Dynamics of oocyst level during vaccination of broiler chickens against eimeriosis

The aim of the work is to reveal the dynamics of the oocysts level during vaccination against eimeriosis of broiler chickens of the Ross-308 cross. Research objectives are to conduct an experiment based on the study of the reproduction of oocysts in the body of broiler chickens after vaccination with various vaccines against eimeriosis. The studies were carried out in 2020-2021 at the Department of Anatomy, Pathological Anatomy and Surgery and in the hospital of the Institute of Applied Biotechnology and Veterinary Medicine of the Krasnoyarsk State Agrarian University within the framework of the department's research work in the area of "Comparative characteristics of vaccines used for eimeriosis of hens." The object of the study was broiler chickens of the Ross-308 cross. The main research methods were scatological method for determining the number of oocysts and identifying the moisture level of the droppings. Chickens at the age of 14 days were vaccinated: the first experimental group received the “Evalon” vaccine, the second experimental group received the “Ejmeriavaks 4M” vaccine in a dose according to the instructions, the third experimental group received a mixture of these two vaccines. The intact group served as a control. Vaccinated chickens release a small number of oocysts into the external environment, which, when pecked, enter their body again, which leads to the maintenance of immunity in the flock at a sufficient level throughout the entire rearing period. The smallest number of oocysts in the droppings was observed in the first experimental group, where the “Evalon” vaccine was used. The number of oocysts in the first experimental group correlated with the moisture index, which indicates a good tolerance of the “Evalon” vaccine by the chickens. The established dependence of the moisture content of bird droppings on the number of oocysts in it can serve as an indicator when choosing the optimal vaccine against eimeriosis of birds at a poultry farm.