Use of equine chorionic gonadotropin to control reproduction of the dairy cow: a review

Systematic review of hormonal strategies to improve fertility in rams

Reviewing the current state of knowledge on reproductive performance and productive traits in rams has many advantages. First, the compilation of this information will serve as a literature resource for scientists conducting research around the world and will contribute to the understanding of the data collected and interpreted by researchers on the different hormonal strategies used to improve reproductive performance in rams. Second, it will allow scientists to identify current knowledge gaps and set future research priorities in ram reproduction. Rams play an important role in the global flock economy, but their reproductive analysis has been limited in the use of hormonal technologies to increase the productivity of sheep flocks. In this review, we cite the most important works on six hormones that, in one way or another, modify the hypothalamus-pituitary-gonadal axis, at different doses, in and out of the reproductive season, breeds, application methods, among other factors. The overall aim is to increase the reproductive efficiency of rams in different scenarios and, in some cases, of other species due to the lack of limited information on rams.

Bovine somatotropin increases the pregnancy rate in fixed-time artificial insemination in beef cattle

This study evaluated the effect of bovine somatotropin (bST) on pregnancy rate (PR) and size of the dominant follicle (DF) on the day of intravaginal progesterone (P4) removal in protocols for fixed-time artificial insemination (FTAI). Bos indicus (Nellore) females (n = 392) were distributed into three groups. The control group (CG; n = 92) received an intravaginal P4 device + estradiol benzoate on day (d)0; prostaglandin F2α on d7 (first application); removal of P4 + estradiol cypionate (EC) + PGF2α (second application) + ultrasound (US) of the DF on d9; the FTAI was performed on d11; and pregnancy diagnosis (PD) was performed on d45. The bST group (bSTG; n = 142) underwent the same protocol as the CG, except that the animals received 125 mg of bST on d7. The equine chorionic gonadotropin (eCG) group (eCGG; n = 158) underwent the same protocol as the CG, except that the animals received 300 IU of eCG on d9. The PRs of the bSTG, eCGG, and CG were 48%, 48%, and 35%, respectively (p < .05); the bSTG and eCGG showed greater PRs, with follicles 6-7.9 mm (p < .05) and 8-8.9 mm in diameter, respectively. The bSTG exhibited a greater dimension of the DF on d9 of the protocol (p < .05). The eCGG had higher PRs with a body condition score (BCS) of 2.5, and the bSTG had a BCS of 3.0 (p < .05). It was concluded that bST increased PR, bST showed better performance in smaller DF and larger follicular diameter on d9 of the protocol, eCG acted better on animals with lower BCSs, and bST can be used in FTAI.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

Exposure to progesterone before an ovulation synchronization protocol increases the follicular diameter and fertility of multiparous suckled Bos taurus cows

The objective of this study was to evaluate the effect of administering injectable progesterone (P4i) before a timed artificial insemination (TAI) protocol on the follicular growth, ovulation, and pregnancy rate of Bos taurus suckled cows. The effect of P4i administration before the TAI on the pregnancy rate (P/AI) was evaluated in 576 suckled Bos taurus cows at 30-90 days postpartum. In addition, the effect of P4i administration before TAI on follicular dynamics was evaluated in subgroup of 401 suckled Bos taurus cows. On Day -10 (D-10), cows were divided into two experimental groups (Control and P4i). In this moment, P4i cows received i.m. 150 mg of injectable long-action progesterone. After that, both experimental groups received a synchronization protocol (Day 0; D0) that consisted of administration i.m. of 2 mg of estradiol benzoate and a progesterone intravaginal insert on D0. On Day 8 (D8), the progesterone insert was removed, and the cows received 500 μg of cloprostenol, 400 IU of eCG, and 1 mg of estradiol cypionate. TAI was performed 48 h after the removal of the progesterone insert. The ultrasound exams were performed in a subgroup of cows on Days 0, 8, 10 and 12 to evaluate the diameter of the largest follicle, rate of follicular growth and risks of single and double ovulation. The pregnancy diagnosis was performed 30 days after TAI in all cows to determine the pregnancy rate. The diameter of the largest follicle, on D10 (P = 0.84), rate of follicular growth (P = 0.14), ovulation rate (P = 0.40) and double ovulation rates (P = 0.23) did not differ between experimental groups. The pregnancy rate was greater in the P4i group [Control 46.2 % (133/288) vs. P4i 55.6 % (160/288); P = 0.03]. The diameter of the largest follicles (LF) on D0 (Control 11.6 ± 0.2 vs. P4i 13.3 ± 0.3) was greater (P = 0.01) in the P4i group. In conclusion, injectable progesterone before the ovulation synchronization protocol increased the diameter of the largest follicle on the D0 and the pregnancy rate in multiparous Bos taurus suckled beef cows.

The Effect of Repeated Blood Harvesting from Pregnant Mares on Haematological Variables

Studies have been carried out on the effect of large-volume blood harvesting from horses, but they were performed on nonpregnant horses of various breeds other than Icelandic horses. This study aimed to investigate the effect on the haematological variables indicating erythropoiesis of repeated blood harvesting from pregnant mares. To account for regional variation, two herds of mares were chosen, both kept under free-range conditions. Sequential EDTA blood samples were collected weekly from 160 mares and analysed for haematological variables in an automated analyser. Serum samples from 115 mares were analysed for total protein. In both herds, after three harvests, mares began to measure below the minimum value for erythrocyte numbers, and mild anaemia was present in up to 37% at one time. Mares in only one herd had moderate or marked anaemia, 14.3% of the herd. Both herds showed evidence of increased erythropoiesis, but there was a difference between the herds in the intensity of the response. In both herds, however, all mares had reached the minimum normal haematocrit value three weeks after the last harvest. It is important to investigate the causes for the differences between these herds, which might be addressed to reduce the risk of anaemia.

Equine chorionic gonadotropin treatment and timed artificial insemination for dairy cow production under heat stress

This study investigated the effects of timed artificial insemination (TAI) and equine chorionic gonadotropin (eCG) administration on lactating dairy cows under heat-stress conditions (average temperature-humidity index: 80). Timed artificial insemination was performed on the cows with (n = 57) or without (control, n = 41) supplementation with 500 IU of eCG at the day of PGF2α treatment using the CIDR-Ovsynch protocol. GnRH was administered, and a progesterone device (CIDR) was inserted on Day -10 of the treatment protocol. The CIDR was removed on Day -3, and the cows were treated with PGF2α. Two days later, a 2nd GnRH injection was administered. Subsequently, AI was performed on Day 0 (16-20 h after the 2nd GnRH injection), and pregnancy was diagnosed on Days 32 and 60. Plasma progesterone (P4) concentrations were measured after AI. Results showed that the eCG group had a higher pregnancy per AI (P/AI) than the control group (43.9 vs. 12.2%, P = 0.002), which was also accompanied by elevated P4 levels. Four cows in the eCG group had multiple calves, representing 7.0 and 16.0% of the group and pregnant cows, respectively. In conclusion, 500 IU of eCG combined with CIDR-Ovsynch in lactating dairy cows under severe heat stress conditions successfully improved fertility. However, the protocol may have a slight risk of multiple births.

