Incidence Of Ovulation Research Articles

A randomised double blind clinical study on effect between clomiphene citrate plus metformin and clomiphene citrate alone on induction of ovulation in women with polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder of women of reproductive age-group, characterised by a combination of hyperandrogenism, chronic anovulation, and polycystic ovaries. It is one of the most common cause of hyperandrogenism, hirsutism and anovulatory infertility. The aim of the study is to determine & compare the rate of ovulation, regularisation of menstrual cycle and rate of pregnancy by use of combination of Clomiphene citrate and Metformin & with use of Clomiphene citrate alone in patients with PCOS.A total 110 patients (55 in each group) having primary subfertility and diagnosed as PCOS in age group of 18 to 40 years of age, selected between April 2017 – March 2018. The primary outcome i.e, incidence of ovulation was detected by folliculometry. The secondary outcomes, i.e, regularisation of menstrual cycle & Pregnancy rates were taken into account and compared in both the groups.Overall ovulation was found highest at the end of 3rd cycle of ovulation induction, 48.8% and 41% respectively in each group. The Primary outcome was significantly higher in group a given combination of clomiphene citrate and metformin (83.3%) with respect to group B given clomiphene citrate only (65.9%). The secondary outcomes were significantly higher in group given CC plus metformin (89.6%). Pregnancy rates were higher in 1st group 33.3% than 2nd group (20.5%).In the present study one group was given combination of Clomiphene citrate with metformin and another group was given clomiphene citrate only for ovulation induction. It was found that combination of clomiphene citrate and metformin was more effective in induction of ovulation in women suffering from PCOS when compared to induction of ovulation with clomiphene citrate alone.

P059Pharmacodynamic evaluation of the etonogestrel contraceptive implant initiated midcycle with and without ulipristal acetate: A pilot randomized controlled trial

<h3>Objectives</h3> To determine the incidence of ovulation within five days of etonogestrel (ENG) implant insertion in the presence of a dominant follicle with and without same-day oral ulipristal acetate (UPA) administration. <h3>Methods</h3> This single site trial recruited people aged 18–35 with regular menstrual cycles and interest in an ENG implant without pregnancy risk. We initiated transvaginal ultrasounds on day 7–9 of menses and randomized participants 1:1 to ENG implant alone or with concurrent oral UPA when a dominant follicle reached ≥14 mm in diameter. We completed daily transvaginal ultrasounds and serum hormone levels for up to seven days post-insertion or transitioned to labs alone if we observed follicular collapse on ultrasound prior to the end of seven days. We defined ovulation as follicular rupture followed by a progesterone level ≥3ng/mL. <h3>Results</h3> We enrolled 35 people: 17 with ENG implant alone (mean enrollment follicular size: 15.2 mm ± 0.9 mm) and 18 with ENG implant and UPA (mean enrollment follicular size: 15.4 mm ± 1.2 mm, p=0.6). Ovulation occurred in 35.3% (n=6) of ENG implant–alone participants and in 61.1% (n=11) of ENG implant and were given UPA(Risk ratio (RR), 0.6; 95% CI, 0.3–1.2; p=0.1). <h3>Conclusions</h3> Although not powered to detect statistically significant differences, mid-cycle ovulation suppression was more common when the ENG implant was inserted alone than with same-day UPA administration, supporting concerns for drug-drug interactions between oral UPA and ENG. Ovulation suppression with the implant exceeds prior reports of oral levonorgestrel. Thus, the ENG implant is worth testing as emergency contraception.

Practical protocols for timed artificial insemination of jennies using cooled or frozen donkey semen

