Superovulation of Holstein heifers by a single subcutaneous injection of FSH dissolved in polyvinylpyrrolidone

This study was undertaken to determine whether a single injection of porcine FSH (pFSH) would induce a superovulatory response in cattle. Holstein heifers were given a single injection of pFSH (30 mg, s.c.) dissolved in saline (Group 1, n = 5); 50% polyvinylpyrrolidone (PVP; Group 2, n = 5); or 25% PVP (Group 3, n = 4). Group-4 heifers (n = 5) were given multiple intramuscular injections of pFSH every 12 h for 3 d at decreasing doses, for a total of 30 mg. All animals received a single injection of 750 microg PGF2 alpha 48 h after the initiation of pFSH treatment. Animals exhibiting estrus were artificially inseminated twice throughout estrus. Ova and embryos were recovered nonsurgically. Ovaries were examined by transrectal ultrasonography or by palpation per rectum on Day 7 or 8 of estrus. Plasma concentrations of pFSH, bovine FSH progesterone, estradiol-17 beta and inhibin were determined by specific radioimmunoassays. The number of corpora lutea (CL) and the numbers of total and transferable embryos which were detected and recovered in Groups 2 and 3 were equivalent to the numbers detected and recovered in Group 4. In Group 1, however, only 1 of 5 animals ovulated even a single oocyte. The present study demonstrated that only a single injection of pFSH dissolved in PVP was capable of inducing a superovulatory response by maintaining a high plasma FSH concentration to allow for the recovery of a sufficient number of embryos for transplantation.     

Superovulatory response and quality of embryos recovered from anestrus ewes after a single injection of porcine FSH dissolved in polyvinylpyrrolidone

The effects of a single injection of porcine FSH (pFSH) administered in long acting vehicle on the superovulatory response of milk (Sarda breed) sheep were determined during the anestrous season. The sheep (n=42), synchronized with intravaginal sponges (40 mg fluorogestone acetate -FGA- for 14 d) were submitted 24 h before sponge removal to three different superovulatory treatments. Group 1 (n=16) was treated with a single intramuscular (im) injection of 16 mg of pFHS dissolved in 30 % polyvinylpyrrolidone (PVP); Group 2 (n=12) was injected im with 6, 5, 3 and 2 mg of pFSH every 12 h over 2 d; Group 3 (n=14) was given 800 IU of PMSG and 12 mg of pFSH. All sheep were mated with a fertile ram. Embryos were recovered surgically at Day 7 of sponge removal and graded for the quality according to their morphology. The percentage of good quality embryos recovered was 84% in Group 1, 68% in Group 2 and 77% in Group 3. Data for the onset of estrus, number of corpora lutea (CL), number of unovulated follicles, embryo recovery rate, embryo quality and fertilization rate were recorded for the 3 groups. The onset of estrus, number of CL, number of unovulated follicles, fertilization rate and number of good quality embryos did not differ significantly among the 3 groups. The embryo recovery rate was significantly lower in the group treated with PMSG-FSH (Group 3) than in the 2 other groups. It is concluded that during the anestrous season a single injection im of pFSH results on average in a superovulatory response as good as the more traditional treatments like multiple injections of pFSH and PMSG-pFSH combined.     

Superovulation of goats with purified pFSH supplemented with defined amounts of pLH

The superovulatory response of goats treated with purified pFSH supplemented with 30, 40 or 50% pLH was compared. Sixty-four Boer goat does were synchronized by progestagen-containing ear implant, randomly allotted to 3 groups and, beginning 2 d before implant removal, treated with purified pFSH supplemented with 30, 40 or 50% pLH. Each animal received 16 Armour Units of pFSH administered in 6 descending doses at 12-h intervals. Along with the last 2 injections, the does received 5 mg PGF(2alpha). Embryos were flushed either surgically or after slaughter on Day 5 or 6 after the last day of standing estrus. The percentage of animals responding to treatment was not different among groups treated with pFSH supplemented with 30, 40 or 50% pLH (76, 71 and 63%, respectively). The corresponding data for number of ovulations was 11.3 +/- 1.6, 16.3 +/- 1.8 and 16.4 +/- 2.6, for number of ova and embryos recovered 8.1 +/- 1.9, 12.0 +/- 1.5 and 13.5 +/- 2.9 and for number of transferable embryos 6.6 +/- 1.9, 9.1 +/- 1.5 and 7.1 +/- 2.1 (x +/- SEM). Results confirm the earlier finding of a good response of goats to pFSH preparations with a high FSH:LH ratio, and, although group differences were statistically nonsignificant (P > 0.05), they suggest that supplementation with approximately 40% pLH may be close to the optimum.     

