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PubMed2026

First evaluation of a novel recombinant eCG molecule in ewes reveals a discrepancy between ovulatory response and pregnancy outcome.

This study evaluated the reproductive performance and clinical safety of a novel recombinant eCG (r-eCG) in ewes. Two weeks prior to study onset (Day 0: intravaginal progesterone device insertion), 45 ewes were randomly assigned to negative control (NC; no eCG; n = 10), positive control (PC; 400IU commercial non-recombinant eCG; n = 20), or treatment group (T; 400IU r-eCG; n = 15). Ewes were inseminated with fresh-diluted semen (200 × 106 sperm). Ultrasonography assessed follicle count/diameter (days 11, 13), ovulation (day 13), corpus luteum (CL) number/characteristics (day 20), and pregnancy (day 44). Serum progesterone was measured on day 20; Group T underwent clinical/hematological evaluations (days 0, 20, and 44). Estrus signs were more frequent (P < 0.01) in T (100%) than NC (50%), while PC (85%) did not differ. Ovulation rates were similar between T (93%) and PC (95%), but higher than NC (50%; P < 0.05). On day 13, largest follicle diameter did not differ (P > 0.05) among groups; however, fewer follicles > 2 mm occurred in PC than NC and T (P < 0.05). CL number was higher in T than PC (2.0 ± 0.3 vs. 1.0 ± 0.0, P < 0.01), while NC did not differ (1.0 ± 0.25). Conversely, pregnancy rate was higher (P < 0.05) in PC (70%) than T (28.6%) and NC (20%). Among ovulated ewes, progesterone concentration and progesterone/CL ratio did not differ among groups (P = 0.92 and P = 0.08, respectively). No relevant r-eCG-related clinical or hematological alterations occurred. In conclusion, 400IU r-eCG effectively induces estrus and ovulation without adverse effects; however, the discrepancy between ovulatory response and pregnancy rate underscores the need for further study refinement to improve fertility.

Animals↗

PubMed1997

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 (</= 3 d) associated with low serum progesterone (maximum of </= 1.4 ng/ml) were detected after superovulation in 1 16 and 6 9 ewes in the Day 0 and Day 3 groups, respectively (P < 0.001). In conclusion, gonadotropin treatment initiated at the time of emergence of Wave 1 induced a superovulatory response in ewes. Response was influenced by the status of the follicular wave. The presence of a large growing follicle at time of superstimulatory treatment was associated with lower follicle recruitment, fewer ovulations, fewer transferable embryos, and the development of functionally subnormal corpora lutea (CL). The results demonstrate that follicle dominance is operative during the early luteal phase of the ovine estrous cycle.

Journal Article↗

PubMed1988

Steroid control of gonadotropin secretion and ovarian function in heifers.

The failure of anti-steroid treatments to induce multiple ovulations in cattle in a repeatable way, prompted us to examine the role of the gonadal steroids in the control of gonadotropin secretion in this species. A better understanding of the control of gonadotropin secretion in the cow would assist in the development of treatments to control prolificacy. Groups of six heifers were implanted with one of three sizes of estradiol (E2) implant on day 9 of a synchronized estrous cycle, and five control heifers received empty implants. All heifers were ovariectomized during the luteal phase of the subsequent estrous cycle and given progesterone-releasing intravaginal devices (PRID). Blood samples were taken every 10 min for 12 h with PRIDs and for 6 h after PRID withdrawal, for the measurement of LH and FSH concentrations. The two larger implant sizes (increasing E2 concentrations to 7.4 and 18.7 pg/ml plasma during the luteal phase of the cycle) decreased ovulation rate, the number of large follicles, and luteal weight. After ovariectomy, the three implant sizes produced E2 concentrations comparable with those during the luteal and follicular phases of the estrous cycle and at estrus (1.5, 4.4, and 10.5 pg/ml, respectively). E2 alone decreased mean LH and FSH concentrations and LH pulse amplitude, whereas progesterone alone reduced mean gonadotropin concentrations and LH pulse frequency. Only in the presence of progesterone did E2 decrease LH pulse frequency. Steroid concentrations which mimicked those of the luteal and follicular phases of the cycle produced luteal- and follicular-phase patterns of LH and FSH secretion. These results confirm that E2 and progesterone are important regulators of gonadotropin secretion in cattle, and question the role of inhibin in this respect.

