This study was conducted to assess effects of two hormonal treatments on ovarian follicular status, estrous synchrony and fertility in dairy goats during the non-breeding season when duration of progestogen device use varied by 12 h. In both experiments, does were administered 60 mg of medroxyprogesterone acetate via intravaginal devices, respectively, for 6 and 6.5 d (G6 and G6.5). At 24 or 36 h before device removal, 200 IU of eCG im and 30 μg d-cloprostenol im were administered. In Experiment 1 (n = 24), data related to sexual behavior and that were collected using ovarian ultrasonography were recorded, and in Experiment 2 (n = 83) fertility was assessed after Flexible Time Artificial Insemination (FxTAI). The interval from device removal to estrus was shorter (P < 0.05) after imposing the G6.5 treatment regimen. Diameter of largest and second-largest ovarian follicles and interval from device removal to ovulation were similar (P> 0.05) between groups. The does treated with the G6.5 hormonal regimen had greater estrous synchrony, associated with greater development of largest follicles at the time of device removal, which might have led to a lesser fertility rate (P > 0.05). Conversely, treatment with the G6 hormonal regimen resulted in a greater conception rate. In conclusion, increasing time the intravaginal device is inserted from 6 to 6.5 d resulted in greater estrous synchrony, advanced ovarian follicular development, abnormal CL function and lesser pregnancy rates in artificially inseminated dairy goats when there were treatments during the non-breeding season.

Keywords: AI; Anestrus; Caprine; Corpora Lutea; Follicular Dynamics; Ultrasound.

Two intramuscular injections of cloprostenol were given 12 days apart to synchronise oestrus in a group of 47 heifers and following the second injection, 38 were found in oestrus in 2 to 6 days, 1 in 11 days and 8 in 22 to 27 days. The conception rate of the synchronised animals was 24 of 38 (63%). Twenty-nine heifers were given injections of cloprostenol in late pregnancy and parturition was induced with a latent period of 6 +/- 3 days when injected at 266 to 267 days. When injected at 254 to 262 days, 3 of 16 heifers (19%) were unresponsive and the remainder calved with a latent period of 12 +/- 6 days. The survival rate of calves from induced heifers was 71% with 80% survival from controls. Approximately 50% of the induced heifers, and none of the controls, retained their foetal membranes.

Conception of dairy cows was investigated in relation to changes in thyroxine (T4) and triiodothyronine (T3) concentrations in March (n = 15), June (n = 10) November (n = 7) after oestrus synchronization by cloprostenol (Oestrophan Spofa) at a dose of 0.05 mg per head. The cows were inseminated from 8.00 to 9.00 o'clock a.m. Blood was taken from 9.00 to 10.00 a.m. from v. jugularis on the day of Oestrophan treatment (-3rd day), on the day of insemination (day 0), and on the 6th and 21st day after insemination. The lowest percentage of pregnant cows (26.67%) was recorded after the March insemination, the highest (50.0%) after the June insemination. 42.86% of cows became pregnant in November. Concentrations T4 in pregnant animals on the day 0 of March insemination were 67.55 +/- 16.95 nmol.1-alpha of serum. Nonsignificant decrease to value 65.60 +/- 10.06 and 49.33 +/- 17.47 nmol.l-1 of serum were observed on the day of June and November insemination. In T3 concentrations an average decrease from the values of 2.53 +/- 0.67 nmol.l-alpha on day 0 of the March insemination to 1.48 +/- 0.67 nmol.l-alpha on day 0 of the June insemination was observed, as well as a significant decrease to 0.80 +/- 0.45 nmol.l-1 of serum (P less than 0.05) on the day of the November insemination. Considering the results we suppose that the conception of dairy cows has an indirect relationship to thyroid hormones.