With the expansion of the donkey industry, timed artificial insemination (TAI) is becoming increasingly important in the reproductive management of jennies, however, TAI has not been widely investigated in donkeys. To develop efficient TAI protocols for cooled or frozen semen in jennies, based around ovulation induction with a GnRH analogue. Experimental exploratory study. In experiment 1, the effects of different GnRH analogue (deslorelin) doses, follicle diameter (FD) at induction, repeated use of a GnRH analogue, and the influence of season on induction efficiency, as well as distribution of ovulations over time after induction were investigated. Induction efficiency was sufficient with 2.2mg deslorelin (≥90% ovulation within 48hours of treatment). Ovulation rate between 24 and 48hours was highest when the FD at treatment was 31-35mm, as compared to 25-30mm or 36-40mm. Repeated use of deslorelin or treatment during different seasons had no effect on induction efficiency. About 70% of ovulations occurred between 32 and 48hours, and highest incidence of ovulation was at 36-38hours after induction. In experiment 2, TAI using cooled semen (1×109 motile sperm in a 10mL volume) was performed once at 8hours after induction (n=59). Pregnancy rate after TAI with cooled semen was 49.2% (29/59). In experiment 3, jennies were inseminated twice with 10 (n=23), 5 (n=31), 3 (n=32), 2 (n=82) and 1 (n=66) straws (more than 50×106 motile spermatozoa in each 0.5mL straw) of frozen semen at 34 and 42hours after induction. The pregnancy rates were 30.4%, 35.5%, 34.4%, 29.3% and 28.8%, respectively (P>0.05). In the frozen semen trial, 22.5% (68/302) jennies were excluded after failure to ovulate during the appropriate time interval. In addition, there were no control groups for the AI trials. When FD reaches 31-35mm, a donkey jenny can be inseminated once using cooled semen at 8hours or twice using frozen semen at 34 and 42hours after deslorelin treatment. The frozen semen TAI protocol resulted in acceptable pregnancy rates using 1×108 motile spermatozoa per cycle.

Effects of a Gonadotropin‐Releasing Hormone IIa 5/20‐μg/kg Dose versus a 20/80‐μg/kg Dose on Channel Catfish Ovulation

AbstractThe production of (male Blue Catfish Ictalurus furcatus × female Channel Catfish Ictalurus punctatus) F1 hybrids by U.S. catfish farmers has increased dramatically during the last 15 years. However, hybrid catfish production requires hormone‐induced ovulation of female Channel Catfish and remains an inefficient process. Previously, we demonstrated that GnRH IIa given as a two‐dose injection (priming/induction) of 20/80 μg/kg of female body weight resulted in superior ovulation rates for Channel Catfish compared with salmon GnRH IIIa and mammalian LHRHa, which are products that are currently used at commercial catfish hatcheries. The objective of the current study was to determine whether GnRH IIa given at a quarter dose (5/20 μg/kg) would achieve results similar to those that were obtained with the full dose (20/80 μg/kg) and whether the response varied over the spawning season. Trials were conducted at three timepoints during the 2017 spawning season: early (May 1), middle (May 15), or late (June 5). At each timepoint, 20 females received an intraperitoneal injection with a full dose of GnRH IIa and 20 females received an injection with a quarter dose of GnRH IIa. Data were collected for female weight, latency, incidence of ovulation, and stripped eggs weight (g) per kilogram of female body weight. The data indicated that the quarter dose of GnRH IIa (5/20 μg/kg of female body weight) achieved results that were similar to those that were obtained with the full dose of 20/80 μg/kg.

Adjuvant gonadotropin-releasing hormone analogues for the prevention of chemotherapy-induced premature ovarian failure in premenopausal women.

Adjuvant gonadotropin-releasing hormone analogues for the prevention of chemotherapy-induced premature ovarian failure in premenopausal women.

Ovarian Function in Adolescents Conceived Using Assisted Reproductive Technologies.

To compare ovarian function between adolescents conceived using assisted reproductive technology (AcART) and adolescents who were conceived spontaneously (AcSP). Multicenter study of ovarian function in AcART because of male or tubal infertility. University Hospital. We evaluated 22 AcART and 53 AcSP at 1-2years after menarche. The participants were born at term (≥37weeks of gestation) with normal birth weights (≥2500g) from singleton pregnancies. None. Differences in ovulation, reproductive hormones, and ovarian morphology. AcART had an older age of menarche than that of AcSP, even after adjusting for maternal age at menarche, gestational age, and birth weight (P=.027). AcART had lower incidence of ovulation (P=.021) and higher luteinizing hormone serum levels (P=.01) than those of AcSP. The incidence of oligomenorrhea and the cycle length were similar between AcART and AcSP. AcART had levels of anti-Müllerian hormone, inhibin B, follicle-stimulating hormone, estradiol, and androgens similar to those of AcSP. The ovarian morphology, ovarian volume, and follicle counts were similar in both groups. AcART had later menarche, lower ovulation rates, and higher luteinizing hormone levels than those of AcSP. Future studies should investigate whether these findings are indicative of a risk of ovarian dysfunction later in life for AcART.

The majority of irregular menstrual cycles in adolescence are ovulatory: results of a prospective study

PurposeWhile ovulation is most likely to occur in adolescent girls with regular menstrual cycles, there are limited data on the incidence of ovulation in girls with irregular menstrual cycles in...