Stimulation of Estrus and Ovulation by Resynchronization in Kangal Sheep during Early Anestrus

A total of 100 Kangal sheep were divided into four groups with the aim of investigating the effectiveness of resynchronization during anestrus for the first time in the literature. The groups were then divided into two further subgroups, namely the resynchronization subgroup group (hCG+resynch) and group (resynch)) and the no resynchronization subgroup (Group (hCG) and group (control)). All the groups started with progesterone-containing sponge insertion on Day 7. The sponge was removed after 7 days (on Day 0), and 600 IU eCG + 131.5 µg PGF2α was injected. The animals in group (hCG+resynch) and group (hCG) received hCG injection at the time of sponge administration. Accordingly, four different groups were established, i.e., resynchronization + hCG administration group (hCG+resynch); n:25), no resynchronization + hCG administration (group (hCG); n:25), resynchronization + no hCG administration (group (resynch); n:25), and no resynchronization + no hCG administration (Group (control); n:25). Estrus rates at the first application in group (hCG+resynch), group (hCG), group (resynch), and group (control) groups were 76%, 88%, 96%, and 76%, respectively, and pregnancy rates were 52%, 64%, 72%, and 60%, respectively; there were no intergroup statistical differences in the two parameters above. It was concluded that resynchronization performed with two consecutive stimulations during anestrus could help save time and provide a pregnancy rate at a level that can provide economic returns.

[Influence of an eCG administration on puerperal involution and fertility in Simmentaler cows]

SUBJECT AND AIM

In the literature, various methods aiming for a promotion of uterine involution and ovarian function in post-partum dairy cattle have been described. Recently, successful use of equine choriongonadotropin (eCG) in this context has been repeatedly reported, while other studies have failed to demonstrate positive effects of eCG administration on puerperal involution in cows. Due to the contradictory results described in the literature, the aim of this field study was to verify whether the administration of eCG on day 10 post-partum exerts a positive effect on uterine involution, ovarian activity and fertility indices in Simmental cows.

MATERIAL AND METHODS

In nine dairy farms, 205 Simmental cows were divided by lot into three groups: Group 1 animals received 500 I.U. eCG, group 2 received 50 µg gonadorelin, and group 3 animals received 250 mg butafosfan and 125 µg cyanocobalamin (control group). Treatment was administered on day 10 post-partum in each case. The animals were examined clinically and ultrasonographically on the 10th, 25th and 42nd day post-partum and the time to insemination and pregnancy were recorded. Group comparison with respect to the recorded parameters was initially performed without considering confounding factors by analysis of variance. In the second step, potential influencing variables (lactation, milk yield, change in backfat thickness, retentio secundarium and serverity of the obstetric intervention) were taken into account, as well as the combination of the random factors "farm" and "individual animal within the farm".

RESULTS

The administration of eCG exhibited no significant effect on uterine involution, however, the cervical involution was influenced significantly. In the group of cows with eCG treatment, ovarian cysts were detected significantly more frequently on day 25 post-partum (p=0.04). This difference did not persist on the 42nd day post-partum. Neither voluntary waiting period nor the days open were significantly shortened by eCG administration. Lactation number showed a significant effect on uterine involution. Heifers exhibited more rapid involution by day 42 post-partum than cows.

CONCLUSION

Administration of eCG in Simmentaler cows at day 10 post-partum showed no positive effect.

CLINICAL RELEVANCE

The use of eCG in early puerperium to promote fertility in the cow should be avoided.

Production of Mare Chorionic Girdle Organoids That Secrete Equine Chorionic Gonadotropin

The equine chorionic girdle is comprised of specialized invasive trophoblast cells that begin formation approximately 25 days after ovulation (day 0) and invade the endometrium to become endometrial cups. These specialized trophoblast cells transition from uninucleate to differentiated binucleate trophoblast cells that secrete the glycoprotein hormone equine chorionic gonadotropin (eCG; formerly known as pregnant mare serum gonadotropin or PMSG). This eCG has LH-like activity in the horse but variable LH- and FSH-like activity in other species and has been utilized for these properties both in vivo and in vitro. To produce eCG commercially, large volumes of whole blood must be collected from pregnant mares, which negatively impacts equine welfare due to repeated blood collections and the birth of an unwanted foal. Attempts to produce eCG in vitro using long-term culture of chorionic girdle explants have not been successful beyond 180 days, with peak eCG production at 30 days of culture. Organoids are three-dimensional cell clusters that self-organize and can remain genetically and phenotypically stable throughout long-term culture (i.e., months). Human trophoblast organoids have been reported to successfully produce human chorionic gonadotropin (hCG) and proliferate long-term (>1 year). The objective of this study was to evaluate whether organoids derived from equine chorionic girdle maintain physiological functionality. Here we show generation of chorionic girdle organoids for the first time and demonstrate in vitro production of eCG for up to 6 weeks in culture. Therefore, equine chorionic girdle organoids provide a physiologically representative 3D in vitro model for chorionic girdle development of early equine pregnancy.

Use of equine chorionic gonadotropin in lactating dairy cattle: a rapid review

AIMS

To use an evidence-based approach to evaluate the available research data on the efficacy of equine chorionic gonadotropin (eCG) to improve reproductive performance of dairy cows when added to oestrus synchronisation programmes for the treatment of cows not detected in oestrus.

METHODS

A rapid literature review was conducted to summarise the existing trial data, primarily the effect of eCG on conception rate (CR) to fixed time artificial insemination (FTAI) from oestrus synchronisation programmes in lactating dairy cows. Relevant papers were identified via databases and auxiliary search strategies, then information was collected using a standardised data collection form. Similar studies were grouped together to create a descriptive summary of CR to FTAI and secondary outcome measures, with the creation of forest plots to visualise results.

RESULTS

A total of 15 studies were identified for review: nine examined the administration of 400-500 IU eCG as part of an oestrus synchronisation programme based on intra-vaginal progesterone-releasing devices, gonadotropin-releasing hormone and prostaglandin (P4-GPG programme). The variable methodologies in the trials evaluated posed difficulties in grouping studies for further analysis and meant that there was insufficient data for a full meta-analysis. A single study reported a statistically significant increase in CR to FTAI from the addition to eCG to a P4-GPG programme in cows with anovulatory anoestrous. Four studies evaluated the addition of eCG to P4-GPG programmes in cows without visible oestrous signs; risk differences for CR to FTAI were between -1.7% and 28.8%, with three out of four studies reporting a positive effect of eCG on CR to FTAI, but all 95% CI values crossed the line of no effect. Two studies reported on the effect of eCG on 42-day pregnancy rate following a P4-GPG programme; one reported a risk difference of -4.9% (95% CI = -10.6-0.8%), while the other reported a risk difference of 7.9% (95% CI = 0.8-15%).

CONCLUSIONS

The results of published studies describing the effect of eCG in P4-GPG programmes on CR to FTAI are inconsistent and further well-designed, adequately powered studies with standardised outcome measures are required to investigate its effect.

Gene Editing of the Follicle-Stimulating Hormone Gene to Sterilize Channel Catfish, Ictalurus punctatus, Using a Modified Transcription Activator-like Effector Nuclease Technology with Electroporation

Follicle-stimulating hormone (fsh) plays an important role in sexual maturation in catfish. Knocking out the fsh gene in the fish zygote should suppress the reproduction of channel catfish (Ictalurus punctatus). In this study, transcription activator-like effector nuclease (TALEN) plasmids targeting the fsh gene were electroporated into fertilized eggs with the standard double electroporation technique. Targeted fsh cleavage efficiency was 63.2% in P1fsh-knockout catfish. Ten of fifteen (66.7%) control pairs spawned, and their eggs had 32.3–74.3% average hatch rates in 2016 and 2017. Without hormone therapy, the spawning rates of P1 mutants ranged from 33.3 to 40.0%, with an average egg hatching rate of 0.75%. After confirmation of the low fertility of P1 mutants in 2016, human chorionic gonadotropin (HCG) hormone therapy improved the spawning rates by 80% for female mutants and 88.9% for male mutants, and the mean hatch rate was 35.0% for F1 embryos, similar to that of the controls (p > 0.05). Polymerase chain reaction (PCR) identification showed no potential TALEN plasmid integration into the P1 channel catfish genome. Neither the P1 nor the F1 mutant fish showed any noticeable changes in in body weight, survival rate, and hatching rate when the reproductive gene was knocked out. F1 families had a mean inheritance rate of 50.3%. The results brought us one step closer to allowing implementation of certain genetic techniques to aquaculture and fisheries management, while essentially eliminating the potential environment risk posed by transgenic, hybrid, and exotic fish as well as domestic fish.

