Exogenous eFSH, follicle coasting, and hCG as a novel superovulation regimen in mares (original) (raw)
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Effect of eFSH on Ovarian Cyclicity and Embryo Production of Mares in Spring Transitional Phase
Journal of Equine Veterinary Science, 2007
The use of equine FSH (eFSH) for inducing follicular development and ovulation in transitional mares was evaluated. Twenty-seven mares, from 3 to 15 years of age, were examined during the months of August and September 2004, in Brazil. Ultrasound evaluations were performed during 2 weeks before the start of the experiment to confirm transitional characteristics (no follicles larger than 25 mm and no corpus luteum [CL] present). After this period, as the mares obtained a follicle of at least 25 mm, they were assigned to one of two groups: (1) control group, untreated; (2) treated with 12.5 mg eFSH, 2 times per day, until at least half of all follicles larger than 30 mm had reached 35 mm. Follicular activity of all mares was monitored. When most of the follicles from treated mares and a single follicle from control mares acquired a preovulatory size (R35 mm), 2,500 IU human chorionic gonadotropin (hCG) was administered IV to induce ovulation. After hCG administration, the mares were inseminated with fresh semen every other day until ovulation. Ultrasound examinations continued until detection of the last ovulation, and embryo recovery was performed 7 to 8 days after ovulation. The mares of the treated group reached the first preovulatory follicle (4.1 AE 1.0 vs 14.9 AE 10.8 days) and ovulated before untreated mares (6.6 AE 1.2 vs 18.0 AE 11.1 days; P < .05). All mares were treated with prostaglandin F 2a (PGF 2a ), on the day of embryo flushing. Three superovulated mares did not cycle immediately after PGF 2a treatment, and consequently had a longer interovulatory interval (22.4 vs 10.9 days, P < 0.05). The mean period of treatment was 4.79 AE 1.07 days and 85.71% of mares had multiple ovulations. The number of ovulations (5.6 vs 1.0) and embryos (2.0 vs 0.7) per mare were higher (P < 0.05) for treated mares than control mares. In conclusion, treatment with eFSH was effective in hastening the onset of the breeding season, inducing multiple ovulations, and increasing embryo production in transitional mares. This is the first report showing the use of FSH treatment to recover embryos from the first cycle of the year.
Strategies for Using eFSH for Superovulating Mares
Journal of Equine Veterinary Science, 2008
The standard treatment for superovulation of mares is to administer equine follicle-stimulating hormone (eFSH) for 4 to 5 days to stimulate multiple follicles and human chorionic gonadotropin (hCG) to induce synchronous ovulations. Objectives of this study were: (1) to determine whether a short-term (3-day) eFSH treatment protocol would result in similar ovulation and embryo recovery rates compared with the standard
Reproduction, 1993
Pharmacological control of reproduction in mares requires the use of equine gonadotrophins to avoid induced immunological resistance. Crude equine gonadotrophins (CEG) have been used but the presence of equine luteinizing hormone (eLH) and follicle-stimulating hormone (eFSH) in CEG has led to disappointing results in superovulation studies. Separation of eLH and eFSH activities from CEG is necessary to overcome this problem. The hydrophobic properties of the two hormones were sufficiently different to permit their separation by hydrophobic interaction chromatography (HIC) on a phenyl Sepharose matrix. Good yields of separate FSH and LH fractions were readily obtained by stepwise elution and the method was adapted for large scale preparations of enriched fractions of eLH and eFSH. Two experiments were performed in vivo to evaluate the biological activity of the HIC fractions. Experiment 1 showed that biological activity of the LH fraction in inducing ovulation of preovulatory follicles was similar to that obtained with CEG, indicating that LH bioactivity was not altered by HIC. Experiment 2 demonstrated that biological activity of the FSH fraction was identical (as far as rate of ovulation was concerned) to that of CEG in superovulating mares, indicating that FSH activity was also not altered by HIC. Although we have not obtained better results with the separate equine gonadotrophins than with CEG, it is potentially advantageous to use preparations with single activity to obtain a controlled balance of FSH and LH activity. The HIC technique was chosen because it could easily be scaled up to provide the large amounts of the separate hormones needed for the treatment of a large number of mares.
Theriogenology, 2009
The objective was to compare the effects of eFSH and deslorelin treatment regimes on ovarian stimulation and embryo production of donor mares in early spring transition. Starting January 30th, mares kept under ambient light were examined by transrectal ultrasonography. When a follicle !25 mm was detected, mares were assigned to one of two treatment groups, using a sequential alternating treatment design. In the eFSH group, mares (n = 18) were treated twice daily with eFSH (12.5 mg im) until they achieved a follicle !35 mm; hCG was given 36 h later. In the deslorelin group, mares (n = 18) were treated twice daily with deslorelin (63 mg im) until a follicle !35 mm was detected, and then they were given hCG. Estrous mares were inseminated with fresh semen. Eight days after ovulation, embryo recovery attempts were performed. In each group, 14/18 (78%) mares ovulated following the eFSH or deslorelin treatment regimes. The mean (95% CI) interval from treatment initiation to ovulation was 8.2 d (7.3, 8.9) and 7.2 d (6.2, 8.1) in the eFSH and deslorelin groups, respectively. In the eFSH group, the number of ovulations was significantly higher (mean AE S.E.M.; 3.4 AE 0.4 vs. 1.1 AE 0.1 ovulations), and more embryos were recovered (2.6 AE 0.5 vs. 0.4 AE 0.2 embryos/recovery attempt). We concluded that eFSH and deslorelin treatment regimes were equally effective in inducing ovulation in early transitional mares, within a predictable time of treatment; however, the eFSH regime increased the number of ovulations and embryos recovered per mare.
