Variability in gonadotrophin preparations as a factor in the superovulatory response

Baculovirus-insect cell production of bioactive porcine FSH

The in vitro and in vivo bioactivity of recombinant porcine FSH (rpFSH) produced from insect cells through use of a baculovirus expression system were studied and compared with those of natural FSH preparations. Determination of in vitro bioactivity, using the rat Sertoli cell aromatase bioassay, indicated that rpFSH is as active as purified pituitary FSH. Determination of in vivo bioactivity, using the mouse uterine weight bioassay, indicated that rpFSH is as active as purified pituitary FSH. Using the mouse Leydig cell testosterone bioassay, it was demonstrated that the intrinsic LH bioactivity of rpFSH is negligible. The increases in ovarian and uterine weight, and the stimulation in follicular growth in immature hypophysectomized rats induced by rpFSH supplemented with hCG were comparable to those induced by natural FSH preparations. Furthermore, rpFSH alone in hypophysectomized mice stimulated preantral follicular growth to preovulatory stages, and the subsequent injection of hCG caused ovulation. These results demonstrate that in vitro and in vivo biological characteristics of rpFSH produced from baculovirus-insect cells are indistinguishable from those of FSH isolated from natural sources.

Temporal aspects of ovarian follicular growth and steroidogenesis following exogenous follicle-stimulating hormone in Angus heifers

Ultrasonography and endocrine assay techniques were used to monitor structural and hormonal alterations made by the ovary in response to the biological actions of pituitary-derived follicle-stimulating hormone (FSH-P). Angus heifers (n = 36) were allotted to receive injections (twice per day) of either FSH-P (up to a total of 28 mg over a maximum of 4 days beginning on Day 10 of a synchronized estrous cycle) or saline in order to quantify temporal relationships among follicle growth and steroid hormone profiles. Transrectal ultrasonography was utilized at 12-h intervals to monitor and record follicle growth. Plasma was collected every 12 h for the first 48 h of the experiment and then every 6 h for the remainder of the experiment. At 48 and 60 h after the onset of treatments, prostaglandin F2 alpha (PGF2 alpha; 25 mg) was administered (i.m.). FSH-treated heifers (n = 6 at each time) were terminated at 24, 48, 72 and 96 h following the onset of treatment. Saline-treated heifers were terminated at 24 and 96 h (n = 6 at each time). After ovaries were obtained, follicular number and size were recorded and follicular fluid (FF) was collected. Plasma concentration of progesterone (P) and estradiol (E2) and FF concentration of P, E2, estrone, testosterone and androstenedione were determined by radioimmunoassays. Plasma concentration of E2 increased (P < 0.05) within 36 h of initiation of FSH treatment. Plasma P decreased (P < 0.0001) by 12 h post-PGF2 alpha. Ultrasonographic examination revealed a significant decrease in the number of small follicles by 48 h, whereas the number of medium follicles increased (P < 0.05) by 60 h after the initiation of FSH treatment. The number of large follicles (LF > or = 10 mm diameter) increased (P < 0.01) over the course of the experiment. The total number of ovarian follicles (TF) 24 h after the start of FSH treatment was correlated (r = 0.99; P < 0.0001) with the number of small follicles (SF < or = 5 mm). At 72 h after the onset of FSH treatment, the number of medium follicles (i.e. 6-9 mm) was correlated with TF (r = 0.97; P < 0.0001). Estradiol was the predominant FF steroid. Follicular fluid E2 was greatest in follicles at 72 h after FSH treatment. Follicular fluid E2 and plasma E2 were positively correlated (r = 0.66; P < 0.001). Follicular aromatase activity was estimated by evaluating the ratio of FF estrogens (E) to androgens (A). Elevated aromatase activity (E:A ratio > 1.0) was detected in 196 of 206 follicles. The estrogen to progesterone ratio was used as an estimate of follicle viability. Eighty-five percent of the follicles were estimated to be viable (E:P ratio > 1.0). The peak E:A ratio in LF preceded by 24 h the peak concentration in FF E2 and plasma E2. In MF and SF the E:A ratio increased by 72 h. Enhancement of ovarian follicular growth (i.e. increased number and size of follicles; increased steroidogenesis) by exogenous, pituitary-derived FSH is characterized by (1) increased activity of aromatase, and (2) accumulation of FF E2, events which temporally preceded the increase in plasma concentration of E2. These observations will aid efforts to incorporate recombinant bovine FSH and somatotropin in an effort to develop more predictable superstimulation and ovulation induction protocols.

