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Rumen development
Morteza nemati
9302275
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Feed concentrates have been formulated for calves
to maximize not only DMI and ADG, but also
VFA production
Ruminal fermentation of dietary concentrates and
their end products (especially butyrate and
propionate) play a central role in ruminal epithelium
differentiation and papilla development
increasing ruminal propionate production by
feeding a high-concentrate diet may be
associated with improved animal performance
and rumen development via its indirect effect on
endocrine hormones
The five requirements for ruminal development are
• Establishment of bacteria.
• Liquid.
• Outflow of material (muscular action).
• Absorptive ability of the tissue.
• Substrate to allow bacterial growth, such as
recycled minerals, as well as feed
nutrients.
• The rumen is incompletely developed both
physically and metabolically at birth (Warner
et al., 1956)
• Increased sodium and chloride transport by
the developing rumen epithelium could reflect
an increase in the SCFA absorptive capacity
by the rumen epithelium (Sehested et al., 1999)
• The rumen develops from a very small organ
in newborn calves (1–2 L) into the most
important part of the gut (25–30 L) by 3
months of age
• The rumen’s capacity and the intake of solid
feed are closely related
• Rumen development is very slow in calves fed
large quantities of milk
• Solid feeds and rumination both stimulate
saliva production and this supplies nutrients
such as urea and sodium bicarbonate to
produce the substrates for bacterial growth
• Urea supplies nitrogen for the microbes
• sodium bicarbonate acts as a rumen buffer
when calves eat large quantities of cereal
grains later in life as the rumen microbes can
produce a lot of lactic acid during fermentation
overloading butyrate and propionate may
promote keratinization of papillae by increasing
the mitogenic rate and decreasing the apoptosis
rate of the epithelium
Because of the lower digestibility of forage in
the rumen of calves, the VFA produced are
insufficient for optimal growth of papillae and
thus, rumen development is slowed
Forage has the potential to encourage early
rumination and enhance rumen pH and rumen
muscle strength, while also reducing cancerous
proliferation and keratinization of rumen papilla
Large amounts of forage in the feed leads to
decreased DMI and ADG in calves
• at weaning, the production
of the ketone body βhydroxybutyrate (BHBA)
from butyrate by rumen
epithelial cells increases
sixfold
Ruminal absorptive capacity is affected by rumen
pH and the gradient of VFA concentration between
the ruminal lumen and epithelial cells.
The blood VFA absorption is a function of rumen
surface area, which is highly dependent on the
number and size of its papillae.
The rumen epithelium itself utilizes VFA for its
energy needs, their availability for whole-body
metabolism depends on the extent of their use by the
ruminal epithelia.
Size of Ruminant Stomach Compartments
Compartment
Adult, %
Newborn, %
Rumen
55
29
Reticulum
7
6
Omasum
24
14
Abomasum
14
51
alfalfa hay and sodiumpropionate in calf
starter diets
The differences in forage source, quantity, and
particle size might have influenced the
differences in ADG and final BW
Biranvand , 2014
• in the case of illness, feeding plans need to be
adjusted because physiological development is
slowed during illness
• Higher milk rations can decrease solid feed intake
before weaning, decreasing feed intake and
growth in days after weaning
• large particle size and bulk of fibrous feed can
provide mechanical stimuli to enhance rumen
weight, its physical capacity, and volume in
calves
• Similar concentrations of blood BHBA (an
indicator of metabolic function of the rumen
wall) in calves fed hay or no hay indicates that
the rumen walls were equally efficient in
converting butyrate to BHBA
Hepatic SCFA metabolism
• Th liver and ruminal epithelium have diffrent
affities towards individual SCFA
• Th low rumen epithelial affity but high liver
affity for propionate ensures that the largest
propionate metabolism occurs in the liver
• Butyrate is removed substantially by the
ruminal epithelium prior to reaching the liver a
large portion of acetate released by the
ruminant liver originates from peroxisomal βoxidation
Grain processing
• Previous studies indicated that grain processing
level influenced rumen VFA production, rumen
pH, and rumen NH3
• Murphy et al. (1994) reported increased total VFA
concentrations and decreased ruminal pH when
whole corn ( WC) was replaced with DRC in allconcentrate diets
• grain processing had less influence on total VFA
production and rumen pH when forages were
incorporated into the ration
• Heat processing of grains has been shown to
increase ruminal propionate production
• Ruminal butyrate production appears to be
enhanced by physical processing
• Some researchers have indicated that increased
grain processing lowers rumen NH3 however,
this is not always the case
GRAIN PROCESSING
the SFC ration had more fine particles that may
have become trapped by rumen papillae or were
less effective in removing dying epithelial cells,
subsequently resulting in keratin buildup and
rumen mucosa thickening
rumen pH was greatest in WC calves throughout
the study, differences between processing
methods were inconsistent
• Crocker et al. (1998) reported decreasing
rumen NH3 concentration as SFC replaced
DRC, attributing this effect to increased
microbial use of available NH3. In addition,
others have reported a tendency for decreasing
rumen NH3 concentrations as starch
degradability increased Rumen NH3
concentrations observed in the current study
fluctuated drastically across all treatments and
do not indicate.
• Any definite effect of heat processing or
mechanical processing on rumen NH3
concentrations. Rumen NH3 concentrations
did appear to decrease as starter intake
increased, indicating ruminal microbial
proliferation and increased incorporation of
NH3 nitrogen into microbial protein
Calves Fed Milk Through Step-Down
and Conventional Methods
• Addition of sodium butyrate (SB) in MR
stimulated pancreatic secretion and intestinal
cell proliferation villus growth , and brush
border and pancreatic enzyme activity, which
resulted in improved digestibility and better
performance and health of calves (Hill et al.,
2007)
• Although liquid feed in the preruminant calf
bypasses the reticulorumen via the reticular groove
it might also affect rumen development indirectly.
Liquid feed determines the growth and health of
animals and thus, solid feed intake and
consequently, rumen development (Khan et al.,
2007)
Gorka et al , 2011
Castells et al, 2013
• The inclusion of chopped forage in the diet of
young calves leads to a better rumen
environment because rumen pH increases and
the expression of MCT1 transporter tends to
increase
• fractional rate of passage in the rumen:
oat hay > alfalfa hay
• The results reported in the present study suggest 2
possible mechanisms that could be involved in the
changes observed in rumen fermentation parameters
when forage is included in the diet of young calves.
First, differences in rumen epithelia gene expression
could explain the lower rumen VFA concentration in
forage-fed calves. Animals fed forage tended to show
increased expression of MCT1 in the ruminal wall.
This transporter is located in the basolateral
membrane of the rumen epithelium and it is involved
in the transport of lactate, acetate, and protons from
the rumen epithelium into the bloodstream
it could be speculated that due to the enhanced
proton export, intracellular pH probably
increased, and it may have heightened absorption
of short-chain fatty acids (SCFA) from ruminal
lumen into epithelium both by simple diffusion
of protonated SCFA and by SCFA−/ HCO3−
exchange. Despite the observed differences in
NHE1 protein expression between AH and OH
animals, overall expression of this gene was low,
and thus the role of this protein in thecontrol of
intracellular pH homeostasis might not be very
relevant.
Effects of dietary carbohydrates