Resumption of ovulatory activity and the timely lysis of the first CL postpartum (pp) are important determinants for the reproductive performance of dairy cows. Cystic ovarian follicles (COFs) and persistent CLs preclude normal ovarian cyclicity and increase the calving interval. The objective of this study was to investigate the effect of GnRH on the incidence of COFs and the effect of PGF2α on the incidence of a prolonged luteal phase (PLP) and on fertility parameters in dairy cows. A total of 476 cows were examined ultrasonographically for the presence of a dominant follicle (12-25 mm, without CL >10 mm; n = 237) or a functional CL (≥20 mm; n = 239) between 28 and 35 days pp and were allocated to one of four groups. Cows with a dominant follicle received 10-μg GnRH (buserelin; group F-T; n = 118) or saline (group F-C; n = 119), and cows with a functional CL received 0.5 mg of a PGF2α analogue (cloprostenol; group CL-T; n = 119) or saline (group CL-C; n = 120) on the day of initial examination, defined as Day 0. Cows were reexamined 7 and 21 days (F-T and F-C) and 3 and 24 days (CL-T and CL-C) later, and COFs were treated immediately after diagnosis in all cows. On the basis of the ovarian findings on Days 21 and 24, cows were treated according to a protocol aimed at timely breeding. The incidence of COFs by Days 7 (F-T vs. F-C; 7.6% vs. 16.8%) and 21 (11.0% vs. 21.8%) decreased (P ≤ 0.03) with GnRH; however, this did not lead to a substantial improvement of calving-to-conception interval (means ± standard error of the mean; 107.91 ± 5.70 vs. 117.94 ± 6.63 days), first-service conception rate (42.3% vs. 41.3%), and number of services per conception (2.06 ± 0.12 vs. 2.31 ± 0.15). Treatment with PGF2α decreased (P < 0.0001) the incidence of PLP by Day 24 (CL-T vs. CL-C; 1.7% vs. 17.5%), decreased calving-to-conception interval(91.28 ± 4.77 vs. 101.75 ± 5.03 days), increased first-service conception rate (63.3% vs. 38.7%), and reduced the number of services per conception (1.65 ± 0.10 vs. 2.08 ± 0.12; each P ≤ 0.01). The results indicate that strategic treatment with GnRH or PGF2α in week 5 pp to induce early ovulation and luteolysis reduces the incidence of COFs and PLP, respectively. Initial treatment with PGF2α also enhanced reproductive performance when used in conjunction with a standardized treatment protocol for all cows in week 8 pp (aimed at timely breeding). In contrast, GnRH did not improve fertility parameters of cystic cows in herds where all cows with COFs were treated as expeditiously as possible.

This study compared the efficacy of two sources of PGF2alpha on the reproductive performance of virgin beef heifers, after synchronization of estrus using melengestrol acetate (MGA) and PGF2alpha. Angus-based heifers (n = 1002) in five herds were fed 0.5 mg per head per day of MGA for 14 days. Nineteen days after the last day of MGA feeding, heifers were randomly assigned to receive (i.m.) either 0.5 mg cloprostenol (n = 504; Estrumate, E) or 25 mg dinoprost tromethamine (n = 498; Lutalyse, L) as a source of exogenous PGF2alpha. Heifers were observed twice daily for 5 days for signs of estrus and artificially inseminated 8-12 h later, except in herd A, wherein animals not detected in estrus by 80 h after PGF2alpha were mass-mated and no longer monitored for signs of estrus. Estrumate and Lutalyse were equally (P>> 0.1) effective among all response variables evaluated, including estrus response (E, 89% and L, 86%), conception rate (E, 67% and L, 67%), and synchronized pregnancy rate (E, 61% and L, 57%). Synchrony of estrus was not affected (P>> 0.1) by PGF2alpha source, and peak estrus response occurred 60 h post-PGF for both treatments. Conception rate to timed insemination was not different (P>> 0.1) among Estrumate- and Lutalyse-treated heifers within herd A (14%, 4/28 and 7%, 2/29, respectively). Herd had a significant (P < 0.05) effect on all indicators of reproductive performance. Conception rates within herds A and D were influenced by technician (P < 0.05), however, this effect was balanced across treatments and no treatment by technician interaction was detected. In conclusion, when administered 19 days after a 14-day MGA feeding period, cloprostenol and dinoprost tromethamine are equally efficacious for synchronous induction of a fertile estrus in virgin beef heifers.

Over several years groups of heifers which were repeatedly treated with the PGF2 alpha analogue, cloprostenol, to synchronise oestrus were artificially inseminated. When sperm treatment was optimised, a reduction in conception rate was observed which was related to the number of synchronisation treatments the animals had received. Although factors such as a seasonal reduction in fertility may have contributed to the effect, there appeared to be a decrease in the proportion of animals becoming pregnant after successive synchronisations. Possible explanations for this observation are suggested.

