DETERMINATION OF THE OPTIMAL IMMUNOSTIMULATORY DOSE OF ETR FOR CHICKENS

Abstract

The immunocompetent system of chickens, especially day-old chicks, is not yet sufficiently formed and, accordingly, it cannot fully function and immunodeficiency conditions may occur. The use of immunostimulants is promising for the treatment of immunodeficiency states, as they increase the immune status of the body, strengthen natural resistance and reduce the loss of livestock, especially young animals. In addition, the use of immunostimulants makes it possible to strengthen the immune response when vaccinating livestock. The ETR immunostimulator developed by us contains many essential amino acids, enzymes, fat- and water-soluble vitamins and trace elements. In previous studies, we prepared the ETR preparation using a special method and established its immunostimulating effect during the vaccination of chickens against Newcastle disease. In this work, the optimal immunostimulating dose of drone brood extract (ETR) was determined when vaccinating chickens against Newcastle disease. In order to determine the optimal dose of ETP immunostimulator for the body of chickens, the immune status was calculated based on serological, biochemical and immunomorphological indicators. For the study, 5 groups of 14-day- old Leghorn chickens, 10 heads in each group, were formed, which were injected intranasally with a live vaccine virus from the La Sota strain against Newcastle disease. The first group was a control, its chickens were only vaccinated, the second group of chickens was injected enterally with ETR in a dose of 0,1 cm³, the third – 0,3 , the fourth – 0,5 , the fifth – 0,7 , the sixth – 0,9 . According to the results of serological studies, a fairly effective immunostimulating dose for chickens is a dose of 0,9 , but doses of 0,5 and 0,7 are also immunostimulating, since the difference between the results of the fourth, fifth and sixth groups is insignificant, and the titer of antihemagglutinins respectively, it was 7,58±0,03 log₂ in the fourth group, 7,60±0,06 log₂ in the fifth group, and 7,64±0,04 log₂ in the sixth group. According to the results of biochemical studies, it was found that the best levels of IgG, Ig M and Ig A were in chickens of group 6, which received an immunostimulant in a dose of 0,9 and were, respectively, 9,12±0,013 mg/, 1,60±0,04 mg/ and 0,65±0,012 mg/ . But doses of 0,5 and 0,7 are also immunostimulating, since the difference in the indicators of the 4-th, 5-th and 6th groups was insignificant. According to the results of immunomorphological studies, the indices of lymphoid organs increased with an increase in the dose of the immunostimulator. A dose of 0,5 in chicks of the 4-th group should be considered optimal, because further increases in the dose were less effective, although a small increase in these parameters was observed in the chicks of the 5-th and 6-th groups.