Improvement of embryo production by the replacement of the last two doses of porcine follicle-stimulating hormone with equine chorionic gonadotropin in Sindhi donors

The aim of this study was to evaluate the superovulatory (SOV) response of Sindhi (Bos indicus) donors submitted to an ovarian follicular superstimulatory protocol replacing the last two doses of pFSH by eCG. Forty-eight SOV treatments were performed in a crossover design in 19 nulliparous and primiparous females that were randomly divided into two groups: FSH (n=24), which consisted of eight pFSH injections, or FSH/eCG (n=24), which consisted of six pFSH injections followed by two eCG injections. Each female underwent two or three SOV treatments that consisted of an i.m. injection of 2mg estradiol benzoate and the insertion of an intravaginal progesterone-releasing device on Day 0. On Day 4, superstimulatory treatments were initiated and 100mg pFSH was divided into twice daily decreasing doses over a 4-day period. In the FSH/eCG group, the last two doses of pFSH were replaced by two doses of eCG (150 IU eCG each). At the time of the fifth and sixth injections of FSH, 0.150 mg PGF(2α) was injected i.m. The intravaginal progesterone-releasing device was removed at the time of the last FSH or eCG injection and ovulation was induced with 0.2 mg GnRH 18 h later. All females were artificially inseminated with frozen-thawed semen from the same bull 6 and 18 h after GnRH treatment. Seven days after GnRH treatment, embryos/ova were recovered and classified. Follicular superstimulatory (number of follicles ≥6mm at the time of the last FSH or eCG injection) and SOV (CL number) responses were determined by transrectal ultrasonography. Data were analyzed using generalized linear models and results were presented as least squares means±standard error. The FSH/eCG group had higher superstimulatory (33.8±3.9 compared to 23.8±2.6 follicles; P=0.03) and SOV (16.8±2.9 compared to 10.8±2.1 CL; P=0.10) responses. Although the number of total ova/embryos was not different between groups (8.2±1.8 compared to 5.9±1.4 for FSH/eCG and FSH groups, respectively; P=0.25), the number (5.8±1.3 compared to 2.6±0.7; P=0.02) and percentage (75.6±5.7 compared to 53.2±9.7%; P=0.05) of transferable embryos was greater for the FSH/eCG females. Therefore, there was improvement in follicular superstimulatory and SOV responses and embryo quality in FSH/eCG-treated females.     

The effects of once or twice daily injections of pFSH on superovulatory response in heifers

Follicle stimulating hormone (FSH) is a glycoprotein hormone with a short half-life and has to be given twice daily for 3-4 days to induce superovulation in heifers. Since such a regimen is time consuming we compared the ovulatory response and yield of embryos in heifers following superovulation with either once or twice daily injections of pFSH for 4 days during the mid-luteal phase of a synchronized estrous cycle or during a prolonged luteal phase in heifers which had been immunized against prostaglandin F2alpha (PG). In Experiment 1, crossbred heifers (n = 42) previously actively immunized against a PG immunogen were superovulated in a 2 (cyclic or persistent corpus luteum) x 2 (once or twice daily injection) factorial plan. The heifers were superovulated with 75 units pFSH, which was injected subcutaneously once (22.5, 22.5, 15 and 15 units per day) or twice daily (9.3 units per injection) for 4 days. In Experiment 2, cyclic crossbred beef heifers (n = 80) were superovulated using pFSH which was given randomly to heifers once daily subcutaneously (T1) or twice daily intramuscularly (T2) using the same daily dose of 9, 7, 5, and 3 mg per day. Estrus was induced in all heifers in both experiments using 500 mug and 250 mug Cloprostenol 12 hours apart on the third day of pFSH injections. All heifers were inseminated twice with frozen-thawed semen at 12 and 24 hours after the onset of standing estrus or at 56 and 72 hours after the first PG if estrus was not observed. Embryos were recovered at slaughter and graded on a scale of 1 to 5 (1 = excellent, 5 = degenerated). Data were recorded for the number of corpora lutea (CL), large (>/=10 mm) and medium (5-9 mm) follicles, number of embryos recovered and embryo morphology. Data were analyzed by least squares analysis of variance procedures. In Experiment 1, there was no difference in ovulation rate between main effects. Fewer embryos were recovered from heifers with a persistent corpus luteum (pCL) and injected once daily (1.71+/-.75 vs 5.75+/-1.27) than from any other group. Heifers with pCL yielded lower (P < 0.05) numbers of freezable embryos than cyclic animals, regardless of injection regimen. In Experiment 2, T2 heifers had a significantly higher number of CL (16.4+/-1.7 vs 7.7+/-1.7; P = 0.0003), large follicles (4.1+/-0.5 vs 2.8+/-0.5; P = 0.04), medium follicles (6.4+/-0.7 vs 4.4+/-0.7; P = 0.04), embryos recovered (9.6+/-1.1 vs 4.9+/-1.1; P = 0.0025) and freezable embryos (4.7+/-0.7 vs 2.1+/-0.7; P = 0.014) than T1 heifers. It is concluded that a single daily subcutaneous injection of pFSH results in a lower superovulatory response than the twice daily regimen in heifers.     