The aim of this study was to compare estradiol benzoate (EB) and GnRH for the induction of ovulation in a TAI protocol in buffalo during the nonbreeding season. In experiment 1, 141 buffaloes (56 cows and 85 heifers) received an intravaginal P4 device (1.0 g) plus EB (2.0-mg, intramuscular [im]) at random stage of the estrous cycle (Day 0). On Day 9, the P4 device was removed, and buffaloes were given PGF2α (0.53-mg im sodium cloprostenol) plus eCG (400-IU im). Buffaloes were then randomly allocated to one of three groups and treated as follows: EB24 (n = 47), EB (1.0 mg im) 24 hours after P4 device removal; EB36 (n = 50), EB 36 hours after P4 device removal; GnRH48 (n = 44), GnRH (10 μg im buserelin acetate) 48 hours after P4 device removal. Ultrasound examinations were performed on Day 0 to ascertain ovarian follicular status, Day 9 to measure follicular diameter, and from Day 11 to Day 14 (every 12 hours for 60 hours) to establish the time of ovulation. There were no significant differences between EB24, EB36, and GnRH48 for diameter of the ovulatory follicle (13.1 ± 0.3, 13.7 ± 0.3, and 13.7 ± 0.3 mm; P = 0.26) and ovulation rate (78.7%, 82.0%, and 84.1%; P = 0.93). When compared with heifers, cows had a greater diameter of the dominant follicle on Day 9 (10.3 ± 0.3 and 8.6 ± 0.2 mm; P = 0.0001), diameter of the ovulatory follicle (14.1 ± 0.3 and 13.1 ± 0.2 mm; P = 0.01), ovulation rate (91.1% and 75.3%; P = 0.02), and interval from P4 device removal to ovulation (76.3 ± 1.3 and 72.5 ± 1.4 hours; P = 0.05). In experiment 2, 511 buffaloes (354 cows and 157 heifers) were assigned to the same treatments described in experiment 1 (EB24, n = 168; EB36, n = 172; and GnRH48, n = 171), and all animals were submitted to timed artificial insemination (TAI) 64 hours after P4 device removal. Pregnancy diagnosis was undertaken 30 days after TAI. There were no significant differences between EB24, EB36, and GnRH48 for pregnancy rate (45.2%, 43.0%, and 49.7%; P = 0.46), and the pregnancy rate did not differ (P = 0.31) for cows (47.5%) and heifers (42.7%). The findings from the two experiments indicated that EB (24 or 36 hours) and GnRH (48 hours) induce comparable follicular responses, ovulation, and pregnancy rates in buffalo cows and heifers. Although there were some differences in the follicular responses between cows and heifers, the pregnancy rate to TAI was nonetheless similar.

Genetic selection for high yield milk production has led to a decline in dairy cattle's reproductive performance over the last 40 years. Low progesterone (P4) plasma content following ovulation is associated with suboptimal fertility in dairy cattle. Several pieces of evidence indicate that the protein beta-nerve growth factor (β-NGF) that is present in the male seminal plasma exerts potent ovulatory and luteotrophic effects following systemic administration in camelids but also in other species. In this study, we determine whether systemic administration of purified llama β-NGF given at the induced preovulatory luteinizing hormone (LH) peak improves corpus luteum (CL) function in dairy heifers subjected to an estradiol (E2) / P4 estrus-synchronization protocol. To achieve this, we first determined plasma E2 and LH hormone profiles to establish the timing of the estradiol benzoate (EB)-induced LH peak in estrus-synchronized heifers. Then, we tested whether the administration of β-NGF given at the end of this peak affects the CL and its function by analyzing diameter, vascular area, and P4 output. Our results show that, with the estrus-synchronization protocol applied, plasma LH concentrations peaked (P < 0.01) 40-h and 16-h after removal of the bovine intravaginal device (DIB; containing 1.0 g of P4) plus cloprostenol injection and subsequent EB administration, respectively; after peaking, plasma LH concentrations remained stable for the next 8-h to then return to basal levels. Heifers synchronized with this protocol and receiving a dose of 1 mg of β-NGF at the end of the LH peak (ie, 48-h after DIB removal) did not show significant differences in CL diameter, but these exhibited a greater CL vascular area (P = 0.01) than the observed in vehicle-injected heifers. Furthermore, plasma P4 concentration in β-NGF-treated heifers was higher (P = 0.001) than those quantified in vehicle-injected heifers. These results support the use of β-NGF in estrus-synchronization protocols to improve the early luteal function in dairy heifers.

