What is the microflora? Where is it located in the digestive system? What is its composition? What is the role of the microflora in feed digestion?
The microflora
Calves at birth are born with a relatively
sterile gut. Thus the newly born calf will be more easily colonised by
pathogenic microorganisms as there is no protective microflora to reduce the
colonisation of pathogens at this stage of life and the immediate environment
to which the calf is born is contaminated with beneficial as well as
potentially pathogenic microorganisms.
Soon after birth the calf begins to acquire a complex collection of
microorganisms which populate its intestinal tract. This collection of
microorganisms is termed as the microflora. The gut microflora contains a
variety of different bacteria and fungi of which there are typically ~400
different types of microorganisms with a total population of ~ 1014 throughout
the length of the intestinal tract.
Location in the digestive system
This complex collection of gut microorganisms is distributed
throughout the whole length of the gut.
Within particular regions the organisms may be found in three niches:
(a)
associated with gut wall. This can either take the form of direct attachment to
the gut epithelium or entrapment in the mucous layer of the epithelium
(b)
attachment to food particles
(c)
suspension in the liquid phase of the gut contents
Composition
The composition of the flora varies in
different regions of the intestine and is dependent on factors such as pH. The
microflora which develops in the calf's intestinal tract is characteristic for
that species, and is a very stable population which has evolved a symbiotic
association with the host.
Role of gut flora in digestion
The microflora forms a symbiotic relationship
with the host and benefits the host by aiding digestion by:
Producing various enzymes which are involved in
the digestion/breakdown of large feed particles/polysaccharides such as
cellulose. The bacteria in the gut can also stimulate an
immune response. For example, germfree animals have lower levels of
gamma-globulin than do conventional animals with a complete gut flora.
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