and broccoli using gas chromatography with atomic emission detection. J. Agric. Food Chem., 43: 1754-1757.
CrossRef  |  

Cantor, A.H., P.D. Moorhead and M.A. Musser, 1982. Comparative effects of sodium selenite and selenomethionine upon nutritional muscular dystrophy, selenium-dependent glutathione peroxidase and tissue selenium concentrations of turkey poults. Poult. Sci., 61: 478-484.
PubMed  |  Direct Link  |  

Ceballos, A., J. Sanchez, H. Stryhn, J.B. Montgomery, H.W. Barkema and J.J. Wichtel, 2009. Meta-analysis of the effect of oral selenium supplementation on milk selenium concentration in cattle. J. Dairy Sci., 92: 324-342.
CrossRef  |  

Chatterjea, M.N. and R. Shinde, 2002. Metabolism of Minerals and Trace Elements: Text Book of Medical Biochemistry. 5th Edn., Jaypee Brothers Med Pub Ltd., New Delhi, India, pp: 526-531.

Chaudhary, M., A.K. Garg, G.K. Mittal and V. Mudgal, 2010. Effect of organic selenium supplementation on growth, se uptake and nutrient utilization in guinea pigs. Biol. Trace Elem. Res., 133: 217-226.
CrossRef  |  Direct Link  |  

Clyburn, B.S., C.R. Richardson and J.L. Montgomery, 2001. Effect of Selenium Source and Vitamin E Level on Performance and Meat Quality of Feedlot Steers. In: Science and Technology in the Feed Industry, Lyons, T.P. and K.A. Jacques (Eds.). Nottingham University Press, Nottingham, pp: 377-392.

Collins, V.C., A.H. Cantor, M.J. Ford and M.L. Straw, 1993. Bioavailability of selenium in selenized yeast for broiler chickens. Poult. Sci., 72: 85-86.

Combs, Jr. G.F. and S.B. Combs, 1986. The Role of Selenium in Nutrition. Academic Press, Boca Raton, Florida..

Combs, Jr. G.F., 1981. Influences of dietary vitamin E and selenium on the oxidant defense system of the chick. Poult. Sci., 60: 2098-2105.
PubMed  |  

Daniels, L.A., 1996. Selenium metabolism and bioavailability. Biol. Trace Elem. Res., 54: 185-199.
CrossRef  |  

Davis, P.A., L.R. McDowell, R. van Alstyne, T.T. Marshall, C.D. Buergelt, R.N. Weldon and N.S. Wilkinson, 2008. Effects of form of parenteral or dietary selenium supplementation on body weight and blood, liver and milk concentrations in beef cows. Professional Anim. Scientist, 24: 52-59.
Direct Link  |  

Downs, K.M., J.B. Hess and S.F. Bilgili, 2000. Fractionation and source effect on broiler carcass characteristics, meat quality and drip loss. J. Appl. Anim. Res., 18: 61-72.

Esaki, N., H. Tanaka, S. Uemura, T. Suzuki and K. Soda, 1982. Selenocysteine lyase, a novel enzyme that specifically acts on selenocysteine: Mammalian distribution and purification and properties of pig liver enzyme. J. Biol. Chem., 257: 4386-4391.
PubMed  |  

FDA, 2000. FDA approves food additive petition for selenium yeast. FDA Veterinarian Newsletter July/August 2000 Volume 15, No. 4, U.S. Food and Drug Administration, Washington, DC., USA.

Fairweather-Tait, S.J., 1996. Bioavailability of dietary minerals. Biochem. Soc. Trans., 24: 775-780.

Foster, L.H. and S. Sumar, 1997. Selenium in health and disease. A review. Crit. Rev. Food Sci. Nut., 37: 211-228.
PubMed  |  

Franke, K.W. and V.R. Potter, 1935. A new toxicant occurring naturally in certain samples of plant foodstuffs. IX. The toxic effects of orally ingested selenium. J. Nutr., 10: 213-218.
Direct Link  |  

Franke, K.W., 1934. A new toxicant occurring naturally in certain samples of plant foodstuffs. I. Results obtained in preliminary feeding trials. J. Nutr., 8: 597-608.

