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Results for “Estrus Synchronization”

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PubMed1996

Farrowing induction with a combination of prostaglandin F(2alpha) and a peripherally acting alpha(2)--adrenergic agonist AGN 190851 and a combination of prostaglandin F(2alpha) and oxytocin.

We studied the effect of prostaglandin (PG) F(2alpha)-AGN 190851 on farrowing induction and compared it with that of PGF(2alpha)-oxytocin. Eighty crossbred, multiparous sows were randomly assigned to the following 4 treatment groups of 20 sows each: 1) control, saline-saline; 2) PGF(2alpha) (10 mg/sow)-oxytocin (30 IU/sow); 3) PGF(2alpha) (10 mg/sow)-AGN 190851 (0.06 mg/kg); and 4) PGF(2alpha) (10 mg/sow)-AGN 190851 (0.1 mg/kg). Either PGF(2alpha) or saline was administered intramuscularly on Day 111 of gestation at 11:30 h; AGN 190851, oxytocin or saline was administered intramuscularly 20 h after the first injection. The PGF(2alpha)-AGN 190851 (0.1 mg/kg) treated sows had the shortest mean farrowing interval (2.1 +/- 1.6 h, mean +/- SD) compared with the remaining treatment groups (control: 67.1 +/- 26.2 h; PGF(2alpha)-oxytocin: 5.6 +/- 6.7 h; PGF(2alpha)-AGN 190851 [0.06 mg/kg]: 3.0 +/- 2.8 h). Duration of farrowing, litter size, litter weight and interval from weaning to first estrus in sows were not significantly changed by these treatments. The PGF(2alpha)-oxytocin group had a significantly higher stillbirth rate than the control group, whereas the PGF(2alpha)-AGN 190851 (0.1 mg/kg) group had the lowest number of pigs born dead and stillbirth rate among the 4 treatment groups. These results suggested that the PGF(2alpha)-AGN 190851 combination can be used as an alternative method to PGF(2alpha)-oxytocin for synchronizing farrowing.

Journal Article↗

PubMed1992

Dynamics of gonadotropin-releasing hormone (GnRH) secretion during the GnRH surge: insights into the mechanism of GnRH surge induction.

Recent studies demonstrate unequivocally that a preovulatory surge of GnRH is secreted into pituitary portal blood during the estrous cycle of the ewe and that this surge is induced by the follicular phase rise in estradiol. These data, obtained at 10-min intervals, suggested the surge results from a continuous elevation of GnRH rather than from a sequence of discrete pulses. This study examines the dynamics of GnRH secretion in more detail to determine if the surge results from strictly episodic release of the decapeptide. Our approach was to monitor GnRH secretion into pituitary portal blood at very frequent intervals during several "windows" of the GnRH surge induced using a physiological model for the estrous cycle. Samples of portal blood were obtained at either 2-min intervals (6 ewes), or 30-sec intervals (12 ewes) at several times during the surge; at other times portal blood was sampled less often to monitor progression of the GnRH surge. All ewes had an unambiguous GnRH surge; amplitude ranged from 100- to 500-fold over pressure levels. Regardless of sampling interval, our results provide no convincing evidence to indicate the enhanced secretion of GnRH is strictly episodic; values remained continuously elevated in portal blood. Our findings are consistent with the hypothesis that the GnRH surge is not composed entirely of discrete synchronous secretory events, and they raise the possibility that one action of estradiol in inducing the GnRH surge may be to switch the pattern of GnRH secretion into portal blood from episodic to continuous.

Anestrus↗

PubMed1997

Effect of pregnancy and exogenous interferon on synchronous pulsatile release of oxytocin and luteolytic prostaglandin F2 alpha in red deer (Cervus elaphus).

