Cosmas C Ogbu, Chioma L Oragwu, Simeon OC Ugwu
The objectives of the study were to evaluate the growth performance, haematological and immune responses of broilers subjected to three vaccination programmes. Ninety day old Anak broilers were used for the study. The birds were randomized into three treatment groups of 30 birds each: group 1 (control, conventional routine vaccination schedule), group 2: one week delay in routine vaccination, and group 3: two weeks delay in routine vaccination. The vaccines commonly used for routine vaccination against Newcastle disease (ND) and infectious bursal disease (IBD) viruses in the study environment were employed for the study. Data collected included weekly body weight, shank length, mortality, haematological values (PCV, and WBC count) and haemagglutination inhibition antibody titer (HI) against NDV-La sota. Delay in commencement of routine vaccination against ND and IBD for one or two weeks was associated with low mortality, and significant (P<0.05) reduction of body weight, body weight gain, and PCV but increased WBC count. Haemagglutination inhibition (HI) test with NDV-La Sota at the end of the study gave GMT values of 26.75, 136.00 and 832.00 (4.8, 7.1, and 9.7 log2, respectively) for control, group 2, and 3, respectively (P<0.05). The standard vaccination schedule was found the best however; initial vaccination against ND and IBD in broiler chicks could be delayed for up to 2 weeks with minimal risk of mortality but with possible reduction in growth performance of the birds. Farmers should therefore adhere to the recommended vaccination schedule for their production environment to enhance the survival and optimal performance of broiler chickens.
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