Superovulation in beef cattle with PMSG and prostaglandins or progestins

The ovarian response to 2000 I.U. PMSG of 76 suckler cows and 153 heifers synchronized by either progesterone (Abbovestrol-PRID/ CEVA), a synthetic gestagen (Norgestomet/ Intervet), prostaglandin F₂ (Dinolytic/ Upjohn) or a prostaglandin analog (Estrumate/ ICI) was recorded after slaughter. The proportion of animals responding with at least one ovulation was between 82 and 92% except for heifers treated with estrumate (56%). Heifers had nearly twice as many ovulations as cows (11.9 ± 0.9 vs 6.8 ± 0.8 (SEM)). The response was slightly more consistent in gestagen-synchronized animals: nevertheless, individual variation was considerable.     

Superovulation in the cow using estradiol 17beta or GnRH in conjunction with FSH-P

A study was designed to evaluate the superovulatory response in the cow when either estradiol 17beta or gonadotrophin releasing hormone (GnRH) was used in a superovulatory regimen with follicle stimulating hormone (FSH-P). Fifty-four cyclic crossbred females were superovulated in replicates between Days 8 and 12 of their cycle. All animals were treated with 28 mg of FSH-P in twice-daily decreasing doses, each receiving 500 mug cloprostenol (PGF) 48 h after initiation of treatment. Group 1 served as FSH-P controls, Group 2 received FSH-P and 400 mug of estradiol 17beta 36 h after PGF, and Group 3 received FSH-P and 250 mug GnRH 48 h after PGF. Inseminations with one vial of frozen semen were done at 12, 24 and 36 h after the onset of estrus. Ova/embryos were collected nonsurgically at Day 7 postestrus. Numbers of corpora lutea (CL) were recorded after palpation per rectum and the recovered ova and embryos were evaluated. All females were bled for endocrine examination. There were no differences in ovarian response among these treatments. Mean total ova/embryos collected in Group 3 was significantly higher than in Groups 1 or 2 (P < 0.05); however, no significant difference existed between groups in the mean numbers of fertilized or transferable embryos. Similarly, no significant differences existed between groups for recovery rate, fertilization rate, or percentage of transferable embryos. Serum estradiol levels were significantly higher at the expected end of ovulation in Group 2, and this tended to be associated with higher fertilization and transferable embryo rates. Furthermore, a significant positive correlation was found to exist between CL numbers and each of the ova/embryo parameters and the estradiol levels at estrus.     

Superovulation and embryo quality in beef cows using PMSG and a monoclonal anti-PMSG

The long half-life of pregnant mare serum gonadotrophin (PMSG) reduces its application in the superovulation of cattle; thus, a monoclonal antibody to PMSG (anti-PMSG) was administered at the onset of estrus to increase the number of transferable embryos. Angus, Hereford and Angus x Hereford cows (n = 149) 3 to 9 yr old were assigned randomly to one of three dosages of PMSG (1500, 3000 or 6000 IU) with or without an equivalent dosage of anti-PMSG. Embryos were collected nonsurgically on Day 8 (estrus = Day 0), and all cows were ovariectomized on Day 9. The percentage of cows exhibiting estrus and ovulating decreased (P<0.05) with an increasing dosage of PMSG (82, 76 and 44% for 1500, 3000 and 6000 IU, respectively). Ovarian and total corpora lutea (CL) weight increased (P<0.001) linearly as PMSG dosage increased, but were reduced (P<0.001) curvilinearly by anti-PMSG, resulting in a PMSG by anti-PMSG interaction (P<0.001); the interaction was also significant (P<0.05) for ovulation rate (14.0 vs 14.3, 21.5 vs 24.4 and 29.2 vs 6.6 CL for 1500, 3000 and 6000 IU PMSG, without vs with anti-PMSG, respectively). Anti-PMSG increased (P<0.001) the number of small ovarian follicles (1 to 3 mm diameter) and decreased (P<0.001) the number of large follicles (>10 mm) at ovariectomy; the number of large follicles increased (P<0.001) with PMSG dosage. The number of total and transferable embryos recovered did not differ among PMSG and anti-PMSG dosages; however, the percentage of transferable embryos decreased (P<0.01) with increasing PMSG dosage. In general, neither PMSG dosage nor anti-PMSG influenced embryo quality.     