Three experiments were carried out to investigate the secretion of luteolytic hormones in red deer hinds during the oestrous cycle, early pregnancy and after administration of interferon, the putative pregnancy recognition signal. Three groups of hinds (n = 8-9 per group) were treated with progesterone-impregnated intravaginal controlled internal drug releasing (CIDR) devices for 13 days (device withdrawal = day 0). Group 1 (n = 9) served as controls; Group 2 (n = 8) received injections of 4 mg recombinant bovine interferon-alpha 1 l twice a day on days 13-18; Group 3 (n = 9) were run with a fertile stag on days 0-3. Plasma samples collected each day on days 16-23 were analysed for progesterone. Plasma samples collected each hour for 16 h on days 4, 10, 16, 18 were analysed for oxytocin and the prostaglandin F2 alpha (PGF2 alpha) metabolite (PGFM). Plasma progesterone concentrations declined to < 1 ng ml-1 between days 18 and 25 in control hinds indicating that luteolysis had occurred, whereas there was no endocrine evidence of luteolysis in interferon-treated or pregnant hinds. Control hinds (6/9) exhibited synchronous pulses of oxytocin and PGF2 alpha secretion on day 18, a greater proportion than on any other day in these hinds or on any day in the interferon-treated or mated hinds (P < 0.05). In a second experiment, close synchrony in secretion of oxytocin and PGF2 alpha pulses was evident in an unmated hind when samples were collected every 12 min on day 18. In a third experiment, oxytocin-induced PGF2 alpha secretion was potentiated by oxytocin administration at an interval of 1 h and inhibited by administration at a 6 h interval (P < 0.05). These results suggest that synchronous pulsatile secretion of oxytocin and PGF2 alpha induces luteolysis and is suppressed by pregnancy or administration of interferon. Oxytocin-induced alterations in uterine oxytocin sensitivity may underlie the pulsatile nature of luteolytic hormone secretion in red deer.

Animals↗

PubMed1996

Variation factors of pregnancy rates after oestrus synchronization treatment in French Charolais beef cows.

An epidemiological study was conducted in Bourgogne (France) in Charolais herds sampled in 1990 (sample 1:54 herds) and from 1991 to 1993 (sample 2:33 herds). The aim was primarily to quantify, at both herd and individual levels, the factors that result in variations in the response to synchronization treatment as estimated by pregnancy rate after first insemination. The second goal was to test a similar model in sample 2, which included only primiparous cows. In sample 1,329 cows of the 627 studied (52%) became pregnant compared with 122 primiparous cows of the 249 studied (49%) in sample 2. Pregnancy rates after treatment per herd ranged from 0-100% across the herds. Mixed logistic regression was used to calculate the odds ratio (OR) and to take into account both individual and herd level variables for each sample. In the first sample, multiparous cows were more likely to become pregnant after synchronization treatment than primiparous cows (OR = 2.4, P < 0.001). The following individual variables also influenced the response to synchronization: body weight at implant insertion (OR = 1.006, P = 0.017) and calving difficulty (OR = 0.33, P = 0.008). In the second sample, results varied with the year of data collection (OR = 3.46, P = 0.016) and with two herd-level variables: presence of a bull (OR = 0.48, P = 0.047) and type of housing (OR = 2.5, P = 0.004). In conclusion, the results after synchronization depended on both herd-level and individual variables and it was necessary to take into account two levels of factors to reduce variability after treatment.

Animals↗

PubMed1998

Effects of repeated ultrasound-guided transvaginal follicular aspiration on bovine oocyte recovery and subsequent follicular development.

