Digestive Physiology For ADVS 1110 Introduction to Animal

Digestive Physiology For: ADVS 1110 Introduction to Animal Science

Digestion – Digestive Systems Simple Monogastric Systems: Animal Food Class Humans Omnivore Monkey Omnivore Pig Omnivore Dog Carnivore Poultry Omnivore

Digestion – Digestive Systems Polygastric Systems: Animal Food Class Cow Herbivore Sheep Herbivore Goat Herbivore

Digestion – Digestive Systems Monogastric – Functional Cecal Systems: Animal Food Class Horse Herbivore Rabbit Herbivore Guinea Pig Herbivore Hamster Omnivore Rat Omnivore Mouse Omnivore

Digestion – GI Tract FUNCTIONS OF THE GI TRACT: n n n Movement of food. Secretion of digestive juices. Absorption of the digested nutrients, water and electrolytes. Storage – body of the stomach, or fecal matter in the descending colon. Digestion – stomach, duodenum, jejunum and ileum. Absorption – of the digestive-end-products (DEPs) in the entire small intestine and proximal half of the colon (large intestine).

Digestion – GI Tract Amount of ingested food determined by: 1. Hunger – the intrinsic desire for food, regardless of food type or preference. 2. Appetite – the specific type of food that is preferentially sought. 3. Capacity—body size, GI tract size

Digestion – GI Tract The mechanical aspects of food ingestion: n Mastication – includes chewing as well as ingestion. q q n Incisors – cutting and food intake action @ 55 psi. Molars – grinding action @ 200 psi. Swallowing – also referred to as ‘deglutition’.

Digestion – GI Tract DENTITION: n Temporary & Permanent Dentition: q Horses q Cattle q Sheep q Pig q Dog q Cat

Digestion – GI Tract DENTITION/TEETH: (front to back) n Incisors = I* n Canines = C* n Premolars = P n Molars = M * Usually absent in the mare.

Digestion – GI Tract DENTITION – SECTION THROUGH A MOLAR TOOTH:

Digestion – GI Tract TWO TYPES OF MOVEMENT IN THE GI TRACT: 1. Mixing Movements – keeps intestinal contents homogenous. 2. Propulsive Movements – causes the food to move anal-ward along the tract at an appropriate rate for digestion and absorption.

Digestion – GI Tract OTHER TYPES OF MOVEMENTS: n Peristalsis – basic propulsive movement. Peristalsis is the rhythmic contractions and movements by which the GI tract propels it’s contents. n Distension – is the usual stimulus for peristalsis. n Analward Peristaltic Movements – peristalsis can occur in either direction, from a stimulated point, but normally dies out rapidly in the oral direction. n Gradient Theory – is that there are more frequent neural impluses (peristaltic) analward than in the oral direction.

Digestion – GI Tract THE HERBIVORE GI TRACT – DESCENDING ORDER: 1. Oral Cavity 8. Abomasum (True Stomach) 2. Incisors 9. Small Intestine: a. Duodenum; b. Jejunum; c. Illeum 3. Molars 10. Cecum 4. Esophagus 11. Large Intestine (Colon): a. Ascending, b. Descending 5. Rumen (Paunch) 12. Rectum 6. Reticulum (Hardware Stomach; Honeycomb; Tripe) 13. Anus 7. Omasum (Manyplies)

Beef Cattle GI Tract

Ruminant Ailments n Bloat-excess accumulation of rumen gas q Frothy bloat caused by rapidly digesting protein n n q Occurs within about an hour of consumption or the second or third day (rapid onset and often fatal) Prevention/treatment with antifoaming agents including oils, dish soap, synthetic nonionic surfactants (poloxalene) Free-gas (secondary) bloat caused by high grain diet, anatomical issues, or esophagus obstruction n Can result in chronic bloating (20% fatal)

Ruminant Ailments n Bloat Risk Factors q Irregular feeding (hunger), sudden feed changes, weather events (frost), genetic pre-disposition, Pneumonia

Twisted Stomach(Displaced Abomasum) n n Abomasum normally rests on the ventral floor of the abdomen. Occasionally it twists to the left or the right. (LDA or RDA) LDA most common and requires surgery RDA usually fatal within 12 -24 hours