Physiological predictors of ovulation and pregnancy risk in a fixed-time artificial insemination program.

The objective of this study was to determine the relative importance and contribution of several physiological factors as predictors of pregnancy risk in an Ovsynch (GnRH-1 - 7d - PGF2α - 56h - GnRH-2 - 16h - artificial insemination) timed artificial insemination program: (1) age of the corpus luteum (CL; original CL, new CL, or both in response to GnRH-1) and resulting progesterone concentrations as they affected luteolysis, ovulation after GnRH-2, and pregnancy risk; (2) progesterone concentration before GnRH-1 and GnRH-2 on subsequent ovulatory response to GnRH-1 and GnRH-2 as well as pregnancy risk; and (3) a combination of these factors in a multivariable logistic regression model to predict pregnancy risk. Original data from 7 published studies were combined including ovulatory responses to both GnRH injections, blood progesterone concentrations before GnRH-1, before PGF2α, and at 48h after PGF2α, pregnancy per artificial insemination at d 32 and 60 after artificial insemination, and intervening pregnancy loss. Ovulation outcomes were greater at lesser progesterone concentrations after both GnRH injections despite the fact that pregnancy outcomes were greatest when progesterone exceeded 3ng/mL before GnRH-1 and PGF2α, suggesting that greater progesterone concentration before GnRH-1 and incidence of ovulation act via different mechanisms to improve subsequent fertility. Ovulation after GnRH-2 and subsequent pregnancy outcome were positively related to lesser concentrations of progesterone at 48h after PGF2α; however, for maximal pregnancy outcome, progesterone should be <0.5ng/mL. Cows with a CL that also formed a new CL after GnRH-1 had the greatest pregnancy outcome, whereas cows with only a new CL (i.e., anovulatory cows and those at or near estrus without a CL at GnRH-1) had the poorest pregnancy outcome. Pregnancy loss was not affected by CL status during the timed artificial insemination program. Receiver operator curves produced cut points of progesterone concentration that predicted ovulation and pregnancy risk. Selected cut points of progesterone concentration 48h after PGF2α produced true positive risks greater than 90% and false positive risks less than 25%, thus demonstrating the high predictability of ovulation after GnRH-2 and subsequent pregnancy outcome based on progesterone concentration. We conclude that progesterone concentration is highly predictive of ovulation and pregnancy risk in addition to body condition, size of ovulatory follicle, and parity.

Can coyote predation risk induce reproduction suppression in white‐tailed deer?

AbstractPredators can have powerful nonconsumptive effects on their prey by inducing behavioral, physiological, and morphological responses. These nonconsumptive effects may influence prey demography if they decrease birthrates or increase susceptibility to other sources of mortality. The Reproductive Suppression Model suggests that iteroparous species may maximize their lifetime reproductive success by suppressing their reproduction until a future time, when conditions may be more favorable. Coyote (Canis latrans) range expansion in the United States has exposed white‐tailed deer (Odocoileus virginianus) populations to increased predation risk, and coyote predation can have profound effects on white‐tailed deer reproductive success. We evaluated effects of temporal variation in predation risk (i.e., coyote–deer ratios) on fecundity and reproductive success of white‐tailed deer on the Joseph W. Jones Ecological Research Center in southwestern Georgia, United States, by exploiting a rapid decline in coyote abundance to establish a natural experiment. We measured fecundity by examining ovaries for evidence of ovulation, and measured reproductive success using evidence of lactation from deer harvested before and after the decline in coyote abundance. We found that incidence of ovulation and lactation increased following the decline in predation risk. Our results suggest coyotes may be able to influence deer recruitment, independent of direct predation, through interactions that result in reduced fecundity. More broadly, our study suggests that in order to understand the totality of the effect of predators on prey population dynamics, studies should incorporate measures of direct and indirect predator effects.

Is progesterone the key regulatory factor behind ovulation rate in sheep?

