Early pregnancy diagnosis in goats by determination of pregnancy- associated glycoprotein concentrations in plasma samples

Abstract

Different RIA systems available for measuring the concentrations of pregnancy-associated glycoproteins (PAGs) in dairy goats were compared in order to evaluate their accuracy in early pregnancy diagnosis. Plasma concentrations of PAGs were determined by 3 heterologous RIA systems with a bovine PAG standard and tracer in combination with antisera anti-ovine PAG (RIA 1), anti-caprine PAG(55+62) (RIA 2), anti-caprine PAG(55+59) (RIA 3), and by 2 homologous RIA systems that employed caprine PAG(55+62) and caprine PAG(55+59) and their specific antisera (RIAs 4 and 5, respectively). In all of the RIAs, the mean concentrations of PAGs were significantly higher (P<0.01) in pregnant than in nonpregnant goats from Day 21 onwards after breeding. On Day 21, the accuracy rates of early pregnancy diagnoses were 56% (RIA 1), 96% (RIA 2), 99% (RIA 3), 95% (RIA 4) and 90% (RIA 5), whereas on Day 28 these rates were >99% for RIAs 2, 3, 4 and 5. The RIAs for PAGs depend on proteins from the placenta being present in maternal plasma and require only a single sample of blood, to distinguish pregnant goats from those that fail to return to estrus for other reasons. The homologous and semi-heterologous assays are highly accurate as early as Day 21 of pregnancy. (C) 1999 by Elsevier Science Inc.