http://horsetrailerworld.com http://www.lelylife.com Herbivore Digestive Anatomy Integrated Rangeland Management REM 456 Spring 2013 Sergio Arispe, Ph.D.
Overview Comparative Digestive Anatomy Herbivory
Digestive Systems Anatomy
Digestive End-Products Foregut Fermenters
Comparative Digestive Anatomy
http://yr11-biology-revision.wikispaces.com Fraction of Primary Production Consumed By Various Herbivores FRACTION VEGETATION TYPE HERBIVORE GRASSLANDS INVERTEBRATES 30-60% GRASSLANDS GRASSLANDS UNGULATES 20-90% (AFRICA)TUNDRA TALLGRASSGRAMINOIDS PRAIRIE BIRDS (GRANIVORES) 58% SALT MARSH
(Modified from Crawley, 1983)
Herbivory
Cellulose
β-1,4 linkages Herbivory
Amylose
α-1,4 linkages and Maltose α-1,6 linkages
Digestive Systems
The major purpose of the digestive system is to provide for the assimilation of nutrients required for biological functions including maintenance, growth, lactation, and reproduction
Digestive Systems
Non-cellulose digestors Hindgut or Post-gastric Fermenters Foregut or Pre-gastric Fermenters Architecture of GIT Location, size, and shape Nature and location of the digestive agents Enzymes and digestive juices, fermentation Chemical nature of the end products of digestion Amino acids, Volatile Fatty Acids (VFA’s), Monoacylglycerol (MAG), Free Fatty Acids (FFA) Gastrointestinal Tract (GIT) Functions Diet
Esophagus Stomach
Large Intestine Anus
Origins of Simple Stomach Animals
(Van Soest, 1994)
Non-cellulose Digestors
Simple stomach animals (Monogastrics)
E.g., Humans, swine, reptiles
Cellulose is not an energy source
(Van Soest, 1994) Cellulose Digestors Hindgut Foregut Fermentors Fermentors
www.tamu.edu
Hindgut Fermenters Diet Mouth Esophagus
Stomach Small Intestine Cecum Large Intestine Colon Anus
Hindgut Fermenters
Cecal Fermenters E.g., Rabbits, Guinea Pigs, Rat
http://www.rabbitfood.org.uk (Stevens, 1977) Hindgut Fermenters
Cecal Fermenters Rabbits, Guinea Pigs, Rat Diet Mouth Esophagus
Stomach Small Intestine
Large Intestine Cecum Colon Feces http://www.rabbitfood.org.uk
Hindgut Fermenters
Colon Fermenters Horse, Elephant, Rhino
ADM Alliance Nutrition®
http://www.mi-feed.com.au/past_nutrition.php?page=Mar2006
Hindgut Fermenters
Location Substrate Digestive Agent End Product
Stomach Pepsin Amino Acids
Carbohydrates Glucose, Maltose
Small Intestine Proteins Trypsin, Carboxypeptidase Lipase MAG’s, FA’s
Microbes VFA’s Large Intestine Mineral & Water absorption Origins of Simple Stomach Animals
(Van Soest, 1994)
Gastrointestinal Tract (GIT) Functions Diet Mouth Esophagus Stomach Small Intestine Large Intestine Anus
Foregut Fermenter Kangaroo
(Van Soest, 1994) Foregut Fermenter
Ruminants
Sheep, cattle, goats, elk, white-tailed deer
(Van Soest, 1994) http://www.youtube.com/watch?v=cWg1u1bUKNc
Feed Prehension Mastication & deglutition (swallowing) & salivation
Nursing No, Larger particles than rumination
Anterior rumen or reticulum
Mixed in Rumen, Fermented
No, Small Yes Particles Small Particles
Small Abomasum Feces Intestine
Rumen
Purpose
Major site of anaerobic fermentation
Mixes rumen contents
Mucosa
Filiform and foliate
Increase surface area Layers in Rumen
Marker
cm scale 40 Gas 1362 g 30 20 10
Centimeters 454 g 1 2 3 (Van Soest, 1994) Minutes
Reticulum
Purpose
Distributes feed tot he omasum
Origin of primary rumen contractions
Some VFA absorption
Mucosa
increase surface area
Traps small particles
Omasum
Purpose
Pump food to the abomasum
Some VFA and H2O absorption
Mucosa
Arranged on muscular laminae
Abomasum
Purpose
Produces HCl
Secretes proteolytic enzymes
pH 2-3.5 to prepare food for lower GIT
Mucosa
Arranged in folds
Ruminants Location Substrate Digestive Agent End Product
Protein Microbial Protein Reticulo-rumen Carbohydrates VFA’s Lipids TAG, FFA’s Water & Mineral Omasum absorption
Abomasum Pepsin Amino Acids
Carbohydrates Amylase, Glucosidase
Small Intestine Proteins Trypsin, Amino Acids Carboxypeptidase Lipids MAG’s, FFA’s Carbohydrate Microbes Large Intestine
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% 100%
(Acker & Cunningham, 1991) Summary
The architecture of the GIT and the agents of digestion are of utmost importance to determine digestive function
Ruminants and hind-gut fermentors have well developed fermentation sites
Hind-gut fermentors have greater rate of passage and can survive on lower quality food
Ruminants can eat lower quality forage but must retain food for a longer period of time