Peak Progesterone Concentrations Research Articles

In vitro fertilization outcome based on the detailed early luteal phase trajectory of hormones: a prospective cohort study

BackgroundOvarian stimulation and the use of human chorionic gonadotropin (hCG) for triggering oocyte maturation in women undergoing in vitro fertilisation (IVF) introduces several differences in luteal phase hormone levels compared with natural cycles that may negatively impact on endometrial receptivity and pregnancy rates after fresh embryo transfer. Exogenous luteal phase support is given to overcome these issues. The suitability of a pragmatic approach to luteal phase support is not known due to a lack of data on early phase luteal hormone levels and their association with fertility outcomes during IVF with fresh embryo transfer. This study determined early luteal phase profiles of serum progesterone, 17-hydroxyprogesterone and hCG, and associations between hormone levels/hormone level profile after hCG trigger and the live birth rate in women undergoing IVF with fresh embryo transfer.MethodsThis prospective single center, cohort study was conducted in Vietnam from January 2021 to December 2022. Women aged 18–38 years with normal ovarian reserve and undergoing controlled ovarian stimulation using a gonadotropin-releasing hormone antagonist protocol were included. Serum hormone levels were determined before trigger, at 12, 24 and 36 h after hCG, and daily from 1 to 6 days after oocyte pick-up. Serum hormone level profiles were classified as lower or upper. The primary outcome was live birth rate based on early luteal phase hormone level profile.ResultsNinety-five women were enrolled. Live birth occurred in 19/69 women (27.5%) with a lower progesterone profile and 13/22 (59.1%) with an upper progesterone profile (risk ratio [RR] 2.15; 95% confidence interval [CI] 1.28–3.60), and in 6/31 (19.4%) versus 26/60 (43.3%) with a lower versus upper serum 17-hydroxyprogesterone profile (RR 2.24; 95% CI 1.03–4.86). Nearly 20% of women had peak progesterone concentration on or before day 3 after oocyte pick-up, and this was associated with significantly lower chances of having a life birth.ConclusionsThese data show the importance of proper corpus luteum function with sufficient progesterone/17-hydroxyprogesterone production for achievement of pregnancy and to maximize the chance of live birth during IVF.Trial RegistrationNCT04693624 (www.clinicaltrials.gov).

Estradiol-17β Injection Induces Ovulation in Llamas

This study aimed to investigate the effect of three different doses of estradiol-17β on ovulation and subsequent luteal development and function in llamas. Twenty-three llamas were examined daily by transrectal ultrasonography until the detection of an ovulatory follicle (≥8 mm). Thereafter, animals were divided into five groups: Control (n = 3; treated with 1.6 ml of saline solution), GnRH group (n = 6, treated with an intravenous injection of 8.4 μg Buserelin), and estradiol groups that received 0.6 mg (E1, n = 4), 1 mg (E2, n = 4), or 1.6 mg (E3, n = 6) of estradiol-17β intravenously. Detection of ovulation was based on ultrasonographic visualization of disappearance of the largest follicle and subsequent presence of a newly formed corpus luteum (CL) and progesterone concentration exceeding 1 ng ml−1. Daily blood samples were collected to determine plasma progesterone concentration. Ovulation rate was 0% for control and E1 groups, 25% for E2 group, and 100% for GnRH and E3 groups. Differences in the mean CL diameter between GnRH and E3 groups were not statistically significant. Plasma progesterone concentration was similar between groups during the different days in ovulated animals. However, the day that the plasma progesterone concentration was above 1 ng ml−1 and the day that the highest plasma progesterone concentration was achieved differed among E3 and GnRH groups, occurring later in females treated with estradiol. In conclusion, an injection of estradiol-17β is capable of inducing ovulation in llamas and the response depends on the dose used. Most of the animals required the highest tested dose (1.6 mg) to induce the ovulatory process. Although the CL diameter in females induced to ovulate with estradiol was similar to that in llamas induced to ovulate with a GnRH analog, the rise in plasma progesterone concentration above 1 ng ml−1 and the peak progesterone concentration were attained 1 day later in the estradiol treated females.

Evaporative cooling in late gestation heat-stressed Murrah buffaloes increases efficiency of next reproductive cycle.

