Progress 10/01/01 to 09/30/06
Outputs
Over the life of this project, numerous studies were conducted to determine if organic selenium is a better source of feed-delivered seleium versus feed-delivered sodium selenite. It was determined that organic selenium provided as selenium yeast was more available than sodium selenite. Furthermore, it was demonstrated that the marker for selenium availability, glutathione peroxidase, was induced to a higher level of activity when organic selenium was fed to broiler chickens. Meat yield was positively affected by provision of organic selenium and it was shown that increased yield of breast and leg plus thigh meat was a result of improved nutritional status. The fact that the antioxidant enzyme, glutathione peroxidase was induced contributed to a better redox status, but additional studies on another selenium-dependent enzyme, thioredoxin reductase, showed that it might be a pivotal enzyme in the antioxidant cascade which allowed for the improved redox status.
Thioredoxin reductase is directly involved in the reduction of vitamin C which then provides the reducing equivalents necessary for the recycling and reduction of vitamin E in cell membranes. Through induction of thioredoxin reductase, it appears that the enzymatic cascade involved in the maintenance of cellular redox status is stabilized and in the face of stressors such as heat stress, broiler chickens given organic selenium as selenium yeast are better able to resist and survive thermal stress. In broiler breeders, results from this project clearly demonstrated that organic selenium supplementation in the feed provided the stimulus for improved reproductive success. Semen quality was improved with fewer abnormal sperm than in sodium selenite fed males and the males were more active for longer times in the breeder barns. Females produced more settable eggs and hatchability improved significantly with more chicks per hen housed. This had a significant impact on revenues for the
breeder farms. Improved performance of chicks from parents fed organic selenium was also noted and this was attributed to improved cellular redox status at the time of hatch and maintenance for the first week after hatch. Overall, organic selenium, which is the type of selenium provided through nature, was found to be a superior source of feed grade selenium for chickens.
Impacts
Results of this study suggest that selenium nutrition and its stimulation of the antioxidant glutathione/glutathione peroxidase and thioredoxin/thioredoxin reduxctase enzyme systems provides a buffer against the potential damaging effects of free radical production. Free radicals have damaging effects on cells and cell membranes, which result in severe stress responses in living systems. The resulting stress is attributed to unthriftiness and poor production of the afflicted birds. Thus, it is important to provide the superior form of selenium to have the greatest influence on the antioxidant systems. In this case, it has been shown that organic selenium is superior to inorganic selenium. The impact of these results can have far reaching benefits to poultry and livestock producers. Those benefits range from improved growth, feed conversion, and less mortality to increased resistance to viral and bacterial challenge.
Publications
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Progress 10/01/04 to 09/30/05
Outputs
Even though organic selenium in Sel-Plex is a superior source of selenium for poultry production, sodium selenite is still used as the principal source of selenium in animal feeds. This seems paradoxical because sodium selenite has a documented pro-oxidant influence in all animals tested including humans. Heat shock protein 70 (hsp70) family of proteins, which functions as molecular chaperones, has been associated with tolerance to stressors in avian species. Selenium (Se) is an essential trace mineral incorporated into the selenoenzymes such as glutathione peroxidase (GSHpx). GSHpx reduces oxidized glutathione (GSSG) to reduced glutathione (GSH) in the GSH/GSSG antioxidant system and protects cells from oxidative damage. This study was conducted to examine if the relationship between dietary supplementation of selenium to turkey (Meleagris gallopavo) hens and the embryonic exspression of hsp70 and GSHpx activity in heat stressed embryos. Livers of embryos developing
in eggs from turkey hens fed diets with or without supplemental Se were analyzed for hsp70 concentration and GSHpx activity before and after recovery from a heating episode. Before heat stress, hsp70 concentrations were equivalent in each treatment, but GSHpx activity was maximized in the SE treatment group. After recovery from the heating episode, hsp70 concentrations were significantly higher ( P <0.05) in the non-Se-supplemented groups, but in the Se-supplemented groups the hsp70 concentrations were not different from pre-stress concentrations. In the pre-stress Se-supplemented group, liver GSHpx activity was significantly higher than GSHpx activity in the non-Se-supplemented embryo livers, and in the livers from embryos recovering from heat stress, GSHpx activity in the non-Se-supplemented group was lower than the pre-stress activity and significantly lower than the GSHpx activity in liver from Se-supplemented embryos recovering from heat distress. Se supplementation to the dams
resulted in a significant increase in their embryos and that condition would facilitate a decreased incidence of oxidative damage to cells. A more reduced redox status in embryos from Se-supplemented dams decreased the need for cellular protection attributed to stress induced hsp70 and presumably allows heat distressed embryos to resume normal growth and development than embryos from dams with inadequate selenium nutrition. Induction of hsp70 in broiler chickens subjected to heat distress or enteropathogenic E. coli was also less than in chickens with low levels of selenium in their diets.
