Composition of peripheral blood leukocytes and immuno-competent bodies of the cross carp “Petrovsky” in different periods of the fishing season

Abstract

Crossing is an effective method of increasing agricultural production. In addition to the productive qualities of the resulting crosses, it is important to maintain and enhance their immune resistance. Breeding for immunity to pathogens of various diseases provides a decrease in economic losses and an increase in breeding efficiency. Cross “Petrovsky” (breeding achievement No. 9153820) is a reciprocal hybrid of Anish Mirror and Chuvash scaled productive carp species. It has been established that this cross is superior to the parental forms in terms of growth intensity and survival of juveniles. The work is devoted to a comparative analysis of the leukocyte composition of peripheral blood and immunocompetent organs of the carp cross “Petrovsky” in different periods of the fish-breeding season. The studies were carried out in late May and early October 2019 in the Kirya breeding farm, Chuvashia (2nd fish breeding zone). In fish, peripheral blood was sampled from the tail vein and tissues of the spleen and head kidney. Blood smears and organ-imprinted smears were taken for the study. The preparations were examined under a light microscope and the leukocyte formula was determined. The study of leukograms of immunocompetent organs and tissues of fish helps to judge the functional state and immune resistance of fish. To determine the index of the abundance of leukocytes in a peripheral blood smear, 100 visual fields were examined in different areas. This indicator allows you to record the intensity of leukopoiesis and indirectly assess the level of leukocytes in a unit of blood volume. Studies have established differences in the proportion of certain types of leukocytes and the intensity of leukopoiesis in different periods of the fish-breeding season. Fish tissues and organs differed in the proportion of lymphocytes, monocytes, and neutrophils. The obtained data can be used in carrying out selection and breeding work aimed at increasing productivity and enhancing the resistance of fish to infectious diseases.