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High-Selenium Beef and Lamb Production: Animal Productivity and Tissue Concentrations
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  1. High-Selenium Beef and Lamb Production: Animal Productivity and Tissue Concentrations J. Bret Taylor USDA-Agricultural Research Service US Sheep Experiment Station Dubois, ID

  2. Historical Background:Deficiency • Reported and “assumed” events • Regions of limited forage selenium • Low Se soils or acidic soils • Management • Clinical – Se-salt injections or drenches • Marginal – feed supplements

  3. Current Outlook:Deficiency • More assumed rather than confirmed • Western rangelands • Less than 0.1 mg/kg is common • Management based on historical reports • “Treat” the potential • Professional health and nutrition consultant diagnosis

  4. Current Outlook:Marginal Deficiency Worries? • Selenium responsive disorders (Underwood and Suttle, 1999): • 10 to 20% decrease in conception rates • 15 to 30% decrease in lamb survival • Increased embryonic and fetal mortality • Increased lamb susceptibility to disease • 4 to 10% decrease in lamb growth rates • 4 to 8% decrease in wool yield

  5. Current Outlook: Manufactured Se Sources • Most common: the Se-salts • Sodium-selenite and -selenate • New on the market: Se enriched yeast • Poultry – 2001; swine – 2002; cattle – 2004 • Route of dietary inclusion • Ration component – limit fed • Salt mix ingredient – free choice • FDA regulated • Cattle ≤ 3.0 mghd-1/d • Sheep ≤ 0.7 mghd-1/d

  6. Need for “Supranutritional” Se?:Se Supplementing Limitations • Rangeland operations • Land use restrictions • Animal availability • Extensive land masses and difficult terrain • Brief periods of accessibility • Prebreeding (flushing) - 7 to 14 days • Parturition - 7 to 35 days • Shipping/processing - < 7 days Opportunities to supplement are short, and may occur only once every 120 to 330 days

  7. Custom Mixes Packaged Mixes Need for “Supranutritional” Se?:Supplementing Practices • Free choice high Se salt mix • 30 to 90 mg/kg salt mixes

  8. Allowable range of intake. (FDA, 2004) Need for “Supranutritional” Se?:Supplementing Practices Daily Se Intake (mg) of a 30, 60 or 90 ppm Se Custom Mix Selenium, mg/head/day

  9. Need for “Supranutritional” Se?:Problems with Se-salt Supplements • Short lived in the body, especially during lactation • Intake of salt mixes is herd based, not individual • Often “crosses over” the FDA intake limit • Individual treatment with injections is laborious and costly • High Se depositing in confined areas

  10. Potential for Natural Se Sources?: Naturally High Se Feeds • Allaway et al. (1967) recognized potential, but dismissed the importing of high Se feeds due to economic constraints and variation in Se content • Levander et al. (1983) emphasized the long term effects on Se status in humans when high Se wheat and yeast are consumed • van Ryssen et al. (1989) clearly demonstrated the ease of enhancing Se burden in sheep by feeding high Se wheat

  11. Feeding Supranutritional Se:High Se Wheat Grain • The majority of Se seems to be selenomethionine • Currently, its use as a feed or ration component for ruminants is not regulated • CAUTION: Wheat grain can result in severe digestive upsets in ruminants when fed improperly

  12. Selenium, ug/g (dry) Feeding Supranutritional Se: High Se Wheat vs. Se-salt J. B. van Ryssen et al. 1989. J. Agric. Food Chem. 37:1358 Comparative metabolism of organic and inorganic selenium by sheep

  13. Feeding Supranutritional Se:High Se Wheat & Forage vs. Se-salt T. L. Lawler et al. 2004. J. Anim. Sci. 82:1488 Effect of supranutritional (2.8 ppm) and organically bound selenium on performance, carcass characteristics, and selenium distribution in finishing beef steers

  14. 0.2 ppm Se feed 2.7 ppm Se feed Selenium, ug/mL Selenium, ug/g (dry) Day Day Feeding Supranutritional Se:Time vs. High Se Wheat J. B. Taylor. 2004. J. Anim. Sci. Submitted. Time dependent influence of supranutritional organically-bound selenium (2.7 ppm) on selenium load in growing wether lambs

  15. 0.2 ppm Se feed 2.7 ppm Se feed Selenium, ug/g (dry) Selenium, ug/g (dry) Day Day Feeding Supranutritional Se:Time vs. High Se Wheat J. B. Taylor. 2004. J. Anim. Sci. Submitted. (continued)

  16. Feeding Supranutritional Se:Se Form vs. Reproductive State J. B. Taylor et al. 2004. J. Anim. Sci. Submitted. Effect of seleno–methionine and –cystine, fed supranutritionally (2 ppm), on selenium load and selenoprotein activities in virgin, pregnant, and lactating rats

  17. Feeding Supranutritional Se:A Potential Management Solution? • There is a need for supranutritional Se • Naturally high Se (selenomethionine) starch grains can meet this need: • Dietary inclusion is not regulated • Rapidly enhances selenium load • Starch grains are being used for dietary energy enhancement (range and finishing systems) • Palatability is high

  18. Future of High Se Feeds in Livestock Production What’s in it for the Producer? • Controlled means of enhancing Se load to offset long periods of inadequate Se intake • Cost must be justified…deficiency should be quantified • Anything else? • Higher nutritional value product? • The producer must see this dollar increase at their level, not at the slaughter and retail levels • Greater return on investment? • Remember, the high Se feed, not the animal, is the investment

  19. Future of High Se Feeds in Livestock Production