Superovulation in the cow with a single intramuscular injection of FSH dissolved in polyvinylpyrrolidone

It is desirable to reduce the number of treatments required to induce superovulation in cows. In this study we examined whether dissolving FSH in polyvinylpyrrolidone(PVP) would reduce the rate of absorption of FSH and allow it to be administered in a single dose for superovulation. In Experiment 1, 10 cows each received a single dose of FSH which contains 0.6% luteinizing hormone (FSH-R; 30mg i.m.) dissolved in 30% PVP (10ml) or in saline. In Experiment 2, a single injection of 30mg FSH-R dissolved in 30% PVP was given to 25 cows, and 32 cows were injected twice daily in declining doses to receive a total of 28mg FSH-R dissolved in saline. Prostaglandin F(2alpha) was given to all the cows 48h after the first FSH treatment. Embryos were collected on Day 7 or 8 post insemination. In Experiment 1, the effect of FSH dissolved in PVP was compared with that dissolved in saline (number of recovered ova and embryos; 9.4+/-4.1 vs. 0). In Experiment 2, the rate of transferable embryos by single injection of FSH-R in PVP were significantly higher (P<0.05) than that of treatment of multiple injection groups. Progesterone concentration measured in serum collected 4 times from estrus (Day-0) to the day of embryo collection, indicated similar patterns in the 2 treatment groups. These findings suggest that PVP is a suitable solvent for prolonging the absorption of FSH given in a single injection thus providing a more practical approach of FSH administration.     

Superovulation and embryo recovery in rabbits (Oryctolagus cuniculus) using different doses of pregnant mare serum gonadotrophin (PMSG)

Present investigation was conducted to study the ovarian response and embryo recovery using different PMSG dose levels. Six rabbits each were assigned randomly to treatment 1 (PMSG 50 IU + hCG 100 IU), treatment 2 (PMSG 75 IU + hCG 100 IU) and the control group (no hormone administered). PMSG injection (im) was followed 68 hr later by natural mating to a fertile rabbit buck and human chorionic gonadotrophin (hCG) injection iv post coitum. Embryos were recovered 96 hr post coitum by a modified surgical method. Mean number of ovulations in the control group differed significantly from treatment 1 and 2, but no significant difference was observed between treatments 1 and 2. Mean embryo recovery percentage was lowest in treatment 2 and highest in the control group. The higher dose PMSG (treatment 2) was observed to be more disturbing in terms of recovery of embryos as well as their morphology.     

Repeated Superovulation via PMSG/hCG Administration Induces 2-Cys Peroxiredoxins Expression and Overoxidation in the Reproductive Tracts of Female Mice

Superovulation induced by exogenous gonadotropin treatment (PMSG/hCG) increases the number of available oocytes in humans and animals. However, Superovulatory PMSG/hCG treatment is known to affect maternal environment, and these effects may result from PMSG/hCG treatment-induced oxidative stress. 2-Cys peroxiredoxins (2-Cys Prxs) act as antioxidant enzymes that protect cells from oxidative stress induced by various exogenous stimuli. Therefore, the objective of this study was to test the hypothesis that repeated PMSG/hCG treatment induces 2-Cys Prx expression and overoxidation in the reproductive tracts of female mice. Immunohistochemistry and western blotting analyses further demonstrated that, after PMSG/hCG treatment, the protein expression levels of 2-Cys Prxs increased most significantly in the ovaries, while that of Prx1 was most affected by PMSG/hCG stimulation in all tissues of the female reproductive tract. Repeated PMSG/hCG treatment eventually leads to 2-Cys Prxs overoxidation in all reproductive organs of female mice, and the abundance of the 2-Cys Prxs-SO_2/3 proteins reported here supports the hypothesis that repeated superovulation induces strong oxidative stress and damage to the female reproductive tract. Our data suggest that excessive oxidative stress caused by repeated PMSG/hCG stimulation increases 2-Cys Prxs expression and overoxidation in the female reproductive organs. Intracellular 2-Cys Prx therefore plays an important role in maintaining the reproductive organ environment of female mice upon exogenous gonadotropin treatment.     