Measurement of inhibin A and follicular status predict the response of ewes to superovulatory FSH treatments

Variability in superovulatory response to FSH stimulation is common to most mammals and imposes practical problems for assisted reproduction. In sheep, we have studied if this response is related to the ovarian follicular population and activity before the stimulation. During the breeding season, 30 ewes were treated with 40 mg FGA sponges for 14 days and 125 microg cloprostenol injection on Day 12, considering Day 0 as the day of progestagen insertion. Superovulatory response was induced with two different FSH regimes using the same total dose (8.8 mg), administered twice daily from 60 h before to 24 h after progestagen withdrawal. At the first FSH injection, all follicles > or = 2 mm were observed by transrectal ultrasonography and plasma FSH and inhibin A levels were determined. The number of corpora lutea and the number of and viability of recovered embryos in response to the treatment were determined on Day 7 after sponge withdrawal. No significant differences were found between treatments. The total mean number of corpora lutea (11.5 +/- 1.2) and recovered embryos (7.9 +/- 1.1) were positively correlated (P < 0.05 and <0.01, respectively) with the number of small antral follicles (2-3 mm: 9.2 +/- 0.7) and inhibin A concentration (240 +/- 18 pg/ml; P < 0.05 for corpora lutea and P < 0.005 for recovered embryos) observed at the onset of the superovulatory treatment, which was also positively correlated with the number of viable embryos (5.8 +/- 0.9, P < 0.005). In 18 ewes with follicles > or = 6 mm prior to FSH treatment, the ovulation rate was unaffected but the number of embryos (6.1 +/- 0.9 versus 11.6 +/- 2; P < 0.05) and their viability (4.5 +/- 0.8 versus 8.5 +/- 2; P < 0.05) was reduced. The lower number of embryos produced when a large follicle is present suggest that a proportion of the smaller follicles are in early stages of atresia and the developmental competence of their oocyte is compromised.     

Superovulation of dairy cows with purified FSH supplemented with defined amounts of LH

This study investigated the effects of a purified follicle stimulating hormone (FSH) preparation supplemented with three different amounts of bovine luteinizing hormone (bLH) and a commercially available FSH with a high LH contamination on superovulatory response, plasma LH and milk progesterone levels in dairy cows. A total of 112 lactating Holstein-Friesian crossbred dairy cows were used for these experiments; the cows were randomly assigned to treatment groups consisting of purified porcine FSH (pFSH) supplemented with bLH. Group 1 was given 0.052 IU LH 40 mg armour units (AU) FSH (n = 6); Group 2 was given 0.069 IU LH (n = 32); Group 3 received 0.423 IU LH (n = 34); while Group 4 cows (n = 36) were superovulated with a commercially available FSH-P((R)). This compound appeared to contain 8.5 IU LH 40 mg AU FSH according to bioassay measurement. All animals received a total of 40 mg AU FSH at a constant dose twice daily over a 4-d period. Levels of milk progesterone and plasma LH were determined during the course of superovulatory treatment. The Group 1 treatment did not reveal multiple follicular growth, and no embryos were obtained. Superovulation of Group 3 cows resulted in significantly (P<0.05) more corpora lutea (CL; 12.6+/-1.1) and fertilized ova (5.1+/-1.3) compared with Groups 2 and 4 (10.1+/-0.9 and 2.6+/-0.6, 9.0+/-0.9 and 2.7+/-0.5, respectively). Due to a high percentage of degenerated embryos (33%) Group 3 yielded only one more transferable embryo than Groups 2 and 4. Among groups, LH levels differed in the period prior to induction of luteolysis and were similar thereafter. The progesterone pattern following FSH LH administration reflected the amount of LH supplementation. Milk progesterone levels on the day prior to embryo collection were correlated to the number of CLs and recovered embryos. It is concluded that under the conditions of our experiment superovulation with 0.423 IU LH 40 mg AU FSH may yield a significantly improved superovulatory response in dairy cows. It is further suggested that LH supplementation exerts its effects mainly on follicular and oocyte maturation during the period prior to luteolysis.     