Ovarian antral follicles in the ewe grow in an orderly succession, producing 3 to 4 waves per estrous cycle. In prolific sheep, some large antral follicles from the second-to-last wave of the estrous cycle are added to the ovulatory follicles emerging just before estrus to give a higher ovulation rate; it is feasible that regression of these follicles is prevented by an increase in serum concentrations of FSH or LH pulsatility at proestrus. Prolific sheep tend to have a shorter luteal phase than nonprolific ewes and there is a great deal of evidence that luteal progesterone (P4), in addition to regulating LH release, may govern the secretion of FSH heralding the emergence of follicular waves. The specific purpose of this study was to determine whether or not extending the duration of the luteal phase in prolific sheep to that typically seen in nonprolific breeds would alter the follicle wave dynamics and ovulation rate. In 2 separate experiments, exogenous P4 (7.5 mg per ewe intramuscularly) was administered on day 11 at PM and day 12 at AM (day 0 = first ovulation of the interovulatory interval studied) in moderately prolific Rideau Arcott × Polled Dorset ewes (experiment 1, n = 8) and highly prolific Olkuska ewes (experiment 2, n = 7; TRT), whereas the equinumerous groups of animals served as controls (CTR). Transrectal ovarian ultrasonography was performed daily, and jugular blood samples were drawn twice a day from day 9 until the next ovulation. Progesterone injections resulted in relatively uniform increments in serum P4 levels, but the mean duration of the interovulatory interval did not differ (P > 0.05) between TRT and CTR groups of ewes in either experiment. The mean ovulation rate post-treatment was 1.6 ± 0.2 vs 3.2 ± 0.4 (experiment 1, P < 0.001) and 3.2 ± 0.8 vs 4.0 ± 1.0 (experiment 2, P > 0.05) in TRT vs CTR, respectively. The number and percentage of ovulating follicles from the penultimate wave of the interovulatory interval studied was 0.25 ± 0.16 vs 1.75 ± 0.45 (P < 0.01) and 25.0 ± 16.4% vs 75.0 ± 16.4% (P < 0.05) in experiment 1, and 0.50 ± 0.30 vs 1.60 ± 0.40 (P < 0.05) and 13.8 ± 9.0% vs 53.4 ± 16.7% (P < 0.05) in experiment 2, for TRT vs CTR, respectively. In summary, administration of P4 at the end of diestrus decreased the incidence of ovulations from the penultimate wave of the estrous cycle in both the moderately and highly prolific strains of sheep, but it reduced the ovulation rate only in moderately prolific ewes.

Feedback effects of estradiol and progesterone on ovulation and fertility of dairy cows after gonadotropin-releasing hormone-induced release of luteinizing hormone

An experiment was conducted with the objective to determine the effects of estradiol, progesterone, presence of a corpus luteum (CL), and size of a dominant follicle on the characteristics and patterns of GnRH-induced LH release and subsequent ovulation during a timed artificial insemination (TAI) program, or a combination of these. In 70 lactating dairy cows, a total of 163 blood collection periods resulting in a GnRH-induced LH release were analyzed. Concentrations of LH were measured in hourly samples (0 through 6 h after GnRH) during each of the blood collection periods, whereas concentrations of progesterone and estradiol were measured in the sample before GnRH treatment (0 h). Measures of LH included time to LH peak concentration during the 6-h blood collection period, the 2 largest concentrations of LH, mean, and variance of the 6 LH concentrations under each LH curve. Individual and combination effects of CL presence and a dominant follicle≤or >13.5mm, in addition to individual and combination effects of progesterone: low (<0.45 ng/mL; n=83), medium (0.53 to 2.41 ng/mL; n=25), and high (2.66 to 10.7 ng/mL; n=55), and estradiol: low (<4.0 pg/mL; n=89) and high (≥4.0 pg/mL; n=74) were independent variables in models to determine their influence on characteristics of LH and ovulation. Injections of GnRH induced LH release during 6 h after each of 163 injections. Measures of GnRH-induced LH concentration were inhibited at greater concentrations of progesterone and in the presence of a CL. In contrast, GnRH-induced LH concentrations were increased when estradiol was ≥4.0 pg/mL, but relatively unaffected by the size of the dominant follicle. Furthermore, resulting incidences of ovulation were decreased at greater progesterone concentrations and presence of a CL, and increased at greater estradiol concentrations and presence of follicles >13.5mm. In cows with or without a CL, the presence of a follicle >13.5mm did not increase mean LH concentration or incidence of ovulation. We conclude that when progesterone concentration exceeded 0.5 ng/mL at the time of GnRH treatment, subsequent LH concentrations and ovulation were suppressed. At that same concentration of progesterone or when concentrations of estradiol were ≥4 pg/mL, TAI pregnancy outcomes were improved in the face of similar incidences of ovulation suggesting greater progesterone or lesser estradiol at the time of AI may inhibit pregnancy establishment by other mechanisms.

