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Mineral Bioavailability

Mineral Bioavailability. Definitions of Bioavailability. The proportion of the element consumed that is utilized for a biochemical or physiologic function (O’Dell, 1997)

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Mineral Bioavailability

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  1. Mineral Bioavailability

  2. Definitions of Bioavailability • The proportion of the element consumed that is utilized for a biochemical or physiologic function (O’Dell, 1997) • A measure of the proportion of the total amount of a nutrient that is utilized for normal body functions (Fairweather-Tart, 1999) • The degree to which an ingested nutrient in a particular source is absorbed in a form that can be utilized in metabolism by the animal (Ammerman et al., 1995) • The fraction of the ingested nutrient that is utilized for normal physiological functions or storage (Jackson, 1997)

  3. Utilization Consists of: • Intestinal absorption (major barrier) • Transport to site of action • Cellular uptake • Incorporation into a biochemically active form

  4. Incorporation into biological processes Small Intestine Fe Frataxin Transferrin Transport Proteins Cu Heme Chaperone Proteins Ceruloplasmin CCS Extracellular Intracellular Superoxide Dismutase

  5. Intrinsic or Physiological Factorsthat Influence Bioavailability • Species and Genetics • Age and Sex • Metabolic Function – growth, lactation, maintenance • Nutritional Status • Intestinal or Rumen Microflora • Physiological Stress

  6. Extrinsic or Dietary Factorsthat Influence Bioavailability • Solubility of element – CuS, CuMoS4 • Binding to other dietary components (fiber, silica) in the intestine • State of Oxidation – Fe+2 vs. Fe+3 • Competitive Antagonisms of similar ions • Chelation effects – Can be positive or negative depending on the • solubility and dissociation constant of the complex formed.

  7. Tissue Utilization Absorbed Cu Cu Transporters Unabsorbed & Endogenous Cu Biliary Cu Dietary Cu Total Fecal Cu

  8. Paracellular Absorption Intestinal absorption changes in a situation of excessive mineral consumption verses normal Normal mineral consumption Excessive mineral consumption High Dietary Zn, Fe Passive Diffusion Zn & Fe Zn & Fe

  9. Responses of various criteria to physiological concentrations of dietary zinc in lambs aBasal diet analyzed 3.7 mg Zn/kg. b,c,dP < 0.05. Droke and Spears, 1993

  10. Suitable criteria for estimating zinc bioavailability

  11. Indices of copper status in cattle fed diets adequate or deficient in copper Legleiter and Spears, 2007

  12. Suitable Criteria For Estimating Copper Bioavailability

  13. Mineral composition of feedstuffs Hale and Olson, MU Epub

  14. Chemical Forms of Trace Minerals in Plant Materials

  15. Mineral Sources

  16. Copper Sources

  17. Relative bioavailability of Cu glycinate based on regression of liver Cu following 6 mg Mo/kg DM 499/332 = 150% RVB P < 0.01

  18. Solubility • Minerals must be soluble at site of absorption • Information on trace mineral bioavailability from feeds is based on GIT solubility

  19. Ruminal disappearance of copper and zinc from forages from dacron bags incubated for 0 or 72 hours in the rumen of cattle aAmount disappearing following washing with water. Emanuele and Staples, 1990

  20. Trace Mineral Concentrations in Feedstuffs vs Bioavailability • Availability of minerals in feedstuffs • Chemical forms • Fiber • Dietary antagonisms • Effect on feedstuff mineral vs. supplemented mineral

  21. Homeostatic mechanisms • Increasing absorption and/or reducing excretion if intake of a mineral is low or marginal relative to the requirement • Reducing absorption and/or increasing excretion if intake of a mineral is above the requirement

  22. Homeostatic Control of Zinc in Lactating Dairy Cowsa aCows were fed diets for 6 weeks. 65Zn was given orally on week 5 and followed for 14 days. b% of 65Zn dose. c,d (P < 0.01). Neathery et al., 1973

  23. Homeostatic Control of Zinc in Lactating Dairy Cows a,b(P < 0.01) Neathery et al., 1973

  24. Selenium • Selenite-selenium absorption in ruminants is much lower than in nonruminants • Selenomethionine is the predominant form of selenium that occurs naturally in feedstuffs

  25. Bioavailability of selenium from selenite vs selenomethionine when added to diets of selenium-depeleted lambsa aControl diet analyzed 0.04 ppm of Se. Selenium was supplemented at 0.05 ppm from d 0 to 28 and 0.10 ppm from d 29 to 56.

  26. Bioavailability of selenium from selenitevsselenomethionine when added to diets of selenium-depleted lambs aU/mg protein. bµg/g dry tissue.

  27. Summary • Research regarding ruminant bioavailability of minerals from feeds is extremely limited • A portion of certain trace minerals in forages appears to be associated with the fiber fraction • Based on in situ studies, a high proportion of trace minerals are released from forages in the rumen • Mineral sources differ in bioavailability which may impact supplementation needs

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