Successful superovulation of cattle by a single administration of FSH in aluminum hydroxide gel

We investigated whether Al-gel could adsorb and release FSH effectively in vitro and in vivo, and whether a single administration of FSH in Al-gel could successfully induce superovulation (SOV) in cattle. Porcine FSH (pFSH; 30 mg) was mixed with 5 mL of Al-gel; 99.98+/-0.01% of pFSH was adsorbed by the gel and 71.6+/-1.1% of the adsorbed pFSH was subsequently released in the presence of BSA. In cattle given a single i.m. treatment of 30 mg of pFSH in 5 mL of Al-gel, the numbers of CL, total ova recovered, and transferable embryos per cow were not significantly different from conventional (twice daily for 4 d) pFSH treatment (12.3+/-1.7 versus 11.7+/-1.8, 10.0+/-2.5 versus 9.3+/-1.7, and 8.6+/-2.3 versus 8.0+/-1.8, respectively, mean+/-S.E.M.); plasma pFSH concentrations were increased for 4 d, indicating sustained release from the Al-gel. Five cows were given 30 mg pFSH in 5 mL of Al-gel i.m. on five occasions (once every 2-3 months); there was no significant difference among treatments for the number of CL (12.4+/-3.8, 13.8+/-4.8, 9.0+/-1.9, 9.8+/-3.0, 12.0+/-2.1), total ova recovered (12.0+/-3.8, 12.6+/-5.1, 6.8+/-1.9, 7.6+/-1.8, 11.4+/-2.5), and transferable embryos (11.4+/-3.9, 10.4+/-5.8, 6.6+/-2.1, 4.8+/-1.4, 10.4+/-2.6). In conclusion, a single i.m. treatment of 30 mg pFSH in 5 mL Al-gel effectively induced SOV in cattle.     

Effect of season and gonadotropins on the superovulatory response in camel (Camelus dromedarius)

The purpose of the present investigation was to study the extent to which season and the gonadotropin preparation interferes with the superovulatory response in the dromedary. Adult camels were treated for superovulation during the breeding (November to April) and non-breeding season (May to October). Animals were synchronized by daily i.m. injections of progesterone (125 mg/animal/day, Jurox, UK) for 10 to 14 days. Superovulation was induced by 400mg pFSH alone (Follitropin V, Vetrepharm, Canada) administered in eight descending doses at 12h intervals or a combination of PMSG (2000IU, Folligon, Intervet, The Netherlands), injected with last injection of progesterone and 400mg pFSH in eight descending doses. The follicular development was daily assessed by ultrasonography of the ovaries. The donors were classified as per their response to the superovulatory treatment into very good (>10 follicles), good (5-10 follicle), poor (2-4 follicles) or no response (1 or no follicle) on each ovary. Ovulation was induced by injecting 3000 IU hCG (Chorulon, Intervet) at the time of first mating. The donors were mated twice at an interval of 12h when all or most of the follicles reached to a size of about 1.0-1.7 cm. Camels were flushed non-surgically on Day 6 or 7 after the ovulation. The proportion of camels showing very good response during the breeding as well as non-breeding season was higher (P<0.05) when a combination of pFSH and eCG was used compared with pFSH only. There was no difference (P>0.05) in the proportion of donors flushed successfully (embryos recovered) when treated either with a combination of pFSH and eCG or pFSH alone during the breeding and non-breeding season. The rate of recovery of ova/embryos and proportion of transferable embryos was higher (P<0.05) when donors were treated with pFSH+eCG compared with pFSH only during the breeding as well as non-breeding season. The results may indicate that ova/embryo recovery rate of the dromedary is influenced by the gonadotropin preparation but is not appreciably affected by the season.     