Animals↗

PubMed2005

Strategic use of gonadotrophin-releasing hormone (GnRH) to increase pregnancy rate and reduce pregnancy loss in lactating dairy cows subjected to synchronization of ovulation and timed insemination.

The objective of this study was to determine the effect of GnRH (100 microg i.m.) treatment 5 and 15 days after timed insemination (TAI) on pregnancy rate and pregnancy loss in lactating dairy cows subjected to synchronization of ovulation. The study included 831 lactating dairy cows subjected to a Presynch-Ovsynch protocol for first service. On the day of TAI (Day 0), cows were randomly assigned to one of four experimental groups. Cows in Group 1 (n = 214) were treated with GnRH on Day 5; cows in Group 2 (n = 209) were treated with GnRH on Day 15; cows in Group 3 (n = 212) were treated with GnRH on both Day 5 and Day 15; cows in Group 4 (n = 196) were not treated. Pregnancy rate was evaluated at Day 27 and Day 45 after TAI. The interestrus interval and the proportion of cows diagnosed not pregnant based on expression of estrus and insemination before pregnancy diagnosis on Day 27 were determined. The results of this study are: (1) GnRH treatment on Day 5 or Day 15 did not increase pregnancy rate, or reduce pregnancy loss between Day 27 and Day 55 after TAI; (2) cows treated with GnRH on both Day 5 and Day 15 had a lower (P < 0.01) proportion of cows diagnosed not pregnant based on expression of estrus before ultrasonography on Day 27 (26.5%) compared to control cows (52.9%), and these cows had an extended (P = 0.05) interestrus interval (23.4 days vs. 21.5 days); and (3) GnRH treatment on both Day 5 and Day 15 after TAI reduced pregnancy rate on Day 27 (36.8% vs. 44.4% for control cows; P < 0.03) and Day 55 (28.3% vs. 36.2% for control cows; P < 0.01). Therefore, strategies to stimulate CL function using multiple doses of GnRH during the luteal phase need to consider potential negative effects.

Abortion, Veterinary↗

PubMed2000

Effect of administering a crude equine gonadotrophin preparation to mares on follicular development, oocyte recovery rate and oocyte maturation in vivo.

In mares, the shortage of oocytes and the variability in nuclear maturation at a certain time of the oestrous cycle hinders the optimization of methods for in vitro maturation and in vitro fertilization. Increasing the number of small-to-medium-sized follicles available for aspiration in vivo may increase the overall oocyte yield. The aims of the present study were to investigate whether administration of crude equine gonadotrophins affects follicular development, oocyte recovery rate, in vivo oocyte maturation and follicular concentrations of meiosis-activating sterols. During oestrus, all follicles >/= 4 mm were aspirated from 19 pony mares (first aspiration: A1). Over the next 8 days, the mares were treated daily with either 25 mg crude equine gonadotrophins (n = 10) or physiological saline (n = 9). Between day 1 and day 8, follicular growth was monitored by ultrasonography. On day 8, all follicles >/= 4 mm were evacuated (second aspiration: A2) and nuclear maturation of the recovered oocytes was assessed after orcein staining. Follicular growth between A1 and A2, as well as the number and size of follicles at A2 were similar for control mares and mares treated with crude equine gonadotrophins. The oocyte recovery rates at A1 and A2 were similar. At A2, the oocyte recovery rate and oocyte maturation in vivo were not affected by treatment with crude equine gonadotrophins. The number of expanded cumulus oophorus complexes recovered from follicles </= 29 mm was significantly higher at A1 than at A2. The number of oocytes at the germinal vesicle stage was significantly higher at A2 (41.5%) than at A1 (17.8%). Meiosis-activating sterols (FF-MAS and T-MAS) were identified in follicular fluid recovered at A2. Follicular concentrations of FF-MAS and T-MAS were unaffected by treatment with crude equine gonadotrophins. The present study demonstrates that follicular aspiration during oestrus allowed a new follicular population to develop and resulted in a higher degree of synchronization of oocyte development with respect to cumulus expansion and nuclear maturation. The availability of a more homogeneous population of oocytes might facilitate a better optimization of in vitro maturation and in vitro fertilization techniques in mares. Administration of crude equine gonadotrophins during early dioestrus did not affect the growth of small follicles, the oocyte yield after aspiration or oocyte maturation in vivo.

