[Behavior of selected veterinary preparations during industrial milk processing]

Since the extensive veterinary-hygienic treatment of herds with insecticidal veterinary preparations may lead to milk contamination, the authors studied the behaviour of some active agents (butonate, dichlorvos (DDVP), trichlorphon, naled, carbaryl, hexachloro-p-xylene and rafoxanide) during the industrial processing of milk to fluid milk, cream, butter, cheese and milk powder, and during the storage of these products. Small-scale model experiments served to investigate the effects of pasteurization (74 and 95 degrees C.), separation and churning as well as of the processing to milk powder and cheese. Analyses for residues were performed by thin-layer chromatography, colorimetry and with the aid of the isotope technique. From the viewpoint of milk processing, the use of TCP and, in part, that of DDVP may be considered as less critical due to their hydrophilic properties and rapid degradation. In view of their lipophilic behaviour, the use of butonate, carbaryl, rafoxanide and hexachloro-p-xylene as active agents in veterinary preparations for milk cows must be regarded as problematic. The utilization of naled is also problematic due to the fact that the toxicology of its metabolites is not yet sufficiently known.