Effects of human chorionic gonadotropin on reproductive outcomes in estrus-synchronized ewes subjected to two different insemination methods

<span>he use of estrogens in artificial insemination protocols for cattle is the least expensive and most efficient method currently available. However, the trend to prohibit the use of estrogens for this purpose has made it necessary to find alternatives that replace estrogens without compromising the reproductive performance of the animals. The objective of this study was to evaluate conception rates in Bos indicus beef heifers treated with a progesterone device (P4) combined with GnRH or an estradiol ester. On day 0, pubertal Nellore heifers (n = 100) received an intravaginal device containing 1 g P4 and were randomly divided into two groups. The GnRH group (n = 49) received an intramuscular injection of 100 µg GnRH, while the E2 group (n = 51) received 2 mg estradiol benzoate (EB). The P4 device was removed after 5 (GnRH group) or 8 days (E2 group), followed by an injection of 125 µg of the PGF2α, analog cloprostenol. On that occasion, the E2 group received an additional injection of 300 IU eCG. Twenty-four hours later, the GnRH group received a second injection of 125 µg cloprostenol, while the E2 group received 1 mg EB. The heifers were inseminated 72 (GnRH group) or 54 hours (E2 group) after removal of the P4 device. At the time of insemination, the GnRH group received additionally an injection of 100 µg GnRH. Estrus was monitored during the period of cloprostenol injection until the time of artificial insemination and pregnancy was diagnosed 40 days after insemination by transrectal ultrasonography. The data were analyzed by Fisher’s exact test. The pregnancy rate was 38.8% and 31.4% in the GnRH and E2 groups, respectively (P&gt;0.05). The ovarian condition of the heifers (estrus or anestrus) tended to influence (P=0.07) pregnancy rates in the GnRH group, but not in the E2 group. At the time of artificial insemination, 33.3% of heifers in the GnRH group showed signs of estrus versus 88.2% in the E2 group (P&lt;0.05). However, the time of estrus manifestation did not influence pregnancy rates. In conclusion, GnRH can be recommended to replace estradiol in estrus synchronization protocols for fixed-time artificial insemination in Nellore heifers.</span>

The aim of the present study was to evaluate the effect of various administration routes of PGF2α analogue, D-cloprostenol, at the time of artificial insemination (AI) on conception rate in a large dairy herd. A total number of 659 lactating dairy cows (101 heifers and 558 cows) were enrolled in the study. Following heat detection, the cows were artificially inseminated according to the AM-PM rule. The animals were divided into a control (29 heifers and178 cows) and three experimental groups; IM (53 heifers and 110 cows), IV (155 cows) and IU (19 heifers and115 cows) groups that received intramuscular 150 µg, intravenous 150 µg and intrauterine 5 µg of D-cloprostenol, respectively, at the time of AI. The control group did not receive any treatment at the time of AI. To measure serum progesterone concentration, blood samples were obtained from 15 cows in each group at the time of insemination and on days 4 and 15 post-insemination. Pregnancy was diagnosed by rectal ultrasound examination between days 35-40 post-insemination. The effects of treatments, parity, milk production, and days in milk (DIM) on conception rate of adult cows were evaluated using the multivariate logistic regression model. Intramuscular administration of D-cloprostenol at the time of AI significantly increased conception rate in dairy cows compared to the control group (60.1% vs. 40.6%; p = .005). However, intravenous and intrauterine administration of D-cloprostenol did not alter the conception rate (32.3%; p = .29 and 50%; p = .11, respectively). D-cloprostenol treatment at AI could not significantly increase the conception rate of heifers followingboth (IM & IU) administration routes. In conclusion, this study showed that intramuscular administration of D-cloprostenol at the time of insemination might improve the conception rate in adult cows, while its intravenous and intrauterine administration did not induce any positive effects on reproductive efficiency of dairy cows. HIGHLIGHTS Intramuscular administration of D-cloprostenol at the time of insemination might improve the conception rate in adult cows. Intravenous administration of D-cloprostenol did not induce any positive effects on reproductive efficiency of dairy cows. Intrauterine administration of D-cloprostenol did not induce any positive effects on conception rate of dairy cows.

