Ruminant stomach Flashcards
(23 cards)
what does cud-chewing mean?
- the animal swallows their food then brings it back up to chew it again
what are the 4 compartments of the ruminant stomach?
- Rumen
- Reticulum
- Omasum
- Abomasum
in ruminants which part(s) of the stomach is the forestomach?
- rumen
- reticulum
- omasum
in ruminants what is the true stomach?
- abomasum
where is the stomach located in ruminants?
- caudal to the diaphragm
- caud-lateral to the liver
- occupies about 3/4 of the abdomen (is more towards the left side of the abdomen)
describe the rumen
- aka pouch or fermentation vat
- largest capacity of the 4 compartments (80% by volume)
- is located on the left side of the abdomen, from the diaphragm to the pelvis
- has external grooves and internal verticle and horizontal pillars incompletely divide the rumen into 4 sacs
- internally covered in papillae of varying lengths (shag carpet)
- function is to soften, mix food, FERMENTATION, initiates rumination and eruction
how is the rumen divided into 4 sacs?
- is divided into dorsal and ventral sacs (based on external grooves)
- each sac is then further divided into the cranial sac and caudal blind sac
which stomach section is covered in papillae of varying lengths?
rumen
what is the function of the rumen
- FERMENTATION
- softens and mixes/churns ingested food (primary role)
- initiates rumination and eruction
Describe the reticulum
- aka ‘honeycomb’ ‘hardware compartment’
- is the most cranial compartment (closest to the liver and diaphragm, is the junction of the esophagus and rumen in the cranial abdomen)
- not completely separated from the reticulum
- is 5% of the stomach by volume
- is a blind sac
- acts as a passage for food, initiates mixing waves for the rumen (controls the pace of rumen contraction)
what controls the pace of rumen contraction?
reticulum
Describe the Omasum
- aka book stomach
- round to oval, bowling ball sized
- on the right side of the abdomen, between the reticulum and abomasum
- internally there are many layers of laminae, resembling leaves hanging from the ‘roof’ that are covered in short, blunt papillae
- is 8 of the stomach by volume
- functions are to grind food, absorb bicarbonate, and reabsorb water (mechanical digestion, absorption)
what are the functions of the Omasum? (3)
- grinds food
- absorbs bicarbonate
- reabsorbs water
(mechanical digestion
absorption)
where is bicarbonate absorbed in the ruminant stomach?
the omasum
describe the abomasum
- aka the true stomach
- glandular stomach
- caudoventral to the omasum
- extends along the right side of the rumen
- 7% by volume
- consists of 12-15 internal, spiral, lengthwise folds (similar to the monogastric stomach)
- functions are: chemical digestion (using acid and enzymes, is the beginning of TRUE chemical digestion), mucus production, mixing
- passes the ingesta (chyme) into the duodenum
what is the order of ventral sacs in the ruminant stomach? (most of the time)
rumen
reticulum
omasum
abomasum
describe the esophageal groove
- 2 thick muscular folds of tissue
- hang from the dorsal roof of the rumen, reticulum, and omasum
- can reflectively close to form a continuous tube to bypass the rumen and go directly to the OMASUM
- the action is initiated by suckling and the presence of sodium/copper salts
- this avoids fermentation
why do we want to avoid the fermentation of milk in calve stomachs?
- it would negatively alter the pH of the rumen
describe rumination
- ‘chewing the cud’
- ruminants eat quickly with little initial chewing
- in rumination, ingesta moves back up into the oral cavity from the rumen, where additional saliva and chewing further break down the plant matter before reswallowing
- cows spend about 8h a day doing this
- this is not vomiting
what is eructation?
- burping
- in ruminants, it is the release of excess gas from fermentation (methane and CO2). stimulus and process is similar to rumination
- occurs about once a minute
what in ruminants possess the risk of obstructing the esophagus resulting in bloat?
- high grain diets (excessive fermentation and gas production)
- diets high in legumes (excessive foam produced that blocks the escape of gas
- hardware disease
what are the 4 steps of rumination?
- regurgitation
- reinsalivation (adding more saliva to the ingesta)
- remastication
- deglutition (re-swallowing)
what is the result of eructation failure?
bloat
