Session 1 intro__books___and_digestive_s


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Session 1 intro__books___and_digestive_s

  1. 1. VTS 150 Animal Nutrition Fall 2013 Beth Alden, DVM Instructor
  2. 2. Course Objectives  Identify the components of the digestive systems of common companion animals  Identify the nutritional needs of common companion animals  Correctly calculate the caloric needs of companion animals  Correctly evaluate a pet food label and ingredients  Identify common toxins for companion animals
  3. 3. Resources for Class  Textbook:  Nutrition for Veterinary Technicians and Nurses, Ann Wortinger,  Blackwell Publishing, 2007
  4. 4. Resource for Class  Case Studies in Veterinary Technology  Authors Jody Rockett and Chani Christensen  Students will be required to complete assigned case studies and turn them in
  5. 5. Resources on Library Reserve Small Animal Clinical Nutrition 4th Edition, Hand,Thatcher, R emillard, Roudebush, The Mark Morris Institute, 2000
  6. 6. Students requirements  Exams  Discussions  Toxin project  Case studies  Final project
  7. 7. Classification of Digestive Systems
  8. 8. Digestive System  Connects animals diet with metabolic needs  A muscular tube from mouth to anus grinding, mixing, moving and absorbing nutrients  Glands manufacture secretions that are added to the tube to assist in digestion  Ruminants harbor bacteria in the digestive tract that assist in digestion and synthesis of essential nutrients  All animals have microbes in the digestive tract that assist in digestion, veterinarians are harnessing their power as nutracueticals ( beneficial bacteria administered to animals)
  9. 9. Diet and digestive tract  Herbivores – plant eaters  Carnivores- meat eaters  Ominivores- plant and meat eaters  Insectivores – insect eaters  Frugivore – fruit eaters ( many species eat fruit as part of their diets, these animals eat only fruit like some bats)
  10. 10. Digestive tracts  The anatomy of the digestive tract is designed for the type of food the animal utilizes  Carnivores have short digestive tracts that hold a small volume of food  Herbivores have large digestive tracts that hold a large volume  Insectivores and frugivores have digestive tracts that are designed for that diet
  11. 11. Herbivores vegetation, nitrogen source, minerals and water Difficult to digest, large complex gut is needed - Plant cell walls are hard to break down - Cellulose is the storage form of the plants glucose - Microbes in the gut break down the cellulose and utilize the glucose to make their energy and volatile fatty acids ( butyric, proprionic and acetic acid) - The animal utilizes these volatile fatty acids - Very little of the food’s energy is actually absorbed
  12. 12. Carnivores  Animal material ( flesh, muscle etc) makes up the diet  More easily digested than herbivore diet  GI tract is basically a simple tube  Most of the food energy is utilized and absorbed  Mechanical breakdown of food is less involved
  13. 13. Digestive system types  Monogastric - One “true” stomach ( dogs, cats, pigs, horses)  Ruminant - Four compartment stomach - Rumen, reticulum, omasum, abomasum - Cows, sheep, goats
  14. 14. Types of Digestive Systems
  15. 15. Monogastric Stomach  Five sections - Cardia - Fundus - Body - Antrum - Pylorus
  16. 16. The Monogastric Stomach 1. Cardia  Area immediately surrounding the opening from the esophagus into the stomach  Muscular tone prevents reflux of stomach contents into the esophagus Source: University of California at Davis CARDIA
  17. 17. The Monogastric Stomach 2. Fundus  Located below the cardia  Blind pouch that distends as food is swallowed Source: University of California at Davis FUNDUS CARDIA
  18. 18. The Monogastric Stomach 4. Antrum  Grinds up food and regulates HCl  Also contains glands BODY Source: University of California at Davis FUNDUS CARDIA BODY ANTRUM G Cells: Gastrin Mucous Cells: Mucus
  19. 19. The Monogastric Stomach 5. Pylorus  Muscular ring (sphincter)  Regulates movement of chyme from stomach into duodenum  Helps prevent backflow of duodenal contents BODY Source: University of California at Davis FUNDUS CARDIA BODY ANTRUM PYLORUS DUODENUM
