Bound chlortetracycline residues in bones: release under acidic conditions

Tetracycline residues were frequently found in the bones of slaughtered animals. These bound residues will contaminate products for human consumption, such as mechanically deboned meat. The aim of this study was to examine the behaviour of bound residues of chlortetracycline during in vitro digestion. Dough batches containing poultry meat and 2.5% by weight of bone splinters and bone meal with chlortetracycline residues were incubated with hydrochloric acid and pepsin at 40°C. With the aid of HPLC and agar diffusion tests, evidence was obtained that these bound residues of chlortetracycline could be released during in vitro digestion and become antimicrobially active. Hens fed with chlortetracycline containing meat and bone meal were also able to release bound tetracycline residues.