Ž . Animal Reproduction Science 58 2000 127–135 www.elsevier.comrlocateranireprosci Development and evaluation of a direct enzyme immunoassay for oestrone sulphate in urine as a tool for diagnosis of early pregnancy in swine A. Stefanakis a , C. Boscos b, ) , C. Alexopoulos b , E. Krambovitis a a Department of Applied Biochemistry and Immunology, Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 711 10 Heraklion, Crete, Greece b Clinic of Obstetrics and AI, Faculty of Veterinary Medicine, Aristotle UniÕersity of Thessaloniki, 540 06 Thessaloniki, Macedonia, Greece Received 17 March 1999; received in revised form 30 August 1999; accepted 11 October 1999 Abstract Ž . A competitive inhibition-type enzymeimmunoassay EIA has been developed using 3-hemi- succinate-oestrone-peroxidase as conjugate for direct measurement of the hormone in swine urine. The method has a minimum detection level at 0.3 ng ml y1 and satisfactory specificity, recovery Ž and reproducibility. In a field trial with a group of 387 sows 7 in oestrus, 16 non-pregnant and . 364 pregnant sows at several stages post service , it was shown that the assay is potentially an accurate pregnancy test in assessing the viability of the fetoplacental unit from day 23 up to day 30 post service. The assay is well suited for routine testing, particularly as a swine early pregnancy diagnosis test since urine sampling is easier and does not disturb the animal, while in the present assay there is no restriction in the time of sampling and the sample storage conditions. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Oestrone sulphate; Urine; Pregnancy diagnosis; Pig-pregnancy 1. Introduction Early identification of pregnancy or non-pregnancy in sows is considered very important, as the management of sows during the post service period is crucial if the Ž . breeding efficiency of a herd is to be maximised Dial et al., 1992 . The most common ) Corresponding author. Sthenonos 1 St., 54633, Thessaloniki, Greece. Tel.: q30-31-994471r228817; fax: q30-31-994470. Ž . E-mail address: pboscos@vet.auth.gr C. Boscos . 0378-4320r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0378-4320 99 00082-2