GI Tract - Ruminant

Question 1

What are the 4 chambers of the ruminant GI tract after the esophagus

Answer 1

1.reticulum
2.rumen
3.omasum
4.abomasum

Question 2

What is the function of the reticulum

Answer 2

-ingesta moves back and forth between the rumen and the reticulum
-tends to collect inedible objects
-muscular wall helps to mechanically process grasses

Question 3

What is the function of the omasum

Answer 3

-muscular leaf like wall projections help filter ingesta and squeeze out liquid
-additional mechanical processing of grass

Question 4

What is the function of the abomasum

Answer 4

analogous to the true stomach of a monogastric

Question 5

The epithelium of the chambers do not produce digestive enzymes, so where do all the required enzymes come from?

Answer 5

microbial enzymes are what cause extensive anaerobic degradation of nutrients

Question 6

What is the most important postnatal development of the ruminant?

Answer 6

The reticulorumen and omasum are not useful at birth, they are completely bypassed until grass consumption begins

Question 7

What stimulates reticulorumen development of the postnatal ruminant?

Answer 7

the abrasive effect of forage

Question 8

How do the forestomachs of bovine differ from browsers (sheep and goats)

Answer 8

browsers have a more homogeneous consistency of fluids, particles, and gasses in the forestomachs; diffuse fermentation

Question 9

What are the 3 main purposes of rumen contractions

Answer 9

1. mix reticulorumen contents before moving to omasum
2. enable regurgitation of rumen contents back to mouth as part of rumination process
3. enable removal of fermentation gasses by eructation

Question 10

What is the normal range of rumen contractions per minute

Answer 10

1-2, cranial to caudal

Question 11

Describe the sequence of a rumen contraction

Answer 11

1. 1st and 2nd reticulum contraction where contents are emptied into the cranial sac of the rumen
   -brief opening of reticulo-omasal sphincter
2. reticulum relaxes and dorsal rumen contraction begins spreading cranial to caudal
   3.ventral rumen contraction
3. secondary mixing contraction begins resulting in eructation

Question 12

What stimulates the rumination reflex?

Answer 12

course feed fibers stimulating sensory nerve endings in the digestive tract

Question 13

How does hypocalcemia influence rumen contractility

Answer 13

decreases strength and frequency of contractions

Question 14

elevated concentration of VFAs (pH <5) result in _____ motility of the rumen

Answer 14

decreased

Question 15

rumen contractility reflex is decreased by what 3 general factors

Answer 15

1. distension of abomasum
2. external factors influencing the ANS: stress pain
3. fever

Question 16

What is the parasympathetic effect on rumen emptying

Answer 16

efferent nerces to the reticulo-omasal sphincter release VIP which relaxes the sphincter and promotes movement into the omasum

Question 17

Rumen osmolarity ____ during fermentation

Answer 17

increases because volume increases due to movement of water by osmosis

Question 18

What would happen if alot of O2 was introduced into the rumen

Answer 18

it would cause nutrients to be degraded all the way to CO2 and water instead of metabolites

Question 19

What is the role of facultative microbes

Answer 19

they use up what little O2 makes it into the rumen

Question 20

What is the main nitrogen sources for microbe protein synthesis

Answer 20

NH4+ or amino acids

Question 21

Where are rumen microbes killed and used for protein/energy?

Answer 21

abomasum

Question 22

What are the 3 primary rumen bacteria?

Answer 22

amylotic, cellulotic, proteolytic

Question 23

What are the main functions of amylotic rumen bacteria

Answer 23

-metabolize starch and soluble carbohydrates
-tolerant of acidic conditions

Question 24

what is the main function of cellulotic rumen bacteria

Answer 24

-degrade carbohydrates that are part of cell walls
-not effective below pH 6

Question 25

What is the role of secondary rumen bacteria

Answer 25

to break down products produced by the primary bacteria

Question 26

What is the function of rumen protozoa?

Answer 26

they thrive on small feed particles and starch and they deposit glucose as glycogen in the cytoplasm which helps curb production of VFAs when starch intake is high

Question 27

What is the function of rumen fungi

Answer 27

important for the digestion of plant fibers, the hyphae help break apart lignin

Question 28

How does the ruminant meet its protein needs?

Answer 28

Non-protein nitrogens, microorganisms convert NPN to NH4+ then to amino acids and proteins

Question 29

What are the two sources of amino acids absorbed in the small intestine

Answer 29

1. feed proteins that have not been digested by microbes in the rumen
2. microbial proteins synthesized in the rumen

Question 30

Where are VFAs absorbed?

Answer 30

almost entirely in the small intestine