Fertilidad mejorada en ganado lechero con baja condición corporal al usar gonadotrofina coriónica equina en inseminación artificial a tiempo fijo

Con el objetivo de evaluar el efecto de la utilización de la gonadotrofina coriónica equina (eCG) en un protocolo de inseminación artificial a tiempo fijo (IATF) a base de progesterona (P4) y la condición corporal (CC), sobre la fertilidad de vacas mantenidas bajo un sistema de producción tradicional (SPT); se desarrolló una investigación, empleando un diseño completo al azar, con arreglo factorial 2×2, siendo los factores la CC (3,00 ≤ CC ≤ 2,75) y la administración de 400 Unidades Internacionales (UI) de eCG, formando cuatro tratamientos (T) con 50 animales cada uno. T1 vacas sincronizadas con CC ≤ 2,75 y sin aplicación de eCG; T2 vacas sincronizadas con CC ≤ 2,75 y con aplicación de eCG; T3 vacas sincronizadas con CC ≥ 3,00 y sin aplicación de eCG; T4 vacas sincronizadas con CC ≥ 3,00 y con aplicación de eCG. El protocolo base fue: Día cero, aplicación del dispositivo intravaginal (DIV) de progesterona, más 2 miligramos (mg) de benzoato de estradiol (BE), el día 7, retiro del DIV más 500 microgramos (µcg) de cloprostenol sódico, día 8, 1 mg de BE, Día 9 la IATF, 56 horas de haber retirado el DIV. La eCG se administró al momento de retirar el DIV. Los valores de fertilidad fueron para el T1: 22,0 %; T2: 44,0 %; T3: 46,0 % y T4: 48,0 %, con diferencias significativas (P<0,05) entre el T1 y los otros T. Los resultados indican que la administración de eCG, mejora la fertilidad de vacas con baja CC, en SPT de leche.

Follicular Dynamics and Pregnancy Rate in Nellore Heifers Submitted to Fixed-Time Artificial Insemination Protocols (FTAI)

This study aimed to evaluate follicular dynamics and pregnancy rates in Nellore heifers submitted to fixed-time artificial insemination (FTAI) protocols associated with equine chorionic gonadotrophin (eCG) or follicle stimulating hormone (FSH). Nellore heifers (n = 259) were used, divided into two studies. Experiment I evaluated the ovarian follicular dynamics in 64 Nellore heifers submitted to different FTAI protocols (n = 32/group) using either FSH or eCG. In Experiment II, the pregnancy rate was evaluated in 195 heifers submitted to FTAI protocols and divided into two groups: FSH (n = 97) and eCG (n = 98). In Experiment I, the ultrasound examination showed that the maximum diameter of the dominant and preovulatory follicles and the ovulation time were similar between the FSH and eCG groups (p > 0.05). However, the ovulation rate was higher in the eCG group when compared to FSH (p = 0.014). In Experiment II, females that received eCG presented a higher pregnancy rate (58.1%) when compared to FSH (40.2%) (p = 0.012). The use of eCG in the FTAI protocol in Nellore heifers promoted a higher ovulation rate and increased pregnancy rate and may be the most suitable alternative to increase conception rates in animals that are raised in an extensive system under tropical conditions in the Amazon.

Effect of ovulation synchronization program and season on pregnancy to timed artificial insemination in suckled beef cows

This study was conducted to (i) evaluate the requirement for the administration of GnRH coincident with insertion of a progesterone-releasing intravaginal device (PRID) and (ii) the effect of supplementing with 400 IU eCG at PRID removal on pregnancy per AI (P/AI) in spring and autumn calving suckled beef cows, subjected to a 7-d CO-Synch + PRID timed artificial insemination (TAI) program. Suckled beef cows (n = 1408) on 62 commercial farms were enrolled and randomly assigned to either of three treatments: 1) cows received a PRID and 100 μg GnRH on Day -10, followed by 25 mg PGF_2α at PRID removal (Day -3) and 100 μg GnRH 72 h later (Day 0) at TAI (Treatment 1; n: spring = 236, autumn = 248); 2) as Treatment 1, but without GnRH at PRID insertion on Day -10 (Treatment 2; n: spring = 232, autumn = 227); 3) as Treatment 1, but cows also received 400 IU eCG at PRID removal on Day -3 (Treatment 3; n: spring = 233, autumn = 232). At Day -10, ovaries were examined by ultrasonography to evaluate the presence or absence of a corpus luteum (CL) and follicle(s) ≥ 10 mm in diameter. Body condition score (BCS) was assessed on a scale of 1-5. Pregnancy diagnosis was carried out 30-35 d after TAI by transrectal ultrasonography. Data were analyzed using the GENMOD and LOGISTIC procedures of SAS. There was a treatment by season interaction for P/AI (P < 0.001). In spring, overall P/AI was 59.1% (414/701) and was affected by treatment (59.3 v 49.6 v 68.2%, for Treatments 1, 2 and 3, respectively P < 0.05). In contrast, in autumn, overall P/AI (51.5%, 364/707) was unaffected (P > 0.05) by treatment (50.1 v 53.7 v 48.7% for Treatments 1, 2 and 3, respectively). Overall, eCG had a positive effect on P/AI for cows lacking a CL at treatment initiation (P < 0.05). In addition, in cows with low BCS (≤2.25), eCG supplementation tended (P = 0.09) to improve P/AI. Seasonal differences in response to synchronization treatment may be reflective of different management regimens (grazing v confinement) and breed type and remain to be elucidated.

Development of a suitable manufacturing process for production of a bioactive recombinant equine chorionic gonadotropin (reCG) in CHO-K1 cells

Equine chorionic gonadotropin (eCG) is a heterodimeric glycoprotein hormone produced by pregnant mares that has been used to improve reproductive performance in different domestic species. Several strategies to produce the hormone in a recombinant way have been reported; nevertheless, no approach has been able to produce a recombinant eCG (reCG) with significant in vivo bioactivity or in sufficient quantities for commercial purposes. For this reason, the only current product available on the market consists of partially purified preparations from serum of pregnant mares (PMSG). Herein, we describe a highly efficient process based on third-generation lentiviral vectors as delivery method for the production of reCG in suspension CHO-K1 cells, with productivities above 20 IU 10⁶ cell^-1.d^-1 and 70% purification yields after one purification step. Importantly, reCG demonstrated biological activity in cattle, since around 30 μg of reCG were needed to exert the same biologic effect of 400 IU of PMSG in an ovulation synchronization protocol. The results obtained demonstrate that the developed strategy represents an attractive option for the production of reCG and constitutes an auspicious alternative for the replacement of animals as a source of PMSG.

