L27: Forestomach motility

Question 1

what is considered normal rumen motility

Answer 1

• continuous mixing of bacteria and feed constituents
• retention of ingesta for microbial digestion in order to down size particles
• removal of fermentation gases, plant material and microbial yield

Question 2

forestomachs are lined w/ what type of epithelium

Answer 2

stratified squamous

Question 3

are there any glands that drain directly into the rumen

Answer 3

only salivary glands

Question 4

what increases SA in the rumen

Answer 4

• honeycomb like folds in the reticulum
• rumen papillae
• omasal laminae

Question 5

what can be absorbed in the rumen & omasum

Answer 5

VFA, electrolytes, water

Question 6

what are the 3 motility patterns of the reticulum and rumen

Answer 6

• Mixing
• Eructation
• Rumination

Question 7

eructation

Answer 7

removal of fermentation gases

Question 8

what is the double reticular contraction that initiates mixing

Answer 8

1st contraction = mixing
2nd = contraction evacuates dense particles through reticulo-omasal orifice

Question 9

what are the 4 components of rumination

Answer 9

1. regurgitation
2. mastication
3. salivation
4. deglutition

Question 10

what happens during regurgitation

Answer 10

• LES/cardia relaxes
• inspiratory excursion of thorax
• glottis remains closed
• reversed esophageal peristalsis

Question 11

when does rumination take place

Answer 11

between feedings when animal rests

Question 12

what triggers saliva production

Answer 12

rumination

Question 13

what is the reason for the different layers of rumen content

Answer 13

caused by different material density and different layers have different bacterial activity

Question 14

why are ruminants always resting in sternal recombancy

Answer 14

they need gravity for floatation and sedementation of rumen digesta

Question 15

when is sediment removed from the rumen

Answer 15

during the mixing movement

Question 16

what determines particle size and reduction rate

Answer 16

• digestibility
• microbial action
• mastication
• physical properties of the ingesta

Question 17

since the rumen volume is limited, the intake rate cannot exceed the ingesta ________ rate

Answer 17

outflow

Question 18

water influx to the rumen determines ______ rate

Answer 18

dilution

Question 19

what results in the production of more saliva vs less saliva

Answer 19

more saliva: more roughage food, more mastication
less saliva: highly digestible feed, less mastication

Question 20

what would a higher dilution rate result in

Answer 20

a more rapid removal of microbes

Question 21

under what conditions can a higher dilution rate stimulate microbial growth

Answer 21

if there is sufficient substrate; it increases the yield for microbes w/ faster replication rates

Question 22

how can dilution rate both positively & negatively affect VFA production and microbial yield

Answer 22

positively: higher dilution rate sitmulates microbial growth when there is sufficient substrate
negatively: VFA producing bacteria could be reduced as a result of the rapid passage of fluid

Question 23

what is considered a favorable environment for optimal microbial fermentation?

Answer 23

• continuous substrate supply
• appropriate & constant temperature
• sufficient time and space
• pH control
• removal of indigestible wastes, microbes and VFAs

Question 24

when are primary and secondary motility patterns occuring?

Answer 24

all the time; continuously

Question 25

in the rumen, unfermented & digestible material will _____ ; fully fermented material will ______

Answer 25

float sink

Question 26

what separates the sediment at the bottom of the rumen from the floating fiber mat

Answer 26

liquid layer

Question 27

why is fluid and gravity crucial for proper stomach functioning

Answer 27

flotation & sedimentation only work in a fluid medium and under the influence of gravity

Question 28

poorly digestible feeds have _____ transit time and are associated with _______ dry matter intake

Answer 28

longer less

Question 29

would grinding of poorly digestible fiber increase dry matter intake?

Answer 29

only initially - then the activity of acid producing bacteria will increase, lowering pH - low pH gives lactate producing bacteria an advantage while hindering cellulolytic, hemicelulolytic, pectinolytic species - smaller particles require less chewing, less chewing = less saliva

Question 30

why could rapid passage of feed (poorly digestible) cause decreased VFA production

Answer 30

rapid passage causes a lower pH lower pH hinders cellulolytic, hemicelulolytic and pectinolytic species

Question 31

how is motility controlled

Answer 31

vagal innervation of the rumen - afferent signals communicate info about distension, ingesta consistency, pH, [VFA] & ionic strength - stretch, tension & chemoreceptors

Question 32

normal pH of rumen

Answer 32

5.5-6.8

Question 33

what occurs when the abomasum has a drop in pH below 2-3

Answer 33

rumen motility is stimulated to advance waste & fluid to the omasum

Question 34

Hoflund syndrome

Answer 34

*** damage to vagal innervation removes or causes erratic motility patterns** * usually results in death

Question 35

Reticuloperitonitis

Answer 35

hardware disease - sharp object get stuck in the reticulum contractions cause object to penetrate reticulum wall, causing leakage of ingesta and bacteria into the peritoneal cavity