Animals↗

PubMed1980

[Hypocalcemia in the horse. A case report].

With reference to previous reports on hypocalcemia in horses special attention is given to the principal symptoms such as anxiety, increased muscular tension, esp. of the musculature of the extremities, in severe cases leading to ataxia, and to a pulse-synchronized respiration (Synchronous Diaphragmatic Flutter). The time of appearance of the symptoms are much more variable than it is the case for hypocalcemic agalactia in cows. Furthermore the condition has been reported in foals as well as in geldings. Thus the triggering factor seems to be somewhat different from that of agalactia. Hypocalcemic horses also develop decreased manganese blood-level. Treatment with Ca-borogluconat in the horse can be as efficient as is the case in agalactia in the cows, but quite often it is necessary to repeat the treatment. This is illustrated by the fact that the relatively high dose (17 mg Ca/kg) administered to the present patient only increased the Calcium blood level to somewhat below normal. The triggering condition, estrus, weaning of the foal, stress, hard (sweat-provoking) work etc., in many cases perhaps a kind of mental stress, must be adequately treated. An all-round and sufficient feed ration in accordance with the working load and eventually with milk production may prove to be much more essential than realized so far for the prevention of hypocalcemia in horses.

Animals↗

PubMed2006

Response to GnRH on day 6 of the estrous cycle is diminished as the percentage of Bos indicus breeding increases in Angus, Brangus, and Brahman x Angus heifers.

Angus (n=6), Brangus (5/8 Angus x 3/8 Brahman, n=6), and Brahman x Angus (3/8 Angus x 5/8 Brahman, n=6) heifers exhibiting estrous cycles at regular intervals were used to determine if the percentage of Bos indicus breeding influenced the secretory patterns of LH in response to a GnRH treatment on Day 6 of the estrous cycle. Heifers were pre-synchronized with a two-injection PGF(2 alpha) protocol (25 mg i.m. Day -14 and 12.5 mg i.m. Day -3 and -2 of experiment). Heifers received 100 microg GnRH i.m. on Day 6 of the subsequent estrous cycle. Blood samples were collected at -60, -30, and -1 min before GnRH and 15, 30, 60, 90, 120, 150, 180, 240, 300, 360, 420, and 480 min after GnRH to determine concentrations of serum LH. Estradiol concentrations were determined at -60, -30, and -1 min before GnRH. On Day 6 and 8, ovaries were examined by ultrasonography to determine if ovulation occurred. On Day 13, heifers received 25 mg PGF(2 alpha) i.m. and blood samples were collected daily until either the expression of estrus or Day 20 for heifers not exhibiting estrus to determine progesterone concentrations. There was no effect (P>0.10) of breed on ovulation rate to GnRH as well as size of the largest follicle, mean estradiol, and mean corpus luteum volume at GnRH. Mean LH was greater (P<0.05) for Angus (7.0+/-0.8 ng/mL) compared to Brangus (4.6+/-0.8 ng/mL) and Brahman x Angus (2.9+/-0.8 ng/mL), which were similar (P>0.10). Mean LH peak-height was similar (P>0.10) for Brangus (13.9+/-3.4 ng/mL) compared to Angus (21.9+/-3.4 ng/mL) and Brahman x Angus (8.0+/-3.4 ng/mL), but was greater (P<0.05) for Angus compared to Brahman x Angus. Interval from GnRH to LH peak was similar (P>0.10) between breeds. As the percentage of Bos indicus breeding increased the amount of LH released in response to GnRH on Day 6 of the estrous cycle decreased.

Animals↗

PubMed1993

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.

Journal Article↗

PubMed1977

Modulation of the proestrous surge of luteinizing hormone by electrochemical stimulation of the amygdala and hippocampus in the unanesthetized rat.