Gonadotropin-releasing hormone (GnRH) is widely used in the timed artificial insemination protocol for sheep. However, there remains a debate regarding its impact on pregnancy rates during artificial insemination. This study aims to evaluate the effect of GnRH on the pregnancy rates in Huyang ewes, analyze the pre-implantation metabolite changes caused by GnRH using metabolomics, and elucidate the mechanism effect on pregnancy rates. All ewes were administered a vaginal progesterone sponge containing 45 mg of flurogestone acetate for 12 days and received 330 units of equine chorionic gonadotropin (eCG) intramuscularly after sponge removal. The experimental group (n = 69) received an intramuscular treatment of 17 μg GnRH agonist triptorelin 48 h after sponge removal on Day 0, while the control group (n = 41) received 1 mL of sterile saline solution. All ewes underwent a single vaginal insemination 58 h after the withdrawal of the progesterone sponge. The difference in pregnancy rates between the two groups was calculated. Metabolomic analysis was performed on plasma samples collected on Day 7 after the treatment of GnRH agonist. Gonadotropin-releasing hormone (GnRH) treatment significantly reduced the pregnancy rate in the experimental group compared with the control group (72.2 vs. 82.9%, p < 0.05). Metabolomic analysis indicated that GnRH treatment affected metabolites involved in collagen synthesis and prostaglandin synthesis in the endometrial tissue, which includes a marked decrease in hydroxyproline amino acid content and a significant increase in corticosterone and prostaglandin D2 lipids and unsaturated fatty acids. In summary, the injection of GnRH agonist Triptorelin 48 h after progesterone sponges removal reduces the pregnancy rate of Huyang ewe following artificial insemination. It also affects the metabolite levels related to endometrial collagen and prostaglandin synthesis, harming embryo implantation.

Background: The time of artificial insemination (AI) concerning ovulation is one of the main factors that affect the pregnancy rate. This study aimed to compare the time of AI with cooled semen in anestrous goats treated with progesterone (P4) plus hCG-based protocol and the effect of management condition on pregnancy rate. Methods: Forty-nine crossbred (local x dairy goats) and thirty-nine Alpine anestrous multiparous goats managed under extensive and intensive production systems respectively, were used (June, 25°N). Goats were treated with 20 mg of P4 followed by 100 IU of hCG 24 h later. On the day of hCG administration (Day 0), goats in each management system were allocated randomly to each of the two treatment groups. Goats in the first group received a fixed-time AI (FTAI) at 48 and 60 h after hCG whereas goats of the second group received a FTAI at 60 and 72 h with cooled semen. Goats were examined by transrectal ultrasonography (7.5 MHz) 45 days after AI to determine the pregnancy rate. Result: There was no significant difference in pregnant goats inseminated at 48 and 60 h (46.8%, 22/47) or 60 and 72 h (46.3%, 19/41) after hCG administration (P greater than 0.05). There was a tendency for a higher pregnancy rate in intensive compared to extensive management conditions (P=0.09) and no interaction was detected between the time of insemination and the management condition system (P greater than 0.05).

