Survey of antibiotic residues in Canadian slaughter animals

Kidneys and urine of cattle, swine, sheep and chickens were tested for bacterial growth inhibitors using Bacillus subtilis and Sarcina lutea as test organisms. Results were as follows: 211 beef kidneys four positive, 611 swine kidneys five positive, 27 sheep and 120 chicken kidneys all negative, 2108 beef urine 76 positive, 2409 swine urine 186 positive, 176 sheep urine 17 positive. Strongest reactions were obtained with B. subtilis on phosphate buffered pH 6.0 plates. Larger zones were produced by urine from injected animals than by tissue samples.