The roles played by the amygdala and hippocampus in controlling the release of pituitary luteinizing hormone (LH) were studied in the freely moving rat. Monopolar stainless steel electrodes were implanted into the corticomedial (CM) amygdala, basolateral (BL) amygdala and dorsal hippocampus of female rats. When the animal had recovered from surgery and shown two consecutive 4-day estrous cycles, a chronic atrial cannula was introduced during the afternoon of diestrus II. On the following day (proestrus) electrochemical stimulation (ECS) was applied (20--50 micronA anodal DC 120 sec) bilaterally to the amygdala or hippocampus and blood samples were taken every 90 min from 12.00 to 21.00 h for radioimmunoassay (RIA) of LH. Next day, uterine tubes were examined for ova as evidence of ovulation. ECS of the amygdala exerted two divergent influences on LH release. Stimulation of the BL amygdala at 13.45 h, just before the critical period (14.00--16.00 h), was effective in delaying and reducing the LH surge, whereas ECS of the CM amygdala at 12.00 h resulted in an early synchronization in the timing of the LH curves. All of the rats in both groups ovulated, in contrast to the results of applying ECS to the dorsal hippocampus; there the LH surge and ovulation were completely blocked in 7 out of 9 rats. Thus, in the freely moving rat, the hippocampus can exert a potent inhibitory influence on LH release whereas the amygdala plays a modulatory role in the process.

Amygdala↗

PubMed1984

Relationship between pituitary responsiveness to Gn-RH and number of Gn-RH-binding sites in pituitary glands of beef cows.

Changes in the ability of Gn-RH to induce gonadotrophin release with time after synchronization of oestrus was determined in 4 groups of 6 cows each. Cows were given Gn-RH at 40-min intervals for 6 h beginning at -24, 0, 18 or 36 h (time 0 = removal of progestagen implant). Changes in concentration (ng/ml) of serum LH after Gn-RH averaged 2.9, 6.2, 6.4 and 33.4, whereas serum FSH averaged 25.7, 35.8, 35.8 and 97.3. Thus the responsiveness of the pituitary to Gn-RH had increased by 36 h after implant removal. Other groups of cows subjected to the same synchronization scheme were slaughtered at 0 h, 24 h or at various times after onset of oestrous behaviour. Gn-RH binding to crude pituitary membrane preparations was assessed. There was no apparent change in the affinity constant of Gn-RH-binding sites with time after synchronization. The number of Gn-RH-binding sites remained unchanged until the period of oestrus when a significant decline with time was detected. We conclude that the increase in pituitary responsiveness to Gn-RH that occurs before the preovulatory gonadotrophin surge was not directly associated with changes in number or affinity of pituitary Gn-RH-binding sites in crude pituitary membrane preparations.

Animals↗

PubMed1982

Estradiol induces and progesterone inhibits the preovulatory surges of luteinizing hormone and follicle-stimulating hormone in heifers.

Objectives were to determine: 1) whether estradiol, given via implants in amounts to stimulate a proestrus increase, induces preovulatory-like luteinizing hormone (LH) and follicle-stimulating hormone (FSH) surges; and 2) whether progesterone, given via infusion in amounts to simulate concentrations found in blood during the luteal phase of the estrous cycle, inhibits gonadotropin surges. All heifers were in the luteal phase of an estrous cycle when ovariectomized. Replacement therapy with estradiol and progesterone was started immediately after ovariectomy to mimic luteal phase concentrations of these steroids. Average estradiol (pg/ml) and progesterone (ng/ml) resulting from this replacement were 2.5 and 6.2 respectively; these values were similar (P greater than 0.05) to those on the day before ovariectomy (2.3 and 7.2, respectively). Nevertheless, basal concentrations of LH and FSH increased from 0.7 and 43 ng/ml before ovariectomy to 2.6 and 96 ng/ml, respectively, 24 h after ovariectomy. This may indicate that other ovarian factors are required to maintain low baselines of LH and FSH. Beginning 24 h after ovariectomy, replacement of steroids were adjusted as follows: 1) progesterone infusion was terminated and 2 additional estradiol implants were given every 12 h for 36 h (n = 5); 2) progesterone infusion was maintained and 2 additional estradiol implants were given every 12 h for 36 h (n = 3); or 3) progesterone infusion was terminated and 2 additional empty implants were given every 12 h for 36 h (n = 6). When estradiol implants were given every 12 h for 36 h, estradiol levels increased in plasma to 5 to 7 pg/ml, which resembles the increase in estradiol that occurs at proestrus. After ending progesterone infusion, levels of progesterone in plasma decreased to less than 1 ng/ml by 8 h. Preovulatory-like LH and FSH surges were induced only when progesterone infusion was stopped and additional estradiol implants were given. These surges were synchronous, occurring 61.8 +/- 0.4 h (mean +/- SE) after ending infusion of progesterone. We conclude that estradiol, at concentrations which simulate those found during proestrus, induces preovulatory-like LH and FSH surges in heifers and that progesterone, at concentrations found during the luteal phase of the estrous cycle, inhibits estradiol-induced gonadotropin surges. Furthermore, ovarian factors other than estradiol and progesterone may be required to maintain basal concentrations of LH and FSH in heifers.