Franke, K.W., 1934. A new toxicant occurring naturally in certain samples of plant foodstuffs. II. The occurrence of the toxicant in the protein fraction. J. Nutr., 8: 609-613.
Direct Link  |  

Ganther, H.E., 1966. Enzymic synthesis of dimethyl selenide from sodium selenite in mouse liver extracts. Biochemistry, 5: 1089-1098.
PubMed  |  

Givens, D.I., R. Allison, B. Cottrill and J.S. Blake, 2004. Enhancing the selenium content of bovine milk through alteration of the form and concentration of selenium in the diet of the dairy cow. J. Sci. Food Agric., 84: 811-817.
CrossRef  |  Direct Link  |  

Gunter, S.A., P.A. Beck and J.K. Phillips, 2003. Effects of supplementary selenium source on the performance and blood measurements in beef cows and their calves. J. Anim. Sci., 81: 856-864.
PubMed  |  

Hall, J.A., R.J. van Saun, G. Bobe, W.C. Stewart and W.R. Vorachek et al., 2011. Organic and inorganic selenium: I. Oral bioavailability in ewes. J. Anim. Sci., 90: 568-576.
CrossRef  |  

Hoffman, J.L., K.P. McConnell, and D.R. Carpenter, 1970. Aminoacylation of Escherichia coli. Biochem. Biophys. Acta., 199: 531-534.

Hsieh, H.S. and H.E. Ganther, 1977. Biosynthesis of dimethyl selenide from sodium selenite in rat liver and kidney cell-free systems. Biochem. Biophys. Acta., 497: 205-217.
CrossRef  |  

Johnson, P.E., 1989. What can in vitro methods tell us about mineral availability? Biol. Trace Elem Res., 19: 3-10.
PubMed  |  

Juniper, D.T., R.H. Phipps, A.K. Jones and G. Bertin, 2006. Selenium supplementation of lactating dairy cows: Effect on selenium concentration in blood, milk, urine and feces. J. Dairy Sci., 89: 3544-3551.
Direct Link  |  

Juniper, D.T., R.H. Phipps, D.I. Givens, A.K. Jones, C. Green and G. Bertin, 2008. Tolerance of ruminant animals to high dose in-feed administration of a selenium-enriched yeast. J. Anim. Sci., 86: 197-204.
PubMed  |  

Kincaid, R.L., M. Rock and F. Awadeh, 1999. Selenium for Ruminants: Comparing Organic and Inorganic Selenium for Cattle and Sheep. In: Biotechnology in the Feed Industry, Lyons, T.P. and K.A. Jacques (Eds.). Nottingham University Press, Nottingham, UK, pp: 537-545.

Knowles, S.O., N.D. Grace, K. Wurms and J. Lee, 1999. Significance of amount and form of dietary selenium on blood, milk and casein selenium concentrations in grazing cows. J. Dairy Sci., 82: 429-437.
CrossRef  |  Direct Link  |  

Koenig, K.M., L.M. Rode, R.D. Cohen and W.T. Buckley, 1997. Effects of diet and chemical forms of selenium on selenium metabolism in sheep. J. Anim. Sci., 75: 817-827.
Direct Link  |  

Kohrle, J., R. Brigelius-Flohe, A. Bock, R. Gartner, O. Meyer and L. Flohe, 2000. Selenium in biology: Facts and medical perspectives. Biol. Chem., 381: 849-864.
CrossRef  |  Direct Link  |  

Korniluk, K., M. Czauderna and J. Kowalczyk, 2007. The influence of dietary conjugated linoleic acid isomers and selenized yeast on the fatty acid profile of the spleen, pancreas and kidneys of rats. J. Anim. Feed Sci., 16: 121-139.

Levander, O., 1986. Selenium. In: Trace Elements in Human and Animal Nutrition, Mertz, W. (Ed.). Academic Press, Orlando, FL, pp: 209-280.

Liao, S.F., K.R. Brown, A.J. Stromberg, W.R. Burris, J.A. Boling and J.C. Matthews, 2011. Dietary supplementation of selenium in inorganic and organic forms differentially and commonly alters blood and liver selenium concentrations and liver gene expression profiles of growing beef heifers. Biol. Trace Elem. Res., 140: 151-169.
CrossRef  |  

Longnecker, M.P., P.R. Taylor, O.A. Levander, M. Howe and C. Veillon et al., 1991. Selenium in diet, blood and toenails in relation to human health in a seleniferous area. Am. J. Clin. Nutr., 53: 1288-1294.
PubMed  |  

Mahan, D.C. and J.C. Peters, 2004. Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny. J. Anim. Sci., 82: 1343-1358.
Direct Link  |  

Mahan, D.C. and N.A. Parrett, 1996. Evaluating the efficacy of selenium-enriched yeast and sodium selenite on tissue selenium retention and serum glutathione peroxidase activity in grower and finisher swine. J. Anim. Sci., 74: 2967-2974.
PubMed  |  

Mahan, D.C. and Y.Y. Kim, 1996. Effect of inorganic or organic selenium at two dietary levels on reproductive performance and tissue selenium concentrations in first-parity gilts and their progeny. J. Anim. Sci., 74: 2711-2718.
PubMed  |  

Mahan, D.C., 1994. Effects of dietary vitamin E on sow reproductive performance over a five-parity period. J. Anim. Sci., 72: 2870-2879.

