Thiamine

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  • Created by: faqihah21
  • Created on: 15-05-24 15:23
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  • Thiamine
    • Functions of thiamine
      • Oxidative decarboxylation reactions (CHO metabolism)
        • essential role in deCO2 of alpha-keto acids
          • Pyruvic acid depend on deCO2 to convert into Acetyl CoA
          • a-ketoglutarate depend on deCO2 to convert into succinyl CoA
        • essential in the TCA cycle
      • pentose phosphate pathway
        • only mechanism for ribose synthesis
      • essential role in neurophysiology
        • independent of its co-enzyme function
        • could synthesize fatty acids, neurotransmitter or Na transport
        • CHO metabolism
    • functional form is thiamine pyrophosphate
    • requirements
      • difficult to determine in ruminants, horse can absorb 25% from large intestine and supplement for monogastric
        • requirement for ruminants - 1-2 mg/kg feed. cereals are rich source of thiamine 2mg/kg. dried brewer yeast >90 mg/kg
        • not deficient = microflora synthesis + whole grain based feeds
      • influence by diet composition and metabolic status - more CHO, more thiamine requirement. Fats and proteins - thiamine sparing
      • proportional to size and age
        • small hens - more than large breeds
        • older animals have more requirement
    • Deficiency
      • beri-beri in humans
      • polyneuritis in poultry
        • muscle paralysis reflexed legs and head back
        • Pigs - reduce feed consumption, body weight gain and vomiting
      • anorexic
      • late stage deficiency = neurophysiological problems (common in all mammals)
        • Thiamine responsive condition
          • Cerebcorticonecrosis (CCN) in UK
            • Development
              • Polioencephalomalacia (PEM) in USA
              • have lesions in both cerebral hemispheres
              • acute and mild form
              • give thiamine treatment for recovery
              • low thiamine margin - reduce thiamine in tissue and high circulating lactate and pyruvate
                • acidosis/low rumen pH
              • potentiated by thiaminases in diet (thiamine antagonists that inhibit thiamine activity)
                • high level of thiaminases = thiamine deficiency
          • Polioencephalomalacia (PEM) in USA
          • affect young ruminants - 4 months, 2 years old in sheep and goats 2-7 months
          • Symptoms
            • neck flexing, spasms, blindness, convulsions then death
      • require CHO for CNS metabolism
      • Young ruminants
        • weakness, uncoordinated, arrhythmia and possible death
  • Thiaminases - compete with thiamine
    • found in raw fish or moldy food
    • requirements
      • difficult to determine in ruminants, horse can absorb 25% from large intestine and supplement for monogastric
        • requirement for ruminants - 1-2 mg/kg feed. cereals are rich source of thiamine 2mg/kg. dried brewer yeast >90 mg/kg
        • not deficient = microflora synthesis + whole grain based feeds
      • influence by diet composition and metabolic status - more CHO, more thiamine requirement. Fats and proteins - thiamine sparing
      • proportional to size and age
        • small hens - more than large breeds
        • older animals have more requirement

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