Animals↗

PubMed2000

Monoamine oxidase activity in some brain areas of sheep after hormonal stimulation.

The influence of hormonal superovulatory preparations Folistiman (450 IU FSH, Spofa, Prague) and serum gonadotropin (1500 IU PMSG, Spofa, Prague) on monoamine oxidase (MAO), the degradative enzyme of catecholamines, was investigated in some areas of the brain regulating reproductive functions (area preoptica of the hypothalamus, pituitary gland, and pineal gland) in ewes with synchronized oestrus (20 mg chlorsuperlutin) during the oestrous period using a radiochemical method. After intramuscular administration of 1500 IU PMSG, marked increase of MAO activity was found in the area preoptica (p < 0.05) and in the pituitary gland (p < 0.01) in comparison with the control group. No change occurred in MAO activity after ovarian stimulation with FSH. Administration of the above superovulatory preparations failed to induce MAO activity in the pineal gland of sheep.

Animals↗

PubMed1979

Reproductive management of mares without detection of oestrus.

The use of photoperiod, progestagen, prostaglandin and hCG treatments was investigated to obtain mating of mares at predetermined times. The objectives were: (1) synchronization of oestrus at an early time of the year, (2) simplification of treatment schedules by use of vaginal sponges, and (3) use of several controlled cycles by successive synchronization. The following conclusions were reached. First, after a 16 h photoperiod was applied beginning on 25 November, hormonal synchronization of oestrus and ovulation followed by cyclicity were obtained on 1 February; i.e. 2 months of light are essential as hormonal synchronization of ovulation was not obtained by 10 January. Second onset of oestrus was well synchronized after vaginal application of progestagens (3.75 days +/- 0.98 s.d. after withdrawal) and in spite of vaginal irritation, fertility was high (71%, N = 24) after mating every 48 h of the induced oestrus. Third, for synchronization of return to oestrus in mated non-conceiving mares, oral progestagens were given from Days 7 to 21 after mating. Predetermined mating (Days 27 and 29) and hCG injection (day 28) for non-pregnant animals were decided after a progesterone assay of Day 21 blood plasma. After 3 controlled mating periods, the cumulative fertility was 88% (N = 24) in non-lactating mares and 58% (N = 19) in lactating mares. Programmed reproductive management is possible in the horse.

Animals↗

PubMed1988

[Timing of transplantation and success of pregnancy in mammals].

In domestic mammals, the optimum time for embryo transfer greatly depends upon the species and its embryo chronology development and the technique used. Three different models (rabbit, pig, bovine) have been studied to set up the importance of cycle synchrony between donor and recipient. In the rabbit, the best survival rates were obtained after tubal transfer to highly synchronous recipients even for frozen or cultured embryos. In the pig, there was no survival difference after embryo transfer on D2 (oviduct) or D6 (uterus) and an asynchrony up to 24 h was possible. In the bovine, embryo transfer is usually performed at the blastocyst stage directly into the uterus. A retrospective study over 2,000 recipients indicates that the highest pregnancy rates were obtained when the recipient was in heat 12 to 24 h before the donor.

Animals↗

PubMed2000

Cyclical endometrial steroid hormone receptor expression and proliferation intensity in the mare.

