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DIET AND CAECAL MOTILITY IN SHEEP
Jean Fioramonti, Y. Ruckebusch
To cite this version:
Jean Fioramonti, Y. Ruckebusch.
DIET AND CAECAL MOTILITY IN SHEEP. Annales de
DIET AND CAECAL MOTILITY IN SHEEP
J. FIORAMONTI
Y. RUCKEBUSCH
/.ato;’afo//e t/e
P/)/s/o/o!/e,
fco/e /Vaf/o!a/e !f!/77?a//!Laboratoire
de
Physio%gie,
Ecole Nationale
Vétérinaire,
23, chemin des
Capelles,
31076 Toulouse Cédex, France.Résumé
REGIME ALIMENTAIRE ET MOTRICITE CAECALE CHEZ LE MOUTON.- L’activité
électrique
de la
paroi
caecale a étéenregistrée pendant
despériodes
de deux mois chez 5 brebis recevantdifférents
régimes
alimentaires. Parrapport
à unrégime
témoin(foin
distribué àvolonté),
la fré-quence des contractions caecales(1 500/24 h)
est diminuée pourl’ingestion
d’une même quan-tité de matière sèche sous la forme de concentrés contenant del’urée,
mais elle n’est pas modi-fiée en l’absence d’urée. Elle estégalement
diminuéelorsque
le niveaud’ingestion
de foin ou de concentrés sans urée est réduit. La distribution des aliments sous la forme d’un repasquotidien
de durée limitée induit une
hyperactivité
dans le cas du foin et une inhibition pour les concentrésavec urée. Les effets excito-moteurs ont pour
origine
le rumen avec intervention des nerfs vagues. Les effets inhibiteurs de l’urée sont liés à laproduction
dans le rumen d’ammoniac et à sadiffusion dans la cavité abdominale.
The caecum
regulates
the flow ofdigesta
between the small intestine and colon. Thefrequency
ofperistaltic
orantiperistaltic
con-tractions
(about 1/min)
which results inmixing
of caecal contentsdepends
on intra-caecal pressure(Fioramonti
andRuckebusch,
1978).
About 10 times per 24 h andduring
thepropagation
of aphase
ofregular spiking
acti-vity
of amyoelectric complex
on the terminalileum,
strong
contractions in series evacuatethe
digesta
towards theproximal
colon insheep
(McRae
eial.,
19731.
However the flow ofdigesta through
terminal ileum varies with the diet. Itaveraged
1.5kg/24
h withdigesti-ble dried grass, but
nearly
twice this amountwith less
digestible hay
(Goodall
andKay,
1965).
Accordingly,
thepattern
ofmotility
of the ovine small intestine is controlledby
theamount of food eaten
(Bueno, 1977),
itsnature and/or end
products
(Bueno
etal.,
1977b).
Diets
containing large
amounts ofgrain
cause the
production
oflarge
amounts of vola-tilefatty
acids which maylead
toatony
of thecaecum
(Svendsen, 1972).
These
experiments
investigate
the effectson caecal
motility
of the amount and thenature of food
eaten,
especially
in the case ofan increased ammonia
production
by
Material and Methods
Five lacaune ewes
weighing
35-49kg
wereused. Five
pairs
of electrodes 2 mmapart
made of insulated nichrome wire were
implan-ted under
thiopentone
anaesthesia on the ileum at 40 cm from the ileo-caecal valve(ICV),
on the caecum near the blindpole,
onthe
mid-caecum,
in front of theICV,
and onthe
proximal
colon at 40 cm from the ICV. Insheep
n° 4 and5,
a cannula (int. diam. 2 cm)was inserted in the caecum and in the dorsal
blind sac of the rumen.
After surgery, animals were
placed
inmeta-bolism cages, ileo-caeco-colic
electromyo-gram was recorded for 3days
each weekduring
2 months on an EEG machine(Reega
VIII,
Alvar, Paris).
Inaddition,
electricalacti-vity
of four chosen sites wasautomatically
plotted
each 20 secby
means of a four lineintegrator
on apotentiometric
recorder(Latour,
1973).