Sexed semen artificial insemination is a reproductive technology that allows producers to enhance genetics through use of superior sires, control gender of offspring, and increase profitability. However, sexed semen practices have yet to be widely used within the beef cattle industry due to reduced conception rates, decreased sperm cell numbers in comparison with conventional semen, and increased costs. The objective of this study was to determine the effects of time of estrus, time of insemination, sire, weight, and age on pregnancy rates within a fixed-time artificial insemination (FTAI) protocol using two fixed-time inseminations and female sex-sorted semen from three sires (SexedULTRA 4M, STGenetics, Navasota, TX). Multiparous commercial beef cows (n = 130) were randomized into synchronization protocol and sire treatments by age, body condition score (BCS), and days post-partum at the University of Arkansas Savoy Research Complex in Fayetteville, AR. Synchronization treatments included the 8&amp;6 Synch protocol using two FTAI times: 66 h or 72 h post-CIDR removal. Each synchronization treatment used a controlled internal drug releasing device (Eazi-breed CIDR; 1.38g progesterone, Zoetis, Kalamazoo, MI) inserted intravaginally -14 d of the protocol simultaneous to administration of prostaglandin F2α (PGF; 25mg dinoprost tromethamine; Lutalyse HighCon, Zoetis). In both treatments (66 h) and (72 h), gonadotropin-releasing hormone (GnRH; 100µg gonadorelin; Factrel, Zoetis) was administered on d -6. Each treatment was then administered PGF simultaneous to CIDR removal on 0 d, 66 ± 2 h prior to FTAI within the 66 h treatment, and 72 ± 2 h prior to FTAI within the 72 h treatment and final administration of GnRH. Standing heat (estrus) was visually detected every 3 h for 30 min intervals between the time of CIDR removal and FTAI. Estrotect patches (Rockway Inc., Spring Valley, WI) were used in conjunction with visual detection. Time of estrus was signified as time of solid footing while standing to be mounted in combination with presenting a patch score of 4 (&amp;gt;75% color rubbed off). Pregnancy rates (PR) were determined via ultrasound 42 ± 1 d after FTAI. PR were analyzed by time of estrus (TE), fixed-time insemination protocol (TRT), age, and body weight using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC). There were no significant effects on PR by age or body weight. TE (P = 0.30) and TRT (P = 0.28) were also found to be non-significant. TE was divided into 4 time groups at &amp;lt; 11 h, 11.01-22 h, &amp;gt;22.01 h (hours prior to FTAI), or non-estrual; resulting in PR of 53 %, 74 %, 50 %, and 64 % respectively. In conclusion, data collected suggests acceptable pregnancy rates may be achieved within a fixed-time artificial insemination protocol using sexed semen regardless of age, weight, synchronization treatment, or time of estrus.

The effects of different PMSG doses on estrus behavior and pregnancy rate in Angora goats

The effect of prostaglandin F 2α administration at the time of insemination on the pregnancy rate of dairy cows

A prospective study of intrauterine insemination of processed sperm from men with oligoasthenospermia in superovulated women

The aim of the study was to evaluate the influence of behavioral reactivity, body condition score (BCS), corral temperature (CT), difficulty and time of insemination on pregnancy rate of Nellore females raised in the Pantanal area and submitted to a fixed-time artificial insemination (FTAI) protocol. Thus, 167 females, kept in an extensive grazing system were evaluated. The variables recorded were BCS, escape velocity (EV), CT, insemination difficulty (ID), chute behavior (CB), insemination time (IT) and pregnancy rate. Initially, Fisher's Exact Test was performed to verify differences between expected and observed for BCS, CB, EV, ID, IT and CT, in which the influence of each variable on pregnancy rate was individually analyzed and it was not significant influence of these variables was observed (P&lt;0.05). Subsequently, the result of the pregnancy diagnosis (success = 1 and failure = 0) was used to study the probability of pregnancy. Multivariate analysis was used to assess the influence of several characteristics together on the conception rate, creating different evaluation scenarios. In none of the scenarios extracted from the cluster analysis was there a statistically relevant influence on the number of pregnancies. Under the conditions in which the study was conducted, there was no influence of corral temperature, reactivity, time and difficulty of insemination, body condition score and animal category on pregnancy rate of bovine females submitted to a FTAI protocol.

Artificial insemination (AI) is the first and the most used biotechnologies in reproduction all over the world. Many studies reported the beneficial role of gonadotropin-releasing hormone (GnRH) administrated some hours before the AI or at the artificial insemination time. This study aimed to assess the effect of GnRH analogs given at the time of insemination on the first, second, and third AIs and to assess the economical implications of GnRH administration. We hypothesized that administration of GnRH at the time of insemination would increase ovulation and pregnancy rate. The study was conducted on small farms in northwestern Romania and included animals of the Romanian Brown and Romanian Spotted breeds. Animals in estrous at the first, second, and third inseminations were randomly divided into groups that received GnRH at insemination and groups that did not. A comparison between the groups was performed and the cost of GnRH administration to obtain one gestation was calculated. The GnRh administration increased the pregnancy rate at the first and the second inseminations by 12 and 18%, respectively. For one pregnancy, the cost of GnRH administration was approximately 49 euros for the first insemination group and around 33 euros for the second insemination group. No improvement of the pregnancy rate was observed after the GnRH administration for the cows at the third insemination, so, for this group, no economic statistics were performed.