The aims of this study were to investigate the steroid hormone receptor expression and the proliferation intensity during the equine endometrial cycle by immunohistological methods, established for routine examination of formalin-fixed, paraplast-embedded specimens. Endometrial biopsy specimens were obtained during one cycle from 7 mares. In comparison with the blood steroid hormone levels the quantity and distribution of oestrogen (ER) and progesterone receptors (PR) and the proliferation marker Ki-67 antigen expression were investigated. Rising 17beta-oestradiol concentrations in preoestrus induce a synchronous expression of ER, PR and Ki-67 antigen in stromal cells. In the early dioestrus 17beta-oestradiol levels decrease and progesterone levels reach their maxima. This correlates with an intense proliferation activity and the highest hormone receptor expression in epithelial cells. In accordance to the morphological features of asynchronous glandular differentiation in fibrotic areas (endometrosis) their epithelial hormone receptor expression is out of phase.

Animals↗

PubMed1997

Response of dairy cows treated with bovine somatotropin to a luteolytic dose of prostaglandin F2 alpha.

The objective of this study was to evaluate the timing of follicular waves in cows treated with bovine somatotropin (bST) by measuring ovarian responses to a luteolytic dose of PGF 2 alpha on d 12 of the estrous cycle. Thirty lactating cows (26 Holstein and 4 Guernsey) were assigned to receive bST (500 mg; n = 18) or saline (control; 1.5 ml; n = 12) every 14 d for three injection cycles. On d 12 of a synchronized estrous cycle, cows were injected with PGF 2 alpha to induce luteolysis. Following PGF 2 alpha, 9 cows ovulated from the dominant follicle during the first follicular wave (4 cows treated with bST and 5 control cows), and 14 cows ovulated from the dominant follicle during the second follicular wave (8 cows treated with bST and 6 control cows). Of the cows that ovulated during the second follicular wave, cows treated with bST had more class 3 follicles (> or = 10 mm) than did control cows. Concentrations of estradiol rose earlier after PGF 2 alpha injection in cows treated with bST than in control cows. This rise in estradiol was parallel to the development of dominant follicles. Serum concentrations of FSH were decreased in cows treated with bST. During the first and second estruses, equivalent numbers of cows treated with bST and control cows ovulated, but fewer cows treated with bST expressed estrus. These results are consistent with the hypothesis that cows treated with bST have reduced FSH, a faster turnover of dominant follicles, and differences in the timing of follicular waves. Treatment of cows with bST also increased the incidence of undetected estrus.

Animals↗

PubMed2004

Use of estradiol cypionate as a substitute for GnRH in protocols for synchronizing ovulation in dairy cattle.

Our purpose was to determine whether estradiol cypionate (ECP) could be substituted for the second GnRH injection of the standard Ovsynch protocol (injection of GnRH given 7 d before and 48 h after PGF(2alpha), with timed AI [TAI] 12 to 20 h after the second GnRH injection). Lactating dairy cows ranging from 61 to 82 d in milk at TAI were studied in 14 replicates. Main effects were hormone (ECP vs. GnRH) to induce ovulation and exposure to progesterone (P4) or not during the week preceding PGF(2alpha)-induced luteolysis. Four treatments were: 1) 100 microg of GnRH at 48 h after PGF(2alpha) (Ovsynch; n = 27); 2) same as Ovsynch, plus a P4-releasing intravaginal insert (CIDR) placed for 7 d beginning at the first GnRH injection (Ovsynch + CIDR, n = 20); 3) same as Ovsynch, but substituting 1 mg of ECP for GnRH, and injecting ECP at 24 h after PGF(2alpha) (Heatsynch; n = 33); or 4) Heatsynch + CIDR (n = 26). The largest follicle was identified by ultrasonography 24 h after PGF(2alpha) and was monitored every 6 h until ovulation. Incidence of estrus was less after GnRH (54%) than after ECP (87%), but more GnRH-treated cows had LH surges detected (95 vs. 65%) and ovulated (100 vs. 86%). Duration of LH surges, but not peak concentrations, was less after GnRH than after ECP (6.1 +/- 0.7 vs. 12.2 +/- 0.9 h). Pre-treatment with P4 reduced the incidence of LH surges but had no effects on incidence of estrus or ovulation. Intervals to the LH surge and ovulation were less after GnRH than after ECP, but intervals between onset of the LH surge and ovulation did not differ (26 +/- 2 vs. 30 +/- 3 h). We concluded that substituting ECP for GnRH resulted in more cows in estrus and slightly fewer ovulating.

Administration, Intravaginal↗

PubMed1994

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.

Journal Article↗