Impacts
Results of this study suggest that selenium nutrition and its stimulation of the antioxidant glutathione/glutathione peroxidase and thioredoxin/thioredoxin reduxctase enzyme systems provides a buffer against the potential damaging effects of free radical production. Free radicals have damaging effects on cells and cell membranes, which result in severe stress responses in living systems. The resulting stress is attributed to unthriftiness and poor production of the afflicted birds. Thus, it is important to provide the superior form of selenium to have the greatest influence on the antioxidant systems. In this case, it has been shown that organic selenium is superior to inorganic selenium. The impact of these results can have far reaching benefits to poultry and livestock producers. Those benefits range from improved growth, feed conversion, and less mortality to increased resistance to viral and bacterial challenge.
Publications
- Edens, F. W., 2005. Manutencion do status redox celular: Foco na participacion do sistema tiorredoxina / tiorredoxina redutase. Pages 63-81. In Biotecnologia Nutricional na Industria de Alimentacion Animal. A. Malaguido and F. Prieto, eds. Curitiba, Brazil.
- Mahmoud, K. Z., and F. W. Edens, 2005. Influence of organic selenium on hsp70 response of heat-stressed and enteropathogenic Escherichia coli-challenged broiler chickens (Gallus gallus). Comp. Biochem. Physiol. Part C 1431:69-75.
- Revira, R. E., V. L. Christensen, F. W. Edens, and M. J. Wineland, 2005. Influence of selenium on heat shock protein 70 expression in heat stressed turkey embryos (Meleagris gallopavo). Comp. Biochem. Physiol. Part A 142:427-432.
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Progress 10/01/03 to 09/30/04
Outputs
Selenium supplementation in poultry has long been associated with energy metabolism, increased feed efficiency, improved reproduction, and improved immune responses. Poultry are constantly exposed to environmental stressors that require the antioxidant protection derived from dietary selenium supplementation. The inorganic forms of selenium, selenite and selenate that are commonly used as a feed source of selenium, have pro-oxidant properties and can be toxic at high levels of supplementation. The organic form of selenium, found in the yeast product Sel-Plex, has been shown to be generally safer and more available to the chicken. High levels of inorganic or organic forms of selenium showed different effects on the developing immune system. At levels as low as 1.2 ppm of selenite, lymphoid organ weights were decreased significantly, and inflammatory responses were elevated, and at levels of 5 , 10 or 15 ppm of dietary selenite, high rates of mortality and almost total
cessation of growth was observed. Up to 15 ppm of Sel-Plex produced no signs of toxicity. These observations indicated that at high levels of dietary inclusion, Sel-Plex has no detrimental effects on the immune system or the mechanisms controlling growth and development. Selenium is an integral part of a range of selenoproteins. Thioredoxin reductase (TR) is one of those proteins and is a key player in the antioxidant cascade. TR has been purified and characterized in many organisms but not the chicken. Chickens are exposed to many stressors, so it was important to study this enzyme in chickens. The distribution of TR protein expression was uniform throughout the chicken's body, regardless of selenium supplementation. However, varying isoforms did appear that have not been reported in mammalian tissues. When TR activity was examined, significant differences were seen among treatments, with the highest activities being measured in Sel-Plex-fed broilers. The subcellular distribution of
TR revealed that the majority of its activity was in mitochondrial fractions. These observations indicate that chicken TR is likely very different than mammalian TR, but additional studies are needed. Recent evidence suggests that the prooxidant properties of sodium selenite might be mediated through extremely high levels of nitric oxide production. In Bordetella avium infected poults, nitric oxide was elevated over control and Sel-Plex fed poults by 10 fold. Nitric oxide in moderate levels is good but such high levels being expressed during inflammatory disease might be harmful. Peroxynitrite is produced from nitric oxide and has the potential to damage cell membranes as much as reactive oxygen metabolites. Thus, sodium selenite is contraindicated for poults with inflammatory disease. Dietary supplementation of Sel-Plex to turkey breeder hens resulted higher glutathione peroxidase activity in poult embryos and lower heat shock protein 70 when the embryos were heat stressed.