Luteotropic effects of human chorionic gonadotropin administered 7.5 days after synchronous estrous induction in Morada Nova ewes

Study question How does the timing of intrauterine insemination (D0, D1, or D2 post-hCG trigger) affect pregnancy rates, and what key factors influence these outcomes? Summary answer Overall pregnancy rates were similar across timing groups. Higher rates were observed in subgroups defined by specific follicle sizes, sperm concentration, or endometrial thickness. What is known already Intrauterine insemination (IUI) is a widely used assisted reproductive technique, valued for its simplicity, affordability, and accessibility. However, its success rates remain modest. Clinical guidelines recommend performing IUI within 24–36 hours following ovulation triggering with human chorionic gonadotropin (hCG). Yet, logistical challenges, such as weekend closures at medical centers, often disrupt adherence to these timelines. While some studies suggest that moderate deviations in timing may not significantly affect outcomes, robust evidence for establishing standardized practices remains limited. Optimizing IUI timing is therefore critical to improve success rates while addressing the logistical barriers faced by both healthcare facilities and patients. Study design, size, duration This retrospective observational study was conducted at Ovo Clinic, a university-affiliated private fertility center in Montreal, Canada, analyzing 1,614 IUI cycles performed between May and September 2024. The primary objective was to evaluate pregnancy rates based on insemination timing: D0 (day of trigger), D1 (24 hours post-trigger), and D2 (36 hours post-trigger). The timing of the insemination was chosen to avoid weekends and to spread out the clinic’s activity. Participants/materials, setting, methods IUI cycles were categorized by insemination timing (D0, D1, D2). The primary outcome was the pregnancy rate (PR), defined as a positive pregnancy test 14 days post-IUI. Data collected included maternal age, post-wash motile sperm concentration, endometrial thickness, and follicle size at induction. An analysis was conducted to assess the impact of these variables on PR, aiming to determine the optimal timing for insemination. Main results and the role of chance Mean maternal age was 34 years, comparable across groups. While post-wash motile sperm concentration was lower in the D0 group (D0: 79.1 vs. D1: 91.6 vs. D2: 100.7 M/mL), pregnancy rates were similar across timing groups: D0 (15.5%), D1 (9.8%), and D2 (12.6%) (p = not significant, NS). Higher PRs were observed in the D0 group when dominant follicle size measured 17-19mm (25%) and 20–22 mm (19.4%), endometrial thickness ranged from 7-10mm (18.4%) and 10–13 mm (16.4%), and post-wash motile sperm concentration exceeded 50 M/mL (20%). Notably, no pregnancies were recorded with endometrial thickness &amp;gt; 13mm or a post-wash motile sperm concentration &amp;lt;4 M/mL. Limitations, reasons for caution This study is limited by small sample sizes in certain subgroups, particularly for D0 cycles. Moreover, our results are based on pregnancy rates, which hold less clinical value compared to live birth rates. Larger prospective studies are required to confirm findings. Wider implications of the findings These findings support flexibility in IUI timing without compromising outcomes. Additionally, this study provides valuable insights into the optimal conditions—such as follicle size, endometrial thickness, and sperm concentration—that can enhance pregnancy rates. Trial registration number No

