A study on the effect of GnRH administration on the ovarian response and laparoscopic intrauterine insemination of Awassi ewes treated with eCG to induce superovulation

Abstract

The effect of GnRH administration on superovulatory response of ewes treated with equine chorionic gonadotrophin (eCG) in breeding and nonbreeding seasons and the contribution of laparoscopic insemination to the improvement of fertilization and embryo recovery were investigated. Twenty-four nonpregnant Awassi ewes of 3-4 years of age were randomly allocated into two groups (n = 12). Each ewe was treated with a progesterone impregnated intravaginal sponge for 12 days. The following superovulation treatment was used: ewes of group 1 received 1,200 IU of eCG once as an intramuscular injection 48 h prior to sponge withdrawal; ewes of group 2 also received 1,200 IU of eCG once as an intramuscular injection, 48 h prior to sponge withdrawal and after 24 h of sponge removal. Ewes were injected with 80 μg of GnRH. Ewes of groups 1 and 2 were further subdivided into four equal groups (n = 6). Subgroups A and C (superovulated with eCG and eCG plus GnRH, respectively) were mated naturally at least two times with Awassi rams of proven fertility at 8-h intervals. Subgroups B and D (same as A and C) had intrauterine insemination at 44-46 h after sponge removal, under laparoscopic visualization of uterine horns, depositing 1 ml of diluted semen containing 100 × 10(6) motile sperm in the distal portion of each uterine horn. Ovarian response was assessed by determining the number of corpora lutea by laparoscopy at day 6 after mating. Embryo recovery was performed by using a semi-laparoscopic flushing procedure in both uterine horns. Results of the present study showed that ewes treated in breeding season with eCG plus GnRH has a higher number (P < 0.05) of corpora lutea than eCG alone as 7.33 ± 0.54 and 4.33 ± 0.39, respectively. There was no significant difference in the number of corpora lutea in nonbreeding season when ewes treated with eCG and eCG plus GnRH. The number of unovulated follicles was significantly higher (P < 0.05) in eCG treated ewes than in ewes treated with eCG plus GnRH, both in the breeding and nonbreeding seasons. The number of recovered embryos from ewes treated with eCG plus GnRH and eCG differ significantly (P < 0.05) as 4.32 ± 0.56 and 1.06 ± 0.26, respectively, in the breeding seasons. No significant difference was observed when these hormones used for superovulation in the nonbreeding season. A higher number of unfertilized ova (P < 0.05) was observed in ewes when naturally inseminated than in ewes inseminated using the intrauterine laparoscopic technique. Higher rate of embryo recovery (P < 0.05) was achieved when ewes were inseminated via intrauterine (4.66 ± 0.66) compared with ewes naturally mated (2.16 ± 0.74). The fertilization rate in ewes inseminated intrauterine using laparoscopic techniques and naturally mated were 91.5% and 44.8%, respectively. Fertilization failure in ewes inseminated intrauterine using laparoscopic techniques and naturally mated were 8.4% and 55.2%, respectively. It could be concluded that administration of GnRH 24 h after sponge removal increased ovulation rate of Awassi ...

Laparotomic intrauterine insemination with frozen-thawed semen in Sopravissana breed ewes in Central Italy

“…In a study conducted by Casali et al (2017), it is reported that an average of 57 animals per hour were inseminated by laparoscopy, leading to 1 min required at least for each ewe to be inseminated. In the study performed by Azawi and Al-Mola (2011), a similar time (5 min on average) was required for laparoscopic intrauterine insemination, which resembles the mean duration of the procedure as found in our study. Pau et al (2019) proposed an innovative techniques which include surgery of ovine cervical folds in order to facilitate the following cervical cannulation and uterine insemination.…”

“…Moreover, in case of accidental vessel rupture and haemorrhage, abdominal cavity is already exposed and emergency haemostasis is easier. Azawi and Al-Mola (2011) state that laparotomic technique is poorly applied due to decreased fertility of animals which undergo this procedure. In our study, using a minimally invasive laparotomic method, ewes were naturally bred in the following reproductive season but no decreased PR was noticed (90%).…”

Effects of exogenous GnRH administration on lambing performance of oestrus‐synchronized Kazak ewes during the breeding season

“…GnRH can be useful to synchronize and ensure ovulation (Azawi & Al‐Mola, 2011; Balaro et al, 2016; Reyna et al, 2007). A single dose of GnRH given 24–36 h after removal of the progestagen pessary synchronizes the LH peak approximately 40 h after pessary withdrawal and ovulation occurs in 90% of ewes within 72 h after pessary withdrawal (Menchaca & Rubianes, 2004).…”

“…An extensive body of literature has shown that gonadotropin hormone‐releasing hormone (GnRH) can be useful to synchronize and ensure ovulation in farm animal reproduction (Azawi & Al‐Mola, 2011; Balaro et al, 2016; Gonźalez‐Bulnes et al, 2004; Menchaca & Rubianes, 2004; Reyna et al, 2007). A single dose of GnRH given 24 to 36 h after removal of the progestagen pessary synchronizes the luteinizing hormone peak approximately 40 h after pessary removal and ovulation occurs in 90% of ewes within 72 h after pessary removal (Menchaca & Rubianes, 2004).…”