Effects of eCG and FSH in timed artificial insemination treatment regimens on estrous expression and pregnancy rates in primiparous and multiparous Bos indicus cows

Effects were evaluated in Bos indicus cows of eCG and FSH on follicular growth, estrous expression, and pregnancy per artificial insemination (P/AI) as a result of fixed-time artificial insemination (TAI). In Experiment 1, extent of timing-of-ovulation synchronization among cows was evaluated after imposing an estrogen/progesterone-based treatment regimen. At progesterone device removal (D8), cows were administered: eCG, or FSH or served as untreated Controls. In Experiment 2, percentage of cows P/AI was evaluated when the Experiment 1-treatment regimen was imposed. On D10, all cows were artificially inseminated. In Experiment 3, cows were assigned to two treatment groups (Control and eCG) on D8 to evaluate percentage of cows P/AI and estrous expression. In Experiment 1, follicular dynamics were similar among treatment groups. In Experiment 2, follicular growth was greater (P =  0.0001) with the eCG treatment. There was an interaction of treatment × parity (P =  0.007) on percentage of cows P/AI. There was a greater percentage of primiparous cows P/AI in the eCG-treated than Control and FSH-treated cows. There was a greater percentage of eCG-treated multiparous cows pregnant as a result of TAI than Control cows. There was an interaction of treatment × parity (P =  0.005) on P/AI in Experiment 3, in which the eCG effect was more pronounced in primiparous cows. Treatment with FSH, therefore, was not as effective as eCG in stimulation of follicular growth or enhancing percentage of cows pregnant as a result of TAI. Physiological effects of eCG, however, were also more evident in primiparous cows.

Effect of ovarian stimulation by different gonadotrophin treatments on in vivo and in vitro reproductive efficiency of rabbit does under high ambient temperature

Non-lactating multiparous NZW rabbit does (n = 227) were used in two experiments. In the 1st experiment (n = 87), does were i.m. injected with 0.1-ml saline/doe in day 0 (control, n = 29). Other does were injected with 25 IU equine chorionic gonadotrophin (eCG), followed by 0.2-ml gonadotrophin-releasing hormone (GnRH, n = 29) or 75 IU human chorionic gonadotrophin (hCG, n = 29) per doe 48 h later. After 60 h of day 0, does in all groups were artificially inseminated (AI). In the 2nd experiment, does (n = 140) were mated (AI) after synchronization of estrus/ovulation with 25 IU eCG, and 75 IU hCG 48 h later. On day 5 post-AI, does were injected with saline (control), 75 IU hCG, 0.2 ml GnRH, or 25 IU eCG per doe. Injection of eCG with GnRH or hCG pre-AI significantly increased corpora lutea number, ovulation rate, total number/doe and recovery rate of embryos, viable embryos, hatched blastocysts, in vivo reproductive parameters, and concentration of progesterone and progesterone/estradiol 17-β ratio. Injection of eCG on day 5 post-AI significantly improved large and total follicle number, and in vivo reproductive efficiency. The corpora lutea number and impantation sites were significantly increased in the hCG and eCG groups. Fetal loss rate significantly increased only in the GnRH group. Under high ambient temperature, administration of eCG with hCG or GnRH injection pre-AI could be synchronized estrus/ovulation for improving in vivo and in vitro embryo production. In addition, pregnancy outcomes could be enhanced in rabbit does induced to ovulation by a single eCG or hCG dose on day 5 post-AI.

[Equine chorionic gonadotrophin: Biology and veterinary use]

The pituitary gonadotrophins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play a prominent role in the control of gonadal functions. Therefore, their use in the treatment of fertility disorders (e. g. anovulatory anestrus) as well as in biotechnology (e. g. superovulation, hormone programs for cycle synchronization) is of substantial interest. Preparations of FSH or LH are relatively expensive due to the laborious extraction from pituitary tissue and are therefore reserved for special indications. In primates and equids, the chorionic epithelium expresses an LH-like molecule (chorionic gonadotrophin, CG). Equine CG (eCG) selectively binds to LH receptors in equids. In all other domestic mammalian species, equine CG (eCG) shows an extraordinarily high FSH activity in addition to its LH activity ("dual activity"). Since its market launch, this has therefore gained considerable importance as a comparatively inexpensive FSH analogue, mainly for use in ruminants and pigs. In contrast to the human CG (hCG), which may be isolated non-invasively from the urine of pregnant women and is widely used as LH analogue, eCG must be extracted from the blood of pregnant donor mares, as eCG concentrations in urine are only minimal. Following reports of deaths and suffering of donor mares associated with eCG collection in South American settings, the current practice of eCG production has given rise to increasing public criticism. This has recently led to calls for a general production ban. Primary aim of this review is therefore to summarize the current state of knowledge concerning the properties and biology of this molecule, which is also highly interesting from the point of view of basic science.

Symposium review: Progesterone effects on early embryo development in cattle

The causes of low fertility in dairy cattle are complex and multifactorial and may be due to compromised follicle development affecting oocyte quality, a suboptimal reproductive tract environment incapable of supporting normal embryo development, or a combination of both. Progesterone (P4) plays a key role in reproductive events associated with establishment and maintenance of pregnancy, through its effects on oocyte quality and its action on the uterine endometrium. Reduced P4 concentrations during growth of the ovulatory follicle are associated with lower fertility, and low concentrations of circulating P4 after ovulation have been associated with reductions in conceptus growth and elongation, decreased interferon-τ (IFNT) production, and lower pregnancy rates in cattle. In contrast, elevated concentrations of circulating P4 in the period immediately following conception have been associated with advancement of conceptus elongation, increased IFNT production, and, in some cases, higher pregnancy rates in cattle. Despite the potential beneficial effects of exogenous P4 supplementation on fertility, results of supplementation studies have been inconsistent. As part of the 2019 ADSA Reproduction Symposium, focusing on the etiology of pregnancy losses in dairy cattle, the aim of this review is to highlight recent findings from our group and others in relation to embryo-maternal interaction during bovine pregnancy establishment and the role of P4 in uterine biology and embryo development.

Towards Improving the Outcomes of Assisted Reproductive Technologies of Cattle and Sheep, with Particular Focus on Recipient Management

The Australian agricultural industry contributes AUD 47 billion to the Australian economy, and Australia is the world's largest exporter of sheep meat and the third largest for beef. Within Australia, sheep meat consumption continues to rise, with beef consumption being amongst the highest in the world; therefore, efficient strategies to increase herd/flock size are integral to the success of these industries. Reproductive management is crucial to increasing the efficiency of Australian breeding programs. The use of assisted reproductive technologies (ARTs) has the potential to increase efficiency significantly. The implementation of multiple ovulation and embryo transfer (MOET) and juvenile in vitro fertilization and embryo transfer (JIVET) in combination with genomic selection and natural mating and AI is the most efficient way to increase genetic gain, and thus increase reproductive efficiency within the Australian livestock industries. However, ARTs are costly, and high variation, particularly between embryo transfer recipients in their ability to maintain pregnancy, is a significant constraint to the widespread commercial adoption of ARTs. The use of a phenotypic marker for the selection of recipients, as well as the better management of recipient animals, may be an efficient and cost-effective means to increase the productivity of the Australian livestock industry.

Quality of Preovulatory (GV) Oocytes in Mice after Injection of eCG at Various Stages of the Estrous Cycle

We studied the influence of the estrous cycle on the morphology of preovulatory (germinal vesicle, GV) oocytes in mice and their capacity to meiotic maturation in vitro. After standard injections of eCG gonadotropin (PMSG, Follimag) to females at different stages of the estrous cycle, the maximum levels of GV oocytes (26±1/mouse) were isolated from the ovaries of animals injected with the hormone during estrus. The capacity of isolated GV oocytes to meiotic maturation in vitro decreased in the following order: estrus (75.5±2.3%), metestrus (67.9±3.4%), proestrus (57.8±4.4%), and diestrus (50.6±5.6%); the differences between estrus and diestrus/proestrus were significant (p<0.05). After eCG injections during estrus, GV oocytes differed from other oocytes by lesser total diameter, lesser diameter of cytoplasm, lesser thickness of zona pellucida, and moderately dilated perivitelline space. These signs reflected higher competence of the "estrous" GV oocytes for meiotic maturation in vitro. Hormone stimulation of females with eCG, with consideration for the stage of the estrous cycle, seems to be an effective method for improving the quality of GV oocytes isolated from mouse ovaries.