A dominant follicle does not affect follicular recruitment by superovulatory doses of FSH in cattle but can inhibit ovulation

It has been suggested that superovulation in cattle is impaired if FSH injections are initiated in the presence of a dominant follicle, but the results of experiments to test this hypothesis have been contradictory. However, previous experiments were conducted during mid-cycle, when the absence or presence of a dominant follicle is difficult to assess. We took a different approach by comparing the effects of initiating superovulatory injections of FSH (11 equal doses of FSH-P, every 12 h) on Day 1 of the bovine estrous cycle, when a dominant follicle clearly is not present, vs initiation on Day 6, when a dominant follicle clearly is present and actively growing (n = 17 heifers in a "crossover" design). In 8 17 heifers initiation of FSH injections in the presence of a dominant follicle (Day 6 group) caused ovulation of the dominant follicle within 1 to 2 days and formation of a smaller than normal CL. These animals had higher than normal concentrations of plasma progesterone around the time of expected estrus (P < 0.05) and failed to exhibit estrus. Although the mean number and diameter of the follicles recruited in response to FSH injections in heifers that ovulated the dominant follicle prematurely were not different from the other heifers in the Day 6 group, no ovulations were observed, and no embryos or ova were recovered 6 d after insemination. Conversely, when FSH injections were initiated on Day 1 in these 8 heifers, they exhibited estrus, and their plasma progesterone around the time of estrus, mean ovulation rate, and number of total and transferable embryos recovered did not differ from the responses observed in the remaining 9 heifers treated either on Day 1 or on Day 6. Taken together, these results indicate that a dominant follicle does not affect the ability of smaller follicles to be recruited in response to exogenous FSH, but may impair their ovulation. These findings provide an explanation for previous reports of decreased superovulatory responses during times of the cycle when a dominant follicle would be expected to be present.

Development of persistent ovarian follicles during synchronization of estrus influences the superovulatory response to FSH treatment in cattle

The synchronization of estrus with synthetic progestins or progesterone (P(4)) results in the development of a large, persistent ovarian follicle. The objectives of the present study were to determine if development of a persistent ovarian follicle during synchronization of estrus suppresses recruitment of additional follicles during FSH treatment. On Day 5 of the estrous cycle (estrus = Day 0), beef cows were treated with 0.5 or 2.0 P(4) releasing intravaginal devices (PRIDs) for 8 d (Experiment 1, n = 20), 5 or 2 d (Experiment 2, n = 44) before initiation of FSH treatment. Prostaglandin F(2alpha) (25 mg) was administered on Days 5 and 6. Superovulation was induced with 24 mg of recombinant bovine FSH (rbFSH, Experiment 1) or 28 mg of FSH-P (Experiment 2) over a 3- or 4-d period, respectively. The PRIDs were removed concurrently with the 5th injection of rbFSH or FSH-P. There was a treatment-by-day interaction (P < 0.001) for the concentration of 17beta-estradiol in cows treated for 8, 5 or 2 d before FSH treatment. In Experiment 1, FSH treatment initiated 8 d after insertion of a 0.5 PRID did not affect the number of CL (6.9 +/- 1.4 vs 6.7 +/- 1.6), ova/embryos (3.7 +/-1.3 vs 3.0 +/- 1.3) and transferable embryos (2.4 +/- 0.9 vs 3.0 +/- 0.9) compared with that of the 2.0 PRIDs. In Experiment 2, FSH treatment initiated 5 d after insertion of a 0.5 PRID decreased the number of CL (4.0 +/- 0.5 vs 8.3 +/- 0.8; P < 0.001), ova/embryos (3.0 +/- 0.6 vs 5.9 +/- 1.2; P < 0.03) and transferable embryos (2.3 +/- 0.6 vs 5.1 +/- 1.0; P < 0.03) compared with that of a 2.0 PRID, respectively. Initiation of FSH treatment 2 d after insertion of a 0.5 PRID compared with a 2.0 PRID had no affect on the number of CL (8.0 +/- 2.1 vs 8.7 +/- 1.2), total ova (4.8 +/- 1.4 vs 6.9 +/- 1.4) and transferable embryos (2.9 +/- 1.2 vs 6.1 +/- 1.7). In conclusion, treatment with low doses of P(4) (0.5 PRID) for 5 d but not for 2 or 8 d before initiation of FSH treatment results in the development of a dominant ovarian follicle, which reduces recruitment of ovarian follicles, and the number of CL, total ova and transferable embryos.

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 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.

