The article presents the results of the study describing the adaptation of the humoral and cellular level of nonspecific resistance and aspects of the immunological adaptation of the duck organism during the critical periods of postnatal ontogenesis. It was established that from 2 to 21 days of life of ducklings indicators of bactericidal, lysozyme and phagocytic activity of the blood serum are characterized by stable numerical values; from 21 to 45 days of life, an increase in the value of phagocytic activity was observed on 20,6% (p <0,05), phagocytic index by 37,8 - 69,8% (p <0,05-0,01) with a simultaneous decrease in the number of circulating immune complexes per 27.4 and 25.3% (p <0.05); from 90 to 240 days of life revealed a sharp increase in the value of bactericidal activity of the blood serum in 1.7 times (p <0,05); the values of lysozyme activity of the blood serum were 32.8% (p <0.05), the decrease in the value of phagocytic activity of the blood serum, the increase of the phagocytic index by 43.5% (p <0.05) and the number of circulating immune complexes. The immunological adaptation of the duck organism in the critical periods of ontogeny is manifested by an increase in the absolute mass of the thymus, bursa, spleen on average by 20.0 times (p <0.01), 9.1 times (p <0.01), 22.7 times (p <0,01) to 240 days of life with simultaneous decrease of the index of investigated organs by 47,6%, 62,0%, 30,3% (p <0,01)
non-specific resistance, thymus, bursa, spleen, ducks, ontogenesis
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