[Increased frequency of CRD in the broiler production in northern Jutland. I. Possible connexion between increased frequency of CRD and recently started vaccination with live infectious bronchitis vaccine (Massachusetts type) in egg producing flocks (author's transl)].

An increased condemnation rate due to CRD (chronic respiratory disease) is documented by means of condemnation lists collected in collaboration with directions and veterinarians at 6 poultry slaughterhouses. The geographic distribution of the 41 affected farms appears from Fig 1. The first outbreaks occurred around the turn of the year 1975/1976 and reached its climax in the 12th period (Table I). The increase in percent CRD of slaughtered chickens culminated in week 23/1976 amounting 0.64% (Fig 2). The increased total condemnation rate closely corresponds to an increase in CRD (Fig 3). These facts are intimately connected with the high number af consultations about respiratory diseases. Although not provable it seems possible and not unlikely that the broiler production has been exposed -- to increased directly or indirectly -- risk of infection from a raised number of IB vaccinated egg producing flocks.