Superovulatory response to a single subcutaneous injection of Folltropin-V in beef cattle

A series of 4 experiments were designed to evaluate the feasibility of superstimulation in beef cattle with a single sc injection of the porcine pituitary extract, Folltropin-V. In the preliminary study (Experiment 1), superovulatory response of cows (n=7) treated with a single sc injection of 400 mg NIH-FSH-P1 Folltropin-V was not different than that of cows (n=8) superstimulated with twice daily im injections over 4 d, or a single sc injection plus an injection of eCG (n=12). Experiments 2 and 3 were designed to determine the optimal site of a single sc injection. In Experiment 2, cows (n=25) with body condition scores (BCS) of 1 to 2 were used. The mean number of CL counted and ova/embryos collected was lower (P<0.05) in cows treated with the single sc injection in the neck region than in cows treated with a single sc injection behind the shoulder, or with the twice daily im injection treatment. In Experiment 3, cows (n=49) with BCS of 3 to 5 were used. There were no differences in the number of CL, total ova/embrvos collected, fertilized ova and transferable embryos whether treatments were given in the neck region or behind the shoulder, or whether the cows were implanted or not implanted with Syncro-Mate-B. Experiment 4 was designed to determine the optimal superstimulatory dosage of Folltropin-V administered by a single sc injection. Superovulatory response of cows treated with the higher doses (400 mg, 600 mg or 800 mg NIH-FSH-P1) was higher (P<0.05) than those treated with 200 mg NIH-FSH-P1. The number of unovulated (>or=10 mm) follicles at the time of ova/embryo collection was higher (P<0.05) in the 600 and 800 mg groups, and progesterone concentration at estrus was higher (P<0.05) in cows treated with 800 mg than with 400 or 200 mg. It was concluded that a single, bolus sc injection of 400 mg NIH-FSH-P1 of Folltropin-V is as efficacious as the 4-d, twice daily im treatment protocol for inducing superovulation in beef cows. The amount of subcutaneous fat and site of injection appeared to affect the efficacy of a single sc injection; a single bolus sc injection of Folltropin-V behind the shoulder resulted in the most predictable superovulatory response.

Comparison of superovulatory response of mature outbred mice treated with FSH or PMSG and developmental potential of embryos produced

A superovulatory treatment for mice based on FSH administration was compared with a standard one based on PMSG. Our aim was to determine if a mean number of embryos recovered per donor could be increased and if in vitro or in vivo viability was affected by the hormonal treatment used. Thus, female Swiss mice were subjected to 2 superovulatory treatments, and the 1-cell and 2-cell stage embryos were cultured in 2 different media to the blastocyst stage or were transferred to pseudopregnant recipients. The data show that despite a lower mating percentage (52% with FSH vs 66% with PMSG), the FSH-treated mice provided twice the number of total embryos (53.4 vs 24.5) with a similar percentage of morphologically normal embryos (74% for FSH vs 69% for PMSG). We also found that in vitro culture results can be influenced by the source of gonadotropins depending on the culture medium used. A culture medium such as CZB which prevents the 2-cell block, provided the same developmental rates regardless of hormonal treatment used. However, with M-16 medium, which does not prevent this blockage, only 39% of the 2-cell FSH-derived embryos and 49% of the PMSG-derived 2-cell embryos developed into blastocysts (P<0.05). FSH-derived embryos resulted in a higher percentage of pregnant recipients (73 vs 56%) than PMSG-derived embryos, but the number of alive fetuses and the number of implantations per pregnant recipient was affected only by the kind of culture system used before transfer. The results show that FSH can provide very good superovulatory response in mice, thus reducing the number of donors needed for a given experiment and providing embryos of at least the same quality as those derived from the standard PMSG treatment.

Ovarian superstimulatory response relative to follicular wave emergence in heifers

