Development of an experimental model of bacterial chondronecrosis with osteomyelitis in broilers following exposure to Staphylococcus aureus by aerosol, and inoculation with chicken anaemia and infectious bursal disease viruses

A series of experiments was designed in an attempt to reproduce bacterial c hondronecrosis with osteomyelitis in broiler chickens using a natural route of infection. Birds in isolators were exposed to a suspension of Staphyloc occus aureus by aerosol or exposed to S, aureus and subsequently inoculated with chicken anaemia virus (CAV) alone, or with CAV and infectious bursal disease virus (IBDV), Subsequently, S. aureus was recovered and bacterial c hondronecrosis with osteomyelitis was diagnosed, by histology, in the proxi mal end of the femur and/or tibiotarsus of lame birds exposed to S. aureus with and without CAV and IBDV infections. Birds fed 60 % of the recommended feed intake for the breed developed a lower incidence of S, aureus infecti on and/or bacterial chondronecrosis (P < 0.05) than birds fed 100 % of the recommended intake. A significantly lower incidence of S. aureus was recove red (P < 0.05) in birds simultaneously exposed to S, aureus and inoculated with CAV and IBDV at day 21, than in birds exposed to S, aureus at day 10, and inoculated with CAV and IBDV at day 21, With the exception of birds exp osed to S, aureus at 1 day old, a higher incidence of bacterial chondronecr osis was diagnosed in birds exposed to S, aureus and inoculated with CAV an d IBDV than in birds exposed to S. aureus alone. It is hypothesised that in oculation with CAV and IBDV at day 21 enhanced the development of bacterial chondronecrosis in birds exposed to S, aureus at day 10 and fed 100% of th e recommended feed intake or ad libitum.