Louisa BowenAdvanced Nonruminant NutritionVitamins Quiz 11/10/141. Vitamins have only been studied in the past century, with inconsistent findings due to the lack of chemistry knowledge of the doctors conducting the research. The synthesis and subsequent absorption rate of some vitamins is still unknown. For example, ascorbic acid is the reduced form of vitamin C, and little is really known about the role or metabolism in the body. Vitamin C can be produced by many animals from glucose. Ascorbic acid is unique in its redox chemistry, and many studies have made erroneous claims as to its function as well as base the research on faulty techniques and experimental design. Many methodologies exist to study vitamins, but they are not without limitations. Separation bychromatography followed by colorimetric assays are often time consuming, and with any absorbance based method may have interference from other compounds. Bioassays can be used as well, but includeproblematic variations due to species, environment, etc. 2. Vitamin needs have increased due to a multitude of factors. Selective breeding and improved genetics have increased yields, growth, and other qualities, so it’s clear that the vitamin need may be changed as well. The growing use of antimicrobials affects the biosynthesis of vitamins within the animal, so those vitamin needs will need to be met by the diet. I think that improved technology overall (breeding, crop varieties, supplements, etc.) has contributed to increased vitamin needs within many species. Addition of vitamins in excess may be a common practice to compensate for factors affecting the nutritional requirement, such as physiological status and presence of vitamin antagonists. 3. Fat soluble vitamins can be easily identified by signs of deficiency and toxicity. Tissue reserves in excess of fat soluble vitamins can lead to toxicity, and often deficiency can be related to vitamin function.Water soluble vitamins are distinguishable because deficiency symptoms are usually correlated to the most limiting vitamin in the diet. Water soluble vitamins do not accumulate in the liver or adipose tissuelike fat soluble vitamins. Instead, they must be supplied constantly by the diet, depending on the species. 4. Vitamin E has antioxidant activity by inhibiting the accumulation of free radicals. Selenium is also partof the natural antioxidant system, but unlike vitamin E, it spares vitamin E and increasing glutathione peroxidase (GPX) activity. Vitamin E deficiency can lead to muscular dystrophy, but a selenium deficiencycan lead to death. Treatment for a vitamin E deficiency involves an injection of vitamin E/selenium, but with selenium it’s important to analyze blood plasma or serum Se for preventative measures.5. The requirement of choline can be affected by levels of folic acid (folacin), vitamin B12, Co, and dietary methionine. The biosynthesis of methionine from homocysteine is reliant on folacin, vitamin B12, and Co. Vitamin B12 is unique in that it is the only vitamin that contains a metal element. 6. Thiamin, riboflavin, and niacin all play important roles in the citric acid cycle. Thiamin pyrophosphate (TPP) is responsible for decarboxylation. Riboflavin has components of active enzymes, called flavoproteins, participate in electron transfer in biological oxidation-reduction reactions. Niacin is an important part of the coenzymes NAD and NADP, which are involved in the citric acid cycle and glycolysis. Pantothenic acid is an important part of coenzyme A and acyl carrier protein, which are imperative in tissue metabolism. Biotin is important in carbohydrate, lipid, and protein metabolism. 7. Thiaminase is an enzyme that can split a thiamin molecule into two parts, rendering it inactive. Niacin can be synthesized in the liver from tryptophan. Avidin binds biotin and is produced in the oviducts of some species. Dietary avidin < biotin can cure or prevent deficiency symptoms. 8. Although Vitamin D is known as the “sunshine vitamin,” it really isn’t an accurate description. Animals in confinement outside may still have deficiencies, and UV light is variable at different locales and seasons. The Ca:P ratio and a variety of physiological factors influence the vitamin requirement to the animal. 9. Vitamin A deficiencies involve nervous system impairment, ocular impairment due to failure of rhodopsin formation, abnormal epithelial cells, and reproductive problems. The problems associated with reproduction are also paired with the failure to maintain normal epithelium. 10. Scurvy can be caused by a variety of disruptions in biosynthesis, such as dietary deficiencies, stress, and temperature. Treatment for inadequate vitamin C usually consists of daily oral supplementation. In ruminant species vitamin C supplementation may not be necessary unless in calves. 11. Several factors are involved with vitamin K and blood clotting. Vitamin K is involved in the post-ribosomal modification of such factors. Gamma-carboxyglutamyl residues chelate calcium ions in the blood clotting mechanism. Use of vitamin K supplementation in animal production is not necessary in some species due to the animal’s capacity to synthesize the vitamin via microbial activity. Vitamin K has a sole unique role of blood coagulation compared to other fat soluble vitamins. 12. The antioxidant effects of some vitamins have been discussed in recent years, especially in their applications to cancer prevention. These vitamins may have a capacity for “catching” free radicals in the body and preventing accumulation in the