The Effect of the Reduced Dose of GnRH on Conception, Ovulation and Ovarian Structures in Ovsynch Program of Lactating Dairy Cows

This study was conducted to evaluate the efficacy of reducing GnRH dose on the formation of ovulation and conception, and sizes of the ovarian structures following an Ovsynch program in lactating cows. The cows were allocated randomly to two treatment groups (full dose; FD, n=20 and half dose; HD, n=20). Cows in the FD group were treated with 10.5 µg buserelin acetate on day 0, with 0.150 mg D- cloprostenol 7 d later and with 10.5 µg buserelin acetate 2 d later. Estrous cycles in HD group were synchronized using the same scheme as FD-treated cows, but the dose of buserelin acetate was reduced to 5.25 µg at both GnRH administration times. Ovarian structures were monitored by ultrasound with a 6-8 MHz linear trans-rectal probe on days 0, 7, 9, 10, and 11. Cows were inseminated at the 16-20 h after second GnRH administration. No significant differences were observed in the dominant or ovulatory follicle diameters in FD and HD groups. Ovulation incidence from second GnRH injection by the 24 hour after fixed-time AI did not differ between FD (85 %) and HD (90 %) groups. Also, the conception percentages did not differ statistically between the HD (50%) and FD (40 %) groups.

Effects of breed, age, season, and multiple ovulations on cyclic, PGF2α-induced, and postpartum estrus characteristics in Spanish jennies

This retrospective, population-based, cross-sectional study analyzed data for a total of 104 jennies reared in southern Spain over the period 1995 to 2014. Intervals to ovulation and incidence of multiple ovulation and pregnancy were charted for spontaneous, PGF2α-induced, and postpartum estrous cycles. In spontaneous estrous cycles, the interovulatory interval varied as a function of breed (P < 0.03) and month of ovulation (P < 0.01), and duration of estrus signs was longer in older jennies (0.04). Spontaneous cycles were also associated with higher ovulation rates from September to January (P < 0.006). When PGF2α was used to induce the estrus, not only did estrus signs last longer in old (P < 0.004) and in polyovular (0.02) jennies but old jennies also displayed significantly higher ovulation rates (P < 0.03). In postpartum jennies, no variations were observed as a function of any of the independent variables analyzed. Comparison of ovulation rates between different types of cycle revealed that postpartum jennies exhibited significantly lower ovulation rates (1.32 ± 0.07) and a lower incidence of multiple ovulation (30.4%) than spontaneous (1.62 ± 0.04, 55.0%) and PGF2α-induced (1.74 ± 0.08, 65.5%) groups. No differences were observed in the incidence of ovulation or pregnancy depending on the location of ovulation in polyovular cycles, and ovulation occurred at similar rates in the right and left ovaries. These findings shed further light on reproductive physiology in jennies and may be of value in improving animal management.

Concentrations of luteinizing hormone and ovulatory responses in dairy cows before timed artificial insemination

The objective was to determine the incidence of LH surges and ovulatory responses in lactating dairy cows enrolled in a timed artificial insemination (TAI) program. Cows were assigned randomly to 2 presynchronization treatments: (1) Pre10 (n=37): 2 injections of PGF2α (PG; PG-1 and PG-2) 14 d apart (Presynch); or (2) PG-3-G (n=33): one 25-mg injection of PG (Pre-PG) administered 3 d before a 100-µg GnRH injection (Pre-GnRH). Ten days after PG-2 or Pre-PG, all cows were enrolled in a 7-d Ovsynch TAI program [injection of GnRH (GnRH-1) 7 d before PG (PG-3) and GnRH (GnRH-2) administered at either 56 or 72 h after PG-3; TAI at 72 h]. Blood was collected to determine LH at (1) Pre-GnRH: 48 to 80 h after PG-2 and hourly from 72 to 78 h (Pre-GnRH at 72 h); (2) GnRH-1: 0 to 6 h after GnRH-1; and (3) GnRH-2: 48 to 80 h after PG-3 and hourly from 56 to 62 h or 72 to 78 h for cows injected with GnRH-2 at 56 or 72 h after PG-3, respectively. Ovaries were scanned and pregnancy per TAI (P/AI) was diagnosed 31 and 61 d post-TAI by transrectal ultrasonography. The Pre-GnRH injection increased the incidences of LH surges (100 vs. 43%) and ovulation (91 vs. 60%) and subsequent concentrations of progesterone in PG-3-G cows compared with Pre10 cows, respectively. Seven days later, incidence of ovulation (48 to 62%) and occurrence of LH surges (100%) did not differ between treatments after GnRH-1. In contrast, LH concentrations and area under the LH curve of Pre10 cows were greater than that of PG-3-G cows because progesterone was greater in PG-3-G than in Pre10 cows (4.6±0.4 vs. 2.8±0.4 ng/mL), respectively. Concentrations of LH did not differ after GnRH-2 at either 56 or 72 h; however, 1 cow receiving GnRH-2 at 56 h and 3 cows at 72 h had early spontaneous LH surges before GnRH-2. Ovulation was suppressed overall in 210 blood collection windows in cows with elevated progesterone concentrations. When progesterone was <1 ng/mL after either PG-2 or PG-3 injections, GnRH-induced LH surges occurred in more than 90% of cows, and incidence of ovulation exceeded 80%. Pregnancy per AI tended to differ for PG-3-G (56.7%) compared with Pre10 (37.8%) and for 56 h (54.5%) compared with 72 h (38.2%), with the Pre10–72 h treatment combination producing less than half (22.2%) the pregnancies compared with all other treatment combinations. Furthermore, in these same cows, post-TAI luteal tissue volume tended to be compromised. We conclude that incidences of GnRH-induced LH surges and ovulation are suppressed in cows with elevated progesterone, possibly contributing to some loss in P/AI in TAI programs.

