Herbivore Digestive Anatomy Integrated Rangeland Management REM 456 Sergio Arispe, Ph.D. Overview Comparative Digestive Anatomy Herbivory Anatomy Digestive End-Products Foregut Fermenters http://www.lelylife.com http://horsetrailerworld.com Comparative Digestive Anatomy http://yr11-biology-revision.wikispaces.com Fraction of Primary Production Consumed By Various Herbivores Herbivory FRACTION VEGETATION TYPE HERBIVORE 9.6% GRASSLANDS INVERTEBRATES 30-60% GRASSLANDS NEMATODES 30-60% GRASSLANDS (AFRICA) UNGULATES 20-90% TUNDRA GRAMINOIDS LEMMINGS 0.17% TALLGRASS PRAIRIE BIRDS (GRANIVORES) 58% SALT MARSH SNOW GEESE Cellobiose β-1,4 linkages Cellulose β-1,4 linkages (Modified from Crawley, 1983) β-d-glucose 1
rbivory Amylose α-1,4 linkages Maltose α-1,4 linkages Amylopectin α-1,4 linkages and α- 1,6 linkages 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 α-d-glucose 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 Origins of Simple Animals Non-cellulose Digestors Simple stomach animals (Monogastrics) E.g., Humans, swine, reptiles Derive energy from starches Cellulose is not an energy source 2
caprophagy Cellulose Digestors Hindgut Fermentors Foregut Fermentors www.tamu.edu Cecum Colon Cecal Fermenters E.g., Rabbits, Guinea Pigs, Rat Cecal Fermenters Rabbits, Guinea Pigs, Rat 90 g 100-120 g (Stevens, 1977) http://www.rabbitfood.org.uk Cecum Colon Feces 10-30 g http://www.rabbitfood.org.uk Colon Fermenters Horse, Elephant, Rhino Location Substrate Digestive Agent End Product Protein Pepsin Amino Acids Amylase, Glucosidase Glucose, Maltose ADM Alliance Nutrition Proteins Trypsin, Carboxypeptidase Lipase Amino Acids MAG s, FA s Carbohydrate Microbes VFA s Mineral & Water http://www.mi-feed.com.au/past_nutrition.php?page=mar2006 3
Origins of Simple Animals Gastrointestinal Tract (GIT) Functions Foregut Fermenter Kangaroo Foregut Fermenter Ruminants Sheep, cattle, goats, elk, whitetailed deer Feed Prehension Mastication & deglutition (swallowing) & salivation Esophageal or Ruminoreticular groove VFA s absorbed Yes Nursing Anterior rumen or reticulum Mixed in Rumen, Fermented Reticulum Small Particles No, Larger particles than rumination No, Small Particles Rumen Major site of anaerobic fermentation Absorption of VFA s Mixes rumen contents Filiform and foliate Increase surface area Abomasum Small Intestine & Cecum Feces 4
Reticulum Distributes feed tot he omasum Origin of primary rumen contractions Some VFA Honeycomb increase surface area Traps small particles Pump food to the abomasum Active exchange of Na + and K + Some VFA and H2O Regulates flow into the abomasum Arranged on muscular laminae Abomasum Produces HCl Secretes proteolytic enzymes ph 2-3.5 to prepare food for lower GIT Arranged in folds Ruminants Location Substrate Digestive Agent End Product Reticulo-rumen Protein Microbes Microbial Protein VFA s TAG, FFA s Water & Mineral Abomasum Protein Pepsin Amino Acids Proteins Amylase, Glucosidase Trypsin, Carboxypeptidase Lipase Glucose, Maltose Amino Acids MAG s, FFA s Carbohydrate Microbes VFA s Mineral & Water Approximate relative capacity of ruminant stomach compartments Summary Compartment At birth At 4 months At maturity Rumen 25% 75% 80% Reticulum 5% 5% 5% 10% 9% 7% Abomasum 60% 11% 8% Total 100% 100% 100% (Acker & Cunningham, 1991) The architecture of the GIT (Gastro-Intestinal Tract) 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 5