exam 2: Non-Ruminant herbivore digestive physiology Flashcards
what are the 2 types of fermenters
Pre-gastric fermenters
Hindgut fermenters (non-ruminant herbivores)
what are the sub-categories of Pre-gastric fermenters
- Ruminants
- Non-ruminant herbivores- Foregut fermenters
What is the difference between pre-gastric and hindgut fermenters
pre-gastric: fermenting prior to gastric stomach and SI
Hindgut: fermenting after the small intestine
examples of ruminants
sheep
cow
goat
deer
camel
what are some animals that are Cecal fermenters
rabbit
guinea pig
chinchillas
rats
what are some animals that are Colon fermenters
horse
gorilla
elephants
rhino
koala
Whether the animal ferments BEFORE or AFTER the gastric stomach and SI has a huge effect on _______________________
efficiency of utilization of
fermentation products
Microbial fermentation is only useful IF digestive system can (2)
- Retain digesta(keep large particles) and microbes for long periods of time
- Maintain an environment suitable for fermentation
what are the 3 factors for utilizing microbial
fermentation
- Volume available for fermentation
- Retention time
- Microbial populations similar in most species
Volume available for fermentation is greatest in ___________
greatest in ruminants
How much of the GI tract in a ruminant is dedicated to fermentation
75%
Does an animal want a longer or shorter retention time
LONGER
the longer the animal can retain, more fermentation, and more contact time with microbes
GIT modifications to facilitate microbial fermentation – what type of modifications?
Pregastric= compartments in stomach to selectively sort and retain fibrous material
vs.
hindgut= either larger cecum or larger colon
Non-ruminant herbivores include what animals
Horse, rabbit, guinea pig, zebra,
elephant, hippopotamus,
kangaroo
what are the Three groups of Non-ruminant herbivores
- Foregut fermenters
- Cecal fermenters
- Colon fermenters
what animal is this
HORSE
One or more pouches for fermentation separate from gastric region – “pre-gastric” fermentation
this is known as a ____________ stomach
Compartmentalized
In animals with compartmentalized stomachs aka Foregut fermenters (non-ruminant herbivore) , they tend to have ___ to ___ pouches for fermentation
2-4 pouches
what region of the stomach is expanded for fermentation in Foregut fermenters (non-ruminant herbivore)
expanded cardiac region
Foregut fermenters can be _________ feeders or ____________
bulk roughage feeders or browsers
Identify these animals as bulk roughage feeders or browsers:
- Sloth
- Colobus monkey
- Kangaroos and wallabies
- Hippopotamus
- Sloth, Colobus monkey= browser
- Kangaroos and wallabies= browzer and graze
- Hippopotamus= bulk roughage
T/F None of the non-ruminant
herbivore domesticated species are
foregut fermenters
true
What is an advantage to being a Foregut fermenters
can degrade plant toxins easily
How would you describe the digestive tract of a kangaroo
Long tube of 3 parts
- sacciform
- tubiform (fiber digestion)
- gastric
How would you describe the tract of a sloth
3 chamber stomach
**leaves take ~1mo to digest
How would you describe the tract of a colobus monkey
4 pouches/chambers
Rodents and lagomorphs are _______ fermenters
Cecal fermenters
Because cecum is ______ sac, digesta must pass out via______________
blind; route of entry
Because cecum is blind sac, digesta must pass out via route of entry
this allows the cecum to selectively ___________
selectively retain certain fractions of feed
In Cecal fermenters, cecal contents enter colon _______ times a day
1-2 times
Rabbit, guinea pig, rodents are _______ fermenters
Cecal fermenters
How do cecal fermenters like rabbits, rodents, etc. handle fiber
- Digestibility of fiber very low
- Evolved strategy to separate and excrete
indigestible fiber
Cecal fermenters seperate particles based on
________ in colon
density
what happens to less dense material in a Cecal fermenter
larger fiber particles remain in the lumen, move on through the colon
what happens to denser, smaller/fluid material in a Cecal fermenter
remain around perimeter( proteins and fiber that is easily digestible) and move into cecum for fermentation
what are the two types of feces produced by Cecal fermenters
- Hard feces
- Soft feces (night feces)
what is hard feces composed of
indigestive fiber
what is Soft feces (night feces) composed of
also called cecotropes
cecal contents coated with mucus, gets consumed by animal because it is full of B vitamins and microbial protein
Hindgut/colon fermentation is limited in ________ and some __________
Limited in omnivores and some
herbivores (ruminants)
what are the 4 major hindgut functions
- Primary site of microbial fermentation in colon fermenters
- Mixing of contents
- Ileum and colonic epithelium secrete bicarbonate
- Reabsorption of fluid and electrolytes
Major hindgut functions:
Mixing of contents promotes what to happen?
movement promotes fermentation and expose content to mucosal surface for absorption of VFA’s
Major hindgut functions:
Ileum and colonic epithelium secrete ________
bicarbonate
Ileum and colonic epithelium secrete bicarbonate. what does this help buffer?
