Infectious bursal disease in New Zealand: Gross and histopathological lesions associated with growth depression but lack of seroconversion in broilers infected close to slaughter

Abstract

Extract

Infectious bursal disease (IBD) was first diagnosed in New Zealand in November 1993, when serological investigation confirmed the presence of antibodies to IBD virus in broilers that had been observed to have smaller-than-normal bursas of Fabricius at slaughter. Histological investigations showed that the lesions were mild, with most bursas showing functional follicles. Few if any effects on performance were noted (B.A.H. Jones, Inghams Enterprises, pers. comm.). The virus was subsequently isolated and characterised as a serotype 1 IBD virus (Motha, 1996). Serological surveys of New Zealand poultry flocks undertaken at the time of the outbreak showed that 52 of 50 1 farms, including eight meat chicken farms, were positive. By 1996, eight farms, including three meat chicken properties, remained serologically positive out of 453 tested (Poultry Industry Association of New Zealand, 1996).