178 IS PROGESTERONE THE DETERMINING REGULATORY FACTOR BEHIND OVULATION RATE IN EWES?

Ovarian antral follicles in the ewe grow in an orderly succession, producing 3–4 waves per oestrous cycle. In prolific sheep, some large antral follicles from the second-last wave of the oestrous cycle are added to the ovulatory follicles emerging just before oestrus to give a higher ovulation rate; it is feasible that regression of these follicles is prevented by an increase in serum concentrations of FSH and/or LH pulsatility at pro-oestrus. Prolific sheep tend to have a shorter luteal phase than non-prolific breeds and there is a great deal of evidence that luteal progesterone (P4), in addition to regulating LH release, may govern the secretion of FSH heralding the emergence of follicular waves. The specific purpose of the present experiments was to determine whether or not extending the duration of the luteal phase would alter the ovulation rate in prolific sheep. In both studies, exogenous P4 (7.5 mg ewe–1 IM) was administered on Days 11 and 12 (Day 0 = ovulation) in moderately prolific Rideau Arcott x Polled Dorset (Exp. 1, n = 8) and highly prolific Olkuska ewes (Exp. 2, n = 7), while the equinumerous groups of animals served as controls (CTR). Transrectal ovarian ultrasonography was performed daily and jugular blood samples were drawn twice a day from Day 9 until ovulation. All single-time point observations were compared between groups by Student t-test. Progesterone injections resulted in uniform increments in serum P4 levels in all animals allocated to the treatment (TRT) groups. However, the mean duration of the interovulatory interval did not differ (P &gt; 0.05) between TRT and CTR groups of ewes in both experiments. The mean (± s.e.m.) ovulation rate was 1.6 ± 0.2 v. 3.2 ± 0.4 (Exp. 1; P &lt; 0.001) and 3.2 ± 0.8 v. 4.0 ± 1.0 (Exp. 2; P &lt; 0.05) in TRT v. CTR ewes, respectively. There were no differences in terms of the timing of penultimate and final wave emergence between the two subsets of animals studied in either experiment. The number/percentage of ovulating follicles from the penultimate wave of the interovulatory interval studied was 0.25 ± 0.16 v. 1.75 ± 0.45 (P &lt; 0.01)/25.0 ± 16.4% v. 75.0 ± 16.4% (P &lt; 0.05) in Exp. 1 and 0.50 ± 0.30 v. 1.60 ± 0.40 (P &lt; 0.05)/13.8 ± 9.0% v. 53.4 ± 16.7% (P &lt; 0.05) in Exp. 2, in TRT v. CTR animals, respectively. In summary, administration of P4 at the end of diestrus reduced the incidence of ovulations from the penultimate wave of the oestrous cycle in moderately and highly prolific strains of sheep. Therefore, progesterone appears to be a key endocrine signal governing the ovulation rate in cyclic sheep, presumably by acting directly at the level of the ovary. The present results may pave a way to devising a simple and inexpensive method of controlling lamb productivity in commercial flocks of sheep and fertility in other polyovulatory species.