Influence of undernutrition in the lactating cow on ovulation induction by serum gonadotropins (PMSG) during the post-partum period

Two experiments were carried out to assess the influence of undernutrition on postpartum ovulation in nursing Charolais cows after PMSG injection. In each experiment, the nursing cows were divided into 2 groups: one fed at a low nutritional level and the other at a normal nutritional level. In the first experiment, 19 animals were injected on post-partum days 15 and 30 with 600 IU of PMSG; in the second experiment, 34 received the same injection on post-partum day 54 after 9 days of priming with a Norgestomet implant. On post-partum day 15, only one cow in each group ovulated. At post-partum day 30, 1 out of 8 cows at the low nutritional plane ovulated vs 5 out of 9 at the normal nutritional plane (P less than 0.05). Likewise, on post-partum day 54, 5 out of 14 cows at the low nutritional plane ovulated vs 17 out of 17 at the normal nutritional level (P less than 0.05). Therefore, there is a time during the post-partum period when the nursing cow ovary does not respond to PMSG by ovulation. The length of this time is increased by undernutrition.     

Superovulatory response of Murciana goats to treatments based on PMSG/Anti-PMSG or combined FSH/PMSG administration

Superovulation in goats is frequently restricted by the cost of gonadotropin or the handling requirements. In this situation PMSG has the advantage of a lower cost and single dose protocol, but the variability of response obtained restricts its use. Thus, 2 alternative treatments with the advantages of PMSG were tested. In Experiment 1, we compared the ovulatory response of does treated with PMSG in combination or not with anti-PMSG antibodies at the onset of estrus, during season and out of season. In Experiment 2, we explored the effect of a partial substitution of FSH by PMSG at the end of treatment, comparing this treatment with a standard FSH protocol. Our results showed a significant (P < 0.01) seasonal effect on the incidence of corpora lutea (CL) regression in both experiments. The mean of viable embryos collected from does treated with anti-PMSG antibodies (mean = 5.75) was significantly higher than in the control PMSG-treated group (mean = 2.74) during spring (P < 0.05). Response during the fall was significantly lower regardless of treatment, and administration of antibody did not provide any significant improvement in superovulatory response (2.14 vs 1.77). In Experiment 2, the partial substitution of 3 doses of FSH by a single administration of PMSG did not reduce the number of CL or viable embryos, and no seasonal differences were observed, confirming that FSH provides a less variable response. From our results, it can be concluded that the use of PMSG antibodies for super-ovulating goats is an efficacious treatment which increases the number of viable embryos collected. However, partial replacement of FSH with PMSG at the end of treatment also did not compromise the number of embryos collected. Both approaches can be considered a valid alternative to treatments based on FSH.     

Superovulation and embryo transfer in Holstein cattle using sexed sperm

The use of sexed bull sperm in multiple ovulation and embryo transfer (MOET) programs for Holsteins was evaluated for (1) heifers housed at a commercial embryo transfer (ET) facility (Experiments 1 and 2), and (2) heifers and cows on dairy farms (Experiment 3). In Experiment 1, superstimulated heifers were inseminated with 5 × 10⁶ sexed (X-sorted; n = 5) or unsexed (n = 5) frozen-thawed sperm from one bull at 12 and 24 h after estrus detection. No difference was observed in the rates of transferable embryos (53.4% vs 68.1%), degenerate embryos (24.8% vs 26.6%) and unfertilized ova (21.8% vs 5.3%) between sexed and unsexed sperm, respectively, except for the percent of female transferable embryos diagnosed by embryo sexing (100% vs 49.3%, P < 0.0001). In Experiment 2, donors were inseminated twice with 5 × 10⁶ sexed unfrozen sperm (n = 10) or sexed frozen-thawed sperm (n = 9). Embryo production rates for both treatments were similar to that observed on a commercial ET facility using unsexed sperm. Pregnancy rates for frozen-thawed embryos were similar for sexed and unsexed sperm (70.4% vs 72.4%, respectively). In Experiment 3, 99 flushes were conducted using sexed frozen-thawed sperm from nine bulls but an overall statistical analysis was not completed because the use of bulls was not balanced. However, for one bull with balanced usage, the rate of transferable embryos was higher in heifers than in cows (P < 0.05) inseminated twice with 5 × 10⁶ sperm/dose (10 × 10⁶ total). We concluded that the use of sexed frozen-thawed sperm (≥90% X-sperm biased and 10 × 10⁶ total sperm) may be economically viable for commercial MOET programs in Holstein heifers.     