VFA’s to maintain pH
If VFA’s build up= acidic pH
what is the most important function of the hindgut
Reabsorption of fluid and electrolyte
products of fermentation used for energy
Volatile fatty acids (VFA)
what are the 3 Volatile fatty acids
- Acetate
- Propionate
- Butyrate
Equids, elephants, koalas are _______ fermenters
Colon fermenters (grazers)
Colon fermenters have an enlarged _______ and cecum for ___________ fermentation
colon, microbial
The enlarged colon and cecum for microbial fermentation in colon fermenters helps ferments material that _____________________
Resists breakdown in SI AND starch/sugar
that escapes SI digestion
Hindgut fermentation is less efficient. Why?
less opportunity to absorb VFA’s and cant utilize microbial protein
**this is a big loss compared to ruminants and why we still have to supplement horses
Hindgut subtrates include (3)
- structural carbohydrates
- non-structural carbohydrates
- proteins
Hindgut: how much of Structural carbs reach the hindgut
acid exposure from gastric stomach can increase susceptibility to microbes
MORE structural carbs= HARDER TO DIGEST
Hindgut: how much of Non-Structural carbs reach the hindgut/what does it affect
How much non-structural reaches the hindgut affects the risk of colic and laminitis
Hindgut: how much protein reaches hindgut/ what is it for
source of nitrogen for microbes
microbes utilize urea recycling to hindgut
Hindgut functional anatomy:
List the functional sections of the equine
hindgut
Cecum, ventral colon, dorsal colon, small
colon
what are Haustra
Saclike invaginations (smooth muscle) in cecum and colon
what are the two important areas of size reduction of the equine hindgut
- at the pelvic flexure
- junction of large to small colon
Hindgut functional anatomy:
Soluble digesta reaches cecum ~_____ hrs
after ingestion – solids take (longer/shorter)
depending on particle size
2 hours, longer
Cecal motility mixes and slowly transports from __________ to ___________
haustra → haustra
Hindgut functional anatomy:
Every _________ minutes, mass movement
contraction to move digesta from cecum
3-4 minutes
Every 3-4 minutes, mass movement
contraction to move digesta from cecum to _______________
right ventral colon via cecocolic orifice
(no retrograde movement)
what are the 3 major types of colon motility
- Haustral segmentation contractions
- Propulsive peristalsis
- Retropulsive peristalsis
what type of colon motility is this:
Mix to promote fermentation and aid in VFA absorption
Haustral segmentation contractions
what type of colon motility is this:
Originates near cecum following mass movements – propel digesta towards left ventral colon
Propulsive peristalsis
what type of colon motility is this:
Antiperistalsis movements in left ventral colon resist digesta flowing forward → results in retention and mixing
Retropulsive peristalsis
During Retropulsive peristalsis, antiperistalsis movements in left ventral colon resist digesta flowing forward → results in _____________
retention and mixing–> allows for more time with the microbes
At the Pelvic flexure, narrow diameter + antiperistalsis movements help to retain larger particles for ____________
further fermentation
Pelvic flexure allows what materials to pass through
liquids and soluble material to pass through
Common site for impactions (near or within flexure)
Pelvic flexure
Actions in dorsal colon mimic those of ________
ventral colon
Diameter decreases at junction of large and small colon – creates ____________
impedance to digesta flow
Colon motility:
Retropulsion originates near __________, which causes mixing and allows more ________
junction; fermentation
Segmentation contractions of small colon form __________
Fecal balls
Small colon recovers water, _____ and _____
electrolytes, and VFAs
Large water and electrolyte fluxes in the large and small colon results in high vulnerability of horses to __________
colonic diseases → fluid and electrolyte
losses can be significant
Overall, transit through colon takes _____ days
2-3 days
As microbes die in hindgut, they are
washed out and excreted in feces
→ this is _________________
wasted microbial protein!
Limited utilization of VFAs produced
in hindgut = limited time for ________
absorption
Hindgut fermentation (less/more) efficient compared to ruminant foregut fermentation in terms of utilizing fermentation products
LESS
Hindgut fermentation less efficient compared to ____________ fermentation in terms of utilizing fermentation products
ruminant foregut