In vivo imaging in the rabbit as a model for the study of ovulation-inducing factors

The study of factors responsible for eliciting ovulation in rabbits has been hampered by the lack of a suitable method of monitoring the ovaries invivo. Ovarian imaging by ultrasound biomicroscopy was used in two experiments designed to determine the effects of seminal plasma on the ovulatory response in rabbits. In Experiment 1, female rabbits were group-housed and treated intramuscularly with saline, gonadotropin releasing hormone (GnRH), or seminal plasma of llamas or rabbits (n = 4 to 6 per group). Rabbits were euthanized eight days later to evaluate the ovarian response by ultrasound biomicroscopy ex situ. No differences among groups were detected in the proportion of rabbits that ovulated or in the number and size of corpora lutea. The high incidence of ovulation in the negative control group was unexpected, and confounded determination of an ovulation-inducing effect of seminal plasma. In Experiment 2, female rabbits were caged individually, and treated as in Experiment 1 (n = 5 to 7 per group). The ovarian response was evaluated invivo by transcutaneous ultrasound biomicroscopy. Ovulation and formation of corpora lutea were detected only in rabbits given GnRH. A preovulatory surge in plasma luteinizing hormone concentration and a post-ovulatory rise in plasma progesterone concentration were detected only in rabbits treated with GnRH. Surgical translocation of the ovaries to a subcutaneous position enabled longitudinal assessment of the ovulatory response by ultrasound biomicroscopy. Results clearly documented the effect of physical/social interaction on ovulation in rabbits, and did not support the hypothesis that seminal plasma elicits ovulation in rabbits.

Infrared technology for estrus detection and as a predictor of time of ovulation in dairy cows in a pasture-based system

The development and application of an algorithm to assess the ability of an infrared thermography (IRT) device to predict cows in estrus and about to ovulate was investigated. Twenty cows were synchronized using a controlled internal drug release and PGF2α. Vulval and muzzle temperatures were measured every 12 hours from controlled internal drug release insertion to 32 hours after PGF2α treatment and then every 4 hours until ovulation occurred or until 128 hours after PGF2α treatment (whichever occurred first). Thermal images obtained with a FLIR T620 series infrared camera were analyzed using ThermaCAM Researcher Professional 2.9 software. Cows were also monitored for behavioral signs of estrus and color changes of an Estrotect applied to the tail head of each cow 36 hours after PGF2α treatment. Algorithms were developed by adjusting body surface temperature of individual animals for ambient temperature and humidity during each observation period, and were expressed as a deviation from the baseline temperature. Of the 20 cows enrolled in this study, 12 (60%) ovulated. An IRT estrus alert was defined using different thresholds (D = 1 °C, 1.25 °C, and 1.5 °C). Sensitivity and specificity to predict estrus depended upon the chosen threshold level. At a threshold D = 1 °C, the highest sensitivity (92%; n = 11) and the lowest specificity (29%) and positive predictive value (64%) were observed. Conversely, D = 1.5 °C resulted in sensitivity of 75%, specificity of 57%, and positive predictive value of 69%. The mean ± standard deviation intervals between onset and the end of IRT estrus alert to ovulation were 30.7 ± 8.2 and 13.3 ± 7.7 hours, respectively. Ovulation occurred 24 to 47 hours after the onset of the IRT estrus alert for eight out of the 11 ovulated cows (73%). Although the sensitivity of the IRT alert was greater than visual observation (67%) and Estrotect activation (67%), the specificity and positive predictive value were lower than these two aids (i.e., the IRT overpredicted the incidence of ovulation). Results presented indicate that IRT shows some potential as an estrus detection aid; however, further studies investigating the potential to improve the specificity and capturing data throughout entire 21-day reproductive cycles would be worthwhile.

Effects of high somatic cell counts in milk on reproductive hormones and oestrus behaviour in dairy cows with special reference to those with concurrent lameness

