Agriculture Reference
In-Depth Information
15.3
Importance of maternal environment in driving gut and
gut-associated lymphoid tissues development
A number of factors related to maternal environment during gestation and lactation are
likely to influence postnatal development of the gut and its mucosal immune system in
young piglets. The intra-uterine environment is not only important for foetal development
and survival but it also impacts postnatal development and health of neonates (Morise
et
al.
, 2008). Compromised maternal-foetal relations, which are the primary cause of intra-
uterine growth restriction (IUGR), induce digestive disorders due to gut immaturity.
Moreover, establishment of the intestinal microbiota after birth plays an important
role in the development of the neonatal gut and its immune system. It appears that the
mother's microbiota is shared to a large degree by the offspring during the first days
of postnatal life (Bauer
et al.
, 2006). Therefore, maternal environmental factors (diet
composition, antibiotic treatment, etc.) that induce changes in maternal microbiota have
huge effects on offspring gut physiology. Finally, there is a body of evidence that maternal
diet composition may influence colostrum and milk composition, leading to changes in
gut functions in piglets.
15.3.1
Dietary-induced changes in maternal microbiota: impact on gut
development of offspring
There is no doubt as to the essential early contact of the neonate with environmental and
colonizing bacteria for healthy intestinal and immune maturation. Studies with germ-free
piglets clearly show that bacteria are essential to growth and development of the digestive
tract (Chowdhury
et al.
, 2007). The comparison of gene expression profiles in enterocytes
of germ-free
versus
conventional piglets has brought insight on the impact of microbiota
on gut barrier function (Chowdhury
et al.
, 2007). More specifically, it was demonstrated
that bacterial colonization induces the expression of genes contributing to intestinal
epithelial cell turn-over and mucus biosynthesis. Gut microbiota also influences the
maturation and function of several components of the mucosal immune system (such as
bactericidal Paneth cell activity, IgA production, intraepithelial lymphocyte development)
in order to prevent inflammatory responses that would compromise the barrier function
(Chowdhury
et al.
, 2007, Hooper, 2004). The major role of microbiota in the development
of the neonatal gut was confirmed in conditions where colonization was altered early
on. In rodents, neonatal administration of antibiotics down-regulates the expression of
genes related to innate host defence and to antigen presentation (Schumann
et al.
, 2005).
Conversely, feeding neonatal piglets with formula supplemented with prebiotics sharply
increases the bacterial load in the colon and results in its increased growth (Aufreiter
et al.
, 2011). The commensal microbiota is also pivotal for degradation of otherwise
indigestible complex carbohydrates, especially when solid feed are first introduced in
the diet. In mice, it was shown that gut bacteria directly modulate the utilization of food,
implying that the true 'caloric value' of food is variable depending on the microbiota
composition and its ability to mobilize potential energy sources for the host (Turnbaugh
et al.
, 2006).
