Effects of Some Antiviral Medicines on the Performance and Antibody Titres of Pullets Challenged with Very Virulent Infectious Bursal Disease Virus

Abstract Infectious bursal disease (IBD) is an acute, highly contagious immunosuppressive disease of chickens associated with high morbidity and mortality rates. In Nigeria, some antiviral drugs are used for the control of IBD with claims of efficacy. This study evaluated the effects of oral administration of some antiviral medicines on the performance and antibody titres of pullets challenged with very virulent infectious bursal disase virus. A total of 200 day-old pullets were procured from a reputable hatchery and fed chicks’ starter mash containing 20% crude protein, ad libitum. The chicks were vaccinated against Newcastle disease using a live La Sota vaccine at 21 days of age. At day 35 of age, the chicks were randomly assigned into six groups labeled A, B, C, D, E and F, comprising of 32 chicks each. Chicks in groups A, B, C, D and E were inoculated with a very virulent infectious bursal disease virus at 0.05 ml, each via oral route at 35 days of age. Chicks in group F (negative control) were not inoculated. Group A was treated with VHK at 1 g/L, B with SHK at 2 ml/L, C with BVC at 1 g/2 L and D with VRX at 1 g/L. All treatments were administered orally from day 3 post-inoculation (pi) for 5 days, ad-lib. Blood was collected from all the groups after treatments at day 35 and 42 of age to determine IBD antibody titres using enzyme linked immunosorbent assay (ELISA) and haematocrit method was used to determine the packed cell volume (PCV). Clinical signs of depression, prostration, recumbence and inappetance were observed in groups A, B, C, D and E on day 3 to 7 pi. The clinical signs were higher in group E (90.63%), followed by B (87.50%), A (84.38%), C (75.00%) and D (71.88%). The duration of clinical signs in group C was 2 days only and others were 3 to 5 days. Group E had higher morbidity rate (90.63%), followed by A (84.34%), B (75.00%) and D (62.50%). Group C had lower morbidity rate (56.25%). Morbidity score was higher in group A and E with a score of 5 (grave); B and D had a score of 4 (very severe). Group C had the lowest morbidity score of 3. Mortality lasted 4 days in group A and E, and 3 days in B, C and D. Mortality rate was lowest in group A (53.13%). Gross lesions were higher in group E and lowest in group A. Antibody titres were higher in group A (3,076 ±415.78), and C (2,996 ±17.68). Chicks in group A and E had lower PCV (27.5%, each) at 7 dpi. The feed intake and live body weight gains were slightly reduced in group A, B, C, D and E at 7 dpi compared to group F which was slightly increased. The drugs used in this study did not prevent signs or mortalities caused by the very virulent infectious bursal disease virus (vvIBDV). A Further study on the use of BVC, VHK and SHK alone or in combinations was recommended for the control of IBD in Nigeria