L9 Animal Nutrition & Digestion
L9 Animal Nutrition & Digestion ASCI 112
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This 11 page Class Notes was uploaded by Yuran Liu on Saturday May 7, 2016. The Class Notes belongs to ASCI 112 at California Polytechnic State University San Luis Obispo taught by Professor Burroughs in Spring 2016. Since its upload, it has received 8 views. For similar materials see Principles of Animal Science in Animal Science at California Polytechnic State University San Luis Obispo.
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Date Created: 05/07/16
Animal Nutrition & Digestion ASCI 112 11/3 Digestion What does digestion entail 需需? Ingestion (需需) of food Digestion I.e. reduction of complex materials to simple compounds that cells can use. Usually involves a combination or a series of mechanical and chemical processes over time. Mechanical: Chewing Chemical: acids, enzymes Absorption (需需) across digestive tract walls to the bloodstream, and then across cellular membranes. (Needs ATP) Elimination of solid wastes – primarily undigested food and sloughed digestive tract cells. Nutrition Is the science of understanding how animals and people convert foods to their chemical components (nutrients), and use (metabolize) them for maintenance, growth, and production. Six types of nutrients Proteins Organic 需需需 has a carbon based core Major classes Essential (can’t be synthesized internally) (must eat to obtain) Non-essential (can be synthesized from amino acids) (需需需需需) Uses Structures (muscle) Biochemical processes (enzymes 需需 speed up reaction) Energy (less net than carbohydrates & fats) Mainly constructed from C-H-O-N, with lesser amounts of S & P Carbohydrates Organic Major classes Monosaccharides 需需 Disaccharides 需需 Polysaccharides 需需 Digestible (alpha bonded) – starch, glycogen Indigestible (to eukaryotes; beta bonded) – cellulose 需需需需需需需需需需, hemicellulose 需需需需 需需 需 bonded 需需需需需需需需需需需需 Cows don’t digest cellulose; the microorganisms in cows’ gut (bacteria) digest cellulose. Uses Fuel (energy) - monosaccharides Molecular skeletons (ex. Ribose, deoxyribose) Plant cell walls (beta-glucose) Lipids (fats/oils) Organic Major classes Fatty acids Saturated 需需 Unsaturated 需需需 Phospholipids Steroids Uses Fuel (energy) 2.5x more energy per gram than carbohydrates (because fats have more hydrogen and less oxygen) Animal cell membranes Vitamin storage (Vitamin A, D, E, K) fat soluble vitamin Vitamins Organic Major classes Fat soluble (A, D, E, K) (can be stored in fat) Too much or not enough can cause problems. Water soluble Uses Catalysts (需需需) in biochemical reactions Many regulatory functions Animals vary in their dietary requirements for vitamins. This may be related to the kinds and numbers of microorganisms in their digestive tract (many of which are capable of synthesizing one or more of the vitamins) Some vitamins require activation. Minerals Inorganic (not made of C & H) Major classes Macro-Minerals (needed in abundance) 需需需需 Micro-Minerals (needed in small amounts) 需需需需 Uses Physical structures Catalysts in biochemical reactions Some minerals can interact Interference (需需)/antagonism (需需) Synergy (需需) Vitamin-Mineral Interactions Example: Vitamin & Selenium Deficiency of either leads to “white muscle disease” in some animals Nature of the relationship is still uncertain Water Inorganic Uses Transport medium (需需) Chemical reagent (需需需) Temperature regulation Cow’s example: Drink more, eat more. Essential nutrients Nutrients that are 1)required, but 2) cannot be synthesized (manufactured) in the body Examples Carbohydrates None identified Amino acids 8 identified, include phenylalanine, lysine Fats 2 identified, linoleic acid (需需需) and alpha-linolenic acid (α-需需需) Vitamins 13 identified, include Vitamin A and Vitamin B Minerals Macro – all required (Ca, Mg, P, K) Micro – some debate continues, but 6 are often named (Fe, Zn, Cu, I, Se, Mo) Main