Food > Meat and Poultry Products > Manual of Procedures > Directives  

January 4, 2006

MEAT HYGIENE DIRECTIVE: 2006 - 01

SUBJECT: Disposition of Carcasses with Bones Discoloured by Tetracyclines

In the last couple of years, some pork slaughter plants have seen carcasses in which some or all of the bones show a distinct yellow discolouration. Often, an entire production lot is affected. The yellow areas fluoresce strongly under ultraviolet light, such as the lights used for reading Sulfa on Site tests.

The most common reason for this discolouration is exposure to one of the tetracyclines (tetracycline, oxytetracycline, chlortetracycline) at some point during the animal's life. Tetracyclines form an insoluble complex with calcium, so will deposit in active areas of bone deposition, where they will remain for much of the animal's life.

The presence of the discolouration in bones is not an indicator of tetracycline residues in muscle or organs. Because the deposits are essentially permanent, the medication may have long since been cleared from other tissues. Meat from hogs with yellow bones does not appear to be at an increased risk of having unacceptable tetracycline residues, and residue testing is not warranted unless there are indications of recent treatment.

However, it has been determined that tetracycline can be released from the bones under some conditions. For this reason, the yellow discolouration is both a quality defect and a potential residue hazard.

Hog carcasses showing a yellow discolouration of the bones must be detained and remain under inspectional control until the discoloured areas are boned out.

Bones removed from carcasses may not be used for mechanically separated meat or any other edible purpose. These bones must be disposed of in a manner that meets the requirements of the Meat Inspection Regulations, section 54.

Dr. William R. Anderson
Director
Food of Animal Origin Division

Attachment