Plasma concentrations of 15-ketodihydro-PGF2α, progesterone, oestrone sulphate, oestradiol-17β and cortisol during late gestation, parturition and the early post partum period in llamas and alpacas

Plasma concentrations of 15-ketodihydroprostaglandin (PG) F2α, progesterone, oestrone sulphate, oestradiol-17β and cortisol during late gestation, parturition and the early post-partum period were measured in six llamas and five alpacas. During the last 100 days of pregnancy, 15-ketodihydro-PGF2α concentrations increased steadily until the day of parturition when a massive release was detected (P<0.01) concomitant with a decrease in progesterone concentrations (P<0.01). The highest PGF2α metabolite concentrations (159±35 nmol l−1 and 92±29 nmol l−1 in llamas and alpacas respectively) were detected in the sample collected during the morning on the day of parturition. Basal concentrations were registered by day 3 after delivery. Plasma concentrations of oestrone sulphate started to increase 80 days before parturition and reached peak concentrations immediately before parturition (15±3 nmol l−1 in llamas and 18±5 nmol l−1 in alpacas). Oestrone sulphate concentrations dropped sharply (P<0.01) on the day of parturition in llamas and one day later in alpacas, whereupon they remained relatively unchanged until at least 20 days postpartum. Oestradiol-17β concentrations were higher than 180 pmol l−1 during the last 45 days of pregnancy, began to decrease on the day of parturition and reached very low concentrations within the following two days. High oestradiol-17β concentrations were registered 7 days postpartum in all alpacas (P<0.05) and within 10 days of parturition in five of six llamas (P<0.01). No significant cortisol peaks were observed around parturition, but mean concentrations were increased in both species.