A survey of the incidence of Salmonella species and Enterobacteriaceae in poultry feeds and feed components.

Between July 1990 and April 1991 the rate of contamination with Salmonella species of poultry feeds and feed components used by the Dutch feed industry was surveyed. Ten per cent of 360, 10 g samples of poultry feeds were found to be contaminated. Mash feeds, mostly used for layer-breeders, were far more frequently (21 per cent) contaminated than pelleted feeds (1.4 per cent). The rate of contamination of 130 samples of fish meal was 31 per cent, of 83 samples of meat and bone meal 4 per cent, 58 samples of tapioca 2 per cent and of 15 samples of maize grits 27 per cent. Twenty-eight serotypes of salmonellae were isolated, but no Salmonella enteritidis was found, despite the occurrence of an epidemic in poultry caused by this serotype since 1987. The serotypes isolated most frequently were not the same as those encountered in poultry flocks. The Enterobacteriaceae isolated from the feedstuffs were predominantly thermotrophic. They were shown to be useful markers of the rate of contamination with salmonellae and of the efficiency of decontamination of the feedstuffs by pelletisation.