Origin of chlortetracycline in pig tissue

摘要: Violative chlortetracycline (CTC) residues in excess of the maximum residue limit (MRL) have been identified 0.9% all pigs tested at slaughter Northern Ireland. Three experiments were carried out to investigate possible reasons. In Experiment 1, fed CTC therapeutic levels (300 mg kg–1 head–1 d–1) for 7 days and slaughtered day 0, 2, 4, 6, 8 10 following withdrawal. Muscle, liver kidney cortex medulla samples analysed by using high-performance liquid chromatography (HPLC). tissues, less than MRL from 2 onwards. Mean concentrations greater (p < 0.05). feed spiked with a sub-therapeutic dose (40 kg–1) was six that after 12 medication. not detected. 3, short term supra-therapeutic administration examined. Eight received 500 head –1 d–1 1 or killed pairs, 24 48 h final medicated feed. detected both groups only. It is concluded that: firstly, recommended withdrawal periods are sufficient avoid violative carcass residues; secondly, do arise dosing but can which could occur inadequately mixed feed; thirdly, difference medullary significant regulatory perspective.