Evaporative cooling during late gestation period improves post-partum reproductive performance in Murrah buffaloes. To prove this hypothesis, sixteen pregnant dry Murrah buffaloes at sixty days pre-partum were selected and divided into two groups of eight animals each. Group 1 of buffaloes (Cooled/CL) was managed under fan and mist cooling during dry period, whereas second group of buffaloes (non-cooled/NCL) remained without the provision of cooling. After parturition, all the animals were managed under evaporative cooling till the end of experimental period. Reproductive performance in cooled (CL) and non-cooled (NCL) groups, respectively, viz. 1st and 2nd ovulation from calving (48.63±2.41, 69.25±2.34days and 57.75±3.35, 93.63±2.84days); calving to conception interval (117.88±4.21days and 117.88±4.21days); conception rate (87.5%±2.16% and 57%±2.26%); and follicular diameter at the time of 1st and 2nd ovulation (14.84±0.16, 15.75±0.13mm and 12.65±0.13, 13.35±0.11mm) varied significantly (p<.05). Total peak oestrogen concentration was significantly (p<.05) higher in cooled (26.7±1.32pg/ml) relative to non-cooled (20.7±1.22pg/ml) buffaloes. Time from onset of oestrus to ovulation varied significantly (p<.05) in cooled (32±2.22hr) and non-cooled (40±2.86hr) buffaloes. The peak progesterone concentration reached to (4.25ng/ml) in cooled group and (4.16ng/ml) in non-cooled group after first ovulation.

Sexual activity, endogenous reproductive hormones and ovulation in premenopausal women

We investigated whether sexual activity was associated with reproductive function in the BioCycle Study, a prospective cohort study that followed 259 regularly menstruating women aged 18 to 44years for one (n=9) or two (n=250) menstrual cycles in 2005–2007. Women were not attempting pregnancy nor using hormonal contraceptives. History of ever having been sexually active was assessed at baseline and frequency of sexual activity, defined as vaginal–penile intercourse, was self-reported daily throughout the study. Serum concentrations of estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and testosterone were measured up to 8times/cycle. Sporadic anovulation was identified using peak progesterone concentration. Linear mixed models were used to estimate associations between sexual activity and reproductive hormone concentrations and generalized linear models were used to estimate associations with sporadic anovulation. Models were adjusted for age, race, body mass index, perceived stress, and alcohol consumption and accounted for repeated measures within women. Elevated concentrations of estrogen (+14.6%, P<.01), luteal progesterone (+41.0%, P<.01) and mid-cycle LH (+23.4%, P<.01), but not FSH (P=.33) or testosterone (P=.37), were observed in sexually active women compared with sexually inactive women (no prior and no study-period sexual activity); sexually active women had lower odds of sporadic anovulation (adjusted odds ratio=0.34, 95% confidence interval: 0.16–0.73). Among sexually active women, frequency of sexual activity was not associated with hormones or sporadic anovulation (all P>.23). Findings from our study suggest that ever having been sexually active is associated with improved reproductive function, even after controlling for factors such as age.

Biological variability in serum anti-Müllerian hormone throughout the menstrual cycle in ovulatory and sporadic anovulatory cycles in eumenorrheic women.

Does serum anti-Müllerian hormone (AMH) vary significantly throughout both ovulatory and sporadic anovulatory menstrual cycles in healthy premenopausal women? Serum AMH levels vary statistically significantly across the menstrual cycle in both ovulatory and sporadic anovulatory cycles of healthy eumenorrheic women. Studies to date evaluating serum AMH levels throughout the menstrual cycle have conflicting results regarding intra-woman cyclicity. No previous studies have evaluated an association between AMH and sporadic anovulation. We conducted a prospective cohort study of 259 regularly menstruating women recruited between 2005 and 2007. Women aged 18-44 years were followed for one (n = 9) or two (n = 250) menstrual cycles. Anovulatory cycles were defined as any cycle with peak progesterone concentration ≤5 ng/ml and no serum LH peak on the mid or late luteal visits. Serum AMH was measured at up to eight-time points throughout each cycle. Geometric mean AMH levels were observed to vary across the menstrual cycle (P < 0.01) with the highest levels observed during the mid-follicular phase at 2.06 ng/ml, decreasing around the time of ovulation to 1.79 ng/ml and increasing thereafter to 1.93 (mid-follicular versus ovulation, P < 0.01; ovulation versus late luteal, P = 0.01; mid-follicular versus late luteal, P = 0.05). Patterns were similar across all age groups and during ovulatory and anovulatory cycles, with higher levels of AMH observed among women with one or more anovulatory cycles (P = 0.03). Ovulatory status was not verified by direct visualization. AMH was analyzed using the original Generation II enzymatically amplified two-site immunoassay, which has been shown to be susceptible to assay interference. Thus, absolute levels should be interpreted with caution, however, patterns and associations remain consistent and any potential bias would be non-differential. This study demonstrates a significant variation in serum AMH levels across the menstrual cycle regardless of ovulatory status. This variability, although statistically significant, is not large enough to warrant a change in current clinical practice to time AMH measurements to cycle day/phase. This research was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, MD (Contracts # HHSN275200403394C, HHSN275201100002I Task 1 HHSN27500001). The authors have no conflicts of interest to declare.