  20. 20. Ruminant Animals
  21. 21. Ruminant  Chews food briefly and swallows  Regurgitates “cud” to chew again and swallow ( vital to help break down cellulose)  The stomach is designed to allow this regurgitation and swallowing, plus the action of microbes on the diet ( four compartment stomach)
  22. 22. The Ruminant Stomach  Four Compartments: Reticulum Rumen Omasum Abomasum Source: University of California at Davis head tail
  23. 23. Source: University of California at Davis head The Ruminant Stomach 1. The Reticulum  Smallest, most cranial compartment  Separated from rumen by the ruminoreticular fold  Muscular wall is continuous with the rumen; contract in coordination tail RETICULUM
  24. 24. The Ruminant Stomach 1. The Reticulum  Honeycombed inside to increase absorptive surface  “Hardware disease”- wires or nails swallowed by animal puncture wall of reticulum Inside of Reticulum Source: Colorado State University RETICULUM
  25. 25. The Ruminant Stomach 2. The Rumen  Large fermentative vat (40 - 50 gallon capacity)  Processes plant material into usable energy  Lined with “Papillae”  Made up of series of muscular “Pillars” Source: University of California at Davis head tail RUMEN
  26. 26. The Ruminant Stomach © University of Bristol, 1988 Pillar PapillaePapillae
  27. 27. Cow Digestive System
  28. 28. The Ruminant Stomach The Rumen During contractions, pillars close off certain sacs of the rumen which allows mixing of rumenal contents Mixing of contents essential for fermentative function of rumen RUMEN
  29. 29. Rumen continued  During contractions, pillars close off certain sacs of the rumen which allows mixing of rumenal contents  Mixing of contents is essential for fermentation in the rumen  Fermentation breaks down the nutrients for the microbes and the animal and produces vitamins B and K  Carbon dioxide and methane are the byproducts of this process
  30. 30. Reticuloruminal contractions  Allow “cud” to be regurgitated into the esophagus and into the mouth where it is re- chewed and re-swallowed ( helps break down this difficult to digest diet)  Allows “eructation” of built up carbon dioxide and methane gas in the rumen. Gasses are forced into the reticulum and up the esophagus  Interference with eructation leads to bloat which can be deadly
  31. 31. Fermentative digestion  Begins in the rumen  Bacterial, protozoal and a small amount of fungi utilize their enzymes to begin breaking down food  The microbes utilize the energy in the diet to grow and reproduce
  32. 32. Carbohydrate metabolism  Cellulase enzymes digest cellulose and transform the complex carbohydrate into simple sugars  These simple sugars are not available to the host animal ( like they are in monogastric animals) instead they are absorbed and utilized by the microbes which produce Volatile Fatty Acids ( VFA’s)  The host animal utilizes the volatile fatty acids
  33. 33. Carbohydrate Metabolism Continued  Volatile fatty acids are the byproducts of anaerobic fermentation by microbes in rumen  Anaerobic fermentation means it does not utilize oxygen  Some of the VFA’s are utilized by the ruminant to produce glucose  Other VFA’s are used to produce adipose tissue and milk fat
  34. 34. Protein Metabolism  Rumen microbes digest proteins just like carbohydrates  Proteases ( enzymes) reduce long proteins to amino acids ( the building blocks of proteins) and short chain peptides ( short chains of amino acids)  Peptides are either incorporated into the protein structure of the microbes OR converted to ammonia ( NH3+) and VFA’s
  35. 35. Protein Metabolism Continued  Liver secretes urea into the rumen, this provides the rumen microbes with additional nitrogen ( the rest of the nitrogen they get from digesting the proteins in the diet)  Microbes get flushed from the reticolorumen to the omasum, abomasum and intestines where they serve as an additional protein source for the host animal  Urea is sometimes added to poor quality feeds to meet the nitrogen needs of the animal
  36. 36. Other rumen notes  Microbes provide B vitamins, and vitamin K  The rumen environment is a delicate balance of food, microbial growth and by-products  Abrupt changes in diet severely affect the production of methane, CO2, VFA’s and ammonia causing fermentation and changes in rumen ph