Two experiments were designed to evaluate the responsiveness of beef heifers to superstimulatory treatments administered during the first follicular wave. Heifers were examined daily (Experiment 1) or twice daily (Experiment 2) by ultrasonography to determine the status of follicular wave development and the day of initiation of superstimulatory treatment. Heifers in both experiments were superstimulated with a total dose of 10 ml Folltropin (equivalent to 200 mg of NIH-FSH-P1), divided into 10 equal intramuscular injections over 5 days. On the last day of treatment, heifers received 500 mug of cloprostenol after each injection of Folltropin to induce luteolysis. In the respective groups, superstimulatory treatments were initiated on Day -1, Day 0 (day of ovulation) or Day +1 for Experiment 1, and on Day -1, Day 0, Day +1 or Day +2 for Experiment 2. In Experiment 1, the number of ovulations in each ovary was assessed by ultrasonography and by counting the number of corpora lutea (CL) in each ovary at slaughter. The correlation between both techniques for assessing ovulatory response was high (r= 0.98; P< 0.0001), and there was no significant difference in the mean number of ovulations detected by ultrasound (5.7+/-1.1) versus the mean number of CL counted at slaughter (6.2+/-1.2). In Experiment 1, the mean (+/- SEM) number of CL counted at slaughter in heifers treated on Day -1 (9.4+/-3.8) and Day 0 (7.3+/-1.6) was higher (P< 0.05) than that of heifers treated on Day +1 (0.7+/-0.3). The mean number of follicles >/=7 mm in diameter on the last day of treatment was also higher (P<0.05) in the Day -1 group compared with the Day +1 group; the Day 0 group was intermediate. In Experiment 2, the mean number of ovulations was higher (P< 0.05) in the Day 0 group (18.4+/-3.4) than the Day -1 (9.5+/-2.3), Day +1 (6.7+/-2.2) or Day +2 (6.5+/-2.3) groups. Heifers in the Day -1, and Day 0 groups had more (P< 0.05) follicles >/=7 mm at the end of treatment compared with heifers in the Day +1 or the Day +2 group. The stated hypothesis was supported: exogenous FSH treatment initiated at the time of wave emergence, near the expected time of the endogenous wave-eliciting FSH surge, has a positive effect on the superstimulatory response. A higher superstimulatory response was elicited when treatments were initiated on the day of, or the day before, wave emergence compared with that of later treatments.

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.

Superovulatory responses in dairy cows following ovulation of the dominant follicle of the first wave

In the present study we investigated the effect of hCG administration on Day 7 (Day 0 = day of standing estrus) to ovulate the dominant follicle of the first wave and the associated increase in progesterone concentration on subsequent superovulatory response in dairy cows. Twenty cyclic lactating cows were allocated at random to 2 groups: control (n = 10) and hCG-treated (n = 10). The ovaries of each cow were scanned using an ultrasound scanner on Day 7, to confirm the presence of the dominant follicle and thereafter every other day until embryo recovery. All cows received a total dose of 400 mg Folltropin-V in decreasing amounts for 5 days (Days 9 to 13) and 35 mg PGF(2alpha) on Day 12. In addition, the treated cows received 1000 IU hCG on Day 7. All cows were inseminated twice during estrus, and the embryos were collected 7 days later by a nonsurgical procedure. Blood smaples were taken at different times of the treatment period for progesterone determination. All cows possessed a dominant follicle at Day 7, and all but one of the hCG-treated cows ovulated the dominant follicle and formed an accessory corpus luteum. Plasma progesterone concentrations were significantly higher (P<0.01) in hCG-treated cows than control cows on the first day of Folltropin treatment and on the day of PGF(2alpha) injection. The mean number of follicles at estrus, the number of ovulations, the total number of embryos and the number of transferable embryos were not different (P>0.05) between control and hCG-treated cows.

Interrelationships of hormonal and ovarian responses in superovulated heifers pretreated with FSH-P at the beginning of the estrous cycle

The objective of this study was to determine the relationships between follicle stimulating hormone, (FSH), estradiol (E(2)), and progesterone (P(4)) concentrations in peripheral blood samples and the follicular dynamics prior to and during superovulation in heifers pretreated with FSH-P (10 mg, i.m.) (FSH-P-primed; n=9) or not (saline-primed; n=9) on Day 3 (Day 0 = estrus) of the estrous cycle. On Day 10, all heifers were superovulated with FSH-P (27.7 mg i.m.) in declining dosages over 5 days. Prior to and during superovulation, blood samples were collected one to five times daily, and the follicular dynamics were monitored daily by ultrasonography. Prior to superovulation, profiles of P(4) and E(2) did not differ (P>1) between the saline- and FSH-P-primed heifers. The FSH concentrations in saline-primed heifers decreased from 0.43 +/- 0.05 ng/ml to 0.30 +/- 0.04 ng/ml between Days 3 and 7 and then increased progressively to 0.59 +/- 0.04 ng/ml on Day 10. In contrast (P<0.002), FSH concentrations in the FSH-P-primed heifers remained constant between Days 3 and 10 and averaged 0.41 +/- 0.03 ng/ml. Higher increases in E(2) during superovulation (maximum values, 100 vs 46 pg/ml) and in P(4) after superovulation (maximum values, 39 vs 22 ng/ml) in the saline-than in the FSH-P-primed heifers reflected the greater increase in the number of follicles (>10 mm) and in the number of corpora lutea (CL) in the saline-primed heifers. Prior to the preovulatory luteinizing hormone (LH) peak during superovulation, there was a parallel (P>0.1) decrease in FSH concentrations in the saline- and FSH-P-primed groups. Within heifers partial correlations indicated that E(2) was correlated positively with the number of follicles (>/= 7 mm) and the size of the largest follicle during superovulation (r=0.54 to 0.81; P<0.01). Negative correlations were detected (P<0.01) between FSH and the number of follicles >/=7 mm prior to (r=-0.26) and during superovulation (r=-0.37). The results cofirm earlier reports indicating that priming with FSH-P decreases the superovulatory response in cattle. Interrelationships of hormonal and ovarian responses support the concept that the presence of large dominant follicles prior to superovulation limits the superovulatory response.