Keywords: Bovine; Corpus luteum; Progesterone; Reproductive biotechnology; Vascular growth.

Eighty crossbred, multiparous sows, weighing between 190 and 320 kg, were randomly assigned to the following four treatment groups of 20 sows each: 1) saline-saline, 2) cloprostenol-saline, 3) saline-xylazine and 4) cloprostenol-xylazine. The mean gestation length of each multiparous sow was calculated. Cloprostenol (250 ug/sow, i.m.) or saline was given 3 d prior to the calculated due date at 11:30 a.m. Xylazine (2 mg/kg, i.m.) or saline was given 20 h after either the cloprostenol or previous saline treatment. Cloprostenol-xylazine treated sows had the shortest mean farrowing interval (1.5 +/- 0.3 h) when compared with the rest of the treatment groups (saline-saline:66.0 +/- 8.1, cloprostenol-saline:10.5 +/- 1.9, saline-xylazine:60.6 +/- 5.6 h). Farrowing time, percentage of stillbirths, average birth weight, d-5 and d-21 postbirth weights, number of pigs born, number of pigs born alive, and number of pigs surviving at 5 and 21 d afterbirth were not significantly different among the four groups. This study demonstrated that cloprostenol-xylazine treatment decreases the time to onset of farrowing with less variation than cloprostenol or xylazine alone. Therefore, the use of a cloprostenol-xylazine combination is suggested as an alternative method for inducing farrowing.

Treatment of pregnant sows with 175 microgram of cloprostenol achieved efficient synchronisation of farrowing; 93% of treated animals commenced farrowing between 20 and 30 hours and 82% between 24 +/- 4 hours after injection. Duration of farrowing and weights of piglets at birth and weaning were not significantly affected by treatment. There was no harmful effect on piglet viability up to weaning and treated sows returned to oestrus within the expected time after weaning. There was a higher incidence of the mastitis-metritis-agalactia syndrome in control sows. The implications of these findings on the management of commercial pig farms is discussed.

Spontaneous prolongation of the luteal phase has been described in horses, but the underlying causes are still unclear. The present study investigated details of gonadotrophin and progestogen secretion in pregnant mares (n = 11) with or without experimentally reduced early postovulatory luteal function. From days 0 to 3 after ovulation, they were treated with the prostaglandin F_2α (PGF_2α) analogue cloprostenol or left untreated. After conceptus collection on day 34, they were assigned to the opposite treatment. Mares were affiliated to the group primary corpus luteum (n = 6) or diestrous corpus luteum (n = 5) depending on diestrous corpus luteum (CL) detection in the PGF pregnancy. For statistical comparisons, a p-value < 0.05 was significant. There was an effect of treatment (p < 0.01), but not of group on progestogen concentration. The concentration of LH was higher in PGF-treated than in untreated pregnancies (p < 0.05), but did not differ between groups. The FSH concentration did not differ between groups nor treatments. The total luteal tissue area was greater in mares with a diestrous ovulation during the PGF treatment pregnancy. Low progestogen concentration in the early postovulatory phase diminish the negative feedback on the hypothalamic-pituitary axis in early pregnancy and, thus, stimulate a luteal tissue response. Detection of secondary CL at the time of pregnancy examination in mares may reflect that early post-ovulatory progestogen concentrations were low.

Keywords: corpus luteum; early pregnancy in mares; hypothalamic-pituitary axis; luteal phase ovulation; negative feedback; progesterone.

Due to the long courtship needed to attain excitation and erection, donkey semen collection can take up to 90 min. ProstaglandinF2α (PGF2α) has been reported to hasten the onset of erection and ejaculation in domesticated mammals, presumably by inducing smooth muscle contractions in the internal genitalia. However, while it has been anecdotally used in donkeys, it has yet to be critically evaluated. This study aimed to compare behavioral and semen parameters in Catalan, Balearic, Amiata, and Miranda jacks treated with the PGF2α analogue cloprostenol sodium immediately prior to exposure to an estrus jenny. Nineteen donkeys were assigned in a crossover design to receive cloprostenol sodium (125µg, i.m.; n = 53 collections) or saline (1 mL, i.m.; n = 53 collections). There were no differences for erection (52/53 vs. 52/53) or ejaculation (52/53 vs. 48/53) for collection attempts assigned to saline or cloprostenol sodium, respectively. Cloprostenol sodium significantly hastened treatment-to-erection and treatment-to-ejaculation times from 12.0 ± 1.6 to 6.0 ± 1.6 min and from 14.0 ± 1.4 to 9.6 ± 1.4 min, respectively. Significant effects of breed and age were observed in behavioral and parameters, but there were no effects of cloprostenol sodium administration on semen parameters. In conclusion, cloprostenol sodium administration immediately prior to semen collection hastened time to collect semen in donkeys with no detrimental effects on semen quality and can be used by practitioners to circumvent long delays in donkey semen collection.