Risk Factors n n n Irregular feeding, sudden feed changes, weather events, genetic pre-disposition 80% occur within 1 month of parturition due to hypocalcemia, hypokalemia, mastitis, metritis, endotoxemia (all result in decreased rumen fill) Periparturient changes in intra-abdominal organ position

Colic (Horses) n n Abdominal pain Clinical signs may include: pawing, looking at flank, curling upper lip and arching neck, repeatedly raising a rear leg or kicking at abdomen, lying down, rolling side to side, sweating, stretching out as if to urinate, straining to defecate, distension of abdomen, loss of appetite, depression, decreased bowel movements

Reasons for Colic n n Intestinal wall stretched excessively by gas, fluid, or ingesta (possible foreign material) Intestinal displacement (tension on mesentery) Restricted blood supply (Ischemia) Inflammation: Entire intestinal wall (enteritis) or abdominal cavity lining (peritonitis)

Prevention/Treatment n n Consistent feeding Adequate water Deworm Treat the symptoms q q Pain Dehydration Intestinal lubricants/laxatives Surgery may be required

Digestion – GI Tract n 1. 2. 3. 4. 5. 6. 7. Terminology: Food As It Moves Through The Digestive System Feed or Feedstuff. Ingesta – after swallowing. Cud – after leaving rumen. Chyme – after leaving the true stomach or only stomach. (Small Intestine) Digestive End Products (DEPs) – those nutrient ingredients absorbed after digestion. Fecal Material or Non-Digested End Products – lower end of large intestine or large colon. Feces – waste matter removed from the rectum after all digestive processes, and deposited outside the body.

Digestion – GI Tract n n The ruminant system is large in relation to the size of the animal. It’s four (4) compartments are bunched and joined together to form a compact structure.

Digestion n n The most important products of the rumen “fermentation vat” process as illustrated in a diagrammatic form, are the “Volatile Fatty Acids” (VFA’s) VFA’s represent the major source of energy derived from the feed in a usable form.

Digestion – GI Tract n n In the digestive process most feed materials follow pathways indicated by arrows. The rumen, consisting of several different regions, is much larger than the three (3) other compartments combined.

Digestion – GI Tract n The possible routes of feed in ruminants:

Digestion – GI Tract n The stomach of a monogastric animal is much smaller than that of the ruminant stomach in relation to the size of the animal and other parts of the digestive tract:

Digestion – GI Tract n Approximate relative capacity of ruminant stomach compartments: Compartment At Birth (%) At 4 Months (%) At Maturity (%) Rumen 25 75 80 Reticulum 5 5 5 Omasum 10 9 7 Abomasum 60 11 8 Total 100 100

Digestion – GI Tract n In contrast with the ruminant system, the stomach of monogastric animals has only one principal digestive cavity, including one (1) non-glandular and three (3) glandular regions:

Digestion – GI Tract n Digestive System of the Horse:

Digestion - Avian n Digestive Tract of the Chicken:

Digestion – GI Tract n The Cecum in Various Animal Species:

Digestion – GI Tract n Digestive tract sizes and capacities of mature ruminant animals: Species Part of Digestive Tract Cow Ewe Rumen 40 gal 5 gal Reticulum 2 gal 2 qt Omasum 4 gal 1 qt Abomasum 4 gal 3 qt Small Intestine 15 gal (130 ft) 2 gal (80 ft) Large Intestine 10 gal 6 qt Stomach

Digestion – GI Tract n Comparative capacities of monogastric (simple stomach) animals: Part of Digestive Tract Horse Pig Man Stomach 20 qts 8 qts 1 qt Small Intestine 48 qts 2 qts Large Intestine 120 qts (cecum also) 8 qts 2 qts

Digestion – GI Tract - Summary n The Digestive Pathway in Monogastrics: Mouth Esophagus Simple Stomach Small Intestine (duodenum, jejunum, ileum) Cecum Large Intestine Rectum Anus

Digestion – GI Tract - Summary n The Digestive Pathway in Poultry: Mouth Esophagus Crop Esophagus Proventriculus (stomach) Gizzard Small Intestine (duodenum, jejunum, ileum) Ceca Large Intestine Cloaca Vent

