Spread of microbial contamination associated with penetrative captive bolt stunning of food animals

Abstract

To determine whether penetrative stunning of animals can result in internal and/or external microbial contamination of meat, experimental animals (lambs) were inoculated with a marker organisms (nalidixic acid resistant Escherichia coli K12 or Pseudomonas fluorescens) into the brain through the stun wound immediately after stunning by a cartridge-operated, penetrative captive bolt pistol. After the animals were slaughtered and dressed, the marker organisms were found, on average, in blood and liver of 90% animals, lungs and spleen of 80%, lymph nodes of 30%, in deep muscle of 20% and on carcass surface of 50% of brain-inoculated animals. When the pistol which had been used to stun one brain-inoculated lamb was used to stun consecutive, non-inoculated lambs, the marker organisms were found, on average, in stun wounds of 100%, in blood of 30% and on the carcass surface of 40% consecutively stunned animals. No marker organisms were detected in their muscle or organs. When the stun spot on the surface of the head of some lambs was inoculated with marker organism and subsequently stunned through the same spot, the marker organism was detected in the air, on hands, and aprons of the worker in the stunning area. Overall, the results from this study indicate that penetrative stunning of food animals can carry risks of internal and/or external microbial contamination of edible tissues and organs.