DEVELOPMENT OF A DIRECT AND SPECIFIC ENZYME-IMMUNOASSAY FOR THE MEASUREMENT OF ESTRONE SULFATE IN BOVINE-MILK

A 12-step procedure is described for the synthesis of an oestrone-3-su lfate-6-hemisuccinate-BSA immunogen with oestradiol as starting materi al and the production of specific polyclonal antibodies. A competitive inhibition type enzymeimmunoassay has been developed based on these s pecific antibodies using 3-hemisuccinate-oestrone-peroxidase as conjug ate for direct measurement of the hormone in body fluids. The method h as a minimum sensitivity of 0.03 ng ml-1 in bovine milk, and satisfact ory specificity, recovery and reproducibility. In a small field trial with a group of 20 pregnant cows that were followed throughout gestati on, it was shown that the assay is potentially an accurate pregnancy t est for assessing the viability of the fetoplacental unit at approxima tely 100 days after insemination. The assay is well suited for routine testing, particularly as a confirmatory bovine pregnancy test.