Ruminant Digestive Physiology I Flashcards
List the ruminant forestomachs
rumen
reticukum
omasum
What is the gastric stomach?
abomasum
What is pre=gastric fermentation accomplished by?
microbes (bacteria, protozoa, fungi, yeast)
What are pseudoruminants?
they have no omasums
camels, llamas, alpacas
Why is pre-gastric fermentation important?
it allows animal to more completely utilize products of fermentation
have all of the small intestine to absorb products
What is the site of fermentation in a cow?
rumen
What is the site of fermentation in a horse?
handgun (cecum, large intestine)
How is the ruminant energy source different?
propionate (starch, cellulose) to glucose in liver
What is prehension?
ability to acquire food, use lips and tongue
wrap tongue around grass to get it
What is rumination?
regurgitation + remastication
How is microbial fermentation accomplished?
bacteria
fungi
yeast
protozoa
What are nasolabial glands?
dermis of muzzle skin
watery fluid to mix with food
What are the major salivary glands?
parotid
sublingual
mandibular glands
What is important for buffering of rumen?
saliva
What is the composition of ruminant saliva?
bicarbonate
urea
K+
inorganic phosphate
Cl-
Saliva is important because it ______
adds moisture to food
adds salivary lipase
What is the appropriate substrate to support fermentation?
starch
cellulose
nitrogen source! (protein, urea)
List some environmental conditions needed to support fermentation
appropriate substrate
temperature around 37C
osmolality around 300 mOsm
anaerobic conditions
frequent mixing of ingesta
particle size reduction
indigestible material removal
synchronized movement of fermented content to intestine
volatile fatty acids must be buffered to maintain neutral pH
What pH do volatile fatty acids have to be to be considered neutral?
average 6.8
Volatile fatty acids must be _____ and ______ to maintain neutral pH
buffered
absorbed
What is the primary site of fermentation?
rumen
The rumen has both _____ & ______ bacterial species
cellulolytic
amylolytic
Cellulolytic species contain _____ and ______
cellulose
hemicellulose
Amylolytic species contain _____ and ______
starch
sugars
More acetate is a high _____ diet
fiber
More propinate is a high _____ diet
grain
What do papillae and extensive capillaries in the rumen do?
increase surface area
absorb vfas to keep pH stable
Papillaer and extensive capillaries are larger on high [fiber/grain] aka [proprionate/acetate] diets
grain
prorpionate
Rumen is composed of _______ and ______ to help with mixing
muscular pillars
folds
What happens in the primary contraction of the rumen?
start in reticulum to move caudally to rumen
What are the 3 major functions of the reticulum?
form bolus for regurgitation
move particles to omasum
move particles to rumen
Where does Hardware disease occur?
reticulum
What kinds of things can accumulate in the reticulum? It leads to _______
sharp, metal objects
peritonitis
Material from the rumen passes into the omasum via the ________
reticulo/omasal orifice
What does the omasum do?
regulates passage of digesta into lower tract
some absorption of water and vfas
The abomasum is equivalent to the _______ stomach
gastric
Microbes are a major source of ______ for the animal and has essential ______ that is digested and absorbed in SMALL INTESTINE
protein
amino acids
Acidity kills ______ washing in from the rumen which starts digestion
microbes
The abomasum has gastric glands to secrete ______
HCl
The abomasum also secretes _________ that hydrolyzes microbial and dietary protein
pepsinogen
How often are abomasa contractions?
2-3/minute
What is liberated when it meets the acid in the abomasum?
CO2
Grains contain mostly ______
starch
protein
sugars
Forages contain ________
cellulose
hemicellulose
sugars
starch
protein
lignin
Define rumen fermentation
attach to substrate and grow
metabolize, ferment, and grow
secrete metabolites into fluid (vFAs)
What do microflora primarily do?
feeding the flora then the cow
Dead microbes flow to the _______ and are digested
small intestine
List the layers of the rumen from top to bottom
gas layer
fiber mat
liquid
small, high density particles
Where is the scratch factor found? What does it do?
fiber mat (low density)
stimulates rumen contraction
What products undergo fermentation in the rumen?
monosaccharides
disaccharides
starch
cellulose
other sugars
Carbohydrates are fermented in the rumen to _______
short chain (volatile) fatty acids
Which carbohydrates are first converted to glucose THEN volatile fatty acids?
starch
cellulose
What is undigested?
lignin
Ruminants use ____ for energy
volatile fatty acids
Ruminants have a [higher/lower] blood glucose vs non-ruminants
lower
Ruminants use _____ in gluconeogenesis to make glucose
proprionate
Ruminants use ______ in fat synthesis (milk fat or body fat)
acetate
What are the fate of proteins in fermentation? Proteins are fermented to _______
peptides
amino acids
ammonia
branched-chain vfas
Microbes use the components of proteins and metabolites in synthesizing ______ and _________
cell wall
cytoplasmic proteins
(uses dietary protein to grow)
_______ provide highest quality protein possible
microbes
(they contain essential amino acids the animal needs)
T/F: You can feed low quality proteins or metabolites (urea), and the cow will absorb the highest quality amino acids from the small intestine
TRUE
How is ammonia produced in the rumen?
from protein fermentation (remember ammonia is part of protein structure)
Ammonia is immediately utilized by microbes or it’s _________
absorbed and converted to urea in the liver
What are the fates of urea?
excreted by kidney
recycled to saliva
recycled to rumen
Primary (major) coordinated rumen contractions move [cranial/caudal] to [cranial/caudal] primarily [for mixing/to eructate gas]
cranial to caudal
for mixing
Secondary rumen contractions move [cranial/caudal] to [cranial/caudal] primarily [for mixing/to eructate gas]
caudal to cranial
to eructate gas
Reticular contractions are associated with _______
cud chewing
Why is rumination important?
keeps food intake constant
reduces particle size, increases surface area, adds saliva
regurgitation, reinsalivation, remastication, reswallowing
regurgitation
What are the steps of rumination?
regurgitation
reinsalivation
remastication
reswallowing
Regurgitation is initiated by _____ AND _______
reticular contraction
relaxation of distal esophageal sphincter
Regurgitation is a __________ event
reverse peristalsis
Rumination occurs when the animal is _______
resting
Ruminants ruminate [more/less] on a HIGH grain diet because they have [more/less] saliva needed to buffer
less
more saliva
The process of rumination is initiated by an “extra” contraction of ______ that pushes the ingesta into the area of the _______
reticulum
cardia
What happens after the contraction of the reticulum that pushes the ingesta into the area of the cardia?
distal esophageal sphincter opens
What happens after the distal esophageal sphincter opens?
inspiratory excursion with closed glottis, causing negative pressure in intrathoracic esophagus
There is [positive/negative] pressure in the intrathoracic esophagus with a closed glottis during inspiratory exursion
negative
When does the bolus of ingesta move into the esophagus?
final step after glottis closed
The process of reinsalivation, remastication, and reswallowing is a complex reflex control mediated by the _______
medulla
Epithelial receptors in the reticulum have a _______ to sense and then regurgitate
“scratch-factor”
