The purpose of the present study was to determine if supplementation of ascorbic acid (AA) to the diet would have a beneficial effect on infectious bursal disease (IBD) vaccination of chickens for protection against infectious bursal disease virus (IBDV) infection. Two hundred forty specific pathogen-free (SPF) chickens were divided into eight experimental groups. A 2 x 2 x 2 factorial arrangement in a completely randomized design was used; AA supplementation at 1,000 ppm in the diet, vaccination, and challenge were the main effects. Prior to challenge and 10 d after challenge, serum AA concentration, serum corticosterone concentration, ELISA antibody titer to IBDV, body weight, bursa-to-body weight (B:B) ratio, and bursal histological score (BHS) were determined. Nonvaccinated chickens fed a diet supplemented with AA did not exhibit clinical signs or mortality following challenge, whereas AA-unsupplemented counterparts had 100% cumulative morbidity and 30% cumulative mortality. Serum AA levels of AA-supplemented and vaccinated chickens were significantly (P < 0.05) higher than AA-unsupplemented and vaccinated chickens. Fourteen days following vaccination, significantly (P < 0.05) higher ELISA titers to IBDV were observed in vaccinated chickens supplemented with AA as compared to AA-unsupplemented counterparts. Ascorbic acid-supplemented chickens, especially those also vaccinated, had higher body weight gains as compared to the AA-unsupplemented chickens. Ascorbic acid-supplemented chickens challenged with IBDV did not show any clinical signs or mortality. The results suggest that supplementation of AA at 1,000 ppm in the diet has beneficial effects on antibody response to IBD vaccination and body weight gain.

Isolation and characterisation of Ghanaian field IBD virus were undertaken as part of a comprehensive study to establish an efficacious vaccination programme against the disease in the country. Bursal homogenates were

A study to assess the epidemiological factors responsible for the recent outbreaks of infectious bursal disease (IBD) in Accra and Kumasi, between October and December 2002 and January to April 2003, was conducted. Case report records at Veterinary Diagnostic Laboratories were examined for IBD cases. Farm investigations were carried out using a combination of questionnaire and interviews to obtain information on the disease situation on farms, where the outbreaks had occurred. The highest occurrence of the disease was recorded between March and April 2003, with Accra showing the highest number of cases in March, coinciding with the Easter season. Day-old chicks imported into the country succumbed more easily to the disease than those produced locally. There was an association between IBD and the chicken type that was significant (P < 0.05) in cockerels and layers. Chickens vaccinated twice were more likely to be protected from the disease than those not vaccinated or vaccinated only once. The prevalence of the disease was also influenced by the age of the chickens with a rise in susceptibility with age from 3 weeks to 6 weeks old. The results of the study indicate that the factors studied, namely source of day old chicks, bird type, vaccination history, and age of chicks at the time of outbreak influenced outbreaks of IBD and are likely to contribute to the endemicity of infectious bursal disease in the poultry producing areas of Ghana. It is recommended that stringent biosecurity measures be observed on poultry farms to control the disease in the country.