RESUMO
For detecting the inhibitory substances in milk, 100 milk samples were collected from dairy shops and farms [50 of each], and subjected for detection of inhibitors. Results indicated that 10% in dairy shops and 24% in dairy farms of the examined samples contained inhibitory substances, respectively. Also, three lactating cows were selected for withdrawal study of erythromycin residues in milk. They were injected intramuscularly with erythromycin. Results revealed that the minimum dilution that inhibited the growth of the tested microorganism was 0.64 ug/ml milk using reference disc assay method. The residues of such antibiotic were found to persist in milk with holding time of 48 hours after leu administration. The public health importance and financial losses of inhibitory substances in milk were discussed