Rumen Motility
Church: 67-106, 108-116, 468-474
Van Soest: 237-244
Ruckebusch and Thivend: 35-51
Sjersen et al.: 155-164
Susenbeth et al. 1998. Energy Requirement for Eating in Cattle. J. Anim.
Sci. 76:2701-2705. http://jas.fass.org/cgi/reprint/76/10/2701.pdf
Cheng et al. 1998. A Review of Bloat in Feedlot Cattle. J. Anim. Sci.
76:299-308. http://jas.fass.org/cgi/reprint/76/1/299.pdf
Majak et al. 1995. Pasture Management Strategies for Reducing the Risk
of Legume Bloat in Cattle. J. Anim. Sci. 73:1493-1498.
http://jas.fass.org/cgi/reprint/73/5/1493.pdf
Rumen contractions
• Functions
– Inoculate incoming feed
– Mix contents
• Minimize effects of stratification
• Move fermentation products to rumen wall
–
–
–
–
Particle sorting
Particle passage
Rumination
Eructation of fermentation gases
• Location
– Contractions are contractions of an entire sac of the
reticulorumen, but are the result of muscular
contraction primarily on the pillars
Types of reticular contractions
• Biphasic contraction
– Action
• Reticulum contracts to about ½ its size, relaxes, and
contracts completely
• Reticulo-omasal orifice is open during contraction, but
closes when reticulum dilates
– Assists in digesta passage from the reticulorumen
– Passage more closely related to duration (r2 = .76) than
amplitude (r2 = .56) or frequency (r2 = .15)
– Duration
• 7 to 12 seconds
– Frequency
• Eating – 35 to 45 seconds
• Resting – 75 seconds
• Triphasic contraction
– Action
• An extra complete contraction precedes a biphasic
contraction of the reticulum
• Contraction is associated with the movement of
digesta up to the cardiac sphincter before rumination.
Types of ruminal contractions
• Primary contraction
– Also called A-wave or backward moving
– Action
• A biphasic contraction of the reticulum
• Anterior pillar contracts lifting the anterior sac.
– Anterior fold rises to form barrier
• Contraction moves across dorsal sac to dorsal blind sac from
contraction of longitudinal pillar and dorsal coronary pillar
• Dorsal blind sac contracts and dorsal sac relaxes from dorsal
coronary pillar
• Ventral sac contracts along longitudinal pillar
• Ventral sac relaxed and Ventral blind sac contracts
– Ventral contraction absent during rumination
– Functions of the primary contraction
• Mixing and inoculation of digesta
• Particle sorting across the reticuloruminal and anterior folds
– Duration of contraction
• Fed animal – 30 to 50 seconds
• Fasted animal – 12 to 18 seconds
The primary contraction of the rumen
• Secondary contraction
– Also called the B-wave or forward-moving contraction
– Usually occurs after a primary contraction
– Action
• Contraction of the ventral blind sac continuing up through
the dorsal blind sac using the dorsal coronary pillar
• Contraction proceeds across dorsal sac forcing gas
pocket to the cardiac sphincter
– Function
• Eructation
– Duration
• 30 seconds
Incidence of pressure waves
Activity
Feeding
Resting
Ruminating
Reticulum
Cranial sac
D
1
10
22
Contraction
DV
DSV
27
5
35
25
28
37
DVSV
56
22
6
Neural control of reticuloruminal contractions
• Nerves
– Vagus nerve involved both in stimuli and inhibition
– Sphlanchic nerve involved in inhibition
• Stimuli for contractions
– Stretch
• Most common
• Receptors
– Low threshold receptors
» Tension receptors
» Stimulated by pressures greater than 4 mm Hg
» Stimulate contractions
– High threshold receptors
» Epithelial receptors
» Stimulated by pressures greater than 20 mm Hg
» Inhibit contractions
– Tactile stimulation
