Digestive System of Animals Animal Science Frameworks Presentation Unit 3.1

Mr. Sullivan

DigestionPurpose: reduce feed particles to molecules that can be absorbed into the bloodMechanical breakdown of foodchewingChemical breakdown of foodHCl in the stomachenzymesContractions of digestive tract

Animals are classified by the types of food they ingestCarnivore - animal productsDogs, CatsHerbivore - plant productsCattle, Sheep, Goats, HorsesOmnivore - combination of plant and animal productshumans, pigs

Animals are also classified by the type of stomach they haveMonogastrics or non-ruminantsRuminants

Monogastric Animals

Monogastric one or simple stomach structuremostly carnivores and omnivoresVery simple: mink and dogCecal digestion: horse, rabbit or ratSacculated stomach : kangaroo

Ruminant Animals

Ruminant - 4 compartment stomach with the compartments before the true stomachherbivorescattle, sheep, goats and pseudoruminants (llamas)

DigestionPrehensionBringing the food to the mouthUpper limbs, head, beak, claws, mouth, teeth and lipsMastication or chewingTo crush the food, increase surface area and allow enzymes to act on moleculesCarnivores need only to reduce the size of the particleHerbivores must chew continuously (40-50,000 times a day)

Monogastric Animal Digestive Tract

Basic anatomymouthstomachsmall intestinelarge intestine or colon

Monogastric Animal Digestive TractFeed passes from the mouth to the stomach through the esophagusTo reduce the size of the feed particlesFrom the stomach it passes through the duodenum (first part of the small intestine)Bile and pancreatic secretions enter here jejunum (second part of the small intestine)Absorption of nutrients ileum (third part of the small intestine)To split food molecules and absorb nutrients

Monogastric Animal Digestive TractLarge Intestinewater absorptionfeces formationRectum

Human and Pig Similarities

Both are omnivoresCannot synthesize B complex vitaminsCannot synthesize amino acidsCan become obese with increased food intake

Monogastric Animal Digestive TractExceptionsherbivoreshorses have a cecum (blind anterior end of the colon) where feed is fermentedCecum is posterior to optimum feed absorption area, thus advantages of the ruminant animal is lost

Enzymes of the Digestive TractEnzyme names often end in -ase

and

begin with a description of the substrate they act upon

Enzymes of the Digestive TractEnzymeSubstrateProductAmylaseStarchDextrin, DisaccharidesChymotrypsinPeptidesAmino AcidPeptidesLactaseLactoseGlucosegalactose

Enzymes of the Digestive TractEnzymeSubstrateProductLipaseLipidsFatty acids glyceridesPepsinProteinpolypeptidePeptidasePeptidesamino acidSucraseSucroseglucoseTrypsinProteinpolypeptide

Monogastric DigestionEnzymes help breakdown large moleculesMouthamylase in saliva of humans and pigs breaks down starch to disaccharides and dextrinStomachHCl - creates acidic environmentpepsin - breaks proteins down polypeptides

Monogastric DigestionEnzymes help breakdown large moleculesduodenumCells release hormones that act on pancreas and gall bladdersecretinpancreozymincholecystokinin

Monogastric Digestionpancreaslipaselipids to fatty acids and glyceridestrypsinproteins to polypeptideschymotrypsinpeptides to amino acids and peptidesamylasestarch to disaccharides and dextrin

Monogastric Digestiongall bladderbileproduced in the liveremulsifies fatsalkaline to neutralize stomach contents that are acidicsmall intestineamino acids, fatty acids and monosaccharides are available for absorption

Ruminant Digestionmouthesophagusrumen reticulum omasumabomasumsmall intestinelarge intestine

Ruminant Digestionrumen - 40 gallons in a cowlarge fermentation vatcovered with papillae to increase the surface areamicroorganisms digest cellulose microorganisms synthesize amino acids from nonprotein nitrogen microorganisms synthesize B-complex vitamins

Ruminant Digestionreticulum - 2 gallons in a cowlining looks like a honeycombinteracts with rumen to mix contents

Ruminant Digestionomasum - 4 gallons in a cowmany folds, perhaps to grind feed

Ruminant Digestionabomasum - 4 gallons in a cowtrue stomach

Ruminant DigestionRuminants eat forage rapidlythey regurgitate food (cud) and chew it again and swallowedRumination - continuous reguritation, chewing and swallowingEructation - elimination of gases (methane and carbon dioxide) in the rumen from fermentation

Rumen MicroorganismsBacteria and Protozoarumen environment is moist, warm, and provides a constant supply of nutrientsentire population of organisms depending on the kind and quality of the feedwhen they are washed out of the omasum into the abomasum the acidic environment kills the microorganismsprovide amino acids and some energy

Ruminant DigestionRuminants to not secrete amylase in their salivabacteria and protozoa in the rumen and reticulum utilize starches and sugars- no glucose available for the ruminantmicroorganisms do produce volatile fatty acids (VFA) that are absorbed and converted to energyacetic, propionic and butyric acidsmajor source of energy

Energy Pathways in the RuminantFrom Rumen to Abomasum Injestion materialsCellulose Starch FatComplex SugarsGlucoseVFAs

Energy Pathways in the RuminantLiver

VFAsGlucose

Ruminant and Monogastric Absorption in the small intestinepassive transportdiffusion by concentrationactive transportvilli engulf molecules to bloodstream or lymph system

Rumen MicroorganismsBacteria and Protozoarumen environment is moist, warm, and provides a constant supply of nutrientsentire population of organisms depending on the kind and quality of the feedwhen they are washed out of the omasum into the abomasum the acidic environment kills the microorganismsprovide amino acids and some energy