Mahan, D.C., 1996. How organic selenium may help reduce drip loss. Misset World Poult., 12: 19-21.

Mahan, D.C., 2000. Effect of organic and inorganic selenium sources and levels on sow colostrum and milk selenium content. J. Anim. Sci., 78: 100-105.
PubMed  |  

Mahima, 2006. Effect of supplementation of different levels and sources of Selenium on the performance of guinea pigs. M.V.Sc. Thesis, UPPDDU Veterinary University, Mathura, Uttar Pradesh, India.

Mahima, A.K. Garg, V. Mudgal, G.K. Mittal and A.K. Verma, 2011. Effect of selenium supplementation on growth, absorption and nutrient utilization in guinea pigs. Proceedings of the 11th Indian Veterinary Congress and 18th Annual Conference of IAAVR and National Symposium on Veterinary Science and Education On Move: Critical Gaps and Needs, February 11-12, 2011, Apollo College of Veterinary Medicine Jaipur -.

Mansoub, N.H., 2011. Influence of organic selenium source on carcass characteristics and oxidative stability of meat of male broilers. Adv. Environ. Biol., 5: 1832-1835.

Markham, G.D., E.W. Hafner, C.W. Tabor and H. Tabor, 1980. S-Adenosylmethionine synthetase from Escherichia coli. J. Biol. Chem., 255: 9082-9092.
PubMed  |  

Mateo, R.D., J.E. Spallholz, R. Elder, I. Yoon and S.W. Kim, 2007. Efficacy of dietary selenium sources on growth and carcass characteristics of growing-finishing pigs fed diets containing high endogenous selenium. J. Anim. Sci., 85: 1177-1183.
CrossRef  |  PubMed  |  

McConnell, K.P. and J.L. Hoffman, 1972. Methionine-selenomethionine parallels in rat liver polypeptide chain synthesis. FEBS Lett., 24: 60-62.
CrossRef  |  

Moxon, A.L., 1937. Alkali Disease or Selenium Poisoning. Agricultural Experiment Station, South Dakota State College of Agriculture and Mechanic Arts, USA., pp: 1-84.

Mustacich, D. and G. Powis, 2000. Thioredoxin reductase. Biochem. J., 346: 1-8.
Direct Link  |  

NRC., 1994. Nutrient Requirements of Poultry. 9th Edn., National Academy Press, Washington, DC., USA.

Naylor, A.J., M. Choct and K.A. Jacques, 2000. Effects of selenium source and level on performance and meat quality in male broilers. Poult. Sci., 79: 117-124.

Nelson, A.A., O.G. Fitzhugh and H.O. Calvery, 1943. Liver tumors following cirrhosis caused by selenium in rat. Cancer Res., 3: 230-236.
Direct Link  |  

Nicholson, J.W.G., R.E. McQueen and R.S. Bush, 1991. Response of growing cattle to supplementation with organically bound or inorganic sources of selenium or yeast cultures. Can. J. Anim. Sci., 71: 803-811.
CrossRef  |  Direct Link  |  

Niedzwiedzka, K.M., J. Kowalczyk and M. Czauderna, 2008. Influence of selenate and linseed oil on fatty-acid and amino-acid profiles in the liver, muscles, fat tissues and blood plasma of sheep. J. Anim. Feed Sci., 17: 328-343.
Direct Link  |  

Ortman, K. and B. Pehrson, 1997. Selenite and selenium yeast as feed supplements for dairy cows. J. Vet. Med. Ser. A, 44: 373-380.
CrossRef  |  Direct Link  |  

Ortman, K. and B. Pehrson, 1999. Effect of selenate as a feed supplement to dairy cows in comparison to selenite and selenium yeast. J. Anim. Sci., 77: 3365-3370.
Direct Link  |  

Pagan, J.D., P. Karnezos, M.A.P. Kennedy, T. Currier and K.E. Hoekstra, 1999. Effect of selenium source on selenium digestibility in exercised thoroughbreds. Proceedings of the 16th Equine Nutrition and Physiology Society, June 2-5, 1999, Raleigh, North Carolina, pp: 135-140.

