Occurrence of false-positive results of inhibitor on milk samples using the Delvotest SP assay

Authors
Citation
Jh. Kang et F. Kondo, Occurrence of false-positive results of inhibitor on milk samples using the Delvotest SP assay, J FOOD PROT, 64(8), 2001, pp. 1211-1215
Citations number
25
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Food Science/Nutrition
Journal title
JOURNAL OF FOOD PROTECTION
ISSN journal
0362-028X → ACNP
Volume
64
Issue
8
Year of publication
2001
Pages
1211 - 1215
Database
ISI
SICI code
0362-028X(200108)64:8<1211:OOFROI>2.0.ZU;2-Z
Abstract
Three hundred twenty-one quarter, 207 whole udder, 310 bulk tank, and 93 ta nk-lorry milk samples were examined for confirmation of the presence of inh ibitor by Delvotest SP assay. Four hundred twenty-six Holstein cows of no d rug treatment for at least 30 days from January 1998 to September 1999 were used. Reading time was 2.50, 2.75, and 3.00 h, and results of sampling wer e recorded by four types according to comparison with the color of the well containing the control milk sample. False-positive outcome was identified by Delvotest SP assay in quarter (13 of 321), whole udder (9 of 207), and b ulk tank milk samples (4 of 310), but was not shown on tank-lorry milk samp les (0 of 93) at the reading time of 2.50 h. All of the 26 false-positive s amples were negative from the examination after heat treatment at 82 degree sC for 5 min. But, two bulk tank milk samples that appeared to have positiv e results in LacTek and Charm II tests were positive from the test followin g heat treatment. Somatic cell counts (SCC) were related to the probability of a false-positive result. The more SCC increased, the more the occurrenc e of a false-positive result increased. In our investigations, 4 of 310 bul k tank milk samples at the reading time of 2.50 h produced false-positive r esults, and no false-positive results were apparent at a reading time of 2. 75 h. Also, the occurrence of false-positive results in quarter and whole u dder milk samples decreased when agar was cultured for 2.75 to 3.00 h. Ther e were no false-positive results from tank-lorry milk samples. These result s indicate that the Delvotest SP assay may provide a suitable means for the detection of drug residues in not only quarter and whole udder milk of cow s but also in bulk tank and tank-lorry milk following reading times of 2.75 to 3.00 h.