Horse Welfare During Equine Chorionic Gonadotropin (eCG) Production

Simple Summary

Equine chorionic gonadotropin or eCG is an important hormone produced by the placenta of pregnant mares and extracted from the blood of these same mares. This hormone is commonly used to enhance reproduction of pigs, dairy cows, sheep, beef cows, and goats. There are currently no alternative sources of this hormone. Horse welfare problems may arise if too much blood is collected at one time or during repeated collections or if the mares are not managed well. In some countries, mares are aborted several months into the pregnancy to improve efficiency since this permits them to become pregnant a second time in one year. We discuss approaches to protect the welfare of pregnant mares kept for eCG production.

Abstract

Collection of blood from pregnant mares for extraction of equine chorionic gonadotropin (eCG) is a critical but relatively unknown and poorly regulated practice in the countries in which it occurs. Equine chorionic gonadotropin is a hormone that is widely used to enhance reproductive performance and management of dairy and beef cattle, sheep, goats, and pigs kept under intensive housing systems. eCG is extracted from the blood of brood mares between days 40–120 of gestation. Although alternatives have been sought, there is currently no efficacious replacement, natural or synthetic, for eCG. Recently, several animal welfare organizations have voiced concerns over the condition and treatment of pregnant mares kept for eCG production in some countries. Animal welfare issues may arise if mares are bled too frequently or if too much blood is collected at any time. In addition, these mares tend to be managed extensively on pastures with minimal veterinary oversight and they may be poorly desensitized and habituated to handling and other practices. This can lead to serious injuries and even death when mares are brought in for bleeding. This paper reviews the process of blood collection for eCG extraction and provides recommendations for ensuring mare welfare.

Characterization of tethered equine chorionic gonadotropin and its deglycosylated mutants by ovulation stimulation in mice

Background

To directly assess the biological role of oligosaccharides in recombinant equine chorionic gonadotropin (rec-eCG) functioning, cDNA encoding the full-length eCGβ-subunit was fused with the mature protein part of the α-subunit, and we examined the expression levels of deglycosylated eCG mutants, the ovulation rate for deglycosylated mutants in C57BL/6 mice.

Results

The characterizations of heterodimeric and tethered mutants were studied following their respective secretions in culture medium, molecular weight and ovulation in vivo. Rec-eCG variants containing mutations at glycosylation sites at Asn82 of the α-subunit (eCGβ/αΔ82) and Asn13 of the β-subunit (eCGβΔ13/α) were not efficiently secreted into the culture medium from transfected cells. Western blot analysis revealed that the rec-eCGβ/α proteins have an approximate broad range of molecular weights of 40–46 kDa. Three rec-eCG mutants—a deglycosylated site at Asn56 of the α-subunit (eCGβ/αΔ56), a deletion of the C-terminal region of the β-subunit (eCGβ-D/α), and the double mutant (eCGβ-D/αΔ56)—turned out to have clearly lower (approximately 4–23 kDa) molecular weights. Protein N-glycosydase F (PNGase F) treatment markedly decreased the molecular weight to approximately 2–10 kDa. Normal oocytes were significantly more abundant in the natural eCG–treated group than in mutant rec-eCG–treated groups. In particular, numbers of nonfuntional oocytes were remarkably lower in all rec-eCG groups.

Conclusions

Our results indicate that the ovulation rates of oocytes are not affected by the deglycosylated rec-eCGβ/α mutant proteins. There are around 20% non-functional oocytes with natural eCG and only 2% with the rec-eCGs tested. These results provide insight into the molecular mechanisms underlying the production of rec-eCG hormones with excellent bioactivity in vivo.

Electronic supplementary material

The online version of this article (10.1186/s12896-019-0550-6) contains supplementary material, which is available to authorized users.

Treatment of male goats with equine chorionic gonadotrophin during the non-breeding season does not affect their sperm characteristics during the subsequent breeding season

Equine chorionic gonadotrophin (eCG) is a hormone having FSH/LH effects. It can be used to enhance sperm quality in male goats (bucks) during the non-breeding season. In a previous study carried out during the non-breeding season, we treated ten bucks with eCG (leaving nine untreated animals as control). Over a 20-day period, the treated bucks received an initial dose of 800 IU of eCG, followed by four doses of 500 IU. We found eCG enhanced semen quality, however, as also happens in female goats (does), eCG also induced a high titer of anti-eCG antibodies. In does, this lowers fertility. The aim of the present study was to determine if the eCG treatment carried out on bucks during the non-breeding season had any negative effects on their reproductive status during the following breeding season. We measured serum concentration of testosterone and anti-eCG antibody, as well as key testicular and seminal characteristics. This study commenced 91 days after the final dose of eCG in the previous study. The anti-eCG titer was higher in the treatment bucks than in untreated ones (181.7 ± 61.3 ng/μL vs 31.1 ± 10.7 ng/μL; P < 0.05). However, there were no significant differences between treated and untreated bucks in testosterone concentration, scrotal circumference, testes pixel intensity, fresh and thawed semen characteristics, or sperm cryoresistance. So, although the eCG-treated bucks had greater titers of anti-eCG antibodies, their reproductive pattern was unaffected.

First comprehensive view on a magnetic separation based protein purification processes: From process development to cleaning validation of a GMP-ready magnetic separator

Magnetic separation processes are known as integrated bioanalytical protein purification method since decades and are well described. However, use of magnetic separation processes in a regulated industrial production environment has been prevented by the lack of suitable process equipment and prejudice against the productivity of the process and its qualification for cleaning-in-place operation. With the aim of overcoming this prejudice, a comprehensive process development approach is presented, based on a GMP-compliant magnetic separator, including an optimization of the batch adsorption process, implementation into a technical-scale, and the development and validation of cleaning routines for the device. By the implementation of a two-step counter-current binding process, it was possible to raise the yields of the magnetic separation process even for very low concentrated targets in a vast surplus of competing proteins, like the hormone equine chorionic gonadotropin in serum, from 74% to over 95%. For the validation of the cleaning process, a direct surface swabbing method combined with a total organic carbon analysis was established for the determination of two model contaminants. The cleanability of the process equipment was proven for both model contaminants by reliably meeting the 10 ppm criteria.

Influence of eCG and breed on the number of oocytes collected and the production of in vitro embryos of young goats during the reproductive season

The objective of this study was to determine the effect of breed and equine chorionic gonadotropin (eCG) on ovarian response and in vitro embryo production from young goats. Thirty-one (12 Alpine, 10 Nubian, and 9 Saanen) were randomly assigned into three treatments of eCG (T1, 0 IU; T2, 500 IU; and T3, 1000 IU). Alpine goats showed the highest amount and largest size of follicles (P = 0.003). The effect of eCG dose 24 h post application was significant (P < 0.05), and was superior in goats undergoing T2. The aspiration rate of cumulus-oocyte complexes (COC) was 34% (P > 0.05), except for percentage of denuded oocytes, which obtained the highest number (P = 0.003) in the Saanen goats. The same difference was found (P = 0.02) in oocytes grade III in T2 and T3, with 42.5 and 37.9% respectively. In vitro embryo production was 80.0% of IVF/cleavage in the Alpine goats (P = 0.003). Embryo production was the greatest for T2 (69.2%; P = 0.004). T3 goats had higher percentage of morula stage (66.6%; P = 0.030). It is concluded that the application of eCG has a significant effect on the ovarian status, and quality and quantity of embryos with a differential response depending on the breed.

