[Residues of antimicrobial substances in the meat and organs of slaughter calves].

Using a modified Gartside diffusion method (1960) the incidence of the residues of antimicrobial substances was followed in two categories of calves commercially slaughtered at the Brno Slaughter House. For testing the following three collection strains were used: B. subtilis (ATCC 6633), B cereus, var. mycoides (ATCC 11778), Sarcina lutea (ATCC 9341). In light weight calves samples of bile, liver, kidney, diaphragmatic and hind limb muscles, in heavy calves, due to technical reasons, only bile, liver and diaphragmatic muscle samples were examined. Residues were demonstrated in 26.2% of 103 light (suckling) calves; the most frequent finding was in the bile (22.2%) and kidney (15.5%). Identical residue findings in the diaphragmatic muscles and in the skeletal muscles of the hind extremities in light calves correspond to the formerly described results in calves from emergency slaughter (Malíková et al. 1974). In heavy calves the residues were demonstrated in 41.7% of 156 examined; the most frequent finding was in the liver (42.3%) and in the diphragmatic muscles (34%). Under the present operation conditions of calf fattening using milk replacer Biosan 20 not even an interval of 17-20 hours between the last feeding and the slaughter proved sufficient for elimination of the antimicrobial substances from the bodies of the slaughter animals.