[AGRI 21 LEC] ANIMAL NUTRITION 1

• Nutrition


  Science of transformation of nutrients in the diet into body tissues
• Nutrient


  Substances that, when taken into the digestive system, are digested, absorbed and utilized to sustain animal body processes
• General functions of nutrients

  • Provide energy for various processes in the body
  • Supply raw materials for synthesis of body substances
  • Serve as structural component
  • Regulate body temperature
  • Act as coenzymes/cofactors
• Classification of animals based on type of digestive system


  • Non-ruminants or monogastrics (swine)
  • Modified simple-stomach animals (poultry species)
  • Herbivorous monogastrics (hindgut fermenters) (horse, rabbit)
  • Ruminants or compound-stomached animals (foregut fermenters) (cattle, carabao, sheep, goat)
• Water


  Found in the animal body as intracellular water, extracellular water, and water present in urinary and gastro-intestinal tract
• Primary functions of water


  • Aid in digestion
  • Nutrient transport
  • Waste excretion
  • Temperature regulation
• Sources of water

  • Drinking water
  • Feed component
  • Metabolic water
• Water losses from the animal body

  • Urine
  • Feces
  • Vaporization from lungs
  • Skin surface
  • Milk (for lactating animals)
• Effects of water deficiencies or restrictions


  • Reduced feed intake
  • Weight loss due to dehydration
  • Increased secretions of nitrogen and electrolytes such as Na and K
• Differences in water requirements due to

  • Environment, age, diet, activities, etc.
  • Nature of nitrogenous end-products of protein metabolism
• Mammals excrete urea through urination (ureotelic), requiring large amounts of water to dilute urea
• Birds have lower water requirement as they excrete uric acid in nearly solid form (uricotelic)
• Fishes mostly excrete ammonia directly from gills (ammonotelic), having low water requirement
• Carbohydrates


  Polyhydroxy aldehydes or ketones, C, H, O, most abundant biomolecules on Earth, ~75% of plant dry matter, only <1% in animal body, main CHO in feeds: starch, cellulose, hemicelluloses

  
• Monosaccharides


  • Pentoses (ribose, xylose, arabinose)
  • Hexoses (fructose, glucose, galactose, mannose)

  
• Classification of carbohydrates based on number of sugar molecules


  • Monosaccharides
  • Disaccharides (sucrose, lactose, maltose, cellobiose)
  • Oligosaccharides (raffinose, stachyose, verbascose, fructotriose, maltotriose, maltotetraose)
  • Polysaccharides (starch, glycogen, cellulose, hemicelluloses, pectins, glycolipids, glycoproteins)

  
• Starch


  Homopolysaccharide, main storage carbohydrate in plants

  
• Glycogen


  Temporary storage carbohydrate in animal tissues
• General functions of carbohydrates


  • Source of energy
  • Components of genetic materials DNA and RNA
  • Stored energy in the body as glycogen and fats
  • Involved in cellular communication