Immune status of broiler chickens during different times of physiological development

The widespread prevalence of immunodeficiencies in farm animals challenges researchers to develop a sound and evidence-based methodology for early detection of immune system deficiencies for prevention and timely correction. In this regard, the strategy of modern scientific research is primarily aimed at a detailed study of the immune system, the mechanisms of immunosuppression and the search for effective means of correction of disturbed immune homeostasis. The aim of this study was to investigate the immune profile of healthy broiler chickens during physiological development. Immune status was assessed in broiler chickens of Arbor Acres cross at the age of 7, 14, 28 and 42 days, including determination of serum levels of cytokines (IL-2, IL-4, IL-10, IFN-γ), immunoglobulins (IgA, IgY) and lysozyme by enzyme immunoassay. It has been established that during postnatal ontogenesis the immune system of broiler chickens undergoes dynamic changes, which have an age direction and phase character. The results obtained indicate a decrease in the efficiency of functioning of the immune system of birds with increasing age. The most pronounced immunological deficiency in the organism of broiler chickens is observed at the age of 7–14 days, which is associated with the immaturity of the immune system and is characterized by the fact that nonspecific humoral and specific cellular defense factors are at a rather low level – the level of lysozyme, IL-2, IL-10 and IgA in blood serum at this age was minimal; starting from 28 days of age, there is a specific humoral immune insufficiency, which is compensated by strengthening of cellular defense factors – serum level of IgY intensively decreases against the background of increase of lysozyme, IL-2, IL-4, IL-10. Such changes in the immune system can affect immunocompetence, susceptibility to diseases, and as a consequence, meat productivity.