Distribution of Salmonella contamination in ten animal feedmills

Detailed sampling of spillage and dust from milling equipment was carried out in nine animal feedmills, three of which were sampled twice. The salmonella isolation rate ranged from 1.1% to 41.7% of the samples and the most contaminated mills were those where the inside of the cooling systems for pellet or mash had been colonised by salmonella. A wide range of salmonella serotypes were isolated which included Salmonella typhimurium and S. enteritidis. Limited sampling every two weeks for an 18-month period in another animal feedmill showed marked variation in the contamination rate of samples and range of salmonella serotypes found. Contamination of ingredient intake pits and outloading gantries for finished products by wild bird droppings containing salmonella was also found in four mills.