Keywords: cloprostenol sodium; donkey; ejaculation; erection; semen collection.

The source of inhibin secretion by the ovary in the sheep at different stages of the oestrous cycle was investigated by in-vivo cannulation of the ovarian veins. Twenty-four Scottish Blackface ewes were allocated to four groups of six ewes, i.e. those operated on during the luteal phase (day 10), and those operated on during the follicular phase 24-30, 36 and 60 h following an injection of 125 micrograms cloprostenol on day 10 of the luteal phase. Samples of jugular and timed ovarian venous blood were collected under anaesthesia before and after enucleation of the corpus luteum. Ovaries were then removed and follicles dissected out. Following injection of cloprostenol, luteal regression occurred as indicated by a fall in the secretion of progesterone. The concentration of inhibin in jugular venous plasma and its ovarian secretion rate were similar at all stages of the follicular phase and during the luteal phase. In contrast, the secretion rate of oestradiol rose from 2.86 +/- 0.73 pmol/min during the luteal phase to 8.70 +/- 2.24 pmol/min 24 h after injection of cloprostenol (P less than 0.05). Following enucleation of the corpus luteum the secretion rate of progesterone fell from 809 +/- 270 pmol/min to 86 +/- 30 pmol/min (P less than 0.001). There was also a smaller, artifactual fall in the secretion rate of oestradiol following enucleation of the corpus luteum, which was of similar size to a fall seen in the secretion rate of inhibin. This resulted in a significant (P less than 0.001) fall in the ratio of progesterone to inhibin, while the oestradiol to inhibin ratio remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral and endocrine changes in the sow following injection with prostaglandin F2 alpha (PGF2 alpha) or its analogue, cloprostenol (CLO), were monitored to identify endocrine correlates of prepartum activity (nest-building). On Day 112 postcoitum, within 15 min after injection with 10 mg PGF2 alpha, sows offered straw in pens engaged in intense prepartum activity, but few behavioral changes occurred during the first 2 h following administration of 175 micrograms CLO. The temporal pattern of prepartum activity, however, was affected by both prostaglandins. In control sows, most prepartum activity came during Hours 16-0 before delivery of first piglet (delivery). After CLO, sows engaged in nest-building more during Hours 32-17 and less during Hours 16-0. In another experiment, sows in farrowing crates were injected with saline, 175 micrograms CLO, or 10 mg PGF2 alpha on Day 112 and blood was collected 0, 15, 30, 60, and 90 min later. Another sample was collected when spontaneous prepartum activity was first observed. For approximately 90 min after PGF2 alpha treatment, sows rooted, pawed, and bit and rubbed faces on crate bars; after saline and CLO, this behavior was rarely observed. After prostaglandin treatment, plasma progesterone tended to decline, a 10-fold rise in relaxin came within 15 min, but estrone did not change. Plasma prolactin rose 10-fold within 30 min after PGF2 alpha treatment, and rose more gradually after CLO treatment. When sows exhibited spontaneous prepartum activity (approximately 7 h before delivery), endocrine status was characterized by low progesterone, high estrone:progesterone ratio, and high prolactin.(ABSTRACT TRUNCATED AT 250 WORDS)

