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Abstract
Abstract
The gastrointestinal (GI) tract has the most extensive exposed surface in the body
and is constantly exposed to a wide variety of potentially harmful substances. The
GI tract acts as a selective barrier between the tissues of the bird and its luminal
environment. This barrier is composed of physical, chemical, immunological, and microbiological
components. A wide range of factors associated with diet and infectious disease agents
can negatively affect the delicate balance among the components of the chicken gut
and, as a result, affect health status and production performance of birds in commercial
poultry operations. Phasing out of antibiotic growth promoters from poultry diets
in Europe and recent moves toward reduction or removal of these compounds in other
parts of the world including North America will likely change the microbial profile
of the GI tract environment in commercial poultry. This paper reviews the GI tract
from developmental, immunological, and microbial standpoints and then discusses factors
that can affect health status of this system. Necrotic enteritis and coccidiosis and
their interactions, and possible consequences of antibiotic growth promoter removal
from poultry diets with respect to these diseases, are discussed in more detail.