The Muscle Stretch Reflex throughout the Menstrual Cycle

The significant sex disparity in sports-related knee injuries may be due to underlying differences in motor control. Although the development of sex-specific movement patterns is likely multifactorial, this study specifically focuses on the potential modulatory role of sex hormones. This study aimed to investigate the muscle stretch reflex (MSR) across the menstrual cycle. We hypothesized that the MSR would fluctuate throughout the menstrual cycle and that the lowest response would correspond with peak concentrations of estrogen. Nineteen healthy women age 18-35 yr participated in this study: 8 eumenorrheic women and 11 women taking oral contraceptives. Serum estradiol and progesterone concentrations, anterior knee laxity (AKL), and the MSR response of the quadriceps muscles were measured three times during the menstrual cycle. The MSR response of the rectus femoris (RF) varied significantly across the menstrual cycle in both groups. Specifically, the RF MSR response was 2.4 times lower during the periovulatory phase when compared with the luteal phase (P = 0.007). The same trend was seen in the vastus medialis, but this did not reach statistical significance (P = 0.070). The MSR response of the vastus lateralis did not change significantly across the menstrual cycle (P = 0.494). A mixed model comparison did not show an association between endogenous concentrations of estradiol and progesterone, exposure to hormonal contraceptives or AKL, and the MSR response for any muscle. Our results demonstrate that the RF MSR response varies throughout the menstrual cycle with the lowest response around the time of ovulation. Additional research is needed to clarify the exact relationship between sex hormones, AKL, and MSR response and to determine the specific origin of the change along the monosynaptic reflex arc.

The Impact of Dietary Folate Intake on Reproductive Function in Premenopausal Women: A Prospective Cohort Study

BackgroundFolic acid is recommended to reproductive-aged women to prevent birth defects, though little is known about the effects of dietary intake on other reproductive outcomes. Improved pregnancy rates have been documented after folic acid supplement use, suggesting a possible link with ovulation, however research is limited. Our objective was to evaluate the association between dietary folate intake, hormone levels, and sporadic anovulation in healthy, regularly menstruating women.Methodology/Principal FindingsThe BioCycle study (2005–2007) prospectively followed 259 healthy women aged 18–44 years from the western New York region for up to 2 menstrual cycles. Total folate and specific sources of folate were assessed up to 4 times per cycle by 24-hour recall. Estradiol, progesterone, luteinizing hormone, and follicle-stimulating hormone were measured in serum up to 8 times per cycle, timed using fertility monitors. Anovulation was defined as a cycle with peak progesterone concentration ≤5 ng/mL and no LH peak in the mid/late luteal phase. Higher intake of dietary folate (in dietary equivalents) across tertiles had a marginally significant association with greater luteal progesterone levels (P trend 0.08). Higher intake of synthetic folate was significantly associated with higher luteal progesterone levels (P trend 0.05). Specifically, women in the 3rd tertile of synthetic folate intake had, on average, 16.0% (95% CI, 0.5–33.8%) higher luteal progesterone levels compared to women in the 1st tertile. Moreover, consumption of synthetic folate was significantly and inversely associated with anovulation such that women in the 3rd tertile had a 64% (95% CI, 8–86%) decreased odds of anovulation compared to the women in the 1st tertile (P trend 0.03).Conclusions/SignificanceThese findings suggest that a diet high in synthetic folate may be associated with increased progesterone levels and lower risk of sporadic anovulation. Further study of the effect of dietary folate and folic acid supplement use on reproductive health is warranted.