Romney ewes were infused with ovine FSH (NIADDK-oFSH-16) for 48 h from the initiation of luteolysis with cloprostenol. Doses of 2.5 or 5 micrograms/h which partly or completely prevented the normal preovulatory decline in plasma FSH concentrations caused a significant increase in mean ovulation rates. Ovulation rates were not increased significantly if the FSH (5 micrograms/h) was infused for only 20 h starting from the initiation of luteolysis or 24 h later. Infusion of a less potent and relatively impure preparation of FSH (i.e. FSH-P) at 0.5 mg/h for 48 h after cloprostenol treatment also increased the mean ovulation rate significantly. However, if the FSH-P was given for only the first 24 h, or if the start of the infusion was delayed for more than 12 h, mean ovulation rates were not increased significantly. Infusion of LH (NIADDK-oLH-25, 5 micrograms/h) for 48 h from the initiation of luteolysis decreased the mean ovulation rate significantly. Administration of bovine follicular fluid to suppress plasma FSH concentrations below normal during the first 24 h after cloprostenol injection did not delay oestrus. However, oestrus was delayed by approximately 2 days if plasma FSH concentrations were reduced by bovine follicular fluid 24 h after the initiation of luteolysis. As ovulation rate increased, the mean weight of individual corpora lutea of each ewe decreased. In ewes with a single ovulation, most corpora lutea weighed greater than 600 mg, but as the ovulation rate increased the proportion of corpora lutea present weighing less than 400 mg rose steadily.(ABSTRACT TRUNCATED AT 250 WORDS)

Passive immunization was used to investigate the importance of inhibin and oestradiol in the control of FSH production during the follicular phase of the oestrous cycle in the sheep. Four groups of five mature Scottish Blackface ewes were injected with normal sheep plasma (control), antiserum to the 1-26 alpha peptide fragment of porcine inhibin, antiserum to oestradiol-17 beta, or a combination of the two antisera, 24 h following cloprostenol-induced luteal regression. There was no difference in the concentration of LH in jugular venous plasma between the control and inhibin-immunized groups following the injection of normal sheep plasma or inhibin antiserum, with both groups exhibiting normal LH surges. In both the groups immunized against oestradiol, the basal concentration of LH rose by 25-30% (P less than 0.05) during the 96-h period following injection, while the LH surge and consequent formation of a corpus luteum was inhibited. In all three immunized groups there was a significant (P less than 0.001) rise in the concentration of FSH starting 3.8-4.8 h after the injection of antiserum. The duration of the rise was similar in the groups injected with oestradiol antiserum alone (43.6 +/- 12.8 h) or in combination with inhibin antiserum (40.6 +/- 11.7 h), but was significantly (P less than 0.05) shorter in the group immunized against inhibin alone (17.0 +/- 0.5 h).(ABSTRACT TRUNCATED AT 250 WORDS)

An experiment was conducted to examine the effect of steroid-free ovine follicular fluid (oFF) on ovarian hormone secretion. Eight Merino x Finnish Landrace ewes in which the left ovary and vascular pedicle had been autotransplanted to a site in the neck were studied during the breeding season. Luteal regression was induced in all animals by injection of cloprostenol (100 micrograms, i.m.) on day 10 of the luteal phase. Four of the eight animals were treated with steroid-free oFF (3 ml, s.c.) in the early follicular phase, 24 and 36 h after injection of cloprostenol. Samples of both ovarian and jugular venous blood were collected at 4-h intervals from 20 h before until 96 h after injection of cloprostenol. Ovarian and jugular venous blood samples were also collected at 10-min intervals from 48 to 52 h after injection of cloprostenol to investigate the pattern of pulsatile secretion of ovarian hormones. Samples were assayed for oestradiol, androstenedione, testosterone and inhibin and the ovarian secretion rates calculated. Both injections of oFF resulted in a fourfold increase in the concentration of inhibin in jugular venous plasma within 4-8 h of administration (P less than 0.01) with concentrations remaining increased (P less than 0.05) until 56 h after cloprostenol (32 h after the first oFF injection). Following oFF injection there was a profound (100%; P less than 0.001) and prolonged decrease in the peripheral concentration of FSH until 60 h after cloprostenol at which time the concentration of FSH increased five- to sixfold (P less than 0.001) to a peak lasting 24 h. In contrast to FSH, the concentration of LH in jugular venous plasma rose immediately following oFF treatment and continued to increase, exhibiting a profile similar to that described for FSH. No preovulatory LH surge was detected in any of the oFF-treated ewes while untreated ewes had an LH surge within 58.0 +/- 1.2 (S.E.M.) h. Within 8 h of the first injection of oFF the ovarian secretion rate of oestradiol, androstenedione and inhibin began to decline to reach a nadir of less than 1 ng/min within 32-36 h (56-60 h after cloprostenol; P less than 0.01). Testosterone secretion, already barely detectable, did not change significantly following injection of oFF but remained low for 36 h following oFF and did not exhibit the increase observed over this period in controls. After injection of oFF the episodic secretion of oestradiol, androstenedione, testosterone and inhibin was markedly suppressed in spite of numerous pulses of LH.(ABSTRACT TRUNCATED AT 400 WORDS)

