Digestive microflora of bird : factors of variation and consequences on bird

Abstract

The microflora of the digestive tract, remained uncompletely known due to the conventional methods used so far. It is mainly located in the crop and the caeca, but also, although in lower number, in the small intestine. In the upper part of the digestive tract, facultative anaerobes dominate, whereas in the caeca it is mainly obligate anaerobes that are present. The microflora depends on numerous factors such as individual, animal age, environment, and diet. Bacteria produce various metabolites that can be useful or detrimental to the host. Interactions between bacteria and the gastrointestinal epithelium lead to various structural and functional modifications of the digestive tract. Bacteria can decrease lipid digestion and may modify carbohydrate and protein digestion. They cause an increase in energy and amino acids requirements. They have a negative impact on vitamin nutrition. Beneficial bacteria can protect against pathogens through a competitive exclusion process. Moreover, the flora is implied in the development of the intestinal immune system. Globally bacteria have a negative impact on bird growth. They may also have an effect on the quality of meat and eggs. Improved knowledges of the microflora of the digestive tract and of its consequences should contribute to its control and to use it beneficially for birds as well as for breeders, consumer and environment.