Digestion – GI Tract - Summary n The Digestive Pathway in Ruminants: Mouth Esophagus Reticulo-rumen Regurgitated, Rechewed, reinsalivated, reswallowed Reticulo-rumen Omasum Abomasum Small Intestine (duodenum, jejunum, ileum) Cecum Large Intestine Rectum Anus

Digestion – Circulation of Blood in Mammals:

Annual Manure Production of Animals: Species Animal Weight (lb. ) Total Manure Production (tons/yr) Dairy Cattle 1, 400 21. 00 Beef Cow 1, 000 11. 50 Beef Feeder 600 6. 60 Swine 200 3. 60 Sheep 100 0. 75 4 0. 05 1, 000 8. 50 Poultry Broiler Horses

Digestion - GI Tract n The Human Alimentary Canal (GI Tract):

Digestion - Avian

Digestion - Avian n q n n n q Mouth – no teeth; therefore coarse feed must move to gizzard. Fowl break their feed into a size that can be swallowed by pecking with their beaks or by scratching with their feet. Crop – is an esophageal diverticulum and serves as a storage area for recently digested food. Proventriculus – is similar to the stomach in carnivorous animals. Gizzard – primary function is the reduction of the size of food particles by a grinding action. Pepsin is present, an acid-base activity takes place, along with meager proteolysis.

Digestion - Avian n n Small Intestine – digestive activity here is similar as in mammals. q Enzymes of the pancreas and the ‘brush border’ aid in digestive activity. q Monosaccharides and amino acids are carried by active transport through the gut wall. q Fat absorption takes place in lower half of small intestine and enhanced by the presence of bile. Ceca – most of the fiber digestion takes place here via fermentation. Large Intestine – concerned with water absorption. Cloaca – chamber into which the urinary and genital tracts also open into.

Digestion n A diagram of a cross-section of the intestinal tract showing it’s tissue layers:

Digestion - Ruminant

Digestion of Feed Nutrients Ruminants

Digestion - Ruminant n Routes of carbohydrate utilization in ruminants:

Digestion - Non-Ruminant

Digestion of Feed Nutrients – Non. Ruminants

Digestion – Non-Ruminant n Routes of carbohydrate utilization in nonruminants:

Digestion – Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Mouth Saliva Ptyalin Starch > Maltose Stomach Gastric Pepsin Proteins > Peptones > Proteoses Stomach Gastric Rennin Casein > Paracasein Stomach Gastric Lipase Fats > Higher Fatty Acids, Glycerol

Digestion – Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Pancreas Pancreatic Trypsin Proteins > Proteoses & Peptones, Peptides > Amino Acids Pancreatic Amylase Starch > Maltose > Glucose Pancreas Pancreatic Steapsin (Lipase) Fats > Higher Fatty Acids & Glycerol

Digestion – Chemistry Location Digestive Juice Enzyme Kind of Food Acted Upon Liver Bile Emulsification of fats (Liquid) Small Intestine Intestinal Juices Erepsin Peptides > Amino Acids Small Intestine Intestinal Juices Invertases (Sugar Enzymes)

Digestion – Chemistry Location Small Intestine Digestive Juice Intestinal Juices Enzyme Kind of Food Acted Upon Invertases (Sugar Enzymes) Maltase Maltose > 2 Glucose Sucrase Sucrose > Glucose & Fructose Lactase Lactose > Glucose & Galactose

Digestion - Monosaccharides n The more common carbohydrates, sources and functions: q This is an abbreviated table and provides only a partial list of the carbohydrates (CHO’s); but includes the important animal science ones. Name Sources Functions Monosaccharides Pentoses (5 -carbon) Not as common Hexoses (6 -carbon ) Glucose Corn syrup, fruit Principal blood sugar Fructose Fruit, honey Converted to glucose Galactose One of the two molecules in milk Converted to glucose

Digestion - Disaccharides n The more common carbohydrates, sources and functions: Name Sources Functions Disaccharides Lactose Milk Yields glucose and galactose in digestion Maltose Germinating seeds Yields two (2) units of glucose in digestion Sucrose Cane & Sugar Beets Yields glucose and fructose in digestion

