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ANIMAL SCIENCE 320. Instructors. Dr. Cheryl L. Morris 201D Kildee Hall clmorris@iastate.edu. Dr. Jim Russell 313 Kildee Hall jrussell@iastate.edu. Graduate TA: Olivia Genther 333 Kildee Hall genthero@iastate.edu. Graduate TA: Matt O’Neil 337C Kildee Hall maoneil@iastate.edu.
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Instructors Dr. Cheryl L. Morris 201D Kildee Hall clmorris@iastate.edu Dr. Jim Russell 313 Kildee Hall jrussell@iastate.edu Graduate TA: Olivia Genther 333 Kildee Hall genthero@iastate.edu Graduate TA: Matt O’Neil 337C Kildee Hall maoneil@iastate.edu
Meeting Times and Locations Monday and Wednesday Lectures: 8:00 – 8:50 AM Kildee 108 Wednesday Labs: 2:10 – 4:00 PM Kildee 203 Computer Labs:
EVALUATION AND GRADE SCALE Grading:
DIGESTIVE SYSTEMS REVIEWPages 63-78 Nonruminant Digestive Tract
FUNCTIONS OF PARTS OF THE NONRUMINANT DIGESTIVE TRACT • Mouth • Chewing • Taste • Secretion of saliva • Amylase? • Stomach • Secretions • Hydrochloric acid • Protease • Pepsinogen → Pepsin • Hormone • Gastrin
Small intestine • Secretions • Pancreas • Proteases • Trypsinogen → Trypsin • Chymotrypsinogen → Chymotrypsin • Procarboxypeptidase → Carboxypeptidase • Carbohydrase • Amylase • Lipase • Lipase • Liver • Bile salts • Intestinal mucosa • Carbohydrases • Maltase • Lactase • Sucrase • Peptidases • Gut hormones • Secretin • Cholecystokinin • Absorption • Large intestine • Structural carbohydrate fermentation • Importance and size dependent on diet
SIGNIFICANCE OF NONRUMINANT DIGESTION • Endproducts of nonruminant digestion are the simple nutrients derived directly from the complex nutrients in the diet • Implications • Nutrient composition of nonruminant animal products resemble the nutrient composition of the diet • Nonruminant nutrient requirements must be met directly from the diet • Essential Amino acids
Which of the following is not an amino acid that is essential in nonruminant diets? • Glutamic acid • Phenylalanine • Lysine • Tryptophan • None of the above
DIFFERENCES BETWEEN AVIAN AND NONRUMINANT MAMMALIAN DIGESTIVE TRACTS • Mouth • No teeth • No amylase • Esophagus • Has crop for feed storage • Stomach • Proventriculus before feed is ground • Gizzard (Ventriculus) • Grinds feed • Small intestine • No lactase • Large intestine (Ceca) • Small in most species • Cloaca • Organ where feces mixed with urinary waste products
FUNCTIONS OF PARTS OF THE RUMINANT DIGESTIVE TRACT • Mouth • Prehension of feed • Lips and tongue • Chewing • Eating and Rumination • Taste • Avoidance • Secretion of saliva • Secretion of buffers • NaHCO3 and NaH2PO4 • Maintain rumen pH • Recycling of N, Na, P, and water to rumen • Bloat prevention • Esophagus • Involved in rumination and eructation
Stomach • Reticulum, rumen & omasum • Fermentation • Absorption of fermentation endproducts • Abomasum • Secretion of hydrochloric acid and pepsinogen • Small intestine • Similar to nonruminant • No sucrase • Large intestine • Similar to nonruminant • More important in browsing species
CARBOHYDRATE DIGESTION IN RUMINANTS Starch Structural CHO Methane Undegraded Small intestine (Digestion similar to NR) Fermented Volatile fatty acids (VFA) Liver & peripheral tissues Energy and fat synthesis
What is the primary volatile fatty acid produced in the rumen fed a high forage diet? • Acetic acid • Butyric acid • Lactic acid • Conjugated linoleic acid • Propionic acid
PROTEIN DIGESTION IN RUMINANTS True protein NPN Undegraded Small intestine Metabolizable Degraded protein Recycled via saliva (20% of dietary N) NH3 Microbial protein NH3 Liver Urea Kidney Excreted
LIPID DIGESTION IN RUMINANTS Fat Undegraded Small intestine (Digestion similar to NR) Degraded Glycerol VFA Long chain FA Saturated FA Liver & peripheral tissues Energy and fat synthesis
SIGNIFICANCE OF RUMINANT DIGESTION • Greater digestion of plant fiber than nonruminants • Major endproducts of carbohydrates are the VFAs • High forage diets→More acetate (C2)→More milk fat • High grain diets→More propionate (C3)→Greater body weight • Low amounts of glucose absorbed • High producing dairy cows subject to ketosis • Protein requirement is primarily met by rumen degradable N • Rumen undegradable protein needed by high producing dairy cows or growing cattle • No requirement for essential amino acids • Ruminant animal products (meat and milk) contain high concentrations of saturated fatty acids (and CLA)