9 EFFECTS OF MECLOFENAMIC ACID ON LUTEAL FUNCTION OF BEEF CATTLE

The objective of this study was to determine the effects of meclofenamic acid, a nonsteroidal anti-inflammatory, on luteal function of beef cattle. A total of 18 Angus cows, aged between 2 and 3 years old, were enrolled in the experiment. All cows were synchronized using a 5-day CIDR protocol. Briefly, cows received 100 μg of gonadorelin diacetate tetrahydrate (GnRH; Cystorelin®, Merial, Athens, GA, USA) and a controlled internal drug release insert (CIDR; Eazi-BreedTM CIDR®, Pfizer Animal Health, New York, NY, USA). Five days later, the CIDR was removed and 50 mg of dinoprost (Lutalyse®, Pfizer Animal Health) was administered intramuscularly. Oestrus was determined by twice daily observations of mounting behaviour and tail painting scores (day of oestrus = Day 0). At 72 h after dinoprost, a second dose of gonadorelin (100 μg, IM) was administered. On Day 14, cows were randomly assigned to the following treatment groups: 1) control: 10 mL of saline solution administered IM; 2) systemic: 2 g of meclofenamic acid administered IM; and 3) oral: 2 g of meclofenamic acid administered orally. Cows were treated once daily for 11 days (i.e. until Day 24) and no adverse reactions were observed. Blood sampling and ovarian ultrasonography were performed every 72 h from Day 0 until Day 12 and then every 48 h until the end of the study. Serum progesterone concentrations were determined by radioimmunoassay and were used to determine functional luteolysis (i.e. progesterone &lt;1 ng mL–1). Ovaries were evaluated for the presence of a corpus luteum and to evaluate follicular growth and subsequent ovulation. One-way ANOVA was used to compare the day of peak progesterone concentration, lifespan of the corpus luteum and the length of the oestrous cycle between groups. Significance was set at P &lt; 0.05 and data are presented as means ± standard error of the mean (Table 1). There were no effects of meclofenamic acid administration on any of the parameters evaluated (P &gt; 0.05). In conclusion, meclofenamic acid administration did not affect luteal function in our study. Potentially, higher doses of meclofenamic acid may be necessary to inhibit prostaglandin synthesis and prevent luteolysis. Table 1.Effects of meclofenamic acid administration on the day of peak progesterone concentration, lifespan of the corpus luteum (CL) and the length of oestrous cycle in beef cows (mean ± standard error of the mean) Funding was provided by The Ohio State University, College of Veterinary Medicine, USDA-Animal Health Formula Funds. The authors are also grateful to the staff at the OSU Beef Center Facility for helping with animal handling and care.

Human chorionic gonadotropin influences ovarian function and concentrations of progesterone in prepubertal Angus heifers1

The effects of administering hCG on subsequent ovarian structure dynamics and concentrations of progesterone in prepubertal heifers were evaluated. Forty-seven purebred Angus heifers were assigned randomly to 1 of 3 treatments: 1) 100 μg of injection of GnRH (GnRH; n = 16); 2) 1,000 IU injection of hCG (H1000; n = 16); and 3) 500-IU injection of hCG (H500; n = 15). From d -1 to 9 relative to treatment (d 0), daily blood samples were collected to determine concentrations of progesterone and ovaries of each heifer were examined daily by transrectal ultrasonography. Diameter of all follicles ≥ 4 mm and all luteal structures were mapped. Disappearance of the largest follicle occurred within 2 d in a greater percentage (P < 0.05) of all heifers in the H1000 treatment (87.5%) compared with GnRH heifers (43.8%), whereas H500 heifers (73.7%) were intermediate. A new luteal structure formed after follicle disappearance in a greater (P < 0.05) percentage of all heifers treated with H1000 (87.5%) and H500 (73.7%) heifers compared with that in GnRH-treated heifers (18.8%). The largest follicle present in ovaries of H1000 and H500 heifers was smaller (P < 0.05) than that of GnRH heifers from d 2 to 5. Heifers treated with H1000 (1.72 ± 0.19 ng/mL) had peak concentrations of progesterone on d 6 that were greater (P < 0.05) than H500 heifers (1.34 ± 0.20 ng/mL), which were greater than heifers treated with GnRH (0.31 ± 0.19 ng/mL). The mean volume of luteal tissue was greater (P < 0.05) in H1000 heifers (1.54 ± 0.15 cm(3)) than in H500 heifers (1.15 ± 0.15 cm(3)), which was greater (P < 0.05) than in heifers treated with GnRH (0.23 ± 0.15 cm(3)). We conclude that hCG was more effective than GnRH in its ability to cause disappearance of the largest follicle, increase volume of luteal tissue in the subsequent developing luteal structures, and increase concentrations of progesterone in prepubertal heifers. In addition, hCG seems to be more effective when administered at 1,000 IU than at 500 IU.