Ovarian response to gonadotropin treatment initiated relative to wave emergence in ultrasonographically monitored ewes

Follicular recruitment and luteal response to superovulatory treatment initiated relative to the status of the first wave of the ovine estrous cycle (Wave 1) were studied. All ewes (n = 25) received an intravaginal progestagen sponge to synchronize estrous cycles, and ewes were monitored daily by transrectal ultrasonography. Multiple-dose FSH treatment (total dose = 100 mg NIH-FSH-P1) was initiated on the day of ovulation (Day 0 group) in 16 ewes. In the remaining 9 ewes, FSH treatment was started 3 d after emergence of the largest follicle of Wave 1 (Day 3 group). Ewes received PGF(2alpha) with the last 2 FSH treatments to induce luteolysis. Daily blood samples were taken to determine progesterone profiles and to evaluate the luteal response subsequent to superovulation. The ovulation rate was determined by ultrasonography and correlated with direct observation of the ovaries during laparotomy 5 to 6 d after superovulatory estrus when the uterus was flushed to collect embryos. Results confirmed that follicular recruitment was suppressed by the presence of a large, growing follicle. In the Day 0 and Day 3 groups, respectively, mean numbers (+/- SEM) of large follicles (>/= 4 mm) recruited were 6.4 +/- 0.6 and 2.7 +/- 0.7 (P < 0.01) at 48 h after the onset of treatment, and 6.7 +/- 0.5 and 5.1 +/- 0.6 (P = 0.08) at 72 h after the onset of treatment. Ovulation rates were 5.6 +/- 0.8 and 3.3 +/- 0.8 in the respective groups (P < 0.05). The number of transferable embryos was 1.8 +/- 0.5 and 0.3 +/- 0.2 in the respective groups (P < 0.05). Short luteal phases (相似文献   

Determination of porcine plasma follitropin levels during superovulation treatment in cows

Porcine follicle stimulating hormone (pFSH) and porcine luteinizing hormone (pLH), are widely used to induce superovulation in cows. An advantage of this treatment is that the LH:FSH ratio can be varied to optimize the growth of the ovarian follicles. However, due to the relatively short half-life of FSH, the superovulatory treatment requires numerous injections. A performant radioimmunoassay system (sensitivity=0.2 ng/ml plasma) was used to determine plasma pFSH levels in cows that were superovulated with 2 daily injections of 4 Armour Units (A.U.) of pFSH for 4 d. From plasma profiles, the half-life and the disappearance of pFSH were estimated at 5 h and at 10 to 12 h, respectively, confirming the necessity of using two daily injections.     

Pretreatment with recombinant bovine somatotropin enhances the superovulatory response to FSH in heifers

One of the primary limiting factors to superovulation and embryo transfer in cattle has been the large variability in response, both between and within animals. It appears that the primary source of this problem is the variability in the population of gonadotropin-responsive follicles present in ovaries at the time of stimulation. We have shown that treatment of heifers with recombinant bovine somatotropin (rbGH) increases the number of small antral follicles (2 to 5 mm) and, therefore, enhances the subsequent superovulatory response to eCG. To investigate further the potential of using this approach to improve superovulatory regimens in cattle, the effect of rbGH pretreatment on the response to pituitary FSH was studied. The estrous cycles of 16 heifers were synchronized using PGF2alpha. On Day 7 of the synchronized cycle, half of the animals were injected with 320 mg sustained-release formulated rbGH, while the other half received 10 ml saline. Five days later, all heifers were given a decreasing-dose regimen of twice daily injections of oFSH for 4 d, incorporating an injection of PGF2alpha with the fifth FSH treatment, to induce superovulation. All animals were artificially inseminated twice with semen from the same bull during estrus. Ova/embryos were recovered nonsurgically on Days 6 to 8 of the following estrous cycle, and the ovulation rate assessed on Day 9 by laparoscopy. Using the same animals as described above, the experiment was repeated twice, 3 and 6 mo later, with no laparoscopy in the third experiment. The animals were randomized both between experiments and for the day of ova/embryo collection. Pretreatment of heifers with rbGH significantly (P < 0.01) increased the number of ovulations, total number of ova/embryos recovered and the number of transferable embryos. The percentage of transferable embryos was significantly (P < 0.05) increased by rbGH pretreatment. In addition, the incidence (2/16) of follicular cysts with a poor ovulatory response (< 6 ovulations) for the rbGH-pretreated heifers was significantly lower (P < 0.05) when compared with the incidence (7/16) in the control animals. It is concluded that pretreatment with rbGH may provide a useful approach for improving superovulatory response in cattle.     