The present study aimed to investigate the fertility of ewes artificially inseminated with three different methods using a synthetic semen extender, AndroMed. The three methods of artificial insemination (AI) were cervical AI with fresh-diluted or frozen-diluted semen at observed estrus, and an intrauterine AI with frozen-thawed semen. A total of 80 ewes were treated with a controlled internal drug release (CIDR) containing 0.3 g progesterone per device for 12 days. In Experiment 1 (26 Suffolk ewes), superovulation was induced with 20 mg follicle-stimulating hormone and 250 IU equine chorionic gonadotropin (eCG) two days and one day before CIDR removal, respectively, during the non-breeding season. In Experiment 2 (54 Suffolk and Suffolk crossbred ewes), an intramuscular injection of 500 IU eCG was administered one day before CIDR removal to synchronize estrus and ovulation during the breeding season. In Experiment 1, fresh-diluted or frozen-thawed semen was deposited into the cervical orifice after estrus detection, and an intrauterine AI with frozen-thawed semen was performed by laparoscopy at a fixed-time basis without estrus detection. Embryos were recovered by uterine flushing 6 days after AI, and the rates of recovered, fertilized (cleaved) ova and embryos at the morula or blastocyst stage were compared among the three AI methods. In Experiment 2, the pregnancy rates after the three AI methods were compared. In Experiment 1, the rates of recovered ova were not significantly different among the three AI methods (52.5-56.7%). The rate of fertilized ova (81.0%) by laparoscopic AI with frozen-thawed semen was significantly higher compared with cervical AI of fresh-diluted (25.5%) or frozen-thawed (3.5%) semen, but the rate of embryos at the morula or blastocyst stage (17.6%) was significantly lower than that of the cervical AI with fresh-diluted semen (69.2%). The rates of ewes yielding fertilized ova were not significantly different among the three groups (44.4, 11.1 and 62.5% for cervical AI with fresh-diluted and frozen-thawed semen and intrauterine AI with frozen-thawed semen). In Experiment 2, the pregnancy rate of ewes intrauterinally inseminated with frozen-thawed semen (72.2%) was significantly higher than those of ewes inseminated cervically with fresh-diluted (5.5%) or frozen-thawed (0.0%) semen. The present results showed that acceptable fertilization and pregnancy rates could be obtained by an intrauterine AI with frozen-thawed semen using a synthetic semen extender (AndroMed), but not sufficient by the cervical AI with either fresh or frozen semen.

Fertility response of artificial insemination methods in sheep with fresh and frozen-thawed semen

Background: The artificial insemination has become a well-established method in the breeding of bitches, and evaluation of the factors that may potentially affect pregnancy success is essential. For this reason, it is essential to evaluate the factors that may affect fertility of the bitch when artificial insemination is performed. Serum progesterone concentrations and vaginal cytology have been used to determine the time of ovulation and stage of the estrus cycle. This study aimed to evaluate the artificial insemination method, the serum progesterone concentration, the breed size, age, the whelping number, vaginal cytology parameters, and their interactions on pregnancy success in bitches. Materials, Methods &amp; Results: A total of 607 bitches that had undergone reproductive consultation with the Mexican Canine Federation from January to December 2016 were enrolled in the present study and assigned to one of 2 artificial insemination methods (intravaginal and transcervical) using fresh semen. Determination of the estrus cycle phase and the time of Artificial insemination was based on vaginal cytology and serum progesterone concentrations. Bitches inseminated by the transcervical technique had a higher pregnancy rate with respect to females inseminated by the intravaginal technique (P &lt; 0.05). Moreover, females with a serum progesterone concentration of 5-10 ng/mL had a greater probability (&gt; 4 times) of getting pregnant than animals with lower or higher progesterone concentrations (P &lt; 0.05). Bitches inseminated by the intravaginal technique and with serum progesterone concentrations &gt;10 ng/mL had a considerable reduction in pregnancy (P &lt; 0.05) compared with females with &lt; 10 ng/mL serum progesterone or with bitches inseminated by the transcervical technique. Discusion: Serum progesterone concentration, the artificial insemination method, and superficial cells without a nucleus modified the pregnancy rate in bitches. Females inseminated by transcervical semen deposition had a higher pregnancy rate than females inseminated by the intravaginal technique. Using fresh or frozen-thawed semen produced a higher pregnancy rate in bitches inseminated by transcervical semen deposition than females inseminated by the intravaginal technique. Differences in the pregnancy rate between transcervical and intravaginal insemination could be associated with the correct semen disposition, the distance that the sperm must travel to reach the oocyte, as well as the number of sperm that reach the oviduct ampulla. Exist evidences that after ovulation, as progesterone rises, the cervix is closed, which may compromise the passage of the sperm deposited into the vagina. Therefore, it is likely that in females with a serum progesterone concentration &gt; 10 ng/mL, the cervix was closed, compromising the ability of the sperm to access the oviduct. Thus, the use of intravaginal insemination should be done in bitches with a serum progesterone concentrations &lt; 11 ng/mL to reduce the possibility of cervical closure and to increase the odds of pregnancy. It is well documented that the serum progesterone concentration and vaginal cytology parameters have a great influence on pregnancy success, and the results confirm these findings. In the present study, 96% of the bitches inseminated with a serum progesterone concentration of 5-10 ng/mL got pregnant and had higher odds of pregnancy than bitches with lower or higher serum progesterone concentrations.