Impacts
Experimental results have shown organic selenium to be a superior source of dietary selenium as compared with the inorganic sodium selenite. Improved body weight, feed conversion and livability are associated with the supplementation of organic selenium. Furthermore, the experimental results clearly show that the humoral and cell-mediated immune responses of chickens fed organic selenium are improved. The issue of safety is also important. It has been long recognized that trace amounts of inorganic sodium selenite are required, but if one exceeds the upper limit of safety, roughly 5 ppm, the chickens immediately show signs of toxicity. Experimental results with the modern broiler suggest that 5 ppm may be too great a level for the upper limit of safety for sodium selenite. As little as 1.2 ppm was sufficient to cause signs of toxicity to develop in chickens given sodium selenite. At higher levels of selenite supplementation, extreme suppression of weight gain and
mortality were observed. However, as much as 15 ppm of the organic selenium in Sel-Plex had no adverse effects in broiler chickens.
Publications
- Edens, F. W., 2004. Immunosuppression Associated with disease, environment and management. Pages 49-68. In: Proceedings XVIII Congresso Centroamericano y del Caribe de Avicultura, San Pedro Sula, Honduras, August 25-29, 2004.
- Edens, F. W., and K. M. Gowdy, 2004. Selenium Sources and selenoproteins in practical poultry production. Pages 35-55. In: Nutritional Biotechnology in the Feed and Food Industries. Proceedings of Alltech's 20th Annual Symposium. T. P. Lyons and K. A. Jacques, eds. Nottingham University Press, Nottingham, NG11 OAX, UK
- Gowdy, K. M., 2004. Selenium supplementation and antioxidant protection in broiler chickens. Master of Science Thesis, The Graduate School, North Carolina State University, Raleigh, NC 27695.
- Macalintal, L. M., 2004. Comparative pathogenicity studies on avian reoviruses. Master of Science Thesis, The Graduate School, North Carolina State University, Raleigh, NC 27695
- Mahmoud, K. Z., and F. W. Edens, 2004. Blood and liver glutathione redox status in heat-stressed broiler chickens fed organic selenium. Poultry Sci. 83:1803.
- Rivera, R. E., V. L. Christensen, and F. W. Edens, 2004. The effect of selenium on heat shock protein 70 expression in turkey embryos/ Poultry Sci. 83:1763.
- Sefton, A. E., and F. W. Edens, 2004. Sel-Plex improves semen quality in broiler breeder males in a cage environment. PDF File 1001. In: Proc. 22nd World's Poultry Congress, Istanbul, Turkey. June 8-13, 2004.
- Sefton, A. E., and F. W. Edens, 2004. Sel-Plex improves broiler breeder performance. PDF File 1044. In: Proc. 22nd World's Poultry Congress, Istanbul, Turkey. June 8-13, 2004.
- Tyner, A. M., F. W. Edens, and G. H. Luginbuhl, 2004. Aspirin and selenium influence on bordetellosis in turkey poults. Poultry Sci. 83(Suppl. 1):185.
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Progress 10/01/02 to 09/30/03
Outputs
Studies in the USA indicated that selenium yeast had marginal effects in broiler production, but other studies showed improved BW and FCR along with decreased breast fillet drip loss. In the UK, the results with several million broilers showed that BW and livability were improved significantly when selenium yeast was added to the diets of both breeders and progeny. In Mexico, several commercial broiler trials with selenium yeast have been monitored in which selenium yeast was used with grains from the USA. There were significant improvements in BW and FCR. In Australia and Thailand, the use of selenium yeast improved BW, FCR and yield of processed carcasses, and in Thailand, the use of selenium yeast singly and in combination with sodium selenite resulted in decreased drip loss from breast fillets. It was of interest that even at 0.1 ppm of selenium yeast in broiler diets in Brazil, there was demonstrable improvement in performance, but even better results were found
when the level of selenium yeast was increased to 0.2 and 0.3 ppm while sodium selenite was decreasing. The results from both university and field trial studies have shown that the use of selenium yeast in diets of broilers has the potential to improve performance. Selenium maximizes immune responses of poultry, but the inorganic and organic forms have not been compared. We have conducted experiments with broilers given diets with no supplemental selenium (NS), sodium selenite (SE), or selenized yeast (SP) and investigated their responses after they were challenged with either an enteropathogenic E. coil (EPEC, 1,000,000 cells at hatch to 4d post hatch) or Salmonella (natural infection). Four groups (NS, SP, NS+EPEC, and SP+EPEC) were in the 2 x 2 factorially arranged EPEC study. Broilers were given either NS (0 ppm supplemental selenium) or SP (0.2 ppm) broiler diets for 6 wk. BW was increased (P< 0.05) by SP compared with NS. In EPEC groups, BW was reduced significantly with NS, but
SP prevented the large losses in BW. Mortality due to EPEC was reduced (P<0.05) by SP. In a second trial to evaluate the influence of NS (0 ppm), SP (0.3, 0.6, or 1.2 ppm) or SE (0.3, 0.6, or 1.2 ppm) on lymphoid organ weight in 3 wk old broilers, 2 of 3 trials were complicated by a natural Salmonella infection. BW was reduced significantly in NS, SE and SP infected groups, but SP supplemented broilers in the infected groups grew better. With no infection, only the 1.2 ppm SP group had a greater BW than SE. Bursa of Fabricius relative weight was increased by 0.6 ppm SP in the uninfected group, and all groups showed decreased bursa weight with infection. Spleen weights were not affected by selenium feeding but were increased by infection. Thymus weights were increased by SE (0.3 and 0.6 ppm) in the uninfected groups, but with infection, NS and SE thymus weights were depressed as compared with SP. The wing web response to PHAP was significantly smaller with SP in the uninfected group.
