Fixed-time Intrauterine Insemination Research Articles

Pregnancy establishment and maintenance after the administration of equine chorionic gonadotropin (eCG) associated or not with gonadotropin-releasing hormone (GnRH) after insemination in sheep

It was recently demonstrated that equine chorionic gonadotropin (eCG) treatment 10 days after ovulation increases serum progesterone concentrations in sheep. The objective of the present study was to evaluate pregnancy outcomes induced with the administration of eCG and gonadotropin-releasing hormone (GnRH) after insemination. Three experiments were conducted in multiparous ewes that received fixed-time intrauterine insemination (Day 0) after a progesterone-based protocol for oestrus synchronisation. Experiment 1 consisted of 408 ewes, randomly assigned to three experimental groups; ewes in the first and second group received 400 IU of eCG on Day 5 and Day 10 after insemination respectively, while ewes on the third (control) group did not receive eCG. In Experiment 2, 587 ewes were randomly assigned to four experimental groups (2 × 2 factorial experiment), to receive or not 400 IU of eCG on Day 5, associated or not with 100 µg of GnRH analogue on Day 6 (i.e. 30 h after eCG administration). In Experiment 3, 715 ewes were randomly assigned to four experimental groups (2 × 2 factorial experiment), to receive or not 400 IU of eCG on Day 10, associated or not with 100 µg of GnRH analogue on Day 11 (i.e. 30 h after eCG administration). Pregnancy diagnosis was determined on Day 30 and Day 70 by ultrasonography. The eCG treatment after insemination failed to improve pregnancy outcomes in Experiments 1 and 2. However, in Experiment 3 the treatment with eCG on Day 10 enhanced pregnancy rate on Day 30, although this improvement was not maintained on Day 70, which showed greater pregnancy failure. The administration of GnRH on Day 6 or Day 11, preceded or not by eCG, did not affect any of the variables related to pregnancy. In summary, the improvement in progesterone profiles induced by eCG treatment on Day 10 after insemination, previously reported in sheep, seems to have a marginal positive effect on pregnancy establishment during the first month, which is not maintained during the second month of gestation.

Luteal response and follicular dynamics induced with equine chorionic gonadotropin (eCG) administration after insemination in sheep

The objective of this study was to evaluate the ovarian response to equine chorionic gonadotropin (eCG) administrated during the luteal phase after insemination in sheep. Thirty cyclic multiparous ewes received a fixed-time intrauterine insemination (Day 0) and were assigned to three experimental groups that received 400 IU of eCG on Day 5 (n=10) or Day 10 (n=10), while another group remained as control group without eCG (n=10). Corpus luteum area and follicular diameter were daily measured by transrectal ultrasonography and serum progesterone concentrations were daily determined by radioimmunoassay during 30days after insemination in pregnant ewes or until the following ovulation in non pregnant ewes. The administration of eCG on Day 10, but not on Day 5, increased corpus luteum size and serum progesterone concentrations (P<0.05). Follicular dynamics were influenced by both eCG treatments on Day 5 and Day 10, promoting the growth of the largest follicle present during treatment or increasing the length of the wave that emerged after treatment (P<0.05). In conclusion, the administration of 400 IU of eCG 10 days after insemination in sheep increased corpus luteum size and progesterone concentrations, as well as promoted follicular development. This information could be useful to develop new pharmacological strategies to improve the establishment of pregnancy in sheep.

Conception rate and litter size in multiparous sows after intrauterine insemination using frozen-thawed boar semen in a commercial swine herd in Thailand.

ABSTRACTThe aim of the present study was to determine the conception rate and litter size in sows after fixed time intra-uterine insemination using frozen-thawed boar semen in a commercial swine herd in Thailand. Sixty-nine Landrace multiparous sows were randomly allocated into two groups, including control (n=36) and treatment (n=33). The control sows were inseminated with extended fresh semen (3 × 109 motile sperm/dose, 100 ml) at 24, 36 and 48 hr after the onset of estrus. The treatment sows were inseminated with frozen-thawed semen (2 × 109 motile sperm/dose, 20 ml) at 24 and 36 hr after induction of ovulation by human chorionic gonadotropin. All inseminations were carried out by using an intra-uterine insemination technique. The time of ovulation was determined by using transrectal real-time B-mode ultrasonography. The conception rate, farrowing rate, total number of piglets born/litter (TB) and number of piglets born alive/litter (BA) were evaluated. The sows inseminated with extended fresh semen yield a higher TB (10.8 versus 9.0 piglets/l, P=0.015) and tended to have a higher conception rate (88.9% versus 75.8%, P=0.150) than sows inseminated with frozen-thawed semen. In conclusion, insemination using frozen-thawed boar semen can be practiced with convinced fertility under field conditions by fixed-time intrauterine insemination with 2 × 109 sperm/ dose of 20 ml at 24 and 36 hr after the onset of estrus.

