Chiba: Advanced Nonruminant Nutrition Vitamins - Quiz (Key) Page 1 Vitamins (Lee I. Chiba, Auburn University) Quiz - Answer Key [Not expecting all those points to be addressed in your response/answer! Also, expressing your own ideas and(or) unique perspectives on some topic would be certainly appropriate! Also, we do apologize in advance for not proofreading the answer key!] [Please answer the following questions briefly yet completely!] 1. It is rather difficult for us to study "vitamins" in general, vitamin metabolism, or establish their requirements. Well, what are some of the inherent difficulties or problems associated with conducting research on vitamins? Please discuss briefly. Perhaps, can mention/discuss, e.g.:  Requirements or needs? - Very low for many/most vitamins?  Synthesis or storage? - Some vitamins can be synthesized within the body or stored in the body in sufficient amount to satisfy the need?  Coenzyme? - Many vitamins are serving as a coenzyme, thus, the effects may not be direct and(or) may not be observed immediately or clearly?  Borderline deficiency? ∘ Fairly common, and animals or humans may be deficient in some vitamin, but not showing obvious/clear deficiency sign/symptoms. ∘ Very difficult to identify deficiency signs/symptom, especially the deficiency for "water-soluble" vitamins!  Multiple deficiency? ∘ Usually don’t see a single vitamin deficiency under practical conditions . . . unless the deficiency for a particular vitamin is very severe! ∘ Symptoms are often a combination of signs described for various vitamins, or may be entirely different symptom(s). ∘ Various conditions/signs observed, such as un-thriftiness, reduced appetite, and poor growth, are common to malnutrition in general, thus, difficult to identify?  Stability or availability? - Many vitamins or vitamin activity can be affected by many factors, and there is always a question on the stability and(or) availability? 2. It seems that the need for "vitamins" has increased in recent years. Why would you think that is? Also, we usually include some vitamins much more than the requirement, i.e., 2, 3 times or even more! What would you think the rationale or reasons behind such a practice?  Increased vitamin needs in recent years? ∘ Vitamins? - Nowadays, perhaps, important in maximizing or optimizing "performance or health!?" Perhaps, providing a "boost?!" ∘ A reflection of changes in, e.g.:  Animals? - e.g., producing leaner animals, which may increase the vitamin need?  Plants? - Development of new varieties, which can affect the content/availability? Advanced Nonruminant Nutrition Fall Semester, 2014Chiba: Advanced Nonruminant Nutrition Vitamins - Quiz (Key) Page 2  Processing of feedstuffs, e.g., pelleting, extruding, and others? - Can affect the content/availability?  Production systems, e.g., the extensive use of the confinement & associated stress? - No coprophagy? Also, stress may increase the vitamin need/requirement?  Rationales/Reasons? ∘ Animals may be deficient in vitamin(s) but hard to identify deficiency signs. ∘ Toxicity is not really a problem - Water soluble vitamins may not cause problems? Fat-soluble vitamins - Can be, but have "high-tolerance!?" ∘ Availability/activity or stability questions - Many vitamins are susceptible to loss due to many factors such as heat, light, water, TM, and others!? ∘ The need can be affected by many factors such as stress, interactions, pathological & physiological conditions, availability, biological variations, etc. ∘ Vitamin supplements are not very expensive. 3. Other than the fact that some of them are fat-soluble and others are water-soluble, how can we distinguish "fat- and water-soluble vitamins," especially in terms of the possibility of developing "deficiency or toxicity" and(or) some "primary functions?"  Storage of fat- soluble vitamins? ∘ Stored in the liver (vitamins A, D, and K) or adipose tissues (vitamin E), thus, can serve as reserves. ∘ Tissue accumulation can reach toxic levels (especially, vitamins A & D), thus, a megadose can be potentially dangerous!? Toxicity? - Possible but not likely because animals can tolerate a high-dose of those vitamins!?  Storage of water- soluble vitamins? ∘ No appreciable storage, thus, generally non-toxic. Must be supplied continuously in the diet though! ∘ "Excess" water-soluble would be excreted from the body. Exception? Vitamin B12, which can be stored in the body to satisfy the need for a long time.  Functions/deficiencysigns? ∘ Fat soluble vitamins? - Mostly involved in the regulation/metabolism of structural units, and signs of deficiency can be directly related to functions of the vitamin!? ∘ Water soluble vitamins? - Mostly concerned with the transfer of energy, and deficiency is rarely caused by a single vitamin!? Often, difficult to relate signs to functions of the vitamin in most instances, i.e., efficiency signs are non-specific, and symptoms are often a reflection of the most limiting vitamin in the diet!? 4. The role of vitamin E and Se in our physiological system seems to be very similar, yet they are little different. How would you differentiate these two nutrients in terms of their function as a biological antioxidant and(or) preventing or alleviating their deficiency signs? Please discuss briefly.  Interdependence of vitamin E & Se? ∘ Se can spare vitamin E by maintaining the integrity of pancreas and allowing normal lipid metabolism, and, as an integral part of glutathione peroxidase, reducing vitamin E required to maintain the integrity of cell membranes. ∘ Vitamin E can reduce the Se requirement by maintaining body Se in an active form or preventing its loss, and preventing a chain-reactive autoxidation of the membrane, which would reduce the needs for Se-containing glutathione.  Difference between vitamin E & Se? - Essentially, the difference would be in the solubility and location? ∘ Vitamin E is fat-soluble vitamin and found mostly in the membrane, whereas Se, as a component of glutathione peroxidase," would be found in the cellular interior or cytosol of the cell. ∘ Although both are important biological antioxidants and working together, the location of the action might be little different . . . thus, not completely "interchangeable!?" 5. It seems that, metabolically, "folic acid, vitamin B12, Co,