Comparative study of the resistance or susceptibility of local Nigerian and exotic chickens to infectious bursal disease.

Local or village chickens are the major source of poultry products in less developed countries, but information is limited on their susceptibility or resistance to diseases. In this work, 6-week-old local Nigerian chickens, pullets and broilers were used. One day before infection the mean body weight of the broilers was more than twice that of the pullets and local chickens. The bursa: body weight (B:BW) indices of the pullets and local chickens were similar, but were significantly higher than those of broilers. Following inoculation intraocularly with pathogenic infectious bursal disease virus (IBDV) drowsiness, drop in feed and water consumption, and diarrhoea were observed among the local chickens and pullets on day 2 post inoculation (p.i.) and in the broilers on day 3 p.i. Body weight losses from 1 to 11 days p.i. were significantly higher in the local chickens and pullets than in the broilers, total mortalities being 17.6, 50.0 and 61.51% in broilers, pullets and local chickens, respectively. Necropsy showed that dehydration and proventricular haemorrhages occurred most frequent in the local chickens. The response correlated with the B:BW indices on day 14 p.i. This showed that local Nigerian chickens are more susceptible to IBD than broilers and slightly more susceptible than pullets, explaining earlier reports that mortality due to IBD was higher in pullets or light breeds of chicken than in broilers or heavy breeds.