uses of nutrients Maintenance Energy and components sufficient to support the baseline physiological functions of an animal at its present size. Homeostasis Growth Additional energy/components needed to increase an animal’s size at some rate (lbs./day, for instance) feed conversion ratio 需需需需需需需需需需需需需 Work/Production Additional energy/components needed to support greater physiological functions of an animal than are needed for maintenance or growth at its present size. Lactation (需需需) Strenuous physical exertion (需需需需) Immune system responses Balancing Energy Net Maintenance Growth, Production, Work Gross Energy 需需 Digestible Energy Metabolizable Energy Usable energy Net Energy Energy System Digestive Systems & Basic Anatomy ASCI 112 11/10 Modes of feeding Continuous feeders (Spend most of the time eating) Examples Blue whale (No teeth but baleen 鲸鲸) Also grazing animals (鲸鲸鲸鲸) Most common in animals that consume either or both Low quality foodstuffs (like grasses) Foodstuffs that are scattered (鲸鲸) in small quantities across large areas. Discontinuous feeders (meal eaters) Example Eagle Most common in animals that Eat high quality foodstuffs (like fruit, eggs, or other animals) Eat foodstuffs that are commonly available in bulk Diets Herbivore (鲸鲸鲸鲸) Carnivore (鲸鲸鲸鲸) Omnivore (鲸鲸鲸鲸) Insectivore – insects (鲸鲸鲸鲸) Frugivore – fruit (鲸鲸鲸鲸) Mucivore – mucus/sap (鲸鲸鲸鲸) Granivore – seeds (鲸鲸鲸鲸) Ossivore – bone Piscivore – fish (鲸鲸鲸鲸) Ovivore – eggs Detritivore – dead stuff (鲸鲸鲸鲸) Folivore – leaves (鲸鲸鲸鲸) Fungivore – fungi (鲸鲸鲸鲸鲸) Planktivore – plankton (鲸鲸鲸鲸鲸鲸鲸) Sanguivore – blood Even though zoologists have categorized animals according to their main dietary preferences, this does not mean that these types of foods are all they eat. Harvesting equipment Ruminant Examples: cattle, deer, sheep, goats, elk, antelope No cutting teeth. Molars (鲸鲸) are adapted for grinding grasses and similar plants. Have lower incisors (biting teeth) (鲸鲸) but not upper incisors. Instead they have a “dental pad.” (firm thick pad of gum-like material) Omnivore mammals Examples: bear, pig Incisors in the front, canines (鲸鲸)/cuspids and grinding teeth (molars) in the rear. Herbivore Example: horse (grazers) Have incisors teeth on both upper and Cow鲸grazer鲸 lower jaws Especi al long grinding teeth Carnivores Examples: red fox, lion, dolphin Molars on the fox and lion could be used for crushing/grinding some plant matter, but they are sharper and more jagged (鲸鲸鲸) than those possessed by herbivores. Dolphins and many other carnivorous cetaceans (鲸鲸鲸鲸) mainly use their teeth simply for catching things (fish, squid, etc.) Their teeth are conical (鲸鲸鲸) in design. 鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸 Digestive tracts – Compared Same basic components: gastric stomach, small intestine, large intestine (with the cecum (鲸鲸) at the beginning of it) Compared in volume/length from simplest and smallest to most complex and longest Carnivores 鲸 Omnivores 鲸 Herbivores Cecum 鲸鲸鲸鲸鲸 microbiofermotation Where bacteria can hang out in the lower digest tract, and undigested plant fibers tend to collect The place where can find bacteria living on plant materials Will find microorganisms living through the large intestine Herbivorous animals have the largest cecum. ruminants | fore-gut fermenters: rumen, reticulum, omasum, abomasum Anatomy of the digestive tract Mouth Captures food Physical breakdown (mastication) (鲸鲸) Salivary amylase (鲸鲸鲸鲸鲸) 鲸鲸enzyme Esophagus Transfers food to stomach (and in some, vice versa) (鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸鲸 鲸鲸) Birds have a large pouch in the esophagus called the “crop” (鲸鲸鲸) which is used to store food in. Ruminants have a large storage tank at the base of the esophagus called the “reticulo-rumen” (鲸鲸) that they use for microbial fermentation of their food. Stomach Initial chemical degradation HCI Pepsin (鲸鲸鲸鲸) Small