THE SUSCEPTIBILITY OF THAI NATIVE, MIXED THAI NATIVE, LAYERTYPE AND BROILER CHICKENS TO INFECTIOUS BURSAL DISEASE VIRUS

Abstract

Thai native, mixed Thai native and layer-type chickens, 50 birds of each and forty broiler chickens, were reared separately, to determine the susceptibility of each breed to infectious bursal disease virus (IBDV). All birds received IBDV when 36-days-old, given by oral inoculation. Mortality rates were observed for 10 days. Blood samples were collected on days 36, 39, 42 and 46 and sera were tested by an enzyme-linked immunosorbent assay (ELISA) for IBDV antibodies. Bursa to body weight ratios and histopathological lesion scores were determined when the birds were 36 and 46-days-old. The results revealed that mortality rate of Thai native, mixed Thai native, layer-type and broiler chickens were 35.71, 35.71, 69.04 and 9.38 percent, respectively. The mortality rate of Thai native and mixed Thai native chickens were significantly lower than those of layer-type chickens but they were significantly higher than the broiler chickens (p<0.05). Increased IBDV antibodies and histopathological lesion scores and decreased bursa to body weight ratios, confirmed that all the birds were infected with IBDV. It is concluded that Thai native and mixed Thai native chickens are less susceptible to IBDV than layer-type chickens but more susceptible to IBDV than broiler chickens.