SELECTION OF A PRECOCIOUS STRAINE OF EIMERIA ACERVULINA 'IN VIVO'

摘要

Coccidiosis is a protozoan disease that causes important economic losses in the poultry farms of the world, either because of mortality or due to decreased rate of weight gain. The eimerian species that infect the chicken, especially in the broilers, are E. acervulina, E. tenella and E. maxima. Because of the chimioresistance phenomenon, it appeard the necessity of finding new prevention methods, such as vaccination, existing many available vaccines at the moment. This paper had the purpose of obtaining a precocious strain of Eimeria acervulina, latter used for immunoprophylactic purpose. The preliminary line obtained was characterised concerning the duration of biological cycle, prolificity and degree of pathogenicity and immunoprophylactic efficacy in comparison with the parental strain. The duration of prepatent period of E. acervulina precocious strain decreased from 97 hours after the first passage to 93,49 hours at the fifth passage, registering a decrease of 3,6 hours, and also it had inferior pathogenicity in comparision with parental one, the lesional score being 2 in the precocious line and 4 in the parental line. The highest rate of weight gain was observed in group 3A (positive control), being of 655,71 g/chicken. In the immunized groups the rate was of 611,72 g/chicken in group 1A, respectively 526,36 g/chicken in group 2A. Regarding food conversion, the highest level of consumed feed was registered in group 2A - immunized and infected 3,20 kg forage/kg rate, followed by group 1A (immunized and uninfected), 2,75 kg foragej/kg rate, the lowest consume being in group 3A positive control, 2,51 kg feed/kg. Regarding the obtained results it is important to continue the line selection for precocity of E. acervulina and to perform additional studies such as, testing of sensibility and chimioresistance to different coccidiostatics and comparative study of the biological cycle (precocious line parental line) by hystological smears.