Romney ewes were injected intramuscularly once or twice daily for 3 days with 0, 0.1, 0.5, 1 or 5 ml of bovine follicular fluid (bFF) treated with dextran-coated charcoal, starting immediately after injection of cloprostenol to initiate luteolysis on Day 10 of the oestrous cycle. There was a dose-related suppression of plasma concentrations of FSH, but not LH, during the treatment period. On stopping the bFF treatment, plasma FSH concentrations 'rebounded' to levels up to 3-fold higher than pretreatment values. The mean time to the onset of oestrus was also increased in a dose-related manner by up to 11 days. The mean ovulation rates of ewes receiving 1.0 ml bFF twice daily (1.9 +/- 0.2 ovulations/ewe, mean +/- s.e.m. for N = 34) or 5.0 ml once daily (2.0 +/- 0.2 ovulations/ewe, N = 25) were significantly higher than that of control ewes (1.4 +/- 0.1 ovulations/ewe, N = 35). Comparison of the ovaries of ewes treated with bFF for 24 or 48 h with the ovaries of control ewes revealed no differences in the number or size distribution of antral follicles. However, the large follicles (greater than or equal to 5 mm diam.) of bFF-treated ewes had lower concentrations of oestradiol-17 beta in follicular fluid, contained fewer granulosa cells and the granulosa cells had a reduced capacity to aromatize testosterone to oestradiol-17 beta and produce cyclic AMP when challenged with FSH or LH. No significant effects of bFF treatment were observed in small (1-2.5 mm diam.) or medium (3-4.5 mm diam.) sized follicles. Ewes receiving 5 ml bFF once daily for 27 days, from the onset of luteolysis, were rendered infertile during this treatment period. Oestrus was not observed and ovulation did not occur. Median concentrations of plasma FSH fell to 20% of pretreatment values within 2 days. Thereafter they gradually rose over the next 8 days to reach 60% of pretreatment values where they remained for the rest of the 27-day treatment period. Median concentrations of plasma LH increased during the treatment period to levels up to 6-fold higher than pretreatment values. When bFF treatment was stopped, plasma concentrations of FSH and LH quickly returned to control levels, and oestrus was observed within 2 weeks. The ewes were mated at this first oestrus and each subsequently delivered a single lamb.

Changes in the concentration of 17beta-oestradiol (E2) and luteinizing hormone (LH) and in the rectal and vaginal temperatures (RT and VT) were studied along with the changes in thyroxine concentration (T4) in three cows and three heifers in the luteal stage of the cycle; the animals had been intramuscularly treated with 2 ml Oestrophan (cloprostenol). The closeness of the correlation between T4 and the remaining parameters under study was determined by the calculation of the correlation coefficient and statistical significance. The concentrations of T4 before and during cloprostenol administration were high in comparison with the post-treatment levels. E2 concentrations at cloprostenol administration time were much higher than those recorded before administration. After treatment the concentrations of T4 and E2 sank. The first E2 peak, recorded in the 44th hour, was immediately followed by a marked drop of E2 as well as T4, the lowest values of both being recorded in the 52nd and 56th hour. The second peak of E2 in the 60th hour was followed by a slow but steady decrease. The rise of the concentration of T4 after the 56th hour was slow and reached the peak in the 74th hour; after a partial decrease no further marked changes in concentrations were recorded. LH concentrations rose at a slow rate to reach the peak in the 64th hour. After a rapid decline they reached the pre-peak value in the 70th hour. The lowest RT and VT levels were recorded in the 54th and 94th hour. It can be assumed on the basis of the behaviour of the hormones and the evaluation of their correlations that thyroidal hormones are involved in the stimulation of the synthesis of ovarial oestrogens which tend, after their synthesis, to eliminate from circulation the T4 as well as their own levels and thereby to influence (as feedback) the stimulation of T4 synthesis, their own synthesis, and LH.

Cloprostenol, a synthetic derivative of prostaglandin F2 alpha, exhibits antiarrhythmic properties against reperfusion induced fibrillation in guinea-pig hearts in vitro. It decreases the incidence of fibrillation from 75.0% to 0%. This antifibrillatory effect of cloprostenol could be confirmed also by in vivo experiments.

