Haematic prostaglandin F2α (PGF2α) pattern following successful or -unsuccessful artificial insemination (AI) in the mare

The release of PGF(2 alpha) was monitored during specific phases of the reproductive cycle of artificially inseminated mares. Daily progesterone concentration was measured to detect a possible corpus luteus failure. Five fertile and regularly cycling mares were inseminated with fresh semen from a fertile stallion. the PGF(2 alpha) main metabolite (PGFM) concentration was measured during time windows of 90 minutes at oestrous, 12 hours after the last A.I., and on days 5, 4, 7, 12 following ovulation. three mares were diagnosed pregnant after the first A.I. session and one mare after the second. The analysis of PGFM concentration (both mean values and area under the curve) did not reveal any significant difference among mares or between pregnant and non-pregnant animals. Progesterone concentration was not correlated to PGFM pattern. There was a high variability among animals, both in basal PGFM values (i.e. before A.I.) and in the subsequent determinations. We found no evidence that barren mares have PGFM concentrations different from pregnant ones in critical phases of the oestrous cycle.