Pharmacologic manipulation of fertility

The professional application of agents to the manipulation of fertility of cows requires basic and applied knowledge of the physiologic mechanisms that are affected and of the pharmacologic agents that are used. In all areas of the pharmacologic manipulation of fertility, the achievement is less than the ideal, and further research is required to improve the efficiency of treatments. The induction of estrus in acyclic animals can involve a reduction in the depth of anestrus, pretreatment with progestagen to ensure estrous behavior and the formation of a normal corpus luteum, and then treatment with exogenous gonadotropin. Responsiveness to treatment can be variable and reflects the depth of anestrus of the animals. Improved treatment regimens require a knowledge of the basic mechanisms involved with the depth of anestrus, a means of assessing the depth of anestrus, and an understanding of the hormonal requirements of ovarian follicles for development and maturation in animals at different depths of anestrus. The optimal precision in the synchronization of estrus (and ovulation) in cyclic animals requires the synchronization of both follicular waves and the end of progestational phase. The end of progestational phase can be synchronized effectively using prostaglandin F2a (or analogs), or by treatment with progestagens with or without luteolytic agents. Procedures to synchronize follicular waves need to be established. The induction of superovulation can be achieved readily using gonadotropins prior to estrus synchronization using prostaglandin F2a. The responses to standard treatments in terms of ovulation rates and yield of transferable embryos are highly variable. The development of procedures to reduce this variability requires an understanding of the intra-ovarian mechanisms involved in recruitment of follicles for a wave of follicular growth, in the selection of dominant follicles for further development, and in the mechanisms controlling follicular atresia. Cystic ovarian disease can be treated effectively using HCG or GnRH (follicular cysts) or prostaglandin F2a (luteal cysts). The basic mechanisms resulting in failure of estrogen positive feedback on LH secretion (that results in cystic follicles) remain to be determined. Small but significant increases in pregnancy rates can be achieved treating cows with prostaglandin during the post-partum period, with prostaglandin to induce estrus for insemination, with GnRH or HCG at estrus, and with GnRH or progestagen treatment during diestrus. Beneficial effects of treatment have been shown in some trials but not in others.(ABSTRACT TRUNCATED AT 400 WORDS)

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. 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.

Human menopausal gonadotropin induces ovulation in sheep, but embryo recovery after prostaglandin F2α synchronization is compromised by premature luteal regression

Using pregnant mares' serum gonadotropin (PMSG) and follicle stimulating hormone (FSH-P) as conventional gonadotropins, human menopausal gonadotropin (hMG) was tested for its comparative ability to induce multiple ovulations in sheep. Estrous cycles were synchronized using either prostaglandin F2alpha (PGF2alpha) or progestogen (MAP)-impregnated pessaries. During the mid-luteal phase, control ewes received serial saline injections, whereas test females (which also served as embryo donors) received either a single PMSG injection (1200 IU) or serial injections of FSH-P (total, 21 mg) or hMG (total, 1350 IU) over 3.5 d. These sheep were naturally mated and artificially inseminated (AI) in utero. Number of CL and transferable-quality embryos 5 d after AI was greater (P<0.05) in FSH-P-and hMG-treated donors than in PMSG-treated ewes. The lower number of transferable-quality embryos produced by PMSG-treated donors was attributed to a reduced (P<0.05) fertilization rate compared with that of the other treatment groups. There were no differences (P>0.05) in daily circulating estradiol-17beta and progesterone concentrations among the gonadotropin treatment groups. Gonadotropin-treated ewes demonstrated estrus approximately 24 h earlier than control ewes and, therefore, exhibited an accelerated estradiol-17beta surge and rise in circulating progesterone. Progesterone production in gonadotropin-treated ewes was also more variable than in the controls; this was due, in part, to premature luteal regression which occurred in 4 of 10 PMSG-, 3 of 10 FSH-P- and 6 of 10 hMG-treated ewes also given PGF2alpha. Ewes with prematurely regressing CL experienced transient luteal tissue development within 4 d of ovulation and produced no embryos. Overall results 1) demonstrate that serial administration of hMG induces multiple ovulations in sheep comparable to FSH-P, and 2) suggest that PGF2alpha treatment during ovulation induction adversely affects newly formed luteal tissue compromising subsequent embryo recovery.