Parsons, M.J., P.K. Ku, D.E. Ullrey, H.D. Stowe, P.A. Whetter and E.R. Miller, 1985. Effects of riboflavin supplementation and selenium source on selenium metabolism in the young pig. J. Anim. Sci., 60: 451-461.
PubMed  |  

Pavlata, L., L. Misurova, A. Pechova and R. Dvorak, 2011. The effect of inorganic and organically bound forms of selenium on glutathione peroxidase activity in the blood of goats. Veterinarni Med., 56: 75-81.
Direct Link  |  

Payne, R.L. and L.L. Southern, 2005. Comparison of inorganic and organic selenium sources for broilers. Poult. Sci., 84: 898-902.
CrossRef  |  Direct Link  |  

Pehrson, B., M. Knutsson, and M. Gyllensward, 1989. Glutathione peroxidase activity in heifers fed diets supplemented with organic and inorganic selenium compounds. Swedish J. Agric. Res., 19: 53-56.
Direct Link  |  

Peters, J.C. and D.C. Mahan, 2008. Effects of dietary organic and inorganic trace mineral levels on sow reproductive performances and daily mineral intakes over six parities. J. Anim. Sci., 86: 2247-2260.
CrossRef  |  

Power, R. and K. Horgan, 2000. Biological Chemistry and Absorption of Inorganic and Organic Trace Metals. In: Biotechnology in the Feed Industry, Lyons, T.P. and K.A. Jacques (Eds.). Nottingham University Press, Nottingham, UK, pp: 277-291.

Puri, D., 2002. Free Radical Reaction in Health and Disease: A Text Book of Biochemistry. 1st Edn., BI Churchill Livingstone Pvt Ltd, New Delhi, pp: 769-778.

Rayman, M.P., 2004. The use of high-selenium yeast to raise selenium status: How does it measure up. Br. J. Nutr., 92: 557-573.
PubMed  |  

Richards, C.J. and H.D. Loveday, 2004. Redefining Selenium Nutrition using Organic Selenium (Sel-Plex®): Defining Maximal Acceptable Tissue Residues in Beef. In: Nutritional Biotechnology in the Feed and Food Industries, Lyons, T.P. and K.A. Jacques (Eds.). Nottingham University Press, Nottingham, UK., pp: 211-220.

Rotruck, J.T., A.L. Pope, H.E. Ganther, A.B. Swanson, D.G. Hafeman and W.G. Hoekstra, 1973. Selenium: Biochemical role as a component of glutathione peroxidase. Science, 179: 588-590.
CrossRef  |  PubMed  |  Direct Link  |  

Ryu, Y.C., M.S. Rhee, K.M. Lee and B.C. Kim, 2005. Effects of different levels of dietary supplementation selenium on performance, lipid oxidation and colour stability of broiler chicks. Poult. Sci., 84: 809-815.
Direct Link  |  

Schallreuter, K.U. and J.M. Wood, 1986. The role of thioredoxin reductase in the reduction of free radicals at the surface of the epidermis. Biochem. Biophys. Res. Commun., 136: 630-636.
CrossRef  |  

Schrauzer, G.N., 2000. Selenomethionine: A review of its nutritional significance, metabolism and toxicity. J. Nutr., 130: 1653-1656.
Direct Link  |  

Schroeder, H.A., D.V. Frost and J.J. Balassa, 1970. Essential trace metals in man: Selenium. J. Chron. Dis., 23: 227-243.
Direct Link  |  

Schwarz, K. and C.M. Foltz, 1957. Selenium as an integral part of factor 3 against dietary liver degeneration. J. Am. Chem. Soc., 79: 3292-3293.
Direct Link  |  

Schweizer, U., L. Schomburg and N.E. Savaskan, 2004. The neurobiology of selenium: Lessons from transgenic mice. J. Nutr., 134: 707-710.
Direct Link  |  

Scott, M.L., M.C. Nesheim and R.J. Young, 1982. Nutrition of the Chicken. 3rd Edn., ML Scott and Associates, Ithaca, New York.