• Near cardiac sphincter
• Epithelial receptors
– Stimulates triphasic contraction of reticulum
– Low abomasal pH
• Stimulates ruminal contractions
– Hypoglycemia
• Inhibition of ruminal contractions
– Abomasal distension
– Hyperglycemia
Factors affecting ruminal contractions
• Feeding
– Increases frequency and amplitude of contractions
Activity
Contractions/min Amplitude
P/S
mm Hg
Resting
1.2
18.2
Feeding
2.0
22.1
1:1
Ruminating
1.1
10.4
Fasting
.3
Weak
5:1
• Diet
– Feeding a finely ground forage
• Reduced rate of contractions
• Reduced amplitude of contractions
– Requires 2-6 weeks to adapt
• Volatile fatty acids
– Acetic, propionic, and butyric acids at 90, 50, and 37 mM
given separately or at 33.5, 29.3, and 21.1 mM given as a
mixture will inhibit primary contraction
• Metabolic problems
– Hardware disease, hypocalcemia, or hyperglycemia will
inhibit ruminal contractions
Need for eructation
• Gas production
– Peak
• Occurs 30 min to 2 hr
post-feeding
• 12-27 l/min
– Average
• 1-2 l/min
• Approximately ¼ to 1/3
of CO2 produced in
rumen is absorbed into
blood and removed
through the lungs
• Only 1/5 of the CH4 is
removed through the
lungs
• Composition of
rumen gas
__Gas__
_%__
CO2
65.35
CH4 (variable) 27.76
N2
7.00
O2 (at wall)
.56
H2
.18
H2S
.01
Mechanism of eructation
•
•
•
•
•
Biphasic contraction of reticulum
Modified primary contraction of rumen
Secondary contraction of rumen
Ruminal gas pocket forced forward
Anterior fold and reticuloruminal fold rise to hold
digesta away from cardiac sphincter
• Cardiac sphincter relaxes allowing esophagus to
fill with gas
• Rapid reverse peristallsis of the esophagus
– Diaphragmatic and Pharyngeal sphincters open
– Nasopharyngeal sphincter closes
• Epiglottis opens while thoracic muscles contract
– Cause 80% of gas to enter trachea
– Acts as a muffler
• Animal exhales
Control of eructation
• Stimulus
– Gaseous distension of the reticulum and rumen
• Inhibition
– Presence of digesta near the cardiac sphincter
• Affects all three sphincters
• Prevents digesta from entering lungs
– Epinephrine
– Histamine
• Inhibition of eructation will cause the animals to
bloat
– Ruminal pressures will increase to 45 to 100 mm Hg.
Bloat
• Types of bloat
– Free gas bloat
• Gas pocket over the digesta is normal, but can’t be
eructated because of a physical obstruction in the
esophagus or anatomical abnormality
– Frothy bloat
• Gases form a foam over the digesta that inhibits eructation
when it touches the reticular wall near the cardiac spincter
• Two types
– Feedlot bloat
– Pasture or legume bloat
Feedlot bloat
• Etiology
– Occurs in ruminant animals fed high grain diets particularly
during adaptation to the diets
• Causes
– Digesta becomes viscous and gel-like that trap gas as a foam
• Viscosity increased by
– The presence of bacterial capsules on some gram + starch-digesting
bacteria such as Streptococcus bovis and lactobacilli
» Streptococcus bovis and lactobacilli only found in large
numbers in animals not adapted to high grain diets
– The presence of short-chain starches (dextrans)
– Increased concentrations of VFAs
• Reduce ruminal motility
– Increased intake of a dense diet
• Lowers cardiac sphincter
– Increased numbers of mucinolytic bacteria
• Mucin will prevent foam
– Reduced outflow rate
• Prevention
– Slowly adapt animals to high grain diets
– Feed adequate fiber
– Use less fermentable grains
• Wheat or barley > Corn or sorghum
• Steam-flaked > Coarse ground
– Feed ionophores (Monensin or Salinomycin)
