Gut immunity in birds: facts and reflections (review)

Gut immunity plays a crucial role in maintenance of the whole body immunity being the first and most important line of defence from various pathogenic organisms and substances consumed with feed and able to colonize host cells and tissues. The role of protective mechanisms in the gut is difficult to overestimate. For example, the process of learning distinguishing between «self and non-self» taking place in the gut are fundamental for the immunity development as well as for the development of nutrient tolerance. It is necessary to underline that structural changes in the gut, in particular at the mucosa level are responsible for decreasing efficacy of nutrient assimilation from the feed. Therefore, gut status determines the chicken health, utilization of nutrients and biologically active substances (FCR) and other important commercially relevant parameters of the poultry production. This review summarises recent knowledge about the development and functioning of protective immunological mechanisms in the gut. A particular attention is paid to the possibilities on the modulation of gut immunity by a mixture of biological active substances.