Reproductive cycles of buffalo

The domestic water buffalo ( Bubalus bubalis) has an important role in the agricultural economy of many developing countries in Asia, providing milk, meat and draught power. It is also used in some Mediterranean and Latin American countries as a source of milk and meat for specialized markets. Although the buffalo can adapt to harsh environments and live poor quality forage, reproductive efficiency is often compromised by such conditions, resulting in late sexual maturity, long postpartum anoestrus, poor expression of oestrus, poor conception rates and long calving intervals. The age at puberty is influenced by genotype, nutrition, management and climate, and under favourable conditions occurs at 15–18 months in river buffalo and 21–24 months in swamp buffalo. The ovaries are smaller than in cattle and contain fewer primordial follicles. Buffalo are capable of breeding throughout the year, but in many countries a seasonal pattern of ovarian activity occurs. This is attributed in tropical regions to changes in rainfall resulting in feed availability or to temperature stress resulting in elevated prolactin secretion, and in temperate regions to changes in photoperiod and melatonin secretion. The mean length of the oestrous cycle is 21 days, with greater variation than observed in cattle. The signs of oestrus in buffalo are less overt than in cattle and homosexual behaviour between females is rare. The duration of oestrus is 5–27 h, with ovulation occurring 24–48 h (mean 34 h) after the onset of oestrus. The hormonal changes occurring in peripheral circulation are similar to those observed in cattle, but the peak concentrations of progesterone and oestradiol-17β are less. The number of follicular waves during an oestrous cycle varies from one to three and influences the length of the luteal phase as well as the inter-ovulatory interval. Under optimal conditions, dairy types managed with limited or no suckling resume oestrus cyclicity by 30–60 days after calving, while swamp types with free suckling do so at 60–90 days. However, in many farming systems prolonged postpartum anoestrus is a major problem, and the causes include poor nutrition and body condition, and stress due to harsh climates and improper management. Synchronization of time or induction of oestrus can be done using the same regimens as applied in cattle, using various combinations of prostaglandins, progesterone releasing devices, GnRH and eCG, but success rate is poor when treatment is done during the periods of marginal breeding activity or seasonal anoestrus.

Differential Effects of Exogenous Progesterone Administration at Different Stages of the Luteal Phase on Endogenous Oestradiol Concentration in Cows

We have investigated the effects administering exogenous progesterone, via insertion of a controlled internal drug release (CIDR) for 4 days, from either day 5 or day 12 of the oestrous cycle on plasma oestradiol concentrations. In study 1, in which progesterone was administered from day 5, measurement of plasma oestradiol in daily samples revealed a significant (p < 0.001) decrease in peripheral oestradiol concentration. In contrast, in study 2, similar administration of progesterone from day 12 had no effect on plasma oestradiol concentration. In study 3, collection of hourly samples following progesterone treatment on day 5 revealed peak progesterone concentrations within 1 h of CIDR insertion and nadir oestradiol concentrations within 4 h. The results demonstrate that treatment with progesterone early in the luteal phase causes a rapid inhibition of oestradiol secretion, while later treatment does not. While improvements in pregnancy rate following progesterone treatment at this time have traditionally been attributed to increases in progesterone, the potential involvement of decreased oestradiol secretion has often been overlooked.

