Studies on the dissemination of Salmonella in nine broiler-chicken flocks.

The salmonella status of nine different broiler-chicken flocks was studied from the day before the chickens were placed in the house until their sixth week of age. The presence of salmonella serotypes in dust, litter, feces, water, and feed was investigated. Dust from different sites was sampled and appeared to be contaminated with salmonellae even after six of the nine houses were disinfected. Defects in the cleaning and disinfection of air inlets and fans seemed to be an important factor for the recontamination of the house. Chickens were often contaminated at the hatchery, and in two houses the percentage of contamination had increased to as much as 82 7% and 88 8% at six weeks of age. Swabbing of intact and fresh feces appeared to be a more reliable technique than culturing the litter for evaluating the shedder state of the flock, and it appeared also to be more rapid and simple than the collection of cloacal swabs.