Some Epidemiological Studies on Infectious Bursal Disease in Broiler Chickens in Parts of Haryana, India

Abstract

During the period from July, 1994 to June, 2003, the epidemiological data related to infectious bursal disease outbreaks in 795 broiler flocks was analyzed. The disease affected 8.89% flocks during the nine year period with morbidity, cumulative mortality and case fatality rate of 5.9, 3.63 and 61.43%, respectively. Most of the affected birds were dull, depressed and had ruffled feathers and yellowish white diarrhoea. Post mortem changes were mainly recorded in the bursa of Fabricius followed by changes in thigh and breast muscles, and in some cases in gizzard. The outbreaks were recorded more in winter season (391) than in summer (249) and rainy (155) seasons. Of the total outbreaks, 83.39% were recorded in broiler chicks of age 21-40 days while rest were in chicks of age less than 20 days or more than 40 days. However, per cent morbidity, cumulative mortality and case fatality rate were significantly more in chicks of age more than 50 days. The disease was recorded both in the vaccinated (472) as well as unvaccinated (323) flocks. However, per cent morbidity and cumulative mortality were comparatively more in the unvaccinated flocks as compared to the vaccinated ones. Improper vaccinations and existence of very virulent strains of IBD virus could be the reasons for outbreaks of disease even in the vaccinated flocks. Poor reporting system and lack of diagnostic facilities are the major constraints in knowing the exact status of the disease and the economic losses.