Effect of eCG on the follicular dynamics and vascularization of crossbred cows with different circulating progesterone concentrations during synchronization of ovulation in an FTAI protocol

ABSTRACT: This study aimed to evaluate the effect of treatment with equine chorionic gonadotrophin (eCG) on the follicular dynamics and function of crossbred cows with different circulating progesterone (P4) concentrations during synchronization of ovulation in a fixed-time artificial insemination (FTAI) protocol. To this end, 30 crossbred cows were submitted to a pre-synchronization protocol to ensure that all of them presented corpus luteum (CL) at the beginning of the protocol, and were evaluated by transrectal ultrasonography (TRUS) to verify the presence of CL. After that, the animals underwent an ovulation synchronization protocol and evaluation of follicular dynamics and vascularization by B-mode and power-Doppler ultrasound (US). High plasma P4 concentrations at the time of ovulation synchronization negatively influenced follicle diameter on day 10 (D10), preovulatory follicle diameter, and preovulatory follicle wall vascularization area (p<0.05). Cows with high P4 concentration at the time of ovulation synchronization that were treated with eCG showed follicle diameter on D10 and preovulatory follicle diameter and wall vascularization area (p>0.05) similar to those of animals with low P4 concentration at the time of ovulation synchronization. Therefore, high P4 concentrations at the time of ovulation synchronization negatively influence follicular diameter and vascularization, and eCG can be used as a strategy to favor better follicular and luteal response in crossbred cows with high P4 concentrations submitted to an FTAI protocol.

FSH in bovine superovulation

Bovine follicle stimulating hormone (FSH) is the hormone mainly used for superovulation treatments. It is used so that several secondary follicles can reach a dominant state at the same time and thus, treated cows can release up to ten or more ovules in each zeal, decreasing the generational interval and increasing livestock production. The hormones available in the current market are obtained mostly from pituitary extracts of swine and sheep, and although they are widely used. Several negative aspects have been reported, implying high risks of contamination with pathogens, contamination with other hormones that interfere with assisted fertilization processes, significant variations between each production batch and the decreased half-life that exhibit FSH leading to excessive handling of donor cows. In this review, we detail some new approaches to overcome these problems, like slow-release FSH formulations that have been developed in order to increase the half-life of FSH and, finally the use of recombinant DNA technology to ensure a pure product.

Effect of equine chorionic gonadotropin administration on day 8 post-partum on ovarian follicular development, uterine health and uterine involution in lactating dairy cows

The objective was to evaluate the effect of equine chorionic gonadotropin (eCG) injection on day 8 postpartum on ovarian cyclicity, uterine health and uterine involution in lactating dairy cows. Lactating dairy cows [n = 34, (21 primiparous and 13 multiparous)] were enrolled in the study. Animals were stratified by calving date, parity and BCS, and randomly assigned to either control (CON n = 18) or eCG treatments (n = 16). On day 8 ± 0.9 post-partum (pp), eCG treatment cows received a 2 ml i.m. injection (500 IU) of eCG and control treatment cows received a 2 ml i.m. injection of 0.9% sodium chloride. Ovaries were examined by transrectal ultrasound every second day from day 10 pp until ovulation or regression of the first follicle wave, and the diameter of the dominant follicle was recorded at each exam. Ultrasound exams were conducted on days 21, 28, 35 and 42 pp to measure the diameter of the cervix and the uterine horns. Vaginal discharge score (VDS) was recorded on a 1 to 5 scale on days 14, 21, 28, 35 and 42 pp. Endometrial cytology samples were collected on day 42 pp, and the percentage of polymorphonuclear neutrophils (PMN) determined. Milk samples were collected three times per week from day 14 pp until day 60 pp for P4 determination. Ovarian follicular development variables, ovarian function variables analysed and incidence of subclinical endometritis were not affected by treatment. There was a treatment by parity interaction for pp interval to commencement of luteal activity (P = 0.04) and number of luteal phases (P = 0.05), whereby eCG treatment caused an earlier pp commencement of luteal activity and a greater number of luteal phases in multiparous cows, but not in primiparous cows. A significant effect of treatment on uterine involution was observed (previously gravid horn: P = 0.03; previously non-gravid horn: P = 0.01) and uterine health status (P = 0.03), whereby eCG cows had smaller mean horn uterine diameter and lesser VDS than CON cows. In summary, parenteral administration of 500 IU eCG on day 8 post-partum did not affect resumption of ovarian cyclicity in all cows but did enhance uterine involution and VDS. In multiparous cows, eCG advanced commencement of luteal activity and increased the number of luteal phases.

Eficácia da associação dupla dose PGF2 alfa-eCG no proestro de vacas leiteiras mestiças submetidas à IATF

RESUMO: Objetivou-se avaliar o efeito de uma ou duas doses de prostaglandina F2α (PGF2α) associada ou não a gonadotrofina coriônica equina (eCG) sobre a dinâmica folicular, a função luteal pré-ovulatória, assim como as características morfofuncionais pós-ovulatórias do corpo lúteo (CL) em fêmeas mestiças cíclicas submetidas a um protocolo de inseminação artificial em tempo fixo (IATF). Para tanto, 29 vacas 3/4 Gir x Holandês multíparas foram submetidas ao exame de ultrassonografia (US) transretal e após a detecção do CL iniciou-se um protocolo de IATF em um dia denominado zero (D0), por meio da inserção do implante de progesterona (P4) associado à aplicação de 2,0mg de benzoato de estradiol. No D7 esses animais receberam 12,5mg de dinoprost trometamina. No D9 realizou a remoção dos dispositivos de P4 e aplicou 0,6mg de cipionato de estradiol. Nesse momento, as fêmeas foram subdivididas nos seguintes tratamentos: Grupo Controle (n=7), foi administrado 2,5mL de solução fisiológica; Grupo 2PGF (n=7), aplicou 12,5mg de dinoprost trometamina; Grupo eCG (n=7), administrou-se 300UI de eCG; Grupo 2PGF+eCG (n=8), realizou a aplicação de 300UI de eCG e 12,5mg de dinoprost trometamina. Para avaliar a dinâmica folicular foram realizados exames de US em modo B e power doppler (Mindray Z5, Shenzhen, China) a cada 12h do D7 até o momento da ovulação ou 96h após a remoção dos implantes de P4, mensurando-se o diâmetro folicular (DFOL), a área da parede folicular (AFOL) e a área de perfusão sanguínea da parede folicular (VFOL). Concomitante a cada exame, foram coletadas amostras de sangue sendo determinada a concentração sérica de P4 pré-ovulatória por meio da metodologia de quimioluminescência. No D24 foi realizada a US modo B e doppler analisando-se o diâmetro luteal (DCL), área luteal (ACL) e área de perfusão sanguínea do CL (VCL), assim como, foi coletada amostra de sangue para averiguar a concentração sérica de P4 pós-ovulatória. Os dados foram avaliados pelo Two-way ANOVA e análise de medidas repetidas considerando os efeitos do eCG, 2PGF e interação eCG*2PGF, P<0,05. Não houve diferença significativa entre os protocolos de sincronização para as variáveis DFOL, AFOL e VFOL ao longo do tempo da dinâmica folicular. Os grupos experimentais apresentaram uma concentração sérica de P4 pré-ovulatória semelhante em cada momento da avaliação. Não foi observada distinção da ACL e VCL entre os tratamentos hormonais, contudo o Grupo eCG demonstrou tendência (P=0,08) a apresentar maior DCL em relação ao Grupo 2PGF e 2PGF+eCG. Adicionalmente a estes achados, também foi constatado tendência (P=0,07) a maiores concentrações de progesterona no dia 24 do protocolo nos animais do Grupo eCG (11,00±3,32ng/mL) em relação ao Grupo 2PGF (6,37±1,31ng/mL), enquanto o Controle e 2PGF+eCG demonstraram resultados intermediários que se assemelham a ambos os grupos, com concentrações de 8,43±3,85 e 9,18±2,82ng/mL, respectivamente. As tentativas de ajustes no proestro foram incapazes de melhorar a qualidade folicular e minimizar a função luteal pré-ovulatória, assim como não incrementaram a morfologia do CL e a função luteal pós-ovulatória, sugerindo que em animais cíclicos mestiços protocolos de IATF com a utilização de uma única dose PGF2α e sem o suporte gonadotrófico da eCG parece promover adequada resposta folicular e luteal.

