Animal Nutrition

• Calorie


  A unit of energy that indicates the amount of energy contained in food. It specifically refers to the amount of heat energy required to raise the temperature of 1 kg (2.2 lb.) of water by 1oC (1.8oF).
• Greater number of Calories in food


  Greater energy it contains
• Nutritional requirements of animals


  • Carbohydrates
  • Proteins
  • Fats
  • Essential Nutrients
• Carbohydrates


  Serve as a major energy source for the cells in the body. Usually obtained from grains, cereals, breads, fruits, and vegetables. Contain 4 Calories per gram.
• Proteins


  Can be used as an energy source but the body mainly uses these as building materials for cell structures and as enzymes, hormones, parts of muscles, and bones. Obtained from dairy products, poultry, fish, meat, and grains. Contain 4 Calories per gram.
• Fats


  Used to build cell membranes, steroid hormones, and other cellular structures; also used to insulate nervous tissue, and also serve as an energy source. Fats also contain certain fat-soluble vitamins that are important for good health. Obtained from oils, margarine, butter, fried foods, meat, and processed snack foods. Contain 9 Calories per gram.
• Essential Nutrients


  • Essential amino acids
  • Essential fatty acids
  • Vitamins
  • Trace Elements or Minerals
• Essential amino acids


  Needed for the synthesis of proteins and enzymes; among the 20 amino acids, 8 could not be synthesized by humans: lysine, tryptophan, threonine, methionine, phenylalanine, leucine, isoleucine and valine.
• Essential fatty acids


  Used for making special membrane lipids; an example is linoleic acid in humans.
• Vitamins


  • Fat-soluble Vitamins A, D, E, K
  • Water-soluble Vitamins B, B2, B3, B12, C
• Trace Elements or Minerals


  • Iodine
  • Cobalt
  • Zinc
  • Molybdenum
  • Manganese
  • Selenium
• Types of endocytosis for food uptake in cells


  • Phagocytosis
  • Pinocytosis
  • Receptor-mediated endocytosis
• Phagocytosis


  Engulfment of organic fragments or big particles, eg. pseudopod formation in Amoeba.
• Pinocytosis


  Uptake of extracellular fluid by a cell using small vesicles derived from the plasma membrane.
• Receptor-mediated endocytosis


  Relies on membrane receptor recognition of specific solutes which are then taken up by the cell via receptor-coated pits.
• Types of animals based on feeding mechanisms

  • Substrate-feeders
  • Filter-feeders
  • Fluid-feeders
  • Bulk-feeders
• Substrate-feeders


  Animals that live in or on their food source. Examples: earthworms that feed through the soil where they live in; caterpillars that eat through the leaves where they live on.
• Filter-feeders


  Include many aquatic animals which draw in water and strain small organisms and food particles present in the medium. Examples: whales and coelenterates.
• Fluid-feeders


  Suck fluids containing nutrients from a living host. Examples: mosquitoes, leeches, head lice, aphids.
• Bulk-feeders


  Eat relatively large chunks of food and have adaptations like jaws, teeth, tentacles, claws, pincers, etc. that help in securing the food and tearing it to pieces. Examples: snakes, cats, man.
• Kinds of digestive compartments in animals


  • Food vacuoles in unicellular organisms
  • Gastrovascular cavity or incomplete digestive system
  • Complete digestive system
• Food vacuoles in unicellular organisms


  These fuse with lysosomes that contain hydrolytic enzymes. Example: food vacuole in a protozoa like Paramecium.
• Gastrovascular cavity or incomplete digestive system


  Composed of a single opening through which food is taken in and where wastes are disposed of; it is a saclike body cavity. Examples: in the cnidarian Hydra and in flatworm Planaria.
• Complete digestive system


  Essentially like a tube with an opening at one end for taking in food (mouth) and an opening at the other end where unabsorbed waste materials are eliminated (anus). In between the mouth and anus, are specialized organs that carry out transport, processing, and absorption of digested nutrients.
• Accessory organs for digestion in a complete digestive system


  • Liver
  • Gallbladder
  • Pancreas
• Liver


  Secretes bile for emulsifying fats.
• Gallbladder


  Stores bile produced by the liver.
• Pancreas


  Secretes enzymes that break down all major food molecules; secretes buffers against HCl from the stomach; secretes the hormone insulin for control of glucose metabolism.