We wished to compare cumulus oocyte complex (COC) recovery and follicle development after single and repeated ultrasound-guided transvaginal follicle aspiration (aspiration). Aspirations were performed in Holstein-Friesian heifers every once weekly (every 7 d; n = 12) or twice weekly (every 3 or 4 d; n = 6) starting on Days 3 or 4 of the estrous cycle (estrus = Day 0) and continuing for 4 wk. During each session, all visible follicles > 2 mm were aspirated using an 7.5 MHz transducer to guide an 18 ga x 60 cm single lumen needle and applying 50 mm Hg vacuum which generated 25 mL/min. The COC's harvested from each follicle were counted and classified into 4 categories. Post-aspiration follicle wave emergence was traced by daily ultrasound examinations. A total of 1410 follicles were aspirated during 96 sessions, yielding 632 (45%)oocytes. There was no difference in average COC/follicle recovered between the single vs the repeated aspiration treatment. However, ovaries of heifers subjected to two aspirations per week yielded more follicles (17.2 +/- 5.7 vs 12.4 +/- 6.1; P < 0.01) and COC's (7.7 +/- 4.5 vs 5.4 +/- 3.7; P < 0.01) per session than those subjected to a single aspiration. Ovaries of heifers subjected to twice weekly aspirations at 4-d intervals resulted in a higher recovery rate (51.1 vs 38.6%), yielded more COC's (9.3 +/- 4.7 vs 6.2 +/- 3.8) and a higher number of viable COC's recovered per session (7.6 +/- 3.8 vs 5.2 +/- 3.3) than those aspirated every 3 d, all P < 0.01. Aspiration-induced follicle waves were indicated by an increased number of follicle > or = 4 mm seen within 2 d of the procedure. We conclude that follicle aspiration appears to induce and synchronize follicle waves, and when it is done twice a week it is associated with higher number of harvestable follicles and more oocytes recovered than when done once a week. These results can be attributed to the aspiration of a newly recruited pull of follicles 3 or 4 d after the first aspiration and before the establishment of follicular dominance and regression of subordinate follicles.

Animals↗

PubMed1980

Effects of long-term adrenalectomy on periovulatory increases in serum gonadotrophins and ovulation in rats.

The effects of chronic adrenalectomy on the oestrous cycle, periovulatory gonadotrophin surges in sera and ovulation in the rat were assessed. Rats which were exposed to a 14 h light : 10 h darkness lighting schedule for at least 3 weeks and those which showed at least two consecutive 4 day oestrous cycles were divided into three groups. One group (controls) was left untreated. The rest were adrenalectomized (ADX) or sham-adrenalectomized (Sham) during oestrus and then placed in a different animal room with the same lighting schedule but with the onset and end of the photoperiod delayed by 4 h. These operations did not interrupt the length of the oestrous cycles. Rats were decapitated for collection of trunk blood on the fifth pro-oestrous or oestrous day after the operation. Both Sham and ADX rats synchronized to the new lighting schedule in terms of the temporal patterns of their periovulatory surges in serum LH and FSH and the timing of ovulation. Neither adrenalectomy nor the sham-operation altered the magnitude of the pro-oestrous or oestrous increases in serum LH or FSH when compared with those in control rats. Body, uterine and ovarian weights as well as the number of ova shed were similar in the ADX and Sham groups. The results indicate that adrenal secretions are not necessary for rats to synchronize the timing of the periovulatory surges in serum LH and FSH or ovulation to a 14 h light : 10 h darkness schedule and the periovulatory surges of LH and FSH are unaltered in chronically adrenalectomized rats.

Adrenal Glands↗

PubMed1984

Evaluation of the involvement of the adrenals in the pheromonal influences on the oestrous cycle of laboratory mice.

Unisexual grouping of female mice induced irregularities in their oestrous cycles. However, no significant difference in body weight and in the weights of adrenals, uteri and ovaries and in the adrenal delta 5 3 beta-hydroxysteroid dehydrogenase (HSD) activity was found between unisexually grouped females and individually housed females. Adrenalectomy of females failed to prevent the oestrous cycle irregularities induced by unisexual grouping. Furthermore, adrenalectomized females in unisexual groups responded to exposure to males by exhibiting oestrus acceleration and synchronization (the Whitten effect). The results rule out the involvement of the adrenals in the oestrous cycle irregularities induced by unisexual grouping and in the induction of the Whitten effect in unisexually grouped females.

3-Hydroxysteroid Dehydrogenases↗

PubMed1978

Time of ovulation in ewes after treatment with a prostaglandin F-2alpha analogue.

Treatment of 18 cyclic Clun Forest ewes with two i.m. injections of ICI 80,996, given 9 days apart and without reference to stage of the oestrous cycle, synchronized ovulation in all ewes at a mean time interval of 73.1 +/- 1.6 (s.e.m.) h from the second injection. The interval from the LH peak to ovulation was 22.6 +/- 0.7 h and this is comparable to previously reported gigures for a natural oestrus.

