Progesterone and estradiol-17β as a potential method for pregnancy diagnosis in the collared peccary (Pecari tajacu)

In this study, the period of pregnancy of nine collared peccary females has been monitored through the analysis of serum progesterone and estradiol-17β profiles. Serum concentrations of progesterone increased by Day 4 after conception, reaching concentrations of 33.4±5.6 ng/mL on Day 10. Between Days 10 and 130 progesterone values were maintained between 20 and 60 ng/mL. In the collared peccary, embryonic estradiol synthesis is first observed in the systemic circulation by Day 15 of pregnancy. Between Days 0 and 50 of pregnancy, average estradiol-17β concentrations were between 0 and 30 pg/mL. From Day 75 of pregnancy onwards, estradiol concentrations were constantly increasing, reaching maximum concentrations (131.4±40.8 pg/mL) on the day of parturition. The combined study of serum progesterone and estradiol-17β concentrations as a potential method for early pregnancy diagnosis presented the best overall accuracy (73%) when the threshold was established at 20 ng/mL serum progesterone and 20 pg/mL serum estradiol. Nevertheless, the accuracy for diagnosing pregnancy of females at mid and late pregnancy was 78% and 95%, respectively. The analysis of the sexual hormones during pregnancy could be a useful tool as a potential pregnancy diagnosis and an efficient predictor of the day of parturition in the captive collared peccary.