Superovulation in mares

Embryo recovery from single ovulating mares is approximately 50 per cent per estrous cycle. Superovulation could be used to increase embryo recovery and provide extra embryos for embryo freezing. This review addresses some historical approaches to superovulation, as well as examines factors that affect the response of mares to equine FSH. eCG, GnRH and inhibin vaccines have been of limited success in stimulating multiple ovulation. Numerous studies have shown that injection of equine pituitary extract (EPE) will result in three to four ovulations per estrous cycle and two embryos. A purified, standardized EPE preparation (eFSH) also results in a similar response to EPE. Factors affecting the response to EPE and eFSH include day of initial treatment, size of largest follicle at initial treatment and frequency of injection. Embryos from single ovulating, untreated mares and eFSH-treated mares provide similar pregnancy rates upon nonsurgical transfer. Five to 7 days of eFSH treatment also has been shown to hasten the first ovulation of the breeding season. Potential problems after eFSH injections include anovulatory or luteinized follicles and overstimulation. Studies are needed to further evaluate the criteria for initiation of treatment and to determine how to increase ovulation rate without decreasing embryo recovery per ovulation.     

Superovulation in cattle: A combined treatment using syncromate B with either pregnant mare serum gonadotrophin or follicle stimulating hormone

A comparison between different superovulatory treatments in dairy cattle was carried out at a commercial embryo transfer unit in Israel. Both pregnant mare serum gonadotrophin (PMSG) and follicle stimulating hormone (FSH) were used, either alone or combined with Syncromate B (SMB). The use of PMSG + SMB significantly decreased the number of corpora lutea present at the time of embryo collection 7 d after insemination, as compared with other treatment regimens. Consequently, a significantly lower number of ova was found in those animals treated with PMSG + SMB. Better superovulatory responses were obtained when FSH, rather than PMSG, was used, regardless of whether they were administered alone or combined with SMB. It was clear that the use of SMB combined either with PMSG or FSH resulted in poorer responses than when either gonadotrophin was used alone.     

Endocrine response of postpartum anestrous beef cows to GnRH or PMSG

Forty-one postpartum anestrous Hereford cows, maintained under range conditions, were used to determine the influence of gonadotropin releasing hormone (GnRH) or pregnant mare serum gonadotropin (PMSG) on ovarian function. Anestrous cows were identified by estrous detection with sterile bulls and concentrations of progesterone in plasma obtained weekly. At 45 +/- 2 days postpartum, cows were allotted to the following treatments: (1) control (saline), (2) 100 mug GnRH, (3) 200 mug GnRH, (4) 200 mug GnRH in carboxymethyl cellulose (CMC), (5) 500 IU PMSG, (6) 1,000 IU PMSG or (7) 2,000 IU PMSG. Cows were bled frequently the first day after treatment and then every other day until 85 days postpartum. The LH responses after 100 and 200 mug of GnRH were not significantly different and mixing 200 mug GnRH with CMC before injection did not significantly alter the LH response. During the first 20 days after treatment, neither GnRH nor 500 IU PMSG altered estradiol concentrations in plasma, but treatment of cows with 1,000 or 2,000 IU PMSG resulted in increased (P<0.01) concentrations of estradiol. The time postpartum required for concentrations of progesterone in plasma to exceed 1 ng/ml was reduced (P<0.05) by all treatments except 100 mug GnRH. These data indicate that GnRH causes LH release in anestrous range cows and that treatment with 1,000 or 2,000 IU PMSG initiates ovarian activity as evidenced by increased concentrations of estradiol in plasma.