Forestomach Motility

Question 1

describe the optimal environment for microbial fermentation?

Answer 1

continuous substrate supply
appropriate temperature, space, pH control
removal of indigestible waste, microbes, VFA

Question 2

what is selective retention facilitated by?

Answer 2

specific forestomach morphology
motility patterns

Question 3

are there any glands directly into rumen?

Answer 3

ONLY salivary glands

Question 4

which parts of the rumen stomach are on the L side?

Answer 4

Question 5

which parts of the rumen stomach are on the R side?

Answer 5

Question 6

list the 3 motility patterns of rumen and reticulum

Answer 6

mixing
eructation
rumination

Question 7

describe the mixing motility pattern

Answer 7

PRiMARY mix pattern
reticulo-rumen contraction

Question 8

list the sequence of events of a single reticulo-rumen contraction cycle

Answer 8

1. initiation of cycle by double reticular contraction (1st - mixing, 2nd - evacuate dense material through ROO)
2. contract cranial pillar aka reticulorumen fold and reticulum moves material into D sac
3. D sac contracts followed by V sac
4. V sac contracts and cranial pillar relaxes which moves dense material into reticulum

Question 9

describe the path of a single food bolus

Answer 9

1. initial chew and some mechanical breakdown/mix of saliva
2. ingesta arrives in reticulum and is transported by mixing contraction into rumen
3. V-caudal sac spills material with smallest particles into cranial-V sac and further to reticulum
4. reticulum contract at beginning of primary cycles forces material in omasum through relaxed ROO
5. 1-3 cycles per min

Question 10

describe eructation process

Answer 10

GAS REMOVAL, SECONDARY motility pattern
1. cranial pillar remains solid and retains solid digesta in rumen
2. D sac contracts and moves gas cap forward
3. reticulum and cranial sac relax. displaced gas cap forces fluid and digesa in reticular region
4. exposed cardia opens and gas moves to esophagus
5. V sac contract and cranial pillar relaxes…dense material moves to cranial sac

Question 11

what are the four components of rumination?

Answer 11

regurgitation
mastication
salivation
deglutition

Question 12

when does rumination occur?

Answer 12

when animal rests between feeding

Question 13

how is rumen content organized (top to bottom)?

Answer 13

TOP - gas cap
unfermented and digestable material floats
liquid layer
fully fermented material aka sediment

Question 14

different rumen layers in rumen content are generated by different material ___ and bacterial ___.

Answer 14

density and bacterial activity

Question 15

sediment layer has ___ density

Answer 15

high

Question 16

why do ruminants always rest in sternal recumbency?

Answer 16

need gravity for floatation and sedimentation for rumen digesta

Question 17

what is bloat?

Answer 17

indigestion marked by excessive accumulation of gas in rumen
failure to clear cardia due to foaming ingesta
prevents gas material removal

Question 18

sediment is ___ from the rumen during the mixing movement

Answer 18

removed

Question 19

only ___ particles leave the rumen

Answer 19

small

Question 20

what determines particle size and its reduction rate?

Answer 20

digestibility, microbial action, mastication, and physical properties of ingesta

Question 21

poorly digestible feed has a ___ transit time and is associated with ___ intake

Answer 21

longer
less

Question 22

does grinding of poorly digestible fiber increase the DM intake? explain

Answer 22

YES, temporarily
but….
activity of acid producing bacteria increases, causing lowered pH, which provides advantage to lactate producing bacteria and disadvantage to CELLULOLYTIC, HEMICELULOLYTIC, PECTINOLYTIC species
smaller particle size requires LESS mastication, so less saliva

Question 23

water influx to rumen determines ___.

Answer 23

dilution rate

Question 24

describe how saliva production depends on chewing time and feed type

Answer 24

more roughage -> more mastication -> more saliva
highly digestible feed -> less mastication -> less saliva

Question 25

how does a higher dilution rate effect microbe removal?

Answer 25

more rapid removal of microbes

Question 26

how can higher dilution rate stim microbial growth?

Answer 26

if sufficient substrate is available

Question 27

is there a sequence of cephalic, gastric, and intestinal phase of secretion in ruminants?

Answer 27

NOPE
since digesta flows continuously from rumen to abomasum, which linked with continuous secretion from stomach and pancreas

Question 28

how is motility controlled?

Answer 28

VAGAL STIM
afferent signals communicate info about distension, ingesta consistency, pH, VFA concentration, ionic strength

Question 29

describe how stretch receptors control motility?

Answer 29

located in wall/pillars
moderate distension causes increased motility

Question 30

describe how tension receptors control motility?

Answer 30

measures tension force generated by rumen wall muscles
large rumen mat provides different resistance than mostly fluid/sluggish rumen content

Question 31

describe how chemoreceptors control motility?

Answer 31

rumen pH 5.5-6.8 NORMAL
pH decrease in rumen causes reduced motility, helps slow down fermentation until enough material is removed from rumen

Question 32

what abomasum pH stim rumen motility? why?

Answer 32

pH < 2-3
advances waste and fluid to omasum
signals that more food can be digested in abomasum

Question 33

describe hoflund syndrome

Answer 33

damage to vagal innervation removes or causes erratic motility patterns
causes death

Question 34

describe reticuloperitonitis

Answer 34

aka hardware disease
sharp object trapped in reticulum mucosa
contractions cause object to penetrate reticulum wall, cause leakage of ingesta/bacteria, which contaminates peritoneal cavity