Animals↗

PubMed2005

Developmental competence of somatic cell nuclear transfer embryos reconstructed from oocytes matured in vitro with follicle shells in miniature pig.

The developmental competence of domestic pig oocytes that were transferred to somatic cell nuclei of miniature pig was examined. A co-culture system of oocytes with follicle shells was used for the maturation of domestic pig oocytes in vitro. Co-cultured oocytes progressed to the metaphase II stage of meiosis more quickly and more synchronously than non co-cultured oocytes. Oocytes were enucleated and fused with fibroblast cells of Potbelly miniature pig at 48 h of maturation. The blastocyst formation rate of nuclear transfer (NT) embryos using cocultured oocytes (24%) was significantly higher (p < 0.05) than that of non-co-cultured oocytes (13%). Cleaved embryos at 48 h after nuclear transfer using co-cultured oocytes were transferred to the oviducts of 14 Göttingen miniature pigs and four Meishan pigs. Estrus of all Göttingens returned at around 20-31 days of pregnancy. Two of the four Meishans became pregnant. Three and two cloned piglets were born after modest number of embryo transfer (15 and 29 embryos transferred), respectively. These results indicated that oocytes co-cultured with follicle shells have a high developmental competence after nuclear transfer and result in full-term development after embryo transfer.

Animals↗

PubMed1995

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.

Journal Article↗

PubMed1989

Developmental competence of pig oocytes matured and fertilized in vitro.

Pig follicles 3 to 6 mm in diameter were everted and matured for 44 h. The oocytes were then collected and exposed to capacitated boar sperm purified by centrifugation in a two step (65 and 70%) Percoll gradient. Of 110 ova fixed 14 h after in vitro fertilization, 78% were penetrated and 47% were monospermic. Next, 681 oocytes were cultured in vitro for 44 h after in vitro fertilization and the 266 embryos which had reached the two- to four-cell stage were transferred into the oviducts of 12 synchronized recipient gilts. Four days later, 211 embryos (79%) were recovered by uterine flushing. 40.7% of these were at the blastocyst stage, and 20% were at the morula stage. In a final experiment, four out of eight gilts which had received 40 to 50 two- to four-cell embryos, were diagnosed pregnant 30 and 37 d after in vitro fertilization. One sow farrowed nine live piglets and one stillborn, two pregnancies were in progress, while one sow returned to estrus 47 d after in vitro fertilization. These results demonstrate that pig oocytes matured and fertilized in vitro can develop to the blastocyst stage and establish a normal pregnancy resulting in the birth of live piglets.

Journal Article↗

PubMed1997

Timing of mating, developmental asynchrony and the sex ratio in mice.

According to the developmental asynchrony hypothesis, changing the time of mating within the estrous cycle could alter the interval between completion of blastocyst development and uterine responsiveness for implantation. This may then lead to sex ratio skews in animals that exhibit sex-differential blastocyst development, because uterine stage may now benefit either slow (female) or fast (male) developing blastocysts. To test this hypothesis, the responses of two strains of mice to altered mating dynamics were compared. In a strain that exhibits higher male than female blastocyst developmental rates, sex ratios became significantly female-biased when mated late during the estrous cycle as opposed to early mating. However, timing of mating did not affect sex ratios in a strain with synchronous development of male and female preimplantation embryos. Hence, it is concluded that developmental asynchrony between male and female blastocysts on the one hand, and blastocysts and uterus on the other, are indeed responsible for the effect of timing of mating on litter sex ratios in mice.

Animals↗

PubMed1983

Survival of bovine embryos stored at 4 degrees C.