intestine Continued chemical breakdown Bile (鲸鲸) Fat emulsification (鲸鲸) Pancreatic NaHCO ne3tralizes chime (鲸鲸鲸鲸鲸鲸) Enzymes Nutrient absorption villus 鲸鲸鲸: increase potential absorption for food Large intestine Parts Cecum (鲸鲸) Colon (鲸鲸) Rectum (鲸鲸) Anus 鲸鲸 Functions Absorbs water, salts, water-soluble vitamins, and some other “small” molecules (incl VFAs). NOT protein. (large molecules) Collects waste for elimination In many herbivores and omnivores (to a lesser extent), microbial fermentation (鲸鲸鲸鲸鲸) of plant fiber and other materials indigestible to the animal (raffinose) (鲸鲸鲸) occurs in the cecum and colon. Volatile fatty acids (鲸鲸鲸鲸鲸鲸) are excreted as waste products by bacteria, which some animals can recover energy from. Special case of herbivores None produce the enzymes needed to break down β-bonded cellulose and hemicellulose. Therefore herbivores, particularly those that live on plant structures like leaves and young twigs, must find ways to let cellulase (鲸鲸鲸鲸)- producing bacteria do that work for them. (including insects, like termites (鲸鲸)) Common herbivore strategies Foregut systems Ruminant Camelids (鲸鲸) Hoatzin (鲸鲸) Hindgut systems Caecal/colonic fermenters Equines, elephants, hippos, rhinos, etc. (mostly big or very big animals) Copraphagy Many rodents (鲸鲸鲸鲸鲸) – some recovery of nutrients (mostly protein) lost to intestinal digestion/absorbtion Caecotrophy Lagomorphs (鲸鲸鲸鲸) – partitioning of feces into “waste” and “recycle” forms. Increases protein recovery efficiency. Anatomy of the ruminant digestive tract (foregut system) Rumen (鲸鲸) → Reticulum (鲸鲸鲸) → Omasum (鲸鲸鲸) → Abomasum (鲸鲸) Camels are plumbed the same, except they have no omasum. A note on herbivore digestion – VFA Microbes break cellulose down in order to use it for their own energy and protein formation. Their herbivore hosts must live on their leftovers/wastes. 鲸鲸鲸鲸鲸鲸VFA Among the waste products of microbial cellulose fermentation are “volatile fatty acids” (VFAs) The liver can convert VFAs to glucose, fatty acids, and other usable energy currencies. So herbivores must collect and cycle VFAs through the liver in order to cash them in. Hindgut 鲸鲸鲸鲸 fermenters 鲸鲸鲸 Like ruminants, hindgut fermenters recover VFAs produced by microbial fermentation of cellulose. Then they are transported to the liver, where they are converted into glucose and fatty acids. Foregut fermenters absorb VFAs through the rumen. Hindgut fermenters absorb VFAs through the cecum/colon. Unlike ruminants, most microbial protein is lost because there are no enzymes available past the small intestine for breaking proteins down, nor can they, or other large molecules, be absorbed from the large intestine (this is another benefit of copraphagy & cecotropy) Avian 鲸鲸鲸 digestive tract Esophagus Thin-walled and highly folded. Larger than in mammals. Food often swallowed in large pieces. The crop (鲸鲸鲸), which is an “outpouching” of the esophagus, stores foods for later processing or sharing with young. Stomach Has two parts, which are just thin-walled sacs in carnivorous species Proventriculus (i.e. “before the ventriculus”) Glandular, producing both acid and enzymes Ventriculus (“Gizzard” 鲸鲸) Muscular part of the stomach Grinds food into smaller particles for digestion Large in herbivorous, garnivorous species Small intestine Main organ of digestion and absorption. Receives pancreatic secretions of Bicarbonate (鲸鲸鲸鲸) Proteases (鲸鲸鲸) Amylase (鲸鲸鲸) Lipase (鲸鲸鲸) Receives liver secretions of Bile salts Ceca (鲸鲸鲸鲸) “Blind” pouches at junction of small and large intestines Site of microbial fermentation Vitamin production Nitrogen conversion to protein by microbes, with some absorption across cecal walls Involved in re-absorption of water and salts Birds have two paired ceca instead of a single cecum. Large intestine (colon) Absorbs water and stores feces Cloaca Fecal exit
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