The results suggest that both SE and SP have a positive influence on the immune system, but they may not affect the immune system the same way. SP appeared to be more beneficial for the broiler.
Impacts
Inorganic selenium in the form of sodium selenite has been the choice for selenium supplementation in poultry diets since 1974 when selenium was first approved for poultry. Even though the inorganic form is known to be effective in improving poultry performance, it also has a strong pro-oxidant property. On the other hand, organic selenium provided in selenized yeast does not have a pro-oxidant influence, and performance of broilers is improved even more when it is provided. Today, the new varieties of broiler stocks are fast-growing, high yielding, and have problems with oxidative stress. Thus, it is imperative to develop nutritional strategies that will effectively reduce oxidative stress. The organic selenium from yeast has the potential to greatly improve the redox status of poultry when compared to birds receiving sodium selenite. This improves the redox status, feed conversion, body weight, the moisture retention properties of processed broiler meat, immune
status, reproductive status of both male and female chickens, and reduces the risk for toxicity from the inorganic sodium selenite. Many different companies are now producing organic selenium for supplementation in poultry feeds. This research will aid commercial nutritionists as they begin to move from an inorganic selenium supplement to an organic form for selenium supplementation for all phases of the poultry industry.
Publications
- Mahmoud, K. Z., F. W. Edens, E. J. Eisen, and G. B. Havenstein, 2004. Effect of ascorbic acid and acute heat exposure on heat shock protein 70 expression by young white Leghorn chickens. Comp. Biochem. Physiol. B (in press)
- Mahmoud, K. Z., F. W. Edens, E. J. Eisen, and G. B. Havenstein, 2004. Ascorbic acid decreases heat shock protein 70 and plasma corticosterone response in broilers (Gallus domesticus) subjected to cyclic heat stress. Comp. Biochem. Physiol. B (in press)
- Edens, F. W., 2003. The interaction between selenium and vitamin E in poultry production. Pages 37-63. In: New Aspects in Vitamin Nutrition. 11th International Symposium on Animal Nutrition. L. Babinsky, ed. University of Kaposvar, Kaposvar, Hungary.
- Edens, F. W. K. M. Gowdy, and A. E. Sefton, 2003. Field results with broilers fed selenium yeast. Poultry Sci. 82(Suppl. 1):130.
- Gowdy, K. M., and F. W. Edens, 2003. Organic selenium affects broiler responses to immunostimulation. Poultry Sci. 82(Suppl. 1):10.
- Mahmoud, K. Z., F. W. Edens, E. J. Eisen, and G. B. Havenstein, 2004. The effect of dietary phosphorus on heat shock protein mRNAs during acute heat stress in male broiler chickens (Gallus domesticus). Comp. Biochem. Physiol. B (in press). Mahmoud, K. Z. and F. W. Edens, 2004. Influence of selenium sources on age-related and mild heat stress-related changes of blood and liver glutathione redox cycle in broiler chickens (Gallus domesticus). Comp. Biochem. Physiol. B (in press).
- Upton, J. R., 2003. The effects of selenium supplementation on performance and antioxidant enzyme activity in broiler chickens. Master of Science Thesis. The Graduate School, North Carolina State University, Raleigh, NC.