These experiments were designed to test the efficacy of storing bovine embryos at 4 degrees C. Of particular interest were the age of embryo at which maximum post-storage survival could be achieved and longevity at 4 degrees C. A greater proportion of day 8 blastocysts developed in vitro at 37 degrees C following refrigeration for 48 hr than did embryos collected 2, 4 or 6 days after estrus (P<0.01). Survival of blastocysts stored at 4 degrees C for 48 hr was similar to that of nonstored blastocysts. In a subsequent experiment, day 8 blastocysts were recovered nonsurgically and assigned to one of the following treatments: (a) immediate transfer; (b) culture at 37 degrees C; or (c) storage at 4 degrees C for 1, 2, 3 or 5 days. Post-storage viability was assessed by either development in culture at 37 degrees C or embryo survival following nonsurgical transfer to synchronized recipients. In vitro survival of nonstored embryos and embryos stored 1 day did not differ. Survival decreased after storage for 2 days (P<0.10) or longer (P<0.05). Similar results were observed for survival after transfer, but embryo viability decreased even more rapidly with increasing duration of storage. In vitro survival was approximately 50% for blastocysts stored for 3 and 5 days, but few pregnancies resulted from transfer of embryos stored for these periods. In another experiment survival after transfer of blastocysts stored at 4 degrees C for up to 2 days was similar to that of nonstored blastocysts.

Journal Article↗

PubMed2000

Use of bovine somatotropin in lactating dairy cows receiving timed artificial insemination.

Objectives of the research were to examine the effect of bovine somatotropin (bST) on pregnancy rates to a timed artificial insemination protocol and to test a resynchronization system with two consecutive synchronized services. Lactating Holstein cows (n = 403) were assigned to the following treatments: bST treatment (500 mg) was initiated at 63 +/- 3 d postpartum concomitantly with initiation of the timed artificial insemination protocol or bST treatment was initiated at 105 +/- 3 d postpartum. At 63 +/- 3 d postpartum, all cows received GnRH (100 microg), an injection of PGF2alpha (25 mg) 7 d later, and a GnRH injection at 48 h after PGF2alpha and were inseminated 16 to 20 h later. Cows were reinseminated at detected estrus or resynchronized with a GnRH injection at 20 d after insemination. At 27 d after insemination, cows were examined for pregnancy. Resynchronized cows diagnosed nonpregnant received an injection of PGF2alpha and were inseminated at detected estrus or received an injection of GnRH at 48 h after PGF2alpha and inseminated 16 to 20 h later. Cows pregnant at d 27 were reexamined for pregnancy at 45 d after insemination. First-service pregnancy rates at d 45 were increased in cows not resynchronized that initiated bST treatment at 63 +/- 3 d postpartum, compared with cows initiating bST treatment at 105 +/- 3 d postpartum (37.7 +/- 5.8% and 22.1 +/- 4.2%, respectively), but the effect of bST treatment was not observed when cows were resynchronized (25.6 +/- 4.3% and 25.8 +/- 5.5%, respectively). Thus, bST increased pregnancy rates to a timed artificial insemination protocol.

Analysis of Variance↗

PubMed1999

Synchronization rate, size of the ovulatory follicle, and pregnancy rate after synchronization of ovulation beginning on different days of the estrous cycle in lactating dairy cows.

Recently a protocol was developed that precisely synchronizes the time of ovulation in lactating dairy cows (Ovsynch; GnRH-7d-PGF2 alpha-2d-GnRH). We evaluated whether initiation of Ovsynch on different days of the estrous cycle altered the effectiveness of this protocol. The percentage of cows (n = 156) ovulating to the first GnRH was 64% and varied (P < 0.01) by stage of estrous cycle. Treatment with PGF2 alpha was effective, with 93% of cows having low progesterone at second GnRH. The overall percentage of cows that ovulated after second GnRH (synchronization rate) was 87% and varied by response to first GnRH (92% if ovulation to first GnRH vs 79% if no ovulation; P < 0.05). There were 6% of cows that ovulated before the second injection of GnRH and 7% with no detectable ovulation by 48 h after second GnRH. Maximal diameter of the ovulatory follicle varied by stage of estrous cycle, with cows in which Ovsynch was initiated at midcycle having the smallest follicles. In addition, milk production and serum progesterone concentration on the day of PGF2 alpha affected (P < 0.05) size of the ovulatory follicle. Using these results we analyzed pregnancy rate at Days 28 and 98 after AI for cows (n = 404) in which Ovsynch was initiated on known days of the estrous cycle. Pregnancy rate was lower for cows expected to ovulate larger follicles than those expected to ovulate smaller follicles (P < 0.05; 32 vs 42%). Thus, although overall synchronization rate with Ovsynch was above 85%, there were clear differences in response according to day of protocol initiation. Cows in which Ovsynch was initiated near midcycle had smaller ovulatory follicles and greater pregnancy rates.

