[Stability and distribution of oxytetracycline HCI during manufacture and storage of pig feed under field conditions].

The distribution of oxytetracycline hydrochloride in two batches of 4,000 kg of pig-rearing pellets (400 ppm) was studied. The stability of oxytetracycline in this feed was also determined. The concentration of oxytetracycline in the feed was determined by high pressure liquid chromatography. The premix contained more oxytetracycline (27 per cent) than the proportion stated. The results show that the first 1,000 kg of feed contained less (350 mg/kg) oxytetracycline than the other 7,000 kg (435 mg/kg). After producing 8,000 kg of feed with oxytetracycline, 4,000 kg of feed not containing oxytetracycline was produced. Still, this feed was found to contain 13 mg/kg of oxytetracycline. When the feed was stored for 150 days at a temperature of from 1 to 2 degrees C and again for 270 days at 20 to 25 degrees C, it contained 86.5 per cent of the oxytetracycline present after production of the feed.