Superovulation of beef heifers with Folltropin: A new FSH preparation containing reduced LH activity

The optimum superovulatory dose of Folltropin was determined and compared with a standard 28 mg dose of FSH-P in beef heifers. In Experiment 1, mean numbers of corpora lutea (CL) did not differ among the groups treated with 10, 20, 30 or 40 mg Folltropin or FSH-P, and the mean CL number was reduced (P<0.05) only in the 5 mg Folltropin group. Mean numbers of ova/embryos recovered, fertilized and transferable were greater (P<0.05) for the 10, 20 and 30 mg Folltropin groups than for the 5 mg group. The 40 mg Folltropin group and the FSH-P group were intermediate. The percentage of fertilized and transferable embryos did not differ over the dosages used in this experiment. In Experiment 2, mean numbers of CL were greater for the 9, 18 and 36 mg Folltropin groups than for the 4.5 mg group, with the 9 mg group being lower than the 36 mg group (P<0.05). The 18 mg group was intermediate and did not differ. Mean numbers of ova/embryos recovered and fertilized ova were greater for the 9, 18 and 36 mg groups (P<0.05) than for the 4.5 mg group. The percent of fertilized and mean number and percentage of transferable embryos did not differ among treatments. We conclude that Folltropin may be a satisfactory superovulatory replacement for FSH-P and that a dose of 18 to 20 mg Folltropin may be within the optimum superovulatory dosage range for beef heifers. Dosages of Folltropin of more than twice the optimum did not result in deterioration of ova/embryo quality.

Superovulation and embryo recovery in Red deer () hinds

In two experiments, Red deer hinds were synchronized with intravaginal progesterone and were given 4 d of treatment (3 d before progesterone withdrawal and 1 d after) with an ovine follicle stimulating hormone (FSH) preparation which had a claimed low level of luteinizing hormone (LH) contamination. In Experiment 1, 12 hinds received one of four FSH levels by osmotic minipump. Hinds were run with fertile stags, and laparotomy and embryo recovery were performed 9 d after progesterone withdrawal. The ovulation rates (mean of three hinds per dosage) were 1.0, 2.0, 4.3 and 15.3 (number of corpora lutea counted) for estimated daily dosages rates of 0.036, 0.071, 0.11 and 0.14 units FSH preparation/day; the response to the increasing dosage was exponential (P<0.01). The recovery rate of ova on flushing was 38% (24 63 ), with all recovered ova being fertilized and of transferable quality. In Experiment 2, performed later in the breeding season, eight hinds received 0.14 units FSH/day either by minipump or by intramuscular injection. The mean ovulation rates were 3.0 and 11.0 (a significant difference, P<0.01), respectively, with a recovery rate of 72% (34 47 ), and with only 18 34 ova considered to be of transferable quality. The recovery rate in Experiment 2 was significantly higher than that in Experiment 1 (P<0.001). Overall, the results were better than those previously recorded for red deer, perhaps a function of both the FSH preparation used and an improved progesterone profile in estrus synchronization.

Ultrasonographic determination of ovarian follicular. Development in superovulated heifers pretreated with FSH-P at the beginning of the estrous cycle

