Serum antibody titre and the first protective vaccination of broiler chickens against Gumboro disease

The research aimed at determining titres of maternal anti-IBDv antibodies in the sera of one and three day old broiler chickens, originating from selected flocks and, basing on the data, at establishing the optimum timing of the first vaccination against Gumboro disease, using weakly attenuated vaccines. The research group included 34 flocks of 1 to 3 day old broiler chickens and the tests were performed on 23 samples from each flock. Titres of IBDv specific antibodies were estimated by ELISA tests (Idexx, USA). Mean antibody titres for individual flocks, variability coefficients (expressed in %) and optimum timing of vaccinations containing so called "hot" vaccines were determined using the xChek computer program (Idexx, USA) developed according to the principles of Kouwenhoven at at. The results of the research demonstrated a variability of anti-IBDv antibody titres in 1 to 3 day old chickens. A similar variability was displayed in the protection period of chickens against IBD disease, after which time the chicken should be subjected to protective vaccinations (optimum timing of vaccinations). In 5,9% examined flocks, very low mean antibody titres and high variability coefficients (>40%) were noted. The flocks were assumed to be sensitive to the disease and requiring immediate protective vaccinations. In 17,6% of flocks the optimum timing of vaccinations varied between the 3(rd) and 9(th) day of life. However, most frequently (73,5% flocks), the protection of chickens imparted by maternal antibodies lasted for 11 to 19 days, and in one flock only (2,9%) it lasted for over 3 weeks (23 days).