• Decreased growth of Streptococcus bovis and lactobacilli
• Decreased feed intake
• Decreased methane production
Pasture bloat
• Occurs in ruminant animal consuming fresh legumes
such as alfalfa, white clover and red clover or the small
grain wheat when immature or immediately after a frost
• Causes
– Presence of high concentrations of soluble protein present in
chloroplasts increases surface tension causing foam
• Earlier research implied that a protein named ribulose-1,5biphosphate carboxylase oxygenase (also called the 18S protein)
– 3 – 6% of DM in bloat-causing legumes
• Recent research shows that total soluble protein concentration is
more highly related to bloat
– Rapid cell wall digestion
• Rapid release of chloroplasts
• Rapid release of cell wall fragments that get trapped in foam
– Pectin
• A cell wall component in high concentration in legume cell walls
• Pectin metabolism
– Pectin fermented to Pectic acid (binds 2000x its weight in water
increasing viscosity)
– Pectic acid rapidly fermented to methane
– Minerals
• K, Ca, Ni, Zn, and Mg stabilize foam
• Frosted legumes
– K is released into cytoplasm
– Decreased Na:K ratio results in increased binding between proteins
– Increases surface tension causing bloat
– Decreased chewing
• Decreased salivary mucin and Na
• Mucin prevents foaming
– Reduced ruminal outflow
Retention time of CoEDTA, hr
Nonsusceptible
8
Susceptible
12-17
• Increases concentrations of chloroplasts and chlorophyll
– Saponin
• Surfactant glucoside
• Minor role in stabilizing foam
– pH less than 6
• Stabilizes foam
– Toxic factors
• Amines like histamine reduce motility
Legume bloat prevention
• Mix grasses with legumes in pastures
• Allow legumes to mature before grazing
• Use of non-bloating legume species
– Birdsfoot trefoil, sanfoin, crownvetch, berseem clover, and
some cultivars of red clover
– Produce high concentrations of tannins
• Polymers of phenolic compounds
• Actions
– Binds proteins preventing release
– Reduce rate of digestion
• Feed some dry hay before putting animals on pastures
• Move to new paddocks after early morning
– Not related to dew
– Appears related to selective retention of chloroplasts
• Increase grazing pressure
– Forces animals to increase consumption of stems to leaves
• Close availability of water
• Use of surfactants
– Vegetable oil
– Poloxalene (Bloatguard)
• Effective at 10 gm/1000 lb/day
• May be used as drench, block or loose supplement
• Questionable palatability
• Antibiotics
– Penicillin and tylosin
• Prevents bloat for a short period
• Bacteria adapt causing bloat
– Ionophores
• Decreased incidence by 50%, but didn’t prevent it
• Genetic selection
– After 10 years, bloat removed from herd
– Phenotype difference
• Increased rumen liquid volume
Rumination
• Functions
– Rechewing to increase particle size
– Saliva flow
• Particle breakdown
– Chewing during eating
• Functions
– Preparation for swallowing
– Release soluble constituents
– Damage plant tissues for microbial attachment
– Chewing during rumination
• Functions
– Decrease particle size for passage
– Damage plant tissues for microbial attachment
– Microbial digestion
– Reticuloruminal contractions
Particle size reduction
Alfalfa Meadow
Ryegrass Red clover Alfalfa
hay
hay
( % of intake)
DM digested in RR
59.9
61.7
55.3
37.1
49.3
Soluble DM released 36.8
37.6
31.9
22.9
20.4
by chewing during
eating
Large particles reduced
to < 1 mm by:
Eating
11.8
14.0
14.5
14.3
14.4
Ruminating
12.0
13.7
16.4
26.6
38.5
(% of particle reduction)
Particle reduction by 50.4