Glial Cells Missing 1 Regulates Equine Chorionic Gonadotrophin Beta Subunit via Binding to the Proximal Promoter

Equine chorionic gonadotrophin (eCG) is a placental glycoprotein critical for early equine pregnancy and used therapeutically in a number of species to support reproductive activity. The factors in trophoblast that transcriptionally regulate eCGβ-subunit (LHB), the gene which confers the hormones specificity for the receptor, are not known. The aim of this study was to determine if glial cells missing 1 regulates LHB promoter activity. Here, studies of the LHB proximal promoter identified four binding sites for glial cells missing 1 (GCM1) and western blot analysis confirmed GCM1 was expressed in equine chorionic girdle (ChG) and surrounding tissues. Luciferase assays demonstrated endogenous activity of the LHB promoter in BeWo choriocarcinoma cells with greatest activity by a proximal 335 bp promoter fragment. Transactivation studies in COS7 cells using an equine GCM1 expression vector showed GCM1 could transactivate the proximal 335 bp LHB promoter. Chromatin immunoprecipitation using primary ChG trophoblast cells showed GCM1 to preferentially bind to the most proximal GCM1-binding site over site 2. Mutation of site 1 but not site 2 resulted in a loss of endogenous promoter activity in BeWo cells and failure of GCM1 to transactivate the promoter in COS-7 cells. Together, these data show that GCM1 binds to site 1 in the LHB promoter but also requires the upstream segment of the LHB promoter between -119 bp and -335 bp of the translation start codon for activity. GCM1 binding partners, ETV1, ETV7, HOXA13, and PITX1, were found to be differentially expressed in the ChG between days 27 and 34 and are excellent candidates for this role. In conclusion, GCM1 was demonstrated to drive the LHB promoter, through direct binding to a predicted GCM1-binding site, with requirement for another factor(s) to bind the proximal promoter to exert this function. Based on these findings, we hypothesize that ETV7 and HOXA13 act in concert with GCM1 to initiate LHB transcription between days 30 and 31, with ETV1 partnering with GCM1 to maintain transcription.

Internalization of Rat FSH and LH/CG Receptors by rec-eCG in CHO-K1 Cells

Equine chorionic gonadotropin (eCG) is a unique molecule that elicits the response characteristics of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in other species. Previous studies from this laboratory had demonstrated that recombinant eCG (rec-eCG) from Chinese hamster ovary (CHO-K1) cells exhibited both FSH- and LH-like activity in rat granulosa and Leydig cells. In this study, we analyzed receptor internalization through rec-eCGs, wild type eCG (eCGβ/α) and mutant eCG (eCGβ/αΔ56) with an N-linked oligosaccharide at Asn⁵⁶ of the α-subunit. Both the rec-eCGs were obtained from CHO-K1 cells. The agonist activation of receptors was analyzed by measuring stimulation time and concentrations of rec-eCGs. Internalization values in the stably selected rat follicle-stimulating hormone receptor (rFSHR) and rat luteinizing/chorionic gonadotropin receptor (rLH/CGR) were highest at 50 min after stimulation with 10 ng of rec-eCGβ/α. The dose-dependent response was highest when 10 ng of rec-eCGβ/α was used. The deglycosylated eCGβ/αΔ56 mutant did not enhance the agonist-stimulated internalization. We concluded that the state of activation of rFSHR and rLH/CGR could be modulated through agonist-stimulated internalization. Our results suggested that the eLH/CGRs are mostly internalized within 60 min by agonist-stimulation by rec-eCG. We also suggested that the lack of responsiveness of the deglycosylated eCGβ/ αΔ56 was likely because the site of glycosylation played a pivotal role in agonist-stimulated internalization in cells expressing rFSHR and rLH/CGR.

Early postpartum administration of equine chorionic gonadotropin to dairy cows calved during the hot season: Effects on fertility after first artificial insemination

Heat stress reduces fertility of high-producing dairy cows, and early administration of equine chorionic gonadotropin (eCG) may improve it. Here, 401 heat-stressed, high-producing dairy cows on a single commercial farm were given eCG (500 UI, n = 214) or saline (n = 187) on days 11-17 after calving, and the effects on fertility after the first artificial insemination (AI) were assessed. On post-partum day 96.34 ± 9.88, all cows were inseminated after a "double short Cosynch" synchronization protocol. Ovarian activity and uterine status were checked by ultrasound on the day of eCG administration and every 7 days thereafter for a total of 3 weeks; checks were also performed during synchronization, and 7 days after AI. On post-partum day 30, cytobrush uterine cytology was performed to check for subclinical endometritis. Pregnancy status was checked on days 30 and 60 after AI. The eCG and control groups did not differ significantly in terms of average lactations per cow (2.33 ± 1.34), days in milk at first AI (96.33 ± 9.88), average milk yield at AI (41.38 ± 7.74 L), or the particular inseminator or bull used for AI. The eCG and control groups showed increasing ovarian activity with time, with approximately 75% of cows in both groups showing a corpus luteum at the beginning of the synchronization protocol. On post-partum day 30, 17.4% of eCG cows and 22.9% of control cows showed subclinical endometritis. Cows treated with eCG showed a tendency toward lower hyperecogenic intraluminal content (16.8 vs. 21.4%, P = 0.15), but ovarian activity during the synchronization protocol was similar between eCG and control groups, with 91% of animals in both groups showing luteolysis after prostaglandin application and 88% showing ovulation after the last administration of gonadotropin-releasing hormone. Fertility was similar between the two groups at both time points after AI (30 days, 34.9 vs. 31.8%; 60 days, 30.6 vs. 28.5%; P > 0.2). These results suggest that early postpartum eCG administration does not improve fertility of heat-stressed dairy cows as long as 60 days after AI. Other strategies may be more effective at mitigating the ability of post-partum heat stress to reduce fertility of high-producing dairy cows.