On Day 3 of the estrous cycle (estrus = Day 0), dairy heifers were given either 10 mg i.m. FSH-P (FSH-P primed; n = 9) or a saline vehicle (saline primed; n = 9). On Day 10, all heifers were superovulated with FSH-P (total = 27.7 mg i.m.) in declining doses over 5 d. Heifers were inseminated artificially at estrus. From Day 2 until estrus, the number and size of follicles >2 mm were monitored daily by ultrasonography. The mean (+/- SEM) number of corpora lutea (CL) (6.2 +/- 1.5 vs 10.7 +/- 0.9; P<0.05) and the mean number of recovered embryos and unfertilized ova (3.6 +/- 1.7 vs 8.4 +/- 2.2; P<0.05) were lower in FSH-P-primed than in saline-primed heifers. Prior to initiation of superovulation, follicles >10 mm appeared on Days 6 to 7 in saline-primed heifers but only on Days 8 to 10 in FSH-P-primed heifers (P<0.05). Also, until Day 10, the mean number of follicles 4 to 6 mm and 7 to 10 mm was higher (P<0.05) in FSH-P-primed than in saline-primed heifers. After initiation of the superovulatory treatment (Day 10 to estrus), saline-primed heifers had a greater and faster increase in the mean number of follicles >10 mm (P<0.02) than FSH-P-primed heifers did. Depletion in the number of follicles 2 to 3 mm (P<0.001) between Day 10 and estrus and in the number of follicles 4 to 6 mm (P<0.05) between Day 12 and estrus occurred in both groups of heifers. Decreased superovulatory response and embryo recovery in FSH-P-primed heifers may have been due to the presence of large follicles (>10 mm) prior to the initiation of the superovulatory treatment which reduced the ability of small follicles to grow into larger size classes during superovulatory treatment.

Endocrine and superovulatory responses in heifers pretreated with FSH or bovine follicular fluid

This study examined the effects of altered serum FSH concentration on subsequent ovarian response to superovulation. Synchronized heifers were assigned randomly on Day 1 of the cycle (estrus = Day 0) to three pretreatment groups that consisted of 6-d of saline (7ml, s.c., b.i.d.; Group I), FSH-P (0.5 mg, i.m., b.i.d.; Group II) or charcoal-extracted bovine follicular fluid (BFF; 7 ml, s.c., b.i.d.; Group III) injections. Superovulation was initiated on Day 7 and consisted of FSH-P in decreasing dosages over 4 d (4,3,2,1 mg; i.m., b.i.d.), with cloprostenol (500 mug) on the morning of the third day. A second replicate with 14 heifers was conducted using the same protocol but twice the pretreatment dosage of FSH-P (1 mg) and BFF (14 ml). Endogenous plasma FSH decreased during BFF and FSH-P pretreatments compared to controls (P < 0.02). Endogenous FSH concentrations in both primed groups (II and III) were similar to control values (Group I) 12 h after the start of superovulation. Basal LH concentrations were not different between pretreatment groups. The interval from cloprostenol treatment to the preovulatory LH surge in Group III was 21.3 and 23.9 h longer (P < 0.0001) than it was in Groups I and II. The postovulation progesterone rise was delayed in Group III. The number of corpora lutea (CL) was lowest in the BFF-primed group (4.2 +/- 0.8) compared with the FSH-primed (7.4 +/- 1.3) and the control (12.0 +/- 1.8; P < 0.003) groups. In the FSH-primed group (0.68 +/- 0.06 cm(3)), CL volumes were larger than in the control group (0.45 +/- 0.03 cm(3)), whereas in the BFF-primed group (0.27 +/- 0.02 cm(3)) CL volumes were smaller compared with the control group (P < 0.0001). Mean FSH concentrations for 48 h preceding superovulation and the number of CL per cow were positively correlated (r = 0.55; P < 0.004; n = 26). We concluded that both FSH-P and BFF pretreatments decreased the superovulatory response of heifers to FSH-P. The mechanism for this would appear to be associated with reduced endogenous FSH prior to the start of superovulation.

Biotechnology. The key to improved animal production?

Biotechnology will influence the reproductive performance of cattle in a number of different ways. In animals breeding, embryo transfer has already had a significant impact on the way in which genetic selection of animals is performed. If other technologies such as embryo splitting, in vitro fertilization, cloning, and sex selection are superimposed on conventional embryo transfer, genetic gains will be achieved at an extremely rapid rate. The net result be a rapidly changing animal population in which genetic gains are maximized. Transgenic animals with altered genetic make-up will also have a dramatic effect on animal production. The general introduction of such animals will be slow and the cost to produce them will be enormous, as conventional selection and progeny testing will be needed to ensure that the "new" introduced genes are functional and do not have detrimental side effects. Simple, sensitive assays of hormones and proteins developed using biotechnology will aid in the monitoring of reproductive performance of animals.

