Investigation of Accidental Lead Exposure in Feeder Cattle

Abstract

A commercial backgrounding feedlot unknowingly fed lead-contaminated feed as evidenced by finding battery casing fragments and particles of lead plating in the feed bunk of a pen of animals with nervous disease. Investigation into the source of the contamination revealed that a large implement battery had been ground through the feed mixer. Over the next week, more than half of the animals within the pen where the exposure was centered showed evidence of nervous disease progressing to death or were humanely euthanized based on animal welfare considerations. The remainder of the pen showed little or no clinical evidence of exposure. Despite documentation that animals exhibiting no clinical evidence of lead toxicity may still have elevated blood and tissue lead levels, there are insufficient guidelines for ensuring that animals with potential lead exposure will be safe for human consumption. No specific regulations exist regarding the amount of lead permissible in Canadian beef. A disease investigation was undertaken to determine the extent of lead exposure in the feedlot and to formulate a plan for the disposition of exposed and unexposed animals.