Three different
feeding regimes
were used insheep
n°1,
2 and 3(long hay
of poorqua-lity,
concentrates with or withouturea) ;
their chemicalcomposition
isgiven
in table 1. Each diet wasgiven
ad libitum or from 10:00 to14:00 hr in
equivalent
quantity,
or was limited(low intake) to 800
g/day
forhay
and 700g/day
for concentratesgiven
in 3 meals at08:00,
13:00 and 19:00 hr. In the latter case,owing
to uneatenfood,
dried matterconsu-med was
nearly
similar (table 31. The influence ofdiet,
of the level of food intake and offee-ding
pattern were studiedaccording
to thedesign
shown in table 2. After thisexperiment,
sheep
n° 1 and 3 were fitted with a silastic muff around each vagus nerve in theneck ;
the rumen was distended in theses
sheep by
insufflation of air
through
a needle insertedthrough
the left flank before and afterinjection
of a local aneasthetic into the muff.In
sheep
n° 4 and 5receiving hay
adlibitum,
a 20 % (w/v)
solution of urea (0.3g/kg body
weight)
and a 1 N solution of ammonia (200ml, pH
11) wererapidly
infused into therumen. Ammonia was also infused into the
caecum (0.1
N, pH 11, 200 ml
in 10 min) and into thejugular
vein (0.03N,
250 ml over 120 minl. The concentration of blood ammoniawas determined from
samples
taken10, 20,
30 min after thebeginning
of infusions then each 30 minduring 4 hours.
The same solutions of ammoniaadjusted
topH
7by
HCI were infu-sed into the rumen or the caecum andammo-nia was also
injected intraperitoneally
(0.06N,
20 mll. Each solution was tested 3 times in each
sheep.
After thisexperiment, samples
of caecal contents were collected(4/day
during
7days)
onhay
diet thenduring
7days
oncon-centrates with urea diet ad libitum.
The
pH
of caecal contents were measuredimmediately
aftersampling ;
theNH
3
concen-tration was determined
by
the Berthelotreac-tion
using
anautoanalyzer
Technicon(Puyt,
1973).
Results
Diet,
level of food intake and meal pattern The amounts ofdry
matteringested
adlibi-tum were identical for the three diets (table 31. On
hay
diet adlibitum,
the motorprofile
of thecaecum was similar for the three ewes : 936 +
92 contractions/24h at the blind
pole
and 1 497 + 129 near theICV,
10.2 + 2.7phases
ofhyperactivity
per 24 h whichappeared
when aphase
ofregular spiking activity
waspropaga-ted on the terminal ileum. An inhibition
lasting
12.3 + 4.1 min then occurred. The number of
The
frequency
of caecal contractions wasnot
significantly
modifiedby ingestion
ofcon-centrates without urea (1 396 + 116/24 h)
compared
withhay
fed ad libitum. But on aconcentrates ration with urea ad
libitum,
the number of contractions was 30 % less.Redu-cing
the food intakeby
40 % decreased the number of caecal contractions/24 h onhay
and concentrates without urea rations
by
38 % and 43 %respectively
near the ICV andby
43 % and 48 % on the blindpole.
Therewas no
change
in thefrequency
of contractionon the concentrates with urea ration on the reduced intake (table 3).
Whatever the diet
given
adlibitum,
eating
did notmodify
the caecalmotility.
When the time offeeding
was limited to 4h/day,
inges-tion ofhay produced,
after adelay
of 15min,
an increase
by
25 % of thefrequency
of caecal contractionsduring
5 hours(fig.
1). Afteringestion
of concentrates with urea, the fre-quency of contractions was decreasedby
halfduring
5-8 h after adelay
of about 2 hours.Ingestion
of concentrates without urea did notmodify
caecalmotility.
For the threediets,
the number of contractions perday
remainedunchanged
whencompared
with the samediet ad libitum.
Ruminal factors
The ruminal distension obtained
by
increa-sing
internal pressure to 20 cmH
2
0
by
the insufflation of airproduced
anhyperactivity
of the whole caecum ; thefrequency
ofcontrac-tions reached 4.5/min and this effet
persisted
during
all the time of distension(fig.
