Relationship between plasma progesterone and pregnancy-associated glycoprotein concentrations during early pregnancy in dairy cows

Abstract

The relationship between the concentration of plasma progesterone (P4) during embryo attachment or at recognition of pregnancy, and that of pregnancy-associated glycoprotein (PAG) was assessed in dairy cows. The outcome of artificial insemination (AI) was classified as positive (AI+), negative (AI-), or late embryonic mortality (EM) by measuring circulating PAG concentrations and by ultrasonography. Based on P4 concentrations at either day 21 or day 15, AI+ and EM cows were classified into 'low' (P4 concentrations mean) P4 groups. In both experiments, the threshold of P4 concentration between the 'low' and 'high' groups was approximately 6. ng/mL. PAG concentrations were lower in the 'low' ..