Enhancing Fertility in Mares: Recombinant Equine Gonadotropins
Journal of Equine Veterinary Science, 2019
Advanced reproductive technologies have been developed to enhance fertility in mares and stallions. Some of these technologies in mares include superovulation, embryo transfer (ET), intracytoplasmic sperm injection (ICSI) oocyte transfer (OT), gamete intrafallopian transfer (GIFT) and cloning. Superovulation can provide multiple oocytes for these techniques. This review will focus in on how recombinant equine follicle stimulating hormone (reFSH) and recombinant equine luteinizing hormone (reLH) are important for superovulation and ET and may be useful for ICSI, OT, GIFT and cloning. Superovulation would increase pregnancy rates in normal and subfertile mares, and enhance reproductive efficiency when using semen from subfertile stallions. Superovulation depends on a timely interaction of gonadotropins and gonadal feedback in the mare. Historically several hormone protocols have been used to manipulate follicular waves in order to increase development and ovulations in cycling, anestrous and transitional mares. Attempts to superovulate cyclic mares or induce the first ovulation of the year in anestrous or transitional mares using preparations of equine chorionic gonadotropin (eCG), gonadotropin releasing hormone (GnRH), GnRH agonists, porcine FSH, domperidone, sulpiride, equine pituitary extracts (EPE), native equine FSH, human chorionic gonadotropin (hCG), progesterone and immunization against inhibin have produced variable results. The use of recombinant technology has improved the ability to produce a reliable product in substantial quantities that is free of other hormones and possible contaminates. Several studies using recombinant equine follicle stimulating hormone (reFSH) and recombinant equine luteinizing hormone (reLH)
Pulsatile administration of gonadotropin-releasing hormone advances ovulation in cycling mares
Biology of Reproduction, 1986
Cycling standardbred mares were infused with saline or 20 pg gonadotropin-rel easing hormone (GnRH) in a pulsatile pattern (one 5-sec pulse/h, 2 h or 4 h) beginning on Day 16 of the estrous cycle. Although serum concentrations of luteinizing hormone (LH) increased significantly earlier in all three GnRH-treated groups (within one day of the initiation of infusion) compared to saline-infused controls, there were no differences in peak periovulatory LH concentrations among treatments (overall mean ± SEM, 8.98 ± 0.55 ng/ml). The number of days from the start of treatment to ovulation was significantly less in mares infused with 20 pg GnRH/h (mean ± SEM, 2.9 ± 0.6 days after the initiation of treatment, or 18.9 days from the previous ovulation; N=7) compared to mares treated with saline (5.9 ± 0.3 days, or 21.9 days from previous ovulation; N= 7) or 20 pg GnRH per 4 h (5.4 ± 0.9 days or 21.4 days from previous ovulation; N=5). Although mares infused with 20 pg GnRH/2 h ovulated after 4.3 ± 0.7 days of treatment (Day 20.3; N=7), this was not significantly different from either the control or 20 pg GnRH/h treatment groups. Neither the duration of the resulting luteal phase nor the length of the estrous cycle was different between any of the treatment groups (combined means, 14.7 ± 0.2 days and 21.3 ± 0.4 days, respectively). We conclude that pulsatile infusion of GnRH is effective in advancing the time of ovulation in cycling mares, but that the frequency of pulse infusion is a critical variable.
Anim. Reprod, 2009
During the recent years, mares have been shown as relevant follicle-related research comparative model for women because of similarities in the number and nature of ovarian follicular waves, a constant relative diameter of the largest follicle between the two species at definable events throughout the ovulatory wave, and similar ultrasonographic characteristics and changes of the preovulatory follicle. In the mare, as in other monovular species (cattle, women), usually only one dominant follicle develops as a result of the deviation mechanism. However, occasionally two or more dominant follicles may also occur. Few studies in mares have addressed the relationships between periovulatory circulating hormone concentrations and single versus multiple dominant/preovulatory follicles. Temporal and mechanistic studies performed recently (years 2005 to 2008) have contributed to elucidation of intriguing relationships among the dominant follicle and circulating hormones and will be the focus of this review. The main topics discussed herein are: (i) development of one versus two dominant follicles with a single ovulation; (ii) development of one versus multiple ovulatory follicles; (iii) conversion of two dominant follicles to double ovulations; (iv) role of hormones in development of double ovulations; (v) interrelationships of periovulatory reproductive hormones; (vi) repeatability of preovulatory follicle diameter and hormones; and (vii) factors that affect preovulatory follicle diameter and hormones, such as breeds and types of mares, season, body condition, and aging.
Control of transitional anestrus in mares by infusion of gonadotropin releasing hormone
Theriogenology, 1988
Ten Standardbred mares were divided into two equal groups during transitional anestrus. One group was left untreated, while the other group received a subcutaneous infusion of gonadotrophin releasing hormone (GnRH) at a rate of 100 ng/kg/h for 28 d, delivered via osmotic minipumps (OMP). Ovarian palpations were carried out, and blood samples were collected every 2 to 5 d and assayed for luteinizing hormone (LH) and progesterone concentrations. Volume of the ovary destined to ovulate almost doubled within 7 d of OMP insertion in treated mares, while volume of the contralateral ovary declined by 50% in the same period. Day (K f SEM) of ovulation was approximately 5 wk earlier (P<O.Ol) in the treated (18.6 t 4.1 d) mares compared to controls (54.8-I 10.8 d). Ovulation was generally associated with an obvious endogenous surge of LH which was followed by a rise in plasma progesterone concentrations. The day of conception in the treated mares (26.6 f 9.7 d) was significantly (P<D.Ol) earlier than the controls (67.8 f 16.0 d). The results indicate that fertile estrus can be induced in Standardbred mares during seasonal anestrus using GnRH infusions. This has important implications for improving reproductive efficiency in the horse breeding industry.