2). The bilateralvagal
anaesthesiaby
injection
of alocal anaesthetic
(procaine
sol. 2 %w/v,
indu-ced an inhibition of the caecal
motility during
10-15 min. The
frequency
of contractions wasreduced to 0.2/min. Ruminal distension
per-formed 2 min after
vagal
anaesthesia had noeffect on caecal
motility.
Effects of ammonia
production
The ammonia concentration of caecal
con-tents increased from 8.6 ± 2.3
mg/100
ml (n= 20) on
hay
diet ad libitum to 22.0 ± 6.1 Img/100
ml on concentrates with ureadiet ;
the
pH
remainedunchanged
(7.55 + 0.33 vs.7.46 + 0.41). Intracaecal infusion of ammonia (0.1
N,
pH
11,
20ml/min,
300 ml) did notmodify
the concentration of blood ammonia 10. 091 ± 0.012 vs. 0. 085 + 0.018mg / 100
m 1). ) . After aslight
excitatory
effectincreasing
thefrequency
of caecal contractionsduring
the first 5 min ofinfusion,
the infusion induced astrong inhibition od caecal
motility during
92+ 13 min. The
frequency
of contractions wasreduced to 0.1 /min. If a
phase
ofregular
spi-king
activity
of amyoelectric complex
reached the terminal ileumduring
thisinhibition,
the caecalhyperactivity
associated with the regu-larspiking
activity
still occurred. Infusion of disodiumhydrogen phosphate
buffer solution(pH
11) or ammonia solution atpH
7 into thecaecum
only produced
aslight
and short inhi-bition of caecalmotility
notlonger
that 10 min. After addition of urea into the rumen (0.3g/kg body weight),
the caecumshowed,
aftera
delay
of 15min,
apronounced
inhibitionlas-ting
about 2 hours. The intraruminalinjection
of a 1 N solution of ammonia (200
ml,
pH
11) induced after 3-4 min a shortphase
of caecalinhibi-tion
during
72 1: 14 min.(fig.
3) ;
atpH
7,
such an addition had no effect.
Intraperitoneal
injection
of an isotonic solution of ammonia (0.06N,
20ml, pH
11)reproduced
the effects of intraruminaladministration,
thedelay
ofapparition
ofhyperactivity
notexceeding
20-30 seconds. Perfusion of ammonia into ajugu-lar vein (0.03
N, 250 ml,
2 ml/min.) did notmodify
thefrequency
of caecal contractions. In all theexperiments performed,
motor chan-ges were similar for caecum andproximal
colon.
The concentration of blood ammonia
rea-ched 0.35 ± 0.09
mg/100
ml 2 hours after addition of urea into the rumen, 0.31+0.11
Img/100
ml 1 hour after the intraruminalinjec-tion of the alkaline soluinjec-tion of ammonia and 0.44 ± 0.15
mg/100
ml 2 hours after thebeginning
of the infusion of ammonia into thejugular
vein.Discussion
The present work shows that the caecal
motor
profile
is alteredduring
differentregi-mes. The 3 factors concerned are the amount
and nature of the food and the time of
fee-ding.
The decrease in the
frequency
ofcontrac-tions
by
40 % when the level of food intake is reduced confirms themajor
roleplayed by
thepressure into the caecum (Fioramonti and
Ruckebusch, 1978),
its volumebeing
reducedby
20 %(Hecker,
1971b).Concurrently,
the transit time ofdigesta
is increasedby
about 40 % (Grovum andHecker,
1973). As transit time increases as caecalmotility
decreases,
wesuggest a
simple
inverserelationship
between these both parameters on the caecum andproximal
colon unlike the morecomplex
rela-tions observed on the colon of otherspecies
such as the rabbit (Fioramonti andRucke-busch,
1976).On
hay
fed once aday,
thepostprandial
hypermotility
is not causedby
an increase in intracaecal pressure as the ileal flow ofdigesta
isunchanged
afterfeeding
(Goodall andKay,
1965). The artificial distension of the rumen
confirms the ruminal
origin
of such responseby
a rumino-caecal reflex(Zalucki,
1963) mediatedby
the vagus nerves. The stimulusmust be
relatively
strong e.g. distension orbrushing
of ruminalwall,
as this responseappeared
only
forrough
hay
diet. Thisexplains
theconflicting
informations about theeffects of a meal on the caecal
motility
insheep (Ulyatt
et al.,
1974).The amount of
dry
matter in the caecum is halved in concentrates diet vshay diet,
con-centrate
digestion being
moreimportant
inproximal
areas of thedigestive
tract(Topps
eta/., 1968).