The present investigation aims to establish the reason(s) why dairy cows with high somatic cell counts (SCCs; >100,000 cells/ml) are less fertile than cows with low SCCs alone. The objective of Study One was to determine whether differences in steroid hormone profiles could explain the low incidence of ovulation in cows with combined High SCC and lameness. Between 30 and 80 days post-partum, animals were scored for SCC and lameness and three groups were formed: Healthy (n=22), High SCC alone (n=12) or High SCC + Lame (n=9). The ovarian follicular phases of all cows were synchronised by administering gonadotrophin releasing hormone (GnRH) followed seven days later by prostaglandin F2alpha (PG). Milk samples were collected daily throughout the entire study period; twice daily during the follicular phase, blood samples were taken and the ovaries were monitored using ultrasonography. Progesterone concentrations were similar in all three groups during each of five specific time periods, i.e. throughout the five days before PG injection, the peri-ovulatory period, on Day 5 and on Day 7, and during the mid luteal phase 12–17 days after ovulation (P>0.13). Mean plasma oestradiol concentrations monitored every 12h during the 36h period before ovulation were similar in all groups (Healthy, 2.80±0.30pg/ml; High SCC alone, 3.82±0.48pg/ml; High SCC+Lame 2.94±0.51pg/ml; P=0.175). The objective of Study Two was to establish whether cows with High SCC (scored and synchronised as above) display different behaviours, especially the intensity and timing of oestrus. Intervals from PG to the onset of oestrus or to the first stand-to-be-mounted (STBM) were longer for the High SCC cows than the Low SCC animals (n=8 and 20; P=0.011 and 0.002, respectively). Also, cows with High SCC tended to have a less intense oestrus and a lower maximum oestrus score per 30-min period than Low SCC cows (P=0.063 and 0.066, respectively). In conclusion, High SCC±lameness did not affect progesterone or twice daily oestradiol profiles but the onset of oestrus was delayed and oestrus tended to be less intense in cows with High SCC. These factors could explain low fertility associated with High SCC.

THE INFLUENCE OF URINARY AND FECAL ODORS ON OVARIAN FUNCTION IN COEXISTING ACOMYS SPECIES

ABSTRACT Nocturnal golden spiny mice, Acomys russatus, become diurnal in the presence of congeneric common spiny mice, A. cahirinus, or to chemical signals released by them. Here we report on the influence of signals from fresh urine and feces released by A. cahirinus on aspects of the estrous cycle of A. russatus. The results of our study show that the length of the estrous cycle of A. russatus is not influenced by the presence of odors released from A. cahirinus. However, the frequency of occurrence of post-ovulatory increases in plasma progesterone concentrations suggests that the incidence of ovulation in A. russatus is affected by signals produced by the urine and feces of A. cahirinus. The mechanisms involved in the apparent suppression of ovulation or the formation of a functional corpus luteum require further investigation.

Effect of progesterone concentration and duration of proestrus on fertility in beef cattle after fixed-time artificial insemination

The objective was to determine the effect of plasma progesterone concentration and the duration of proestrus during growth of the ovulatory follicle on fertility in beef cattle. Heifers (N = 61) and postpartum cows (N = 79) were assigned randomly to four groups in a two-by-two design involving luteal-phase versus subluteal-phase plasma progesterone concentrations and normal versus short proestrus. To synchronize follicular wave emergence, estradiol-17β was given im during the midluteal phase (Day 0) and concurrently, a once-used controlled intravaginal progesterone-releasing device was placed intravaginally. In the subluteal-phase progesterone groups, a luteolytic dose of PGF2α was given on Day 0 and again 12 hours later. In the luteal-phase progesterone groups, PGF2α was not given (so as to retain a functional CL). The controlled intravaginal progesterone-releasing device was removed and PGF2α was given on Days 7 or 8 in the normal- and short-proestrus groups, respectively. Cattle were given lutropin im 12 or 36 hours later in the short- and normal-proestrus groups, respectively, with AI at 12 hours after lutropin treatment. Transrectal ultrasonography was used to monitor ovarian response during treatments and to diagnose pregnancy 60 days after AI. Cattle (heifers and cows combined) in the subluteal-phase progesterone groups and normal proestrus groups had a larger follicle at the time of AI, and a larger CL that secreted more progesterone 9 days after AI than cattle with luteal-phase progesterone concentrations or those with short proestrus (P < 0.03). There was a higher incidence of ovulation (P < 0.01) the day after AI in heifers (55/61; 90%) than in cows (44/79; 56%). Pregnancy rates ranged from 11% to 54%, and were higher in cattle (heifers and cows combined) in the subluteal-phase progesterone groups and normal proestrus groups than in the luteal-phase progesterone or short proestrus groups, respectively, (P < 0.02). In conclusion, a short proestrous interval reduced pregnancy rate after fixed-time AI in beef cattle. A low progesterone environment during growth of the ovulatory follicle increased the preovulatory follicle size and subsequent CL size and function, and compensated for the effect of a short proestrus on pregnancy rates.