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Progress 10/01/01 to 09/30/02
Outputs
These investigations examined effects of different sources of selenium on age-related changes of blood and hepatic reduced and oxidized glutathione, glutathione peroxidase and reductase, and glucose-6-phosphodehydrogenase (GSH, GSSG, GPX, GR, G-6-PDH, respectively) during mild heat stress. Basal diets (BS) with organic (Sel-Plex;OS) or inorganic (sodium selenite;IS) selenium supplementation raised selenium content of the diet to 0.45 ppm. Birds from each treatment were bled by the end of weeks 2, 3 and 4. After the 4 week bleeding, birds were exposed to mild heat stress for 3 hrs and then 48 birds were bled. Hepatic and blood GPX and GPX/GR in BS diet were lower (P<0.001) compared to both OS and IS diets. Although selenium source did not affect GSH and GSSG, it is noteworthy to mention that birds fed OS diet maintained a higher hepatic and blood GSH/GSSG and GPX/GR ratios. The level of all measured variables were affected by age (P<0.001) except blood GSSG, GPX and
GR. Heat stress did not change blood levels of GR and G-6-PDH. However, there was an increase in blood levels of GSH (P<0.001), GSSG (P<0.01), GPX (P<0.001) and GPX/GR (P<0.05). Nevertheless, hepatic levels of all the above-named variables were not affected by heat stress, but there were numerical reductions in their levels. The results suggest that hepatic glutathione mobilization increases during mild heat stress. Birds fed OS maintained higher ratios of GSH/GSSG and GPX/GR that was indicative of its superiority in controlling the effects of oxidative stress. In another study of oxidative stress, the influence of OS and IS were evaluated in broiler chickens given diets containing oxidized poultry fat. Neither oxidized fat nor selenium source altered liver GR activity. GSH-Px was affected significantly by both oxidized fat and selenium source. IS induced elevated liver GSH-Px even in diets with no added oxidized fat, but liver GSH-Px in OS-fed birds was elevated only when feed
peroxide level was at 6 meq/kg. These results indicated that OS was a superior form of selenium that is utilized more efficiently to maintain a greater resistance to oxidative stress as compared with IS. Studies in field settings suggest that the use of OS improves reproductive potential of broiler breeders. Both male and female broiler breeders benefit from the supplementation OS in their diets. In males, semen production and quality were improved. This may be associated with earlier development of secondary sexual characteristics as well as hormonal development in the earlier maturing males. Improved structural integrity of the spermatozoon may be due to both improved antioxidant status in the seminal plasma and the sperm cells and also due to improved content of the modified selenium-dependent phospholipid hydroperoxide glutathione peroxidase in the spermatozoon's capsular membrane. In the females, there was improved egg production, fertility, hatchability, settable eggs, and in
chicks per hen capitalized. Improved fecundity of the female appeared to be related to improved antioxidant status due the presence of OS in their diets.
Impacts
Organic selenium for poultry production and reproduction appears to be superior to the use of inorganic sodium selenite or selenate that are in reality pro-oxidants. Organic selenium supplementation to the diets of poultry improves reproduction of both male and female broiler breeders. It appears that the improvement is associated with improved antioxidant activity in tissues similar to the conditions found in broiler chickens given organic selenium. It has been demonstrated that there are increased numbers of chicks per hen housed, improved fertility, and improved male performance as indicated by increased numbers of normal and motile sperm cells. Results from field trials have demonstrated profits of $0.49 to $1.27 per hen housed. In broilers there are noted improvements in feed conversion and in live and processed carcass weights. Organic selenium supplements have the potential to improve profitability of the poultry industry by many millions of dollars. This
improvement is associated with antioxidant protection, not only from GSH and GSH-Px but with ascorbate and vitamin E.
Publications
- Edens, F. W., 2002. Practical Applications for Selenomethionine: Broiler Breeder Reproduction. Pages 29-42. In: Science and Technology in the Feed Industry. From Niche Markets to Mainstream. T. P. Lyons and K. A. Jacques, eds. Nottingham University Press, Nottingham NG11 0AX, United Kingdom.
- Edens, F. W., 2002. Benefits of selenomethionine for poultry. Page 28-36. In: Proc. 29th Ann. Carolina Poultry Nutri. Conf. October 30-31, Research Triangle Park, NC
- Edens, F. W., and A. E. Sefton, 2002. Selenomethionine supplementation to diets of broiler breeders improves performance. Poultry Sci. 80(Suppl.1):91.
- Edens, F. W., C. R. Parkhurst, and A. E. Sefton, 2002. Selenomethionine from selenized yeast improves spermatozoal integrity. Poultry Sci. 80(Suppl.1):90.
- Mahmoud, K. Z., and F. W. Edens, 2002. Influence of selenium supplementation on age-related changes in blood and hepatic glutathione oxidation and redox state in broiler chicks during mild heat stress. Poultry Sci. 80(Suppl.1):46.
- Upton, R. J., F. W. Edens, and K. Z. Mahmoud, 2002. The effects of feeding oxidized fat and selenium source on performance, glutathione peroxidase, and glutathione reductase activity in broiler chickens. Poultry Sci. 80(Suppl.1):72.
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