REM 456 – Integrated Rangeland Management

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Herbivore Digestive Anatomy•Integrated Rangeland Management

• REM 456

•Sergio Arispe, Ph.D.

http://www.lelylife.comhttp://horsetrailerworld.com

Overview

Comparative Digestive Anatomy

Herbivory

Digestive Systems

Anatomy

Digestive End-Products

Foregut Fermenters

Hindgut Fermenters

Comparative Digestive Anatomy

http://yr11-biology-revision.wikispaces.com

Fraction of Primary Production Consumed By Various Herbivores

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

(Modified from Crawley, 1983)

Herbivory

Cellulose

β-1,4 linkages

Cellobiose

β-1,4 linkages

β-D-Glucose

REM 456 – Integrated Rangeland Management

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Herbivory

Amylopectin

α-1,4 linkages and α-

1,6 linkagesMaltose

α-1,4 linkages

α-D-Glucose

Amylose

α-1,4 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 GITLocation, size, and shape

Nature and location of the digestive agentsEnzymes and digestive juices, fermentation

Chemical nature of the end products of digestionAmino acids, Volatile Fatty Acids (VFA’s), Monoacylglycerol (MAG), Free Fatty Acids (FFA)

Gastrointestinal Tract (GIT) Functions

Diet

Mouth

Esophagus

Stomach

Small Intestine

Large IntestineAnus

Origins of Simple Stomach Animals

(Van Soest, 1994)

Non-cellulose Digestors

Simple stomach animals(Monogastrics)

E.g., Humans, swine, reptiles

Derive energy from starches

Cellulose is not an energy source

(Van Soest, 1994)

REM 456 – Integrated Rangeland Management

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Cellulose DigestorsHindgut Fermentors

Foregut Fermentors

www.tamu.edu

Hindgut Fermenters

Diet

Mouth

Esophagus

Stomach

Small Intestine

Large Intestine

Anus

Colon

Cecum

Hindgut FermentersCecal Fermenters

E.g., Rabbits, Guinea Pigs, Rat

http://www.rabbitfood.org.uk(Stevens, 1977)

Hindgut FermentersCecal Fermenters

Rabbits, Guinea Pigs, Rat

Diet

Mouth

Esophagus

Stomach

Small Intestine

Large Intestine

Feces

ColonCecum

capro

phag

y

90 g100-120 g

10-30 g

http://www.rabbitfood.org.uk

Hindgut FermentersColon 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 Protein Pepsin Amino Acids

Small Intestine

Carbohydrates

Proteins

Lipids

Amylase, Glucosidase

Trypsin,

Carboxypeptidase

Lipase

Glucose, Maltose

Amino Acids

MAG’s, FA’s

Large Intestine

Carbohydrate Microbes VFA’s

Mineral & Water

absorption

REM 456 – Integrated Rangeland Management

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Origins of Simple Stomach Animals

(Van Soest, 1994)

Gastrointestinal Tract (GIT) Functions

Diet

Mouth

Esophagus

Stomach

Small Intestine

Large IntestineAnus

Foregut Fermenter

Kangaroo

(Van Soest, 1994)

Foregut Fermenter

RuminantsSheep, cattle, goats, elk, white-tailed deer

(Van Soest, 1994)

Feed Prehension Mastication & deglutition

(swallowing) & salivation

EsophagusEsophageal or

Ruminoreticular groove

Anterior rumen or reticulum

Mixed in Rumen, Fermented

Reticulum

VFA’s absorbed

Small ParticlesOmasum

AbomasumSmall

Intestine

Large Intestine

& CecumFeces

No, Small

ParticlesYes

No, Larger

particles than

rumination

NursingRumen

Purpose

Major site of anaerobic fermentation

Absorption of VFA’s

Mixes rumen contents

Mucosa

Filiform and foliate

Increase surface area

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ReticulumPurpose

Distributes feed tot he omasum

Origin of primary rumen contractions

Some VFA absorption

Mucosa

Honeycomb

increase surface area

Traps small particles

OmasumPurpose

Pump food to the abomasum

Active exchange of Na+ and K+

Some VFA and H2O absorption

Regulates flow into the abomasum

Mucosa

Arranged on muscular laminae

AbomasumPurpose

Produces HCl

Secretes proteolytic enzymes

pH 2-3.5 to prepare food for lower GIT

Mucosa

Arranged in folds

RuminantsLocation Substrate Digestive Agent End Product

Reticulo-rumen

Protein

Carbohydrates

Lipids

Microbes

Microbial Protein

VFA’s

TAG, FFA’s

OmasumWater & Mineral

absorption

Abomasum Protein Pepsin Amino Acids

Small Intestine

Carbohydrates

Proteins

Lipids

Amylase,

Glucosidase

Trypsin,

Carboxypeptidase

Lipase

Glucose, Maltose

Amino Acids

MAG’s, FFA’s

Large Intestine

Carbohydrate Microbes VFA’sMineral & Water

absorption

Approximate relative capacity of ruminant stomach compartments

(Acker & Cunningham, 1991)

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%

Summary

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