  37. 37. The Ruminant Stomach Omasum  Muscular organ located off the reticulum  Ingesta moves into omasum from reticulorumen  Prevents large particles from leaving rumen and entering abomasum OMASUM Source: University of California at Davis head tail
  38. 38. Omasum primary functions  Break down food particle further and move them into the abomasum  Absorb any excess VFA’s  Remove bicarbonate ions from ingesta ( to avoid altering acid ph of abomasum)  Bicarbonate ions come from the saliva ( ruminants produce a huge amount of saliva which goes into the rumen to help buffer ph)  If saliva flow is blocked by a foreign object or lack of production, the animal can become severely acidotic ( remember VFA are ACIDS)
  39. 39. The Ruminant Stomach Abomasum  “True stomach” of ruminant  Functions similar to monogastric stomach ABOMASUM Source: University of California at Davis head tail
  40. 40. Young Ruminant Digestive Tract  Functions as a monogastric stomach  No fermentative digestion ( rumen and reticulum are non functional)  Reticular groove or esophageal groove forms when suckling and allows milk to go directly to omasum  Bucket fed calves don’t form this groove and milk spills into the rumen and reticulum
  41. 41. Young ruminant continued  Abomasum is largest of 4 stomachs for the first few weeks of life  Rumen and reticulum development rate depends on diet  - grain and hay fed- develops at 3 weeks  - milk fed develops at 3 months  Veal calves are fed milk for their entire short lives to produce a very tender soft meat,
  42. 42. Digestive System Chronology  GI tract extends from mouth to the anus and performs different functions at different sections 1. Prehension 2. Mechanical grinding down of food 3. Chemical digestion of food 4. Absorption of nutrients and water 5. Elimination of waste material
  43. 43. Prehension  Grasping with teeth or lips  Cows do not have upper incisors, they have a toothless area called a dental pad  Cows use the bottom incisors and dental pad to bite grass  Dogs, cats have sharp tearing teeth to rip flesh
  44. 44. Mechanical grinding down of food  Carnivores have pointed teeth to facilitate holding and tearing of food  Herbivores have flat surface molars that grind from side to side to break down plant material ( watch a rabbit chew, horses, cattle chew the same way)  horses form sharp edges ( points) on their molars that have to be filed down from time to time ( floating the teeth)
  45. 45. Chronology of Digestion: Mechanical Grinding Down of Food Carnivore Teeth Pointed to facilitate holding and tearing of food © Clinical Textbook for Veterinary Technicians 6th ed.; McCurnin, Bassert
  46. 46. Chronology of Digestion: Mechanical Grinding Down of Food Incisors – Teeth in the front for holding and tearing Canines – Pointed teeth located at corners for tearing and shredding Premolars – Located just before the molars and are used for grinding in all species Molars – Used for grinding
  47. 47. Chronology of Digestion: Mechanical Grinding Down of Food Herbivore Teeth Flat, occlusal surface for grinding
  48. 48. Ruminant Teeth No upper incisors or upper canine teeth Chronology of Digestion: Mechanical Grinding Down of Food Dental Pad Thick connective tissue Diastema
  49. 49. Teeth terminology  Maxilla – upper jaw  Mandible- lower jaw  Lingual- inner side of lower arcade of teeth that face the tongue  Labial- outer surface of upper and lower arcade teeth that face the lips  Palatal- inner side of upper arcade teeth that face the palate  Buccal- outer side of teeth on sides of mouth that face the cheeks
  50. 50. Canine Triadan Numbering
  51. 51. Canine Dental Formula  Triadan
  52. 52. Feline Triadan Numbering
  53. 53. Feline Dental Formula Triadan
  54. 54. Chemical digestion of food  Saliva mixes with food during chewing  Three pairs of salivary glands located bilaterally ( one on each side)  Parotid (2), mandibular(2), lingual (2) salivary glands  Saliva 1. moistens, softens, shapes and lubricates food 2. Aids in taste, acts as a buffer 3. Provides digestive enzymes
