The production of pig tissue sulphadimidine reference material

The production of stable homogeneous reference materials containing the antimicrobial agent sulphadimidine in pig tissue is described. These were commissioned by the Community Bureau of Reference (BCR), established by the Commission of the European Communities, to promote improvements in analytical accuracy and to ensure uniformity of results determined by member states. Sulphadimidine-containing tissue powders (400 vials each of muscle, liver and kidney) were prepared by orally dosing pigs with drug, producing lyophilized tissue powders and blending these with negative tissues from unmedicated animals to achieve target concentrations. Details of the production process, the stabilizing procedure developed and the analytical assessments of homogeneity and stability are given.

DETERMINATION OF THE CONCENTRATIONS OF THE STEROIDS ESTRADIOL, PROGESTERONE AND TESTOSTERONE IN BOVINE SERA - COMPARISON OF COMMERCIAL DISSOCIATION ENHANCED LANTHANIDE FLUORESCENCE IMMUNOASSAY KITS WITH CONVENTIONAL RADIO AND ENZYME IMMUNOASSAYS

The performance of three conventional enzyme and radioimmunoassays routinely used to detect residues of anabolic steroids in cattle sera were compared with dissociation enhanced lanthanide fluorescence immunoassay (DELFIA) kits designed for the hospital market. Slight modifications to the kit reagents were required for the analysis of bovine sera. Owing to the large sample volumes used in conventional assays, detection limits were generally better than those obtained with DELFIA kits, however, assay reproducibility was enhanced using the DELFIA technology. Comparison of sera obtained from cattle implanted with anabolic steroids revealed a good correlation between alternate methods (r(2) from 0.91 to 0.97). The DELFIA kits offer a faster method for measuring estradiol, progesterone and testosterone with adequate sensitivity and in a safer environment than that encountered using radioimmunoassays.

RESIDUES OF CLENBUTEROL IN CATTLE RECEIVING THERAPEUTIC DOSES - IMPLICATIONS FOR DIFFERENTIATING BETWEEN LEGAL AND ILLEGAL USE

Clenbuterol (CBL) can be used legally in the treatment of respiratory diseases and illegally as a growth promoter in animals, Liver and eye have previously been shown to be effective matrices for the detection of residual concentrations of the drug.

OBSERVATIONS ON THE EFFECTS OF LONG-TERM WITHDRAWAL ON CARCASS COMPOSITION AND RESIDUE CONCENTRATIONS IN CLENBUTEROL-MEDICATED CATTLE

The detection of the illegal use of clenbuterol (CBL) as a growth promoter has relied on detecting residual concentrations of the drug in body fluids or tissues. Analysis of retinal extracts has recently been shown to considerably extend the detection period following withdrawal. The withdrawal periods required to eliminate residues from the liver and retina were investigated by medicating 20 cattle with CBL for 30 days; 6 control animals remained unmedicated. Residual concentrations were monitored throughout this period and for the subsequent 140 days. Concurrent changes in muscle areas and backfat thicknesses were recorded by ultrasound.

EFFECTIVE LABORATORY MONITORING FOR THE ABUSE OF THE BETA-AGONIST CLENBUTEROL IN CATTLE

The use of the beta-agonist clenbuterol (CBL) as a growth promoter has been outlawed in European meat production. The detection of its illegal use is dependent on CBL residues persisting in animal tissues for longer than the withdrawal times given by abusers. A comparison of urine, bile and liver matrices indicated that analysis of the liver offered the best possibility for CBL detection. However, an experimental study showed that CBL detection following withdrawal could be further extended (up to 56 d) if the retina was used as the target tissue. Analysis of 703 retina and liver samples from cattle suspected of CBL medication revealed that 96 cattle had CBL residues present in their retinas, only 46 of these were liver positive. There were no instances of liver CBL residues being detected without the associated retina also being positive.

SULFADIMIDINE IN DRINKING TROUGHS AT BACON FACTORIES

Water troughs in the lairages of three bacon factories were examined. Pigs were observed drinking from the troughs, some of which were contaminated with faeces. Some of the troughs contained detectable concentrations of sulphadimidine, and the highest concentration recorded was 17 mu-g/ml. Pigs which drank this contaminated water before slaughter could contain tissue residues of sulphadimidine above the permitted concentration.