Superovulation of a low fecundity sheep breed using a porcine gonadotrophin extract with a defined LH content (Pluset)

The aim of this study was to determine the efficiency of a porcine pituitary gonadotrophin extract with a defined pLH content in the superovulation of sheep. Estrus was synchronized in 61 Polish Mountain ewes with intravaginal fluorogestone acetate sponges. Twenty-four hours before the sponges were removed, the ewes underwent different superovulatory treatments: Group I 250 IU of pFSH with 250 IU of pLH (n=19); Group II 500 IU of pFSH with 500 IU of pLH (n=19); and Group III 750 IU of pFSH and 750 IU of pLH (n=18). Gonadotrophine was administered intramuscularly twice a day over a 3-day period in decreasing dosages. A control group of ewes (n=5) was treated with saline. In most of the ewes estrus began about 20 hours after sponges were removed. All the ewes were bred naturally every 12 hours. Superovulation was confirmed in 75% of the treated animals. The ewes receiving 250 IU each of pFSH and pLH produced an average of 7.6 +/- 3.1 corpora lutea (CL), 6.3 +/- 2.4 ova and 4.3 +/- 4.1 transferable embryos. Group II (500 IU of pFSH and pLH) produced 8.5 +/- 4.0 CL, 7.6 +/- 4.1 ova, and 4.1 +/- 2.9 transferable embryos. Group III (750 IU each of pFSH and pLH) produced 8.3 +/- 5.2 CL, 7.5 +/- 5.5 ova and 5.2 +/- 5.1 transferable embryos. The mean embryo recovery rate was 87% for all three groups. Differences in superovulatory response and embryo recovery rate among the groups were not statistically significant (P>0.05).     

The effect of immunization of heifers against alpha 1-26 inhibin conjugate on the superovulatory response to pFSH

A total of 121 heifers was blocked by time and diet and then randomly assigned, within block, to an inhibin-immunized (I) or a control (C) group. Immunized heifers (n = 61) received a primary immunization (Day 0) with 0.33 mg of an alpha 1-26 bovine inhibin fragment-human serum albumin (HSA) conjugate injected with non-ulcerative Freund's and DEAE-dextran adjuvants. Booster injections were given on Days 28 and 56. Control heifers (n = 60) received HSA and adjuvants. On Days 56 and 83 the ovaries of heifers were examined by ultrasound to determine the ovulation rate, and blood samples were collected for antibody titer determination. On Day 84, 61 heifers (C, n = 30; I, n = 31) received a total of 24 mg of porcine follicle stimulating hormone (pFSH), while 60 heifers (C, n = 30; I, n = 30) received 12 mg im pFSH, which was administered twice daily for 4 d in decreasing doses during the mid-luteal phase of the estrous cycle. Luteolysis was induced with prostaglandin F(2alpha) analog. The heifers were artificially inseminated and were slaughtered 7 d after estrus. Embryos were recovered and morphologically graded on a scale of 1 to 5 (1 = excellent; 5 = degenerated). Antibody titers (percentage binding at 1:125 serum dilution) differed (P < 0.01) between Group C and I heifers at Days 56 (0.1 vs 30%) and 83 (0.2 vs 37%), and 26% of Group I and 1% of Group C heifers (P < 0.01) had twin ovulations on Day 83. The mean number of embryos recovered was reduced (P = 0.02) in Group I heifers (8.9 +/- 1.2) compared with C heifers (12.1 +/- 1.1); however, the mean number of freezable embryos (Grades 1 and 2) was not affected (P = 0.61) by immunization, and there was no interaction with pFSH (P = 0.36). Ovulation rate as well as embryo yield and quality were not different (P > 0.10) between Group C and I heifers when 12 mg pFSH were administered; however, immunization decreased the superovulatory response to 24 mg of pFSH.     