  55. 55. Chemical Digestion of food continued  Digestive enzymes and buffers in saliva 1. amylase- in omnivore saliva, not present in carnivores, breaks down amylase a sugar component of starch 2. Lipase- breaks down lipids 3. Bicarbonate and phosphate buffers- in cow saliva, neutralizes acids in rumen and maintain normal rumen ph ( up to 25-30 gallons of saliva a day)
  56. 56. Chemical Digestion of food continued  Food moves from mouth to pharynx where the epiglottis prevents food from entering the trachea  Food is transported into the esophagus  Esophagus utilizes peristalsis, rhythmic contractions to propel food to the stomach
  57. 57. Chemical digestion of food  Stomach 1. Stores food 2. Continues enzymatic breakdown of food ( pepsin, gastrin, mucus, hydrochloric acid all play a role) 3. Mechanical breakdown of food, mixing, grinding, contractions that move food 4. Ruminants have specific compartments with different functions ( rumen, reticulum, omasum, abomasum)
  58. 58. Chemical Digestion continued  Liver- secretes bile acids to help with digestion of fats, keeps the fats in solution  Pancreas- secretes enzymes into small intestine for breaking down nutrient 1. Protease for proteins 2. Amylase for carbohydrates 3. Lipase for fats/lipids 4. Bicarbonate to neutralize stomach acid
  59. 59. Absorption of nutrients and water  Small intestine consists of three parts, duodenum, jejunum and ileum  Continues peristalsis  Villi and microvilli increase surface area for absorption  No clear demarcation between three segments  All 3 segments perform peristalsis, absorb nutrients and water
  60. 60. Small Intestine  Duodenum- first portion of the small intestine receives contents of stomach  Jejunum- majority of small intestine  Ileum- where small intestine enters the colon ( the cecum is located at this junction)  Cecum is very small in carnivores and large in herbivores like horses
  61. 61. Villi  Villi- - millions of cylindrical fingerlike projections from the intestinal wall - Provide large surface area for absorbing nutrients - Crypts surround villi and replenish the cells that cover the villi
  62. 62. Microvilli  Microvilli - Brush border, extensions of the surface of the cells that cover the villi - Increase the surface area of the cells and the absorptive capacity - Contain digestive enzymes - Clinical example TGE transmissable gastroenteritis in pigs and parvovirus in dogs attack and destroy the villi preventing absorption of nutrients from the intestinal tract
  63. 63. Functions of Small Intestine  Small intestine absorbs electrolytes ( Na, Cl, K, etc) water, and vitamins  Absorbs carbohydrates, fats, proteins after chemical digestion via enzymes
  64. 64. Nutrient digestion in the small intestine  Carbohydrates- digested by amylase secreted from the pancreas  Proteins- digested by proteases secreted by the pancreas  Fats- digested by bile acids from liver ( helps emulsify fat ( keep in solution), further broken down by lipase secreted from pancreas
  65. 65. Elimination of Waste Material  Large intestine: cecum and colon - Recover fluid and electrolytes - Store feces until elimination - Some microbial action - Differences between species dependent on diet
  66. 66. Elimination of Waste material  Carnivores - colon- simple, tubular, contracts to move feces through - Cecum “ blind sac” poorly developed  Herbivores - Colon – large bacterial population of microbes for fermentation - Cecum “blind sac” more developed, larger than carnivore
  67. 67. Colon  Colon in carnivore is much smaller than in herbivores  Responsible for reabsorbing water and electrolytes
  68. 68. Elimination of Waste in herbivores such as horses  Colon and cecum comprise the “Hindgut”  4 sections, cecum, ventral colon, dorsal colon, small colon  More highly developed than small intestine  Has greater capacity for fermentation  Unique digestion path- colonic impaction is most common form of colic in horses
  69. 69. Equine Digestive System
  70. 70. Rectum and Anus  Rectum - Terminal portion of colon - Contains mucus secreting glands - Sensory receptors detect stretching/distension and triggers defecation  Anus - Internal and external sphincters allow controlled passage of feces
  71. 71. Next Week… Session 2: Basic Nutrients