49.4
53.1
65.0
72.8
rumination
Mechanism of rumination
• Triphasic contraction of the reticulum
– Forces digesta to cardia
• Animal inhales with epiglottis closed
– Produces a vacuum of 60 to 80 mm water in esophagus
• Cardia opens and esophagus dilates
– Negative pressure sucks digesta into esophagus
• Rapid reverse peristalsis moves digesta to mouth
• Bolus is rechewed
– Chewing is slower and more deliberate than during eating
• Digesta reinsalivated
– Saliva composition is different than during eating
• Parotid glands secrete more saliva during rumination than eating
– Saliva from parotid glands secrete more HCO3- than other glands
• Reswallowing
– After reswallowing, the rumen undergoes a primary
contraction to move it back in the rumen
– 20 to 65% of the DM is released in a fine state and will not
return to the mouth again
Control of rumination
• Controlled by tactile receptors (epithelial
receptors) near the cardiac sphincter,
reticuloruminal fold and anterior sac
• Stimulated by scratching of feed against the
rumen wall
• Reflex is semiautomatic
– Can be stopped anytime
• EEG resembles sleeping
Rumination time
• Average times for a grazing animal
– Eating – 8 hours
– Ruminating – 8 hours
– Resting – 8 hours
• Ruminating time is quite variable
• Factors affecting rumination time
– Fiber content of diet
– Physical form of diet
Effects of diet on rumination
• Increasing the proportion of grain in the diet will
decrease rumination
Hay
Dried grass
Concentrate
Chews/day
50,100
36,100
11,000
• Increasing the maturity of the forage in a diet will
increase rumination
• Decreasing the particle size of the diet will decrease
the rumination time
• Increasing feed intake will reduce the rumination time
per gm of feed consumed
• Cattle ruminate less per kg NDF than sheep or goats
Roughage value index
Total chewing, min/kg DM
Alfalfa hay,
Chopped
Long
Pelleted
Oat straw
Cottonseed hulls
Alfalfa silage
Fine chop
Medium chop
Corn-ground
Soybean meal
Minerals
Molasses
Urea
44.3
61.5
36.9
160
30.1
22.3
26.0
5.1
6.0
0
0
0
Effects of rumination of the animal
• Saliva flow
– More saliva secreted during rumination than eating
– Affects
• Rumen pH
–
–
–
–
–
–
Fiber digestion
Microbial growth
VFA and methane production
Maintenance of intake
Structure of rumen epithelium
Prevention of liver abscess and laminitis
• Liquid rate of passage
– Efficiency of microbial growth within the rumen
• DM intake
– Ruminating time is a limiting factor controlling intake of
high fiber diets
Maximum time, hours
Ruminating
10-11
Grazing
13
– Lower rumination efficiency (min/g CWC) limits intake of
smaller and growing animals
Body weight
Animal
kg
kg.75
Lambs
40
16.0
Goats
39
15.6
Mature sheep 82
27.3
Calves
119
35.9
Heifers 1
213
55.7
Heifers 2
342
79.6
Heifers 3
456
98.6
Mature cows 561
115.0
Rumination
min/g CWC
2.05
1.30
1.18
.78
.42
.19
.16
.10
Max. CWC intake/d
g/kg BW g/kg.75 BW
5.8
14.6
9.4
23.7
4.9
14.9
5.2
17.2
5.4
20.8
7.4
31.8
6.5
29.9
8.2
40.1
• Energy cost
– Total chewing
• increases maintenance cost by .24 kcal/hr/kg BW and
accounts for 30% of maintenance requirement
• Accounts for difference in maintenance energy
requirements of cattle fed high grain or high forage diets.
– Contribution of rumination to energy cost of total
chewing varies
Time, min/kg DM consumed
Feedstuff
Eating
Ruminating
Oat straw
41-58
94-133
Medium quality hay
20-40
63-87
Good quality hay
27-31
55-74
Concentrates, pelleted
4-10
0-25
Finely ground oat straw 11-24
0-20
Finely ground hay
13
0-6