The absence of a reduction incae-cal
motility
on concentratediets, expected
because of the decrease of caecal
volume,
may be attributed to a permanent ruminalexci-tatory
effect,
thequantity
ofingested
dry
mat-terbeing
similar for bothregimes.
Thiscons-tant control may be mediated
by
the vagusnerves : their anaesthesia in cervical area
decreasing
thefrequency
of caecalcontrac-tions.
Amplitude
of contractions is decreasedby
volatile
fatty acids,
theproduction
of which is increased on a cereal diet(Svendsen,
19721. In this case, the concentrates do not induce anychange
in caecalmotility ;
but an increase in ammoniaproduction
linked to urea addition is associated with a decrease inmotility.
Ammo-nia has acomplex
effect on caecalmotility.
Theinhibitory
effect of intracaecal ammoniadepends
uponpH
of caecal contents as obser-ved for the rumen (Bueno etal., 1977a) ;
on aconcentrates with urea diet
ad libitum,
the role of ammonia concentration in the caecum(2.5
times
higher
than forhay)
is diminished whencompared
to the effects of an alkalineammo-nia infusion
by
thepersistence
of anearly
neu-tral
pH.
The inhibition of caecal
motility
by
addition of urea or of ammonia into the rumen shows theimportance
of the role of intraruminal ammonia. Intraruminal ammonia actsthrough
its diffusible fraction
(NH
3
) :
only
injection
ofan alkaline solution is effective. Caecal
inhibi-tion
occuring
15 min after urea additioncor-respond
to an increase in ruminalpH (Repp
eta/., 1955),
inducing
an increase inNH
3
/NH,
*
ratio. It issuggested
that ammonia from therumen acts after direct diffusion in the abdo-minal
cavity
(Chalmers
andWhite, 1969) ;
indeed,
intraperitoneal injection reproduces
the inhibition whilst ammonia
by
intravenousroute has no effect
despite
an increase of the concentration of blood ammonia identical tothat observed for the intraruminal
injection
of ammonia. Such a mechanism may be also considered for ammoniaproduced
in thecae-cum, its
absorption by
the caecal walloccur-ring
by simple
diffusion(Hecker,
1971a).
Inaddition,
thepersistence
of a caecal responseand
Ruckebusch,
1978) at the occurrence ofan ileal
regular
spiking
activity
anddespite
the inhibition due to intraluminal infusion ofammonia,
shows that such aphenomenon
hasno relation with the metabolic control
by
ammonia.
In
conclusion,
feeding
does alter caecalmotility by altering
caecalfilling,
by
arumino-caecal reflex mediated
by
the vagus nervesand
possibly by
the diffusion of ammoniapro-duced from concentrate diets with urea into the abdominal
cavity.
Accepted
forpublication September
10th 1978.Summary
The electrical
activity
of the caecum was recordedduring periods
of two months in 5 ewesrecei-ving
different diets. For a similar amount ofdry
matteringested,
thefrequency
of caecalcontrac-tions was diminished on concentrates with urea versus
hay
ad libitum but not on concentrateswithout urea. The
frequency
also decreased when the level of food intake onhay
diet or oncon-centrates without urea diet was reduced. On a
daily
meal foodintake,
induced caecalhyperacti-vity occurred
orhay
and inhibition for concentrates with urea. Thepostprandial
hyperactivity
hada ruminal
origin
and was mediatedby
the vagus nerves. Theinhibitory
effects of urea werecorre-lated with the ruminal
production
and ammonia and its diffusion into the abdominalcavity.
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