The gastrointestinal tract of the newborn is challenged with 3 differe
nt tasks: During the first 24 hrs after parturition, the transfer of c
olostrum-derived IgG has to take place. In addition, rapid adaptation
is necessary for oral uptake and enzymatic digestion of milk, the main
source of energy during the first weeks of life. Thirdly, the sterile
gut lumen will quickly be invaded by a variety and large quantity of
microorganisms. This microbial invasion is on one hand potentially har
mful, but it is also essential for the establishment of the cellulolyt
ic flora in the hindgut of the horse.