Fluphenazine decanoate is a long-acting phenothiazine neuroleptic that attenuates the stress response and may be useful during intensive handling for reproductive procedures in non-domestic ungulates. However, phenothiazines are also associated with elevated serum prolactin, which can suppress fertility in some species. For this study, 10 female domestic goats were used as a model for non-domestic caprids to test effects of fluphenazine decanoate on serum cortisol and reproductive cyclicity following estrus synchronization. Two identical trials were conducted during the breeding season, employing a random crossover design. First, females underwent estrus synchronization using a 14-day treatment with progesterone (330 mg; CIDR). After 7 days of CIDR exposure, the treatment group (n = 5) received fluphenazine decanoate (1.0 mg/kg IM) and controls (n = 5) received an equivalent volume of 0.9% saline IM. At CIDR withdrawal (Day 14), animals received 125 mg cloprostenol sodium to lyse any luteal tissue and synchronize estrus. Blood was collected every 2 hr from 36 hr after CIDR withdrawal until 24 hr after standing estrus, or up to 5 days to monitor stress and reproductive hormones. Serum cortisol, prolactin, luteinizing hormone (LH) and progesterone concentrations were determined by enzyme immunoassay. While treatment with fluphenazine was associated with lower cortisol concentrations compared to controls (P = 0.001), 4 of the 10 treated animals experienced elevated serum prolactin, suppression of the LH surge and inhibition of ovulation. These findings suggest that long-acting neuroleptic drugs reduce the adrenal stress response, but may interfere with reproductive responses and negatively influence breeding success.

The phytochemical, pharmacological and toxicological feature of plant Rhaphidophora pertusa (Roxb.) was done. Phytosteroids, flavonoids, tannins and glucosides were detected in the plant extracts. In cross-bred (Zebu X Holstein-Friesian or Jersey) dairy cows, subsequent to prostaglandin (PG) induced oestrus, to each group (n=4), cloprostenol (PG control) 100 microg i.m. on day 10, the rice gruel (vehicle) was fed on day 10 or the fresh stem (1 kg/animal/day) in rice gruel on day 9, or days 9 and 10, or days 9-11 of the oestrous cycle. Each group received subcutaneously either 5% gum acacia suspension or the plant ethyl acetate or methanol extract (1g in gum acacia) on days 8 (to bannur ewes) or 10 (to dairy cows) of the oestrous cycle. In PG control cows or ewes, there was induction of oestrus in 48 h and a fall in serum progesterone concentration. The feeding of fresh stem in the rice gruel or the s.c. administration of the plant extract did not induce oestrus or significantly (P>0.05) alter the serum progesterone, bilirubin, calcium, creatinine, phosphorus, magnesium and glucose concentrations or the total erythrocyte and leucocyte count, differential leucocyte count and haemoglobin concentration. The plant did not cause any toxicity in the cow or ewe. In immature rats, the aqueous or methanol (hot or cold) extract did not cause any follicle-stimulating hormone (FSH)-like activity. The methanol extract increased the uterine weight in ovariectomised rats. This suggested the presence of oestrogenic activity in the plant. In conclusion, the present study revealed the presence of oestrogenic activity in the plant and the absence of luteolytic or FSH-like or toxic activity.

Current study evaluates effects from breed and management background on follicular dynamics and endocrine output during the follicular phase of sheep oestrous cycle. Follicular phases were synchronized with three cloprostenol doses, 10 days apart, in three groups of 10 females of different non-prolific Spanish breeds (Manchega, Rubia del Molar and Negra de Colmenar). Development of all follicles reaching antral diameters>>or=2 mm was assessed by daily transrectal ultrasonographies, whereas follicular function was evaluated by measurement of plasma oestradiol concentrations. All the ovulatory follicles were present at induced luteolysis in Manchega sheep, while a 93.7% were detected in Rubia del Molar and Negra de Colmenar ewes. The mean size of these ovulatory follicles was similar between breeds at 0 h, but their growth rates were higher in Manchega ewes, reaching a larger size at oestrous detection than in Negra de Colmenar and Rubia del Molar sheep (p < 0.05). Conversely, the oestradiol levels increased with time in Rubia del Molar and Negra de Colmenar (p < 0.05); whilst remained stable in Manchega females. However, the patterns of follicular turnover were similar between breeds. These results indicate that, though differences in follicular size and size distribution, patterns of follicular turnover in sheep are affected neither by the breed nor by the background of management and selection.