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General Nutrient Requirements

General Nutrient Requirements. Animals eat to acquire specific chemicals and energy. Intake determines level of productivity. Classes of Nutrients. Energy – Common currency for many aspects of animal ecology. Nutrient most often studied by ecologists.

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General Nutrient Requirements

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  1. General Nutrient Requirements • Animals eat to acquire specific chemicals and energy. • Intake determines level of productivity

  2. Classes of Nutrients • Energy – Common currency for many aspects of animal ecology. Nutrient most often studied by ecologists. • Protein – Building blocks for nearly everything in an animal. • Water – Necessary for normal metabolism, thermoregulation, and waste elimination. • Vitamins – Organic molecules required in small amounts for normal metabolism. Part of enzymes. • Minerals – Inorganic materials required for normal metabolism. Various functions in an animal.

  3. Energy • Ability to do work • Necessary for movement, smooth muscle activity (heart, diaphragm, GI tract), and cellular metabolism. • Laws of thermodynamics • Energy cannot be created or destroyed • C6H12O6 + 6 O2 6 CO2 +6 H2O and 686 kcals • Sunlight  Sugar  Fat  Work in animal • Energy transformations produce heat • No chemical reaction is 100% efficient

  4. Energy • Energy measured as: • Calories = energy to raise 1 g water from 14.5 15.5 C • Joules = energy to lift 102 g 1 m in earth’s gravity • 1 calorie = 4.184 joules • Energy content of food (Gross energy) • Carbohydrate = 4.0 kcal/g (50% mass is oxygen) • Lipid = 9.5 kcal/g (10% mass is oxygen) • Protein = 5.5 kcal/g (25% mass O, 16% is N) • Mineral = 0.0 kcal/g

  5. Energy • Gross energy of some foods fed to bears • Deer meat 7.32 kcals/g dry matter • Beef 6.74 • Trout (entire carcass) 5.71 • Squirrel (entire carcass) 5.28 • Blueberries 4.47 • Clover 4.83 • Pine nuts 6.48 • Gross energy of animal material more variable than GE of plant material. Why?

  6. Energy • Animals eat to meet energy requirements • Animals will eat more if they are deficient in energy, subject to physical limitations • Energy intake regulation is remarkably efficient • A 70 kg animal eating 10% beyond energy requirements will gain 10 kg (22 lbs) of fat in a year • If another nutrient is limiting, animals cannot eat more of the same foods; must eat different foods.

  7. R R R R | | | | NH2 – C – C – NH – C – C – NH – C – C – NH2 – C – COOH | | | || | || || H H H O H O O Protein • A component in every part of an animal • Muscle fibers • Enzymes • Structural function (hair, feathers, bone matrix) • Hormones • Transport (hemoglobin, lipoproteins) • Composed of amino acids

  8. Protein 20 amino acids commonly found in animal proteins

  9. Protein • Non-essential amino acids • Animal can make these amino acids from other amino acids or from precursors • Essential amino acids • Animal cannot make these or cannot make them fast enough to meet demand • Arginine, histidine, isoleucine, leucine, threonine, lysine, methionine, phenylalanine, tryptophan, and valine • A concern for monogastric species • Cats require arginine and taurine

  10. Protein • Proteins in the body are continually being lost (hair, skin, feces) or reconfigured • Amino acids recycled, but some daily loss • Thus, animals need amino acids (not protein per se) or precursors in their diet • Some proteins have better amino acid composition than other proteins. Less of these proteins are required to meet an animal’s needs.

  11. Protein Quality • Nitrogen balance of infant Cebus monkeys fed soy and milk proteins (After Ausman et al. 1986, Am. J. Clinical Nutrition 43:112-127)

  12. Protein Estimating requirements difficult because: • Many amino acids can be interconverted • Protein catabolized for energy. • Diet insufficient in energy could result in elevated nitrogen excretion, indicating excess protein • Animals eat to satisfy energy requirements. • Ratio of protein to energy important g protein/100 kj DE • 36 salmon; 19 eggs; 6.3 carrots; 0.8 apple • What happens if diet is deficient in N or a.a.? • Non-protein nitrogen for a.a. production

  13. Protein • Very little wildlife research on a.a. requirements. Nearly all research on protein • Protein measured by measuring N and multiplying by 6.25. Average protein is 16% nitrogen (1 / 0.16) • A couple of problems: • Not all nitrogen is in protein. • The % of a protein that is N varies among proteins • Milk protein is 15.7% N  Conversion factor is 6.37 • Wheat protein is 17.5% N  “ “ 5.70 • Nut protein is 18.9% N  “ “ 5.29 • Study of 90 plants  3.28 to 5.16 Recommend = 4.43

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