ABSTRACT
The colonization of the digestive tract in animals begins soon after birth or hatching and
the normal microbiota changes dramatically during the life of the host. The composition
of gastrointestinal microbiota differs between animal species, between individuals within
the same species and between the body sites of the host. The gut microbiota is a complex
interactive community of organisms and its functions are the result of activities of all
microbial components. Together with the host, the microorganisms constitute an
ecological system, beneficial for the host, as well as for the microbial species. In
principle, the role of gut microbiota in animals is the same as in humans-salvaging
energy from the undigested feed components through fermentation, providing the basis
for a barrier that prevents pathogenic bacteria from invading the gastrointestinal tract,
protective functions together with the gut immune system, a role in metabolism
of xenobiotics and contribution to the vitamin and amino acids requirements of the
animals (1). Some of these functions are emphasized in farm animals with regard to their
environment, character of their feed and the economy of farm animals’ rearing. The
composition and metabolism of the gastrointestinal microbiota affects the performance of
farm animals in many ways, especially in the young, which are subjected to many
stressful conditions.