Reproductive season affects inhibitory effects from large follicles on the response to superovulatory FSH treatments in ewes

The main objective of this study was to compare the effect of the presence of large follicles at the start of FSH treatment on the superovulatory response in ewes in the breeding and nonbreeding seasons. A second objective was to verify the effect on the superovulatory response of the presence of a corpus luteum at the start of the FSH treatment during the breeding season. Fifteen ewes in breeding season (October) and 14 in nonbreeding season (May-June) were treated with 40 mg FGA sponges (Chronogest) for 14 days, together with a single dose of 125 microg cloprostenol on Day 12, considering Day 0 as day of progestagen insertion. Superovulatory treatments consisted of eight decreasing doses (1.5 ml x 3, 1.25 ml x 2 and 1 ml x 3) of Ovagen twice daily from 60 h before to 24h after sponge removal. Ovarian structures were assessed by transrectal ultrasonography using a 7.5 MHz linear array probe. Luteal activity at progestagen insertion (Day 0) and presence of corpus luteum and of large follicles at first FSH dose (Day 12) were determined. There were no significant differences between the breeding season and nonbreeding season for ovulation rate (11.6+/-1.4 versus 11.6+/-1.3), number of recovered embryos (8.0+/-1.1 versus 9.6+/-1.3) or number of viable embryos (7.2+/-1.1 versus 5.8+/-1.2). During the breeding season, there were fewer recovered embryos in ewes with a large follicle (> or =6mm) at first FSH dose (6.9+/-1.1 versus 12.3+/-1.8, P<0.05) and fewer viable embryos (5.0+/-1.2 versus 10.5+/-0.5, P<0.05) than in ewes without such a follicle. During the nonbreeding season, however, there were no significant differences between ewes with or without a large follicle for either recovered (9.0+/-2.5 versus 11.3+/-1.2) or viable embryos (6.3+/-2.3 versus 8.1+/-1.2). Analysis of seasonal differences in ewes with a large follicle showed a lower number of recovered embryos in the breeding season (P<0.05) due to a lower recovery rate (65.7% versus 92.3%, P<0.05), since mean number of corpora lutea in response to the FSH treatment was similar (10.9+/-1.3 versus 10.0+/-2.5). These results indicate that, in sheep, the inhibitory effects of large follicles during the nonbreeding season are not as obvious as during the breeding season.     

Evaluation of two treatments in superovulation of mares

The efficiency of superovulating mares with an enriched fraction of equine follicle-stimulating hormone (feFSH) and an equine pituitary extract (EPE) with similar FSH content but differing in the LH amount was compared. Mares were randomly assigned to an feFSH (n = 5) or EPE (n = 5) treatment. The experimental period was of 2 successive estrous cycles, with the first cycle as the control. At Days 6 and 7 of the estrous cycle, the mares received 250 micrograms i.m. cloprostenol. The treatments consisted of daily injections of 25 mg feFSH or EPE beginning on Day 6 post ovulation. Mares were inseminated every other day until the last ovulation was detected. When the mares in the control and treatment cycles developed at least 1 or 2 > or = 35-mm follicle, respectively, the treatment was interrupted, and a single injection of EPE (25 mg, i.v.) was administered to induce ovulation(s). Nonsurgical embryo recovery was performed 6 or 7 d after ovulation in both control and treatment cycles. The number of ovulations per mare was not significantly different (P > 0.05) between feFSH and EPE groups, but both were higher (P < 0.05) than that of the control cycle. The number of recovered embryos per ovulation was similar (P > 0.05) for control, feFSH and EPE groups. The high amount of LH presented in EPE did not affect the superovulatory response of the mares. Superovulatory treatments increased the ovulation rate of mares but did not affect the embryo recovery rate per ovulation.     

The effect of co-treatment with recombinant bovine somatotrophin on plasma progesterone concentration and number of embryos collected from superovulated Holstein heifers

Mature Holstein heifers were induced to superovulate with twice-daily injections of porcine follicle-stimulating hormone (FSH), and were given either 20 mg i.m. of recombinant bovine somatotrophin (rBST) or saline with each FSH injection. The animals were artificially inseminated and the embryos were collected nonsurgically at Day 7. There was no significant difference in the mean (+/-S.D) total number of embryos collected from rBST-treated animals (8.3+/-5.3) when compared with that of the controls (7.2+/-6.6), or in the mean number of transferable embryos (5.3+/-4.0 vs 5.2+/-4.5). However, co-treatment with rBST tended to increase the ovulatory response, and it significantly increased plasma progesterone concentrations at Day 6 (P = 0.04). Based on these latter observations, we conclude that treatment with rBST enhanced the superovulatory response in heifers.     

