Transcript Horse and Cattle Digestion

Horse and Cattle Digestion
Horse oddities
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Unable to vomit
Lack a gallbladder
Stomach
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Esophageal region of stomachnonglandular
Margo plicatus
Horse-large intestine
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Hindgut fermenters-ferment feedstuffs
in Large intestine
Cecum- via ileocecal orifice
Ventral colon- via cecocolic orifice
Dorsal colon
Small colon=descending colon
Horse-large colon
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Flexures-”turns” in the colon; named
for where they are in the abdomen
Sternal flexure
 Pelvic flexure**
 Diaphragmatic flexure
** Sites of impactions or twists-leads to colic
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Cranial
left
right
Caudal
A=ileum
B=Cecum
C=right ventral colon
D=left ventral colon
E=pelvic flexure
F=left dorsal colon
G=right dorsal colon
H=transverse colon
I=descending colon
Horses-carbohydrate digestion
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Carbohydrates-poorly digested in
small intestines
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Needed to feed the microbes in hindgut
Excess carbs-highly fermented, leads to
gas production---BAD!
http://www.wcds.afns.ualberta.ca/Proceedings/1996/figures/wc96-058.gif
Horses-protein digestion
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Efficiently digested in small intestines
Microbes in the hindgut need proteins
Liver secretes urea-helps feed
microbes
Horses
Microbes produce Volatile Fatty Acids
(VFA’s) that are absorbed for energy
(other animals-what is the primary
energy source??)
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Acetic acid, Proprionic acid, Butyric acids
Acids in the colon still need to be
buffered
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Bicarbonate secreted in colon
Cows where is bicarb from???
http://eduforum.ugent.be/vakgroep/fysiologie/theorie/LasMinuteTheo2de2006.htm
Horses-small colon
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Absorb electrolytes, water, VFAs
Other nonruminant hindgut
fermenters?
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Guinea pigs
Rats
Rabbits
Swine
Ruminant digestion
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Ruminate their food
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Swallow
Regurgitate
Chew their “cud”=remastication
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Breaks down large plant fibers
Increase surface area for microbes
Swallow again
Cattle, sheep, and goats are ruminants
Rumination
Ruminant digestion
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Prestomach vs.
True stomach
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Prestomach
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Reticulum
Rumen
Omasum
True stomach
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Abomasum
Reticulum
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“Honeycomb”
Cranial most chamber
Ruminoreticular folds
Coordinated
contractions with
rumen
“Hardware Disease”
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magnet
Rumen
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Fermentation Vat
L. side of the cow
Muscular pillars with
separate chambers within
rumen for mixing
Ruminoreticular contraction
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Regurgitation
Eructation-escape of CO2 and
methane
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Bloat
Control of Rumen
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Vagus nerve
Other factors-rate and strength of
contractions
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pH
Presence of VFAs ( )
Consistency of feedstuffs
Stretch receptors
Fermentative Digestion
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= protozoal and bacterial action on
remasticated plant material
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Enzymes from microbes!
Mammals do not have cellulase! (complex
carbohydrate)
Simple sugars (glucose)
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Microbes utilize
Convert to VFAs
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Absorbed – liver converts to glucose
Microbes also provide Vitamin B and K
Protein digestion
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Proteins eaten
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Microbe converts to peptides, then amino
acids
Used by microbes, then converted to:
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Ammonia –used by other microbes for protein
production
VFAs-absorbed by animal
So where do cows get protein????
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Liver converts ammonia to urea
Bug bodies!!
Bypass proteins
Delicate balance
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Fermentation balances:
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Substrate used by microbes (glucose and
peptides)
Microbe number
Amount of microbes product (VFAs and
ammonia
No rapid changes in diet!!!
Omasum
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The “book”
Break down food
particles further
VFA absorption
Remove
bicarbonate ions
Water absorption
Abomasum
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“True stomach”
Similar function as simple stomach
animals
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Left displaced abomasum (LDA), RDA
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Calf digestion
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Do calves eat
fermentable material??
Rumen/reticulum small
and nonfunctional
Reticular groove
(esophageal groove)esophagus to omasum
Ruminants-hindgut
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Spiral colon
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Modification of ascending colon
Some fermentation in hindgut!
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