Digestion - Polysaccharides n The more common carbohydrates, sources and functions: Name Sources Functions Polysaccharides Pentosans Hexosans Starch Seeds, tubers Principal energy source for monogastrics Cellulose Plant leaves & stems (cell Major source of energy for walls) ruminants; requires microbial enzyme cellulase Glycogen Limited supply in animal tissues Reserve form of glucose in muscles and liver

Digestion The Liver is vital to digestion, filtering and absorption of nutrients Liver Function: n Produces exocrine secretion named bile. q Bile is stored in the gall bladder until it is required for digestive purposes. n Synthetic Reactions: q Synthesis of certain amino acids, plasma proteins, prothrombin, antibodies, urea, creatine, cholesterol. q Glycogen and glucose (gluconeogenesis). q Phospholipids ( for cell membranes). q Fatty acids. q Ketone bodies.

Digestion Liver Function: (continued) n Metabolic Reactions: q Breakdown of glucose, glycogen, fatty acids, glycerol, amino acids q Metabolism of hormones (insulin, aldosterone, testerone, estrogens, and thyroid hormone). q Inter-conversion of certain amino acids to simple sugars and vice-versa. q Adenine Tri-Phosphate formation. (ATP) n Embryonic formation of blood cells. n Destruction of aged blood cells.

Digestion Liver Function: (continued) n Storage: q Glycogen Amino acids q Fats q Vitamins (A, B complex, D and E) q Iron and Copper. Detoxification q Conversion of toxic substances to harmless compounds. q n

Digestion Hormones Other Than Those of the Pituitary: Hormone Source Primary Function Thyroxin Thyroid Growth, metabolic rate Thyrocalcitonin Thyroid Lowers blood calcium and phosphate Parathyroidhormone Parathyroid Elevates blood calcium, lowers blood phosphate Epinephrine Adrenal Medulla Mobilization of glycogen, increased blood flow

Digestion Hormones Other Than Those of the Pituitary: Hormone Source Primary Function Insulin Pancreas Lowers blood glucose, increase utilization of glucose, and synthesis of protein and fat, decreases glucogenesis Glucocorticoids (Cortisol, Corticosterone) Adrenal Cortex Promotes synthesis of carbohydrates; protein breakdown Mineral Corticoids (Aldosterone) Adrenal Cortex Sodium retention and potassium loss through kidney

Digestion Hormones Important in Gastro-Intestinal Function: Hormone Origin Releasing Mechanism Function Gastrin Pylorus Distension and movement of stomach Stimulation of acid secretion by gastric glands Entero-gastrone Duodenum Fat and fatty acids Inhibition of gastric + bile in duodenum secretion and motility Secretin Duodenum Acids and peptones in duodenum Stimulation of pancreatic secretion (water & electrolytes)

Digestion Hormones Important in Gastro-Intestinal Function: Hormone Origin Releasing Mechanism Function Pancreozymin Duodenum Acids and peptones in duodenum Stimulation of pancreas secretion (enzymes) Chole-cystokinin Duodenum Fat in duodenum Contraction of gall bladder and relaxation of the sphincter of ‘oddi’ Enterocrinin Jejunum Food digestion products Simulation of intestinal secretions: 1) sucrase; 2) maltase; 3) lactase; & 4) Intestinal lipase

Digestion - Blood n Distribution of total blood volume in different portions of the cardiovascular system: Part of Cardiovascular System Percent of Total (%) Arterioles & Capillaries 7 Heart 9 Arteries 11 Pulmonary Circulation 12 Veins & Venules 61

Digestion - Blood Components of blood: n Plasma: q q q Liquid portion of blood Straw colored 55 -57% of blood volume n n n n Water Electrolytes (Na+, K+, Ca++, Cl-, HCO 3 -, PO 4) Carbohydrates (Glucose) Lipids Vitamins Urea CO 2 (Gases from lungs or tissue) O 2

Digestion - Blood Components of blood: (continued) n Proteins (Mostly manufactured from liver, some from cell disintegration) q Important – All of the prior components, Plasma and Proteins are absorbed from the gut. n Formed Elements of blood: q Erythrocytes – RBC q Leukocytes – WBC q Platelets: n n Non-nucleated Aids in clotting

Digestion - Blood n Mammalian Heart in Longitudinal Section:

Digestion - Blood

Digestion

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