Improvement in recovery of embryos/ova using a shallow uterine horn flushing technique in superovulated Holstein heifers

The aim of this study was two-fold: (1). to compare recovery of embryos/ova from superovulated Holstein heifers by flushing the uterine horns through insertion of the catheter very close to the tip of the horn (deep) or just after the uterine bifurcation (shallow) and (2). to evaluate the hormonal and superovulatory response to estradiol benzoate (EB) treatment prior to superovulation. Ten Holstein heifers (12-16 months) underwent two superovulatory treatments in a cross-over design. Heifers were treated with decreasing doses of FSH from Days 8 to 12.5 of a synchronized estrous cycle. At 4 days prior to superovulation, half of the heifers received EB (5mg, i.m.) or served as Controls, followed by the alternative treatment in the subsequent superovulation. At embryo recovery, one uterine horn was flushed with deep ( approximately 7 cm caudal to the tip of the horn) and the other with shallow ( approximately 5 cm cranial to the beginning of the uterine bifurcation) flushing techniques. Embryos/ova were recovered, counted, and scored. Number of ovulations was estimated by ultrasound. Pretreatment with EB reduced circulating FSH and regressed the first wave dominant follicle with no change in number of large follicles, number of ovulations, number of embryos/ova recovered, or number of transferable embryos. The shallow flushing technique was superior to the deep technique for number of embryos/ova recovered per horn (5.4+/-1.1 versus 3.9+/-0.8) or percentage of embryos/ova recovered per CL (63.9+/-8.6% versus 37.4+/-6.5%). Thus, flushing the entire uterine horn increased recovery of embryos/ova.     

The effects of previous ovarian status on ovulation rate and early embryo development in response to superovulatory FSH treatments in sheep

A total of 64 ewes was used to determine if the changes in superovulatory yields related to the ovarian status at the start of superovulatory treatment are due to differences in the population of gonadotrophin-responsive follicles, alterations in the processes of ovulation or transport of embryos from oviduct to uterus and/or developmental competence of the oocyte/embryo. Ovarian status at the start of a superovulatory FSH step-down treatment, administered coincidentally with a progestagen, was assessed by ultrasonography. On Day 4 after progestagen withdrawal, embryos were recovered from oviduct and their viability was determined by assessing development in vitro culture (IVC) until the hatched blastocyst stage. In all the ewes, the ovulation rate was related positively to the number of 2-3 mm follicles at first FSH injection (P<0.005). However, the total number of embryos and their viability were related to the more limited category of 3 mm follicles (P<0.05), whereas a higher degeneration rate was related to the number of 2mm follicles. The presence of a corpus luteum (CL) at the start of superovulatory treatment exerted a protective effect on embryonic viability, decreasing the degeneration of embryos. On the other hand, the presence of a dominant follicle at first FSH dose affected the mean size of the pool of follicles responding to the superovulation treatment, because ovulation arose from 3 to 5 mm follicles in absence of large follicles (P<0.05), but from 2 to 3 mm follicles when large follicles were present (P<0.005), indicating atresia in medium sized follicles in the presence of a large follicle.     

The effects of FSH-priming and dominant follicular regression on the superovulatory response of cattle

Thirty superovulatory treatments were administered to 19 mixed-breed, nonlactating cows. In 10 superovulatory treatments, the cows were primed with follicle stimulating hormone (FSH) on the second and third day of the estrous cycle, and in another 10 superovulatory treatments, the cows received no priming dosage of FSH. Initiation of the superovulatory treatments in both groups was determined by ultrasonically monitoring for regression of the dominant anovulatory follicle. Still another 10 superovulatory treatments were begun on Day 10 without regard for regression of the dominant anovulatory follicle and without a priming dosage of FSH. The mean days for starting the superovulatory treatment in the FSH-primed cows, in the nonprimed cows and in the controls were 10.5, 11.9 and 10 days, respectively. All cows were treated with eight injections of FSH at 12-hour intervals in a declining dosage (36 mg total). Cows were bred naturally and embryos collected nonsurgically seven days later. There was no significant difference (P>0.05) between the total number of embryos or transferable embryos in the three treatment groups. In this study neither priming on Days 2 or 3 nor initiating the superovulatory treatment, based on the morphologic regression of the dominant anovulatory follicle, was an effective means for improving the superovulatory response in cattle.