Use of GnRH for Synchronization of the Follicular Wave in Assisted Reproductive Technologies in Sheep: A Preliminary Study

• Published in: Animals (Basel) Vol. 10; no. 7; p. 1208
• Main Authors: Año-Perello, Aina, Santos-Jimenez, Zurisaday, Encinas, Teresa, Martinez-Ros, Paula, Gonzalez-Bulnes, Antonio
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16.07.2020; MDPI
• Subjects: Animals; Artificial insemination; assisted reproduction; Communication; Drug dosages; Embryos; Estrus cycle; estrus synchronization; Fertility; follicle; Follicles; GnRH; Gonadotropin-releasing hormone; Hypotheses; Insertion; Luteinizing hormone; Ovaries; Ovulation; Pituitary (anterior); Plasma; Progesterone; Reproductive technologies; Reproductive technology; Sheep; Synchronism; Synchronization; Ultrasonic imaging; Spain; assisted reproduction; estrus synchronization; GnRH; follicle; sheep
• ISSN: 2076-2615; 2076-2615
• DOI: 10.3390/ani10071208

The present study aimed to set up a short-term protocol for synchronization of follicular wave emergence in sheep, concomitant with estrus synchronization, which would improve ovarian response in assisted reproductive technologies. Administration of a single GnRH dose, concomitant with the insertion of a progesterone-loaded CIDR device, caused regression of gonadotrophin-dependent follicles ≥4 mm in all the GnRH-treated sheep and in around 80% of the controls treated only with CIDR ( < 0.05). Similar percentages of ewes lost all follicles (around 70%) or only the largest one (around 30%) in both groups. Hence, 54.1% and 70% of the sheep lost all large follicles and initiated a new follicular wave in the control and GnRH groups, respectively ( < 0.05). The remaining sheep showed follicles that were still not dependent of luteinizing hormone (LH). So, in fact, all the sheep had non-dominant follicles after treatment. In conclusion, a treatment including GnRH at CIDR insertion would offer a time- and cost-efficient protocol for inducing follicular turnover and synchronizing a new follicular wave at any stage of the estrous cycle.