الفهرس 
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Abstract
A total of 200 carcasses representing 600 samples (200 muscles, 200 livers and 200 kidneys) were obtained randomly from bovine carcasses (cattle and buffaloe) at Mansoura abattoir in Dakahlia Province, Egypt and were examined for the presence of antibiotic residues. A microbial inhibition test using Bacillus subtilis ATCC- 6633 was employed to screen the obtained samples for antibiotic residues in meat. The results showed that 12 samples from 10 animals) (2%) were positive while the other 588 samples from 190 animals) (98%) were negative for antibiotic residues.
Positive carcasses distributed according to species into 5 (3.57%) cattle and 5 (8.33%) buffaloes, while according to sex they distributed into 5 (2.77%) males and 5 (25%) females, also they distributed according to age into 4 (5%) young animals with temporary teeth only and 6 (5%) aged animals with permanent teeth. Out of 12 positive samples which analyzed by high performance liquid chromatography (HPLC) technique, 8 (l.33%)
had detectable levels of oxytetracycline residues, from which 5 (0.83%) had oxytetracycline residues at violative levels above the maximum residue limits (MRLs) while the other 3 (0.5%) had levels below (MRLs).
Experimental study indicated the withdrawal time of oxytetracycline in broilers as follow: 6 days in breast and thigh muscles- 8 days in liver- 9 days in kidney after intramuscular injection of drug in the thigh muscle in a dose of 20 mg/kg B. W for