Relationship Between Milk Progesterone Profiles and Genetic Merit for Milk Production, Milking Frequency, and Feeding Regimen in Dairy Cattle

Milk progesterone profiles were determined from samples obtained twice weekly for 100 d postpartum in 100 Holstein primiparous cows at a Dutch experimental farm. Three treatments were applied in a 2×2×2 factorial arrangement with high-low genetic merit for overall production, high-low caloric density diet, and 2-3 times milking/day as factors. Milk progesterone profiles were characterized by start of first ovarian cyclical activity (commencement of luteal activity, C-LA), length and peak milk progesterone concentration of first ovarian cycle, and number of ovarian cycles in first 100 d postpartum, as well as classified into normal, delayed, prolonged, and interrupted ovarian cyclical activity. Cows with a greater milk production had lower peak progesterone concentrations, especially if the high milk production was caused by milking 3 times a day. A more negative energy and protein balance was associated with later C-LA and less ovarian cycles within 100 d postpartum. Relationships between protein balance and C-LA differed between cows with a high genetic merit and a low genetic merit. Cows with a high genetic merit for production showed delayed C-LA with more negative protein balances, whereas this association was not observed among cows with a low genetic merit. Cows in negative energy balance had greater risk for prolonged ovarian cycles when there was no delay in C-LA than when C-LA was delayed.

Chlortetracycline supplementation of yearling dairy heifers1,2

Chlortetracycline is an antibiotic that is used to increase weight gain, efficiency of gain, carcass grade, and conception rates. The objective of this experiment was to evaluate the effects of supplementation of 350 mg/d of chlortetracycline on ADG, G:F, BCS, thyroxine, and systemic glucose concentrations in yearling dairy heifers. Forty 12-mo-old Holstein heifers (initial BW = 363 +/- 21 kg) were housed in a free-stall barn with ad libitum access to feed and water for 104 d. A transition period was begun 14 d before the age of 12 mo to acclimate the heifers to the diet. The chlortetracycline-fed group (n = 20) consumed 328 +/- 8.2 mg of chlortetracycline/heifer daily. Measurements for BW, withers and hip heights, BCS, and health score were recorded weekly. Dry matter intake was measured daily. Blood was sampled every 4 d to determine plasma thyroxine and glucose concentrations and every 2 d to determine progesterone concentrations. Heifers were artificially inseminated on the first observed standing heat after 13 mo of age. There were no effects of chlortetracycline on ADG, G:F, withers and hip heights, BCS, blood glucose concentrations, peak progesterone concentrations, health, or conception rate. There was an interaction between treatment and time for chlortetracycline on serum thyroxine concentration. In the beginning of the experiment, serum thyroxine concentration was lower in heifers supplemented with chlortetracycline. There was no difference between treatments in thyroxine concentration at the end of the experiment. Chlortetracycline supplementation was not beneficial for yearling dairy heifers.

16 PROGESTERONE RELEASE PATTERNS FROM CUE-MATE IN COMPARISON TO OTHER INTRAVAGINAL PROGESTERONE-RELEASING DEVICES IN LACTATING DAIRY COWS

