8/29/2014 1 Course Outline Introduction, Overview of Industry I. Nutrient Analysis II. Digestive Tract Anatomy / Function - Anatomy - Digestive enzymes III. Classes of Nutrients Classification based on site of fermentation Class Species Dietary Habit Hind gut fermentors Cecal fermentors Colonic digestors Rat Rabbit Horse Pig, human Dog cat Omnivore Selective herbivore Grazer Omnivore carnivore Pregastric fermentors Ruminants Nonruminants Cattle, sheep, deer Colobine monkey, hamster, kangaroo, hippo Herbivore Herbivore More general term is ruminant and non-ruminant (monogastric)8/29/2014 2 Classification based on diet: birds Carnivore Faunivore Macrofaunivore: carnivore (mammals) piscivores (fish) Microfaunivore: insectivore crustacivore molluskivore planktonivore Hawk Pelican Swallow Penguin Kiwi Flamingo Herbivore Florivores Nectafivore (nectar) Frugivore (fruit) Granivore (grain) Graminivore (grass) Folivore (leaves) Leaves, buds, grasses Hummingbird Toucan Sparrow Ostrich Hoatzin Geese, grouse, duck Omnivore Generalist feeder Quail, crows, pheasants Classification based on diet: Primates • Frugivore (fruit): orangutans • Folivore: leaf eating monkey • Insectivore: Tarsiers (also eat snakes, lizards) • Gumminivore (sap and gums): tammarins and marmosets • Omnivores: most species (diet includes other mammals) Rainbow Trout (carnivore) Catfish (omnivore- animals) Carp (omnivore-plants) Milkfish (microphagous Planktove, plankton) Fish Digestive Tract Anatomy8/29/2014 3 General aspects of digestive tract anatomy in non-ruminants Primary Components Sub-regions Accessory organs Mouth Pharynx Esophagus Teeth Salivary glands Liver Gall bladder pancreas Stomach Esophogeal Cardiac Body or corpus pyloric Small intestine Duodenum Jejunum Ileum Large intestine Colon Cecum Rectum Digestive capacities (% of total) Animal Large Intestine Small Intestine Stomach Cow 70 19 11 Sheep 67 21 12 Horse 8 26 66 Pig 30 33 37 Dog 63 23 14 Cat 69 15 16 Human 17 67 178/29/2014 4 Red (ruminants) b g i, j k, l Eland giraffe Buffalo, bison camels Blue (hindgut, colonic fermenters) a, b, c g, h I, j, k Zebras Elephants (africa, asia) rhinos Yellow (foregut fermenters) 1 2, 3, 4 Red kangaroo Hippos on different forages Cell Wall Digestibility and Fiber Retention Time The Pig _________________________________________ Large Intestine (16’, 2 gal) Cecum (10”, 0.5 gal) Small intestine (60’, 2.5 gal) Stomach (2 gal) Esophagus Mouth Human Digestive Tract8/29/2014 5 Horse Digestive Tract: • Stomach and small intestine are structurally similar to the pig or human. • Horses do not have a gall bladder. Bile is continuously secreted into the duodenum. • Fermentation occurs in the cecum and colon (similar to what happens pre-gastrically in the ruminant). • VFA are produced and absorbed. These provide a major portion of the energy needed by the animal. • Microbial protein produced in the hind gut, but the resulting amino acids are not absorbed. • Water soluble vitamins ??? The Horse _________________________________________ Large Colon (12’, 19 gal) Cecum (4’, 8 gal) Small intestine (70’, 12 gal) Stomach (3.5 gal) Esophagus Mouth Small Colon (12’, 3 gal) Digestive Tract of the Horse8/29/2014 6 Avian Digestive Tract: • Anatomical differences: – Crop = temporary storage of food – Proventriculus = secretes HCl and pepsinogen (true stomach) – Gizzard = muscular organ, grinds food. • Passage rate is faster than in mammals. • Fermentation occurs in the colon and cecum, but no nutrients are absorbed. Mouth Esophagus Crop Small intestine Liver Proventriculus Gall Bladder Gizzard Pancreas Ceca Large intestine Cloaca Vent Digestive Tract Anatomy and Function • Anatomy: – Species differences • Function – Stomach – Small intestines8/29/2014 7 Pig Stomach Stomach Cell Types: Parietal Cell fundus and body HCl and intrinsic factor (B-12 absorption) Chief fundus and body pepsinogen (protease) G- cells antrum gastrin (hormone) Goblet cells fundic, cardiac, phyloric secrete mucin (protective secretion) Gastric Secretions Exocrine cells (parietal, chief, Goblet cells) - Release secretions of water, hydrochloric acid (HCl), digestive enzymes, mucus, intrinsic factor - Forms gastric mucosal barrier Endocrine cells (G cells) - Release hormones into blood Phases of Gastric Function • Cephalic – Anticipation, seeing, smelling food – Stimulates gastrin, HCl secretion – Motility stimulated • Gastric – Food in stomach (stretch, distention) – Gastrin, acid, pepsin secretion – Muscular contractions • Intestinal – Food entering into small intestine – Inhibitory signals from duodenum, reduce stomach motility and secretions.8/29/2014 8 Small Intestine • Duodenum – Digesta from the stomach enters here (acidic) – Bile and pancreatic ducts empty into Duodenum • Start to emulsify dietary fat • Neutralize acidity • Add digestive enzymes (amylase, lipase, protease) – Digestion but little absorption • Jejunum & Ileum – Major sites of absorption • Large surface area is a key physical characteristic • Human: duodenum (10 inches), jejunum (8 ft), ileum (12 ft) Human Digestive System Intestinal modifications to increase surface area8/29/2014 9 Digestion and Absorption8/29/2014 10 Venous drainage of the intestines forms the portal vein that goes to the Liver. Small Intestine secretions • Mucous – lubricate and protect cells lining the lumen • Brush border (epithelial cells) enzymes – Sucrase, lactase, maltase, isomaltase – Amino and di-peptidase, enterokinase • Bile • Pancreatic juice – enzymes (proteases, amylase, lipase) – Bicarbonate to neutralize stomach acid Human Digestive System Bile from the liver empties into the duodenum. Most species have a gall bladder that stores bile.8/29/2014 11 Bile • Function is to emulsify fat • No enzymes in bile • Produced in liver, stored in gall bladder • Composition – Bile salts (cholic, glycocholic, taurocholic, etc.) derived from cholesterol. – Phospholipids – Pigments (bilirubin) – Cholesterol – 95% of bile salts and cholesterol are reabsorbed from the intestine and reused. Called enterohepatic circulation. Human Digestive System Pancreatic duct also empties into the duodenum. Pancreas