GENERAL RULES OF THE CONTROL OF RESPIRATO RY-DISEASES IN BROILERS

In Hungary, the losses due to death and culling have significantly inc reased in broiler flocks since the summer of 1994. Mainly diseases cau sed by different viral infections, varying flock by flock, and bacteri a (E. coli, salmonellae and recently Ornithobacterium rhinotracheale) were detected in the background. In the infected flocks, the grade of losses was decisively influenced by the hatching hygiene and in relati on to that by the quality of day-old chickens, as well as by the defic iencies in the environmental requirements of high yielding broilers (e specially the population density/m(2), quality of air and bedding, as well as the method of drinking and purity of water). Losses are increa sed when the farm is populated protracted. The in vitro effective anti biotic or sulfonamide treatments hardly influence the losses in the al ready diseased flocks. The losses could be diminished even in affected flocks when the hatching hygiene was improved (by the appropriate dis infection of egg shell!), the rules of epizootiological protection (by an appropriate vaccination schedule against the existing viral infect ions in the flock) and technology were maintained. In flocks already d iseased, better results could be obtained by diminishing significantly the population density/m(2) and improving the efficacy of ventilation than by any kind of repeated drug medication.