Sen, C.K., 1995. Oxygen toxicity and antioxidants: State of the art. Indian J. Physiol. Pharmacol., 39: 177-196.
PubMed  |  

Sevcikova, S., M. Skrivan, G. Dlouha and M. Koucky, 2006. The effect of selenium source on the performance and meat quality of broiler chickens. Czech J. Anim. Sci., 51: 449-457.
Direct Link  |  

Shamberger, R.J., 1983. Selenium Deficiency Diseases in Animals. In: Biochemistry of Selenium, Shamberger, R.J. (Ed.). Plenum Press, New York, pp: 31-58.

Skrivan, M., G. Dlouha, O. Masata and S. Sevcikova, 2008. Effect of dietary selenium on lipid oxidation, selenium and vitamin E content in the meat of broiler chickens. Czech J. Anim. Sci., 53: 306-311.
Direct Link  |  

Slavik, P., J. Illek, M. Brix, J. Hlavicova, R. Rajmon and F. Jilek, 2008. Influence of organic versus inorganic dietary selenium supplementation on the concentration of selenium in colostrum, milk and blood of beef cows. Acta Vet. Scand., 50: 43-49.
Direct Link  |  

Smet, K., K. Raes, G. Huyghebaert, L. Haak, S. Arnouts and S. de Smet, 2008. Lipid and protein oxidation of broiler meat as influenced by dietary natural antioxidant supplementation. Poult. Sci., 87: 1682-1688.
CrossRef  |  

Spears, J.W., J. Grimes, K. Lloyd and T.L. Ward, 2003. Efficacy of a novel organic selenium compound (zinc-l-selenomethionine, available Se) in broiler chicks. Proceedings of the 1st Congress of the Latin American Annual Nutrition College, August 18-23, 2003, Cancun, Mexico, pp: 197-198.

Steele, R.D. and N.J. Benevenga, 1979. The metabolism of 3-methylthiopropionate in rat liver homogenates. J. Biol. Chem., 254: 8885-8890.

Sunde, R.A., 1997. Selenium. In: Handbook of Nutritionally Essential Mineral Elements, O'Dell, B.L. and R.A. Sunde (Eds.). Marcel Dekker Inc., New York, pp: 493-556.

Surai, P.F., 2006. Selenium in Ruminant Nutrition. In: Selenium in Nutrition and Health, Surai, P.F. (Ed.). Nottingham University Press, Nottingham, pp: 487-587.

Svoboda, M., R. Ficek and J. Drabek, 2008. Efficacy of organic selenium from se-enriched yeast on selenium transfer from sows to piglets. Acta Vet. Brno, 77: 515-521.
CrossRef  |  

Tapiero, H., D.M. Townsend and K.D. Tew, 2003. The antioxidant role of selenium and seleno-compounds. Biomed. Pharmacother., 57: 134-144.
Direct Link  |  

Ursini, F., S. Heim and M. Kiess, 1999. Dual function of the selenoprotein GSHPx during sperm maturation. Science, 285: 1393-1397.

Vasudevan, D.M. and S. Sreekumari, 2001. Mineral Metabolism: Text Book of Biochemistry. 3rd Edn., Jaypee Brothers Med Pub Ltd., New Delhi, pp: 284-298.

Wang, Y.B. and B.H. Xu, 2008. Effect of different selenium source (sodium selenite and selenium yeast) on broiler chickens. Anim. Feed Sci. Tech., 144: 306-314.
CrossRef  |  Direct Link  |  

Whanger, P.D., N.D. Pedersen, J. Hatfield and P.H. Weswig, 1976. Absorption of selenite and selenomethionine from ligated digestive tract segments in rats. Exp. Biol. Med., 153: 295-297.

Wright, P.L. and M.C. Bell, 1966. Comparative metabolism of selenium and tellurium in sheep and swine. Am. J. Physiol., 211: 6-10.
Direct Link  |  

Yi, Y.S., S.G. Park, S.M. Byeon and Y.G. Kwon and G. Jung, 2003. Hepatitis B virus X protein induces TNF-a e xpression via down regulation of selenoprotein P in human HePG2. Biochem. Biophys. Acta, 1638: 249-256.
CrossRef  |  

Yoon, I. and E. McMillan, 2006. Comparative effects of organic and inorganic selenium on selenium transfer from sows to nursing pigs. J. Anim. Sci., 84: 1729-1733.
PubMed  |  

Yoon, I., T.M. Werner and J.M. Butler, 2007. Effect of source and concentration of selenium on growth performance and selenium retention in broiler chickens. Poult. Sci., 86: 727-730.
CrossRef  |  Direct Link  |  

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