role of prostaglandin F2α on ovulation and LH release in cows

Abstract

This study aimed to evaluate the role of prostaglandin F2α (PGF) on ovulation. In Experiment 1, cows were randomly allocated to two treatments to receive 150 μg of d-Cloprostenol (PGF Group, n = 12) or 2 mL of NaCl 0.9% (Control Group, n = 11) and CIDRs, were removed 4 days later. No cow ovulated in Control and PGF groups. In Experiment 2, cows were randomly separated into two experimental groups to receive 4 injections of 150 μg of d-Cloprostenol (n = 9) or 2 mL of NaCL 0.9% (n = 9). In this experiment, ovulation was not observed in any cows. In Experiment 3, ovariectomized cows receive three injections of 300μg of PGF analog (PGF Group, n = 5), 100μg of Lecirelin (GnRH Group, n = 5) or 2 mL of PBS (Control Group, n = 4). The LH concentration was higher (P <0.0001) in cows from the GnRH group than in the PGF and Control groups. In experiment 4, cows with preovulatory follicles (>11.5 mm) were treated with Saline (Control Group, n = 6); Lecirelin (GnRH Group, n = 7) or Cloprostenol Sodium (PGF Group, n = 6). There was a significant increase in the vascular area of follicles from 0 to 24 h in GnRH and PGF treatments. In conclusion, PGF was not able to induce ovulation in cows with high or low plasma progesterone concentration. Additionally, PGF alone was not able to induce LH release and follicle luteinization, but increased follicular vascularization.

In Vivo Follicular and Uterine Arterial Indices as an Indicator of Successful Hormonal Stimulation for Inactive Ovaries in Repeat-Breeder Crossbred Dairy Cows Using a Short-Term Progesterone-Based Programme

“…Investigations in normal beef heifers and cows receiving the 7-day Co-Synch + CIDR protocol [23] have observed that blood flow (vascularised area in pixels) of large POF (14.1-17.5 mm in diameter) tended to be greater than small POF (10.8-12.8 mm in diameter). Moreover, the significant increase in vascularity (vascularised area in percent) in POF (>11.5 mm in diameter) suggested that systemic hormonal stimulation may locally induce the ovulatory process [24]. In the cyclic buffalo model, a previous study applied the total blood supply (vascularised area in pixels) of ovarian follicles for predicting the effective hormonal synchronisation that the total blood flow to the DF was greater in females receiving the CIDR-PGF-based protocol than buffaloes receiving the Ovsynch-CIDR-based protocol at oestrous onset [25].…”