Name: Mary N.
How do the microbes in ruminants' rumen initially get
there? Do the microbes come from the mother? From the feed?
Probably all: from the mother, from the feed, from
faecal contamination of the grass...the gut of mammals
is sterile at birth, but soon becomes colonized with
micro-organisms. For humans the mother donates many
species (this is true for mouth flora also), and the
gut microflora goes through considerable changes
during childhood, the most noticeable when a child
changes from being breast-fed exclusively to other
foods. Even in adults the gut microflora is not
completely constant. Dietary and environmental changes
(travelling, antibiotic use) can result in changes of
the microflora composition but soon a 'healthy'
balance is restored in most cases without trouble.
A developing mammalian fetus is sterile, but is quickly exposed to bacterial
flora @ birth. Colonization of the GI tract begins with the 1st milk
feeding. So one could say that the bacteria are derived from the mother,
but neonatally rather than pre-natally. The following web site from the
Univ. of Wisconsin has a detailed discussion of the various bacterial flora:
The differences between humans & ruminants might be of particular interest.
Thank you for the good question,
Jeff Buzby, Ph.D.
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Update: June 2012