Synchronization of Ovulation and Fixed Time Intrauterine Insemination in Ewes

A novel method for oestrus-ovulation synchronization in sheep followed by fixed time insemination is presented herewith. Mature dry ewes (n = 28) of Karagouniko breed being at an unknown stage of the oestrous cycle, were used during the middle of breeding season. The treatment protocol consisted of an initial administration of a GnRH analogue followed 5 days later by a prostaglandin F2alpha injection. Thirty-six hours later a second GnRH injection was administered to synchronize ovulation, and laparoscopic intrauterine insemination was performed 12-14 h later. Three days after insemination, fertile rams were introduced into the flock twice daily and oestrus-mating detection was carried out. For progesterone (P(4)) determination, blood samples were collected on alternate days, starting 2 days before the first GnRH injection and continuing for 17 days after insemination. An additional sample was taken on the day of insemination. Pregnancy diagnosis was carried out by trans-abdominal ultrasonography. Fourteen ewes (50%) conceived at insemination and maintained pregnancy; from the remainder 14 ewes 10 became pregnant at natural service, while four, although they mated at least two to three times, failed to conceive. In response to the first GnRH, P(4) concentration increased at higher levels in ewes that conceived at AI compared with those that failed to conceive (47.54 and 22.44%, respectively; p < 0.05). Significant differences (p < 0.05) in mean P(4) concentration between pregnant and non-pregnant animals were detected 1 day before AI (0.17 +/- 0.06 and 0.26 +/- 0.14 ng/ml, respectively) on the day of AI (0.15 +/- 0.04 and 0.24 +/- 0.08 ng/ml, respectively) as well as 9 and 11 days thereafter (0.48 +/- 0.12 and 0.38 +/- 0.12 ng/ml; 0.68 +/- 0.14 and 0.50 +/- 0.18 ng/ml, respectively). These results indicate that using the proposed protocol, an acceptable conception rate can be achieved which could be further improved by modifying the time intervals between interventions.

Effect of Insertion Periods of Controlled Internal Drug Release Device (CIDR) on Conception Rate by Fixed-Time Intrauterine Insemination with Frozen Semen in Seasonally Anestrous Ewes.

Conception rates and plasma hormonal patterns were investigated after treating ewes with CIDRR (controlled internal drug release device) for different lengths of time during the non-breeding season. In Experiment 1, 101 Suffolk ewes were treated with CIDRR for 6, 9, 12 days; pregnant mare's serum gonadotropin (PMSG) was injected the day before CIDRR removal. At 42 to 50 h after treatment, ewes were inseminated with frozen-thawed semen using a laparoscope. Lambing rates were not significantly different among the groups (66.7, 76.5 and 85.3% for 6, 9, and 12 days, respectively). Seven days after insemination, the re-insertion of CIDRR for 14 days (n=51) did not improve the pregnancy and lambing rates or prolificacy compared to the controls (n=50). In Experiment 2, the mean plasma progesterone concentration on the day of CIDRR removal in Booroola-Dorset ewes treated for 12 days was significantly (P<0.01) lower than those in ewes treated with CIDRR for 6 or 9 days. However, the onset of estrus after treatment was similar in ewes treated for different periods with CIDRR. These results indicate that a satisfactory lambing rate (67 to 85%) can be obtained with frozen semen in ewes treated with CIDRR, regardless of the insertion period (6 to 12 days) during the non-breeding season.

Lambing Rates by Fixed-Time Intrauterine Insemination with Frozen Semen in Seasonally Anestrous Ewes Treated with a Progestogen-Impregnated Sponge or CIDR Device.

During the non-breeding season (April to July), 187 ewes treated wth either an intravaginal sponge impregnated with medroxyprogesterone acetate (MAP) or a controlled internal drug release (CIDR®) device for 9 days and an injection of pregnant mare serum gonadotropin (PMSG) at one day before the cessation of progestogen treatment were inseminated into the uterus by laparoscopy with frozen-thawed semen at fixed-time basis (36, 48 or 60h after the removal of sponge or device). Insemination was also performed at 18 h after estrus detection as a control. The time to the onset of estrus after CIDR® treatment was significantly (P<0.05) earlier (mean: 24.9h) than that in ewes treated with MAP sponge (mean: 30.0h). The percentages of ewes lambing and lambs born per ewe lambing for inseminations at 36, 48 and 60 h were 66.7% and 1.69; 52.0% and 1.31; 46.2% and 1.75 for MAP-treated ewes, and 33.3% and 1.50; 73.9% and 1.53; 40.9% and 1.56 for CIDR®-treated ewes. For control ewes, they were 59.1% and 1.62; and 47.6% and 1.90 for MAP and CIDR® treatments, respectively. There was no significant differences in the lambing rates and prolificacy between MAP and CIDR® treatments and among the insemination times. An optimum time for an intrauterine insemination with frozen-thawed semen appears to be different in the use of MAP sponge (range: 36 to 60h) and CIDR® (48h). A significant difference in the lambing rate was found among the sheep farms conducting the present study.