Animals↗

PubMed1980

Hormonal correlates of hypophagia in white-tailed deer.

Deer exhibit a number of adaptive annual changes in common with hibernators. Each winter deer have a period of voluntary hypophagia and losses of body weight. This is accompanied by a shift to fat metabolism and increased recycling of urea nitrogen to maintain positive nitrogen balance. Deer also show alterations in activity patterns and decreased metabolic rates, heart rates, and body temperatures during winter. Male deer exhibit an additional period of hypophagia associated with rut. Rut-associated hypophagia is either directly controlled by serum testosterone or internally coupled to the annual testosterone cycle. The adaptive value of rut-associated hypophagia is unknown but may be associated with insuring reproductive success. Both winter and rut-associated hypophagia are most likely synchronized to the environment by photoperiod. The winter adaptive changes may be caused by a primary alteration in appetite control with secondary changes in thyroid hormone economy, or the hypophagia may be independent but internally coupled to other neuroendocrine changes.

Animals↗

PubMed2005

Configurations of germinal vesicle (GV) chromatin in the goat differ from those of other species.

Configuration of germinal vesicle (GV) chromatin has been studied and found correlated with the developmental competence of oocytes in several mammalian species. A common feature in the configuration of GV chromatin in the species studied so far is that the diffuse chromatin (the so called "NSN" pattern) condenses into a perinucleolar ring (the so called "SN" configuration) with follicular growth. However, no study has been published on the configuration of GV chromatin in the goat. Nor is it known whether the perinucleolar ring of condensed chromatin (CC) in an oocyte represents a step toward final maturation or atresia. Changes in configurations of GV chromatin and RNA synthesis during goat oocyte growth, atresia and maturation in vivo and in vitro were investigated in this study. Based on both the size of nucleoli and the degree of chromatin condensation, the GV chromatin of goat oocytes was classified into GV1 characterized by large nucleoli and diffuse chromatin, GV2 with medium-sized nucleoli and condensed net-like (GV2n) or clumped (GV2c) chromatin, GV3 with small nucleoli and net-like (GV3n) or clumped (GV3c) chromatin, and GV4 with no nucleolus but clumped chromatin. The results showed that (i) the configurations of GV chromatin in the goat differ from those of other species in that the chromatin did not condense into a perinucleolar ring; (ii) most of the goat oocytes are synchronized at the GV3n configuration before GVBD; (iii) the GVn pattern might represent a healthy state, but the GVc an atretic state; (iv) in both goats and mice, the GC-specific (Chromomycin A3, CMA3) and the AT-specific (Hoechst 33342) fluorochromes followed the same pattern of distribution in GV chromatin; (v) the nucleolar size decreased significantly with oocyte growth and maturation in vivo and in vitro; and (vi) goat oocytes began GVBD at 8 hr and had completed it by 20 hr after onset of estrus. The peculiar configuration of GV chromatin of goat oocytes can be a useful model for studies of morphological and functional changes of different nuclear compartments during the cell cycle and cell differentiation, and the functional differentiation between GV3n and GV3c might be used for reference to the question whether the "SN" configuration in other species inclines toward ovulation or atresia.

Animals↗

PubMed1986

Ovarian activities of the West African dwarf goat (Capra hircus) during oestrus.

Ovarian activity was studied by laparotomy of 9 adult nulliparous goats in which oestrus was synchronized. Ovulation occurred in animals operated on 20-48 h from the onset of sexual receptivity. There was a mean ovulation rate of 1.57 ova per doe and the right and left ovaries had similar follicular activity in relation to sizes of follicles and ovulations.

Animals↗