Lack of effects of an equine chorionic gonadotropin (eCG) administration between days 9 and 15 postpartum on reproductive performance in a Holstein dairy herd

Recently, it has been demonstrated that administration of equine chorionic gonadotropin (eCG) in the postpartum period in dairy cows can enhance follicle growth, reduce the interval from calving to first ovulation and increase plasma estradiol concentrations, and, thus, could enhance reproductive performance in a dairy herd when administered on day 6 postpartum. The aim of this study was to investigate the effects of a single dose of eCG between days 9 and 15 postpartum on parameters of reproductive performance in dairy cows. German Holstein cows (n = 1937; primiparous cows: n = 748; pluriparous cows: n = 1189) in a commercial dairy farm were randomly assigned to three experimental groups. Animals within the group eCG received a single dose of 600 IU eCG intramuscularly (i.m.) between days 9 and 15 postpartum followed by an i.m. administration of 500 μg cloprostenol after 14 days. Those of treatment group PG received cloprostenol only between days 23 and 29 postpartum. Cows of the control group remained untreated. Starting on day 49 postpartum, cows were subjected to a Presynch-Ovsynch protocol and inseminated artificially. The impact of application time (days postpartum) of eCG on the intervals calving to first service and calving to conception was statistically not significant. Outcomes of reproductive performance (i.e. first service conception rate, proportion of pregnant cows until 100 and 150 days in milk [DIM], number of inseminations until 150 DIM, calving to first service interval and calving to conception interval) did not differ significantly between treatment group eCG and group PG compared to control group. Regarding postpartum eCG administration, significant interactions between treatment and parity, season, milk yield, and early puerperal disorders, respectively, could not be shown. In conclusion, an eCG treatment of dairy cows between days 9 and 15 postpartum to increase reproductive performance cannot be recommended under the given circumstances.

Effects of periovulatory gonadotrophin treatment on luteal function and endometrial expression of selected genes in cyclic pony mares

Progestin concentration in plasma during the early luteal phase is crucial for endometrial function and conceptus development. We hypothesized that periovulatory gonadotrophin treatment via support of luteal function affects endometrial gene expression in horses. Effect of age was analyzed as well. Shetland mares (n = 8, age 4-25 years) were assigned to the following treatments during five consecutive cycles in alternating order following a cross-over design: treatment hCG/-: preovulatory injection of hCG, but no gonadotrophin injection at detection of ovulation, treatment -/hCG: no preovulatory gonadodrophin injection, but injection of hCG at detection of ovulation, treatment eCG/-: preovulatory injection of eCG, but no gonadotrophin injection at detection of ovulation, treatment -/eCG: no preovulatory gonadotrophin injection, but injection of eCG at detection of ovulation, treatment control: no treatment. Concentration of progestin was analyzed by ELISA from the day of ovulation until Day 10. On Day 10, endometrial cells were collected transvaginally by cytobrush technique. Expression of mRNA of cyclooxygenase-2 (COX-2), prostaglandin F2α-synthase, prostaglandin E-synthase, progesterone receptor (PR), estradiol receptor (E2R), acyl-CoA-dehydrogenase (ACAD), uteroglobin (UGB), uteroferrin, and uterocalin was analyzed by RT qPCR. Immunohistological staining of endometrial tissue, obtained via biopsy, was performed for COX-2, PR and UGB. The P4 concentration was influenced by day of cycle (P < 0.01), but not by treatment. No effects of age on gene expression were determined. Neither of the periovulatory gonadotrophin treatments nor age influenced mRNA expression of the genes of interest. Treatment did also not affect immunohistological staining of the endometrium. In contrast, age affected the percentage of PR positive stromal cells (e.g. mare 1 (4 years): 65.5 ± 2.6, mare 2 (24 years): 82.7 ± 2.2%, P < 0.05) and COX-2 positive stained ciliated cells (e.g. mare 1: 15.8 ± 2.9, mare 2: 33.4 ± 6.0%, P < 0.05). In conclusion, no effects of periovulatory gonadotrophin treatment and age on endometrial gene expression in luteal phase pony mares were reported. A lack of treatment effects on luteal function and expression of PRs in the endometrium can at least in part be explained by differences in the reproductive physiology between horses and ponies.

The efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes

The aim of this study was to evaluate the efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes. A total of 158 crossbred buffaloes divided into four groups and were intramuscularly injected with 1×10(10) (T1, n=41), 1×10(9) (T2, n=37), 1×10(8) (T3, n=37) or 0 (C, n=43) CFU/ml bacteria delivered inhibin vaccine in 10ml PBS on day 0 and 14, respectively. All animals were administered with 1000 IU PMSG on day 28, 0.5mg PGF2α on day 30 and 200μg GnRH on day 32. The results showed buffaloes immunized with the bacteria delivered inhibin vaccine had significantly higher titers of anti-inhibin IgG antibody than control group (P<0.01). The number and diameter of large follicles (≥10mm) as well as ovulatory follicles in group T1 was significantly greater than group C (P<0.05). The growth speed of dominant follicles in group T1 was significantly faster than groups T3 and C (P<0.05), resulting in a greater conception rate in buffaloes with positive antibodies. These results demonstrate that immunization with the bacterial delivered inhibin vaccine, coupled with the estrus synchronization protocol, could be used as an alternative approach to improve fertility in crossbred buffaloes.

Equine Chorionic Gonadotropin and Human Chorionic Gonadotropin Stimulation Increase the Number of Luteinized Follicles and the Progesterone Level Compared with Cabergoline Stimulation in Anoestrus Bitches

In this study, ovarian morphologies and blood progesterone concentrations following oestrous induction in bitches were examined. Fifty-three clinically healthy anoestrus bitches received cabergoline at a daily dose of 5 μg/kg of body weight per os for 21 days (group I) or subcutaneous equine chorionic gonadotropin at a dose of 20 IU/kg of body weight for five consecutive days with an additional 500 IU s.c. per bitch of human chorionic gonadotropin on the last day of treatment (group II). Twenty bitches that spontaneously displayed oestrous signs were left untreated and served as controls (group III). The induced oestrous rates and ovulation rates in groups I and II were 60.0% vs 64.3% and 86.7% vs 83.3%, respectively. Morphological assessments of the ovarian structures after ovariohysterectomy revealed an increase in the number of luteinized follicles and cysts in group II compared with the two other groups (p < 0.001). In contrast, the numbers of corpora lutea and follicles were similar in all groups. In accordance with the above-mentioned alteration, the progesterone concentration in the gonadotropin group (II) was increased (p < 0.001) in the periovulatory period compared with the other two groups. During the entire sampling period, the progesterone profiles in the cabergoline (I) and control (III) groups were similar and typical of normally cycling bitches. In conclusion, gonadotropin treatment is associated with an increased progesterone level during the periovulatory period that probably originates from luteinized follicles, whereas cabergoline treatment induces cycles with both physiological progesterone concentrations and ovarian morphologies.

Reproductive performance of seasonally anovular mixed-bred dairy goats induced to ovulate with a combination of progesterone and eCG or estradiol

Adult goats (n = 32) were randomly assigned to one of four treatments (n = 8, each): (i) progesterone (P4 ) + equine chorionic gonadotropin (eCG), treated with 25 mg progesterone intramuscularly (i.m.) + 250 IU eCG 24 h later; (ii) cronolone + eCG, treated with vaginal sponges - 20 mg cronolone × 7 days + 250 IU eCG at pessary removal; (ii) P4 + estradiol (E2 ), treated with 25 mg progesterone i.m. + 1 mg estradiol 24 h later; (iv) cronolone + E2 , treated with vaginal sponges - 20 mg cronolone × 7 days + 1 mg of estradiol i.m. at pessary removal. Goats were tested for estrus throughout the presence of a buck. Seven days prior and after treatment, an ovarian ultrasonographic scanning was performed to determine ovarian function and structures. An ultrasonographic pregnancy diagnosis was performed on day 30 post-service. In all groups, 100% estrus response was observed within 96 h post-treatment. While ovulation occurred in 100% of P4 + eCG and cronolone + eCG treated goats, the other groups only depicted 50% ovulatory activity (P < 0.05). Pregnancy rate was higher (P <0.05) in the P4 + eCG and cronolone + eCG groups (88 and 100%, respectively), compared with 38% in P4 + E2 and cronolone + E2 groups. The best treatments were those in which eCG was applied. The P4 + eCG treatment was a pessary-free, cheaper and effective protocol to induce ovulation in goats during the seasonal anovulatory period.