Premature ovulations in superovulated cattle

The incidence and consequences of premature ovulations in superovulated cattle were studied. These ovulations, presumably induced by the luteinizing hormone content of the gonadotrophin preparation used, were found in 17 of 133 (13%) stimulated cows and heifers used as oocyte donors. In general this group of donors exhibited deviating periovulatory patterns of plasma hormone profiles (progesterone, estradiol17beta and LH), estrus behaviour, follicular steroidogenesis of progesterone and estradiol-17beta, and oocyte meiosis. It is concluded that superovulated donor cattle exhibiting premature ovulations constitute a group of poor oocyte donors that also must be considered as inferior embryo donors.

The efficiency of two nonsurgical techniques for bovine embryo recovery on days 6 and 7 of the estrous cycle

Two nonsurgical techniques for embryo recovery were employed and used in Days 6 and 7 of the estrous cycle. A significant difference between techniques was observed in both days of collection, with the closed system being more efficient in Day 6 and the opened one more efficient in Day 7. The bacteriological contamination of flushing medium (11% for the closed system and 21% for the opened technique) was of saprophytic bacteria and did not affect the percentage of pregnancies in either system.

In vitro fertilization and embryo transfer in domestic animals: applications in animals and implications for humans

Extensive research has been conducted in domestic animals, particularly in cattle, in the reproductive technologies of sperm handling, capacitation, and acrosome reaction, superovulation, and embryo handling, sexing, bisection, cryopreservation, and transfer. Because of the economic importance of cattle these technologies have been tested and improved under clinical conditions. The results of employing these procedures are available on tens of thousands of pregnancies and offspring. This information has implications in applying some of the same technologies in human reproduction. The large number of normal progeny produced in cattle after a long prenatal development period, similar to humans, provides some assurance that these technologies, carefully applied, are safe. The basis for these conclusions is documented in the publications cited in this review.

Superovulatory and endocrine responses in heifers treated with FSH-P at different stages of the estrous cycle

Forty-two Holstein heifers were superovulated with FSH-P (total dose, 30 mg) and cloprostenol. Treatment was initiated on Day 3 (Group D3, n = 11), Day 6 (Group D6, n = 11), Day 9 (Group D9, n = 10) or Day 12 (Group D12, n = 10) of the estrous cycle. Heifers were bled daily for serum progesterone and estradiol-17beta determinations and every 6 h for a 48-h duration at the expected time of estrus for luteinizing hormone (LH) assay. Ova and embryos were flushed from the reproductive tracts and the number of corpora lutea (CL) were recorded after slaughter on Day 7 post-estrus. Mean (+/- SEM) numbers of observed CL were higher (P < 0.05) in Group D9 (33.3 +/- 4.8) than in Group D3 (15.3 +/- 3.8), with Group D6 (17.0 +/- 2.9) and Group D12 (23.9 +/- 7.3) being intermediate. Similarly, mean (+/- SEM) numbers of fertilized embryos were highest (P < 0.05) in Group D9 (13.3 +/- 2.2). There was also a nonsignificant trend for the number of transferable embryos to be greatest in Group D9. Neither serum progesterone concentrations 3 d after the LH peak nor peak serum estradiol 17beta concentrations differed among groups, but both were significantly correlated with numbers of observed CL and total ova and embryos.

Superovulation of beef heifers with Pergonal (HMG): A dose response trial

A study was designed to establish a dose-response curve for Pergonal (Human Menopausal Gonadotrophin) and to compare its efficacy in inducing superovulation with commercial FSH-P. A recognized treatment schedule for HMG of two ampoules at 0, 12, 24 and 36 hours and one ampoule at 48, 60, 72, 84, 96 and 108 hours was considered to be our 100% effective dose level. Fifty mature cycling cross-bred beef heifers were superovulated on day 10 +/- 1 of their cycle. Treatment groups were HMG I (200% dose), HMG II (100% dose), HMG III )50% dose), HMG IV (25% dose) and FSH-P (total dose 32 mg). All groups received 500 ug of cloprostenol 72 hours after initiation of treatments. The heifers were observed for onset of estrus and inseminated at 12, 24 and 36 hours. All heifers were slaughtered on day 7 post-estrus and their reproductive tracts removed for processing. All heifers were bled once daily for progesterone estimation and four times daily for two days beginning 24 hours after cloprostenol injection, for luteinizing hormone and estradiol-17beta estimations. A dose response to HMG was demonstrated for number of corpora lutea and all classes of ova/embryos. HMG II (100% dose) closely approximated the optimum dose for superovulation. There was no significant difference between the HMG II group and the FSH-P group for mean number of transferable embryos. The 200% HMG dose did not increase the numbers of ovulations or ova recovered but did decrease the numbers of fertilized and transferable ova.