Microbiological quality of protein feed supplements produced by rendering plants.

Samples of protein feed supplements produced by rendering plants were examined for salmonellae, total aerobic bacterial counts, coliform counts, and enterococci. Isolations of salmonellae were more frequent from products with high counts; however, 6% of the samples with total counts of less than 1,000 per gram and 14% of the samples with coliform counts of less than 1 per gram contained salmonellae. Serotypes of Escherichia coli which have been associated with disease in domestic animals and poultry were also isolated from products. Although the distribution of serotypes of salmonellae isolated from environmental swabs and flies was similar to that isolated from products, the isolation of several serotypes from flies which had not been isolated in plants suggested that flies may be a potential source of contamination.