Various intravaginal progesterone-releasing devices are commercially available and each is impregnated with different amounts of progesterone. An experiment was designed to characterize plasma progesterone release profiles from Cue-Mate in comparison with other commercially available progesterone-releasing devices. Cycling, lactating Holstein cows (n = 60; BCS between 2.0 and 3.0 out of 5) from commercial dairy farms in Argentina were used in 2 replicates. All cows received 2 injections of D+ cloprostenol (PGF, Bioprost-D�; Biotay, Buenos Aires, Argentina) 14 days apart and were randomly assigned to one of four groups to receive intravaginal devices as follows: Cue-Mate (1.56 g progesterone; Bioniche Animal Health, A/Asia Pty, Armidale, Australia; n = 10), DIB (1 g progesterone; Syntex SA, Argentina; n = 10), CIDR with 1.9 g progesterone (Pfizer Salud Animal S.A., Buenos Aires, Argentina; n = 10), or CIDR with 1.38 g progesterone (Pfizer Animal Health, Groton, CT, USA; n = 10). All devices were inserted 24 hours after the second PGF and were left in place for 31 days. Blood samples were taken for progesterone analysis at 6-hour intervals for the first 24 hours, then daily for a week, and every 2 days for an additional 25 days. Plasma progesterone concentrations were measured with a modified human double-antibody RIA kit (DPC Coat-A-Count�; Diagnostic Products Corporation, Los Angeles, CA, USA). Cows were observed twice daily to confirm that vaginal inserts were still in place. Time-series hormone data were analyzed using the MIXED procedure for repeated measures (SAS Institute, Inc., Cary, NC, USA). Main effects of device and time, the highest mean concentration of progesterone, and the mean day on which this occurred were compared by a protected LSD test. There was no evidence of cow discomfort with any of the vaginal devices, and loss rates did not differ. There was an effect of group (P &amp;lt; 0.001) and day (P &amp;lt; 0.001) for progesterone concentrations, but there was no interaction (P = 0.89). Peak concentrations of progesterone (ng mL-1) did not differ among groups (Cue-Mate: 5.0 � 1.1; DIB: 3.9 � 0.6; 1.9-g CIDR: 4.6 � 0.6; 1.38-g CIDR: 3.7 � 0.4; P = 0.51). Mean (� SEM) concentrations of progesterone over the 31-day insertion period differed between 1.9-g CIDR (1.8 � 0.2 ng mL-1) and DIB (1.5 � 0.1 ng mL-1, P &amp;lt; 0.006), with Cue-Mate (1.5 � 0.2 ng mL-1) and 1.38-g CIDR (1.6 � 0.1 ng mL-1) intermediate and not different from either. When data were evaluated from insertion until Day 7, mean plasma progesterone concentrations did not differ among groups (Cue-Mate: 2.2 � 0.2 ng mL-1; DIB: 2.2 � 0.1 ng mL-1; 1.9-g CIDR: 2.6 � 0.2 ng mL-1; 1.38-g CIDR: 2.1 � 0.1 ng mL-1). However, progesterone concentrations from insertion until Day 21 were higher (P &amp;lt; 0.03) in cows with a 1.9-g CIDR (2.1 � 0.1 ng mL-1) than in those with a DIB (1.6 � 0.1 ng mL-1) or a 1.38-g CIDR (1.6 � 0.1 ng mL-1), with Cue-Mate (1.7 � 0.1 ng mL-1) intermediate and not different. Based on progesterone release patterns, it was concluded that Cue-Mate intravaginal devices can be used in protocols for synchronization of estrus and ovulation as with other progesterone-releasing devices.

Supplementation with Urea and Molasses and Body Weight, Milk Yield and Onset of Ovarian Cyclicity in Cows

Ten multiparous crossbred local Zebu cows were randomly divided into two nutritional groups (A and B) to determine the effect of urea-molasses-mineral block supplementation on body weight gain, milk production, and onset of ovarian cyclicity after calving. Both groups had farm rations daily, but the supplemented group (B) was provided with an additional diet daily of 250 g urea-molasses-mineral block. The cows in group A required 80-120 days (98.0 +/- 6.7 days) until peak milk progesterone concentrations and 60-80 days (72.0 +/- 3.8 days) were required for group B (p<0.05). Group B needed a shorter period for expression of standing estrus (91-101 days; mean 96.2 +/- 2.3 days) than group A [130-153 (141.6 +/- 4.6) days; p<0.01]. For groups A and B, body weight gain was 8.4 +/- 3.4 kg and 18.4 +/- 3.2 kg, respectively (p<0.01). The average milk production of groups A and B were 3.3 +/- 1.0 and 4.8 +/- 1.6 L/day, respectively (p>0.05). There was linear improvement in milk yield from Day 60 postpartum up to Day 90 of lactation in group B (supplemented). However, in group A, milk production decreased starting on Day 40 after parturition.

Oestrous cycle of captive southern hairy-nosed wombats ( Lasiorhinus latifrons) in South Australia, Australia

There is limited information available on the oestrous cycle of female southern hairy-nosed wombats ( Lasiorhinus latifrons). This is mainly due to an extremely poor breeding success in captivity and the difficulty in routine recapturing of these cryptic, semi-fossorial animals in the wild. The aim of this study was to characterise the oestrous cycle of this species by monitoring peripheral plasma concentrations of progesterone and oestradiol, assessing changes in vaginal cytology, pouch condition and the urogenital sinus. Eight adult female wombats were monitored during the breeding season (July–December) over 2 years (2002–2003). Samples were collected up to three times a week. Vaginal smears contained several cell types, categorised by morphology, as either superficial epithelial cells or parabasal–intermediate cells. Leucocytes were also counted. Plasma progesterone profiles showed a mean oestrous cycle length of 36.33 ± 0.67 days with a peak progesterone concentration of 139.53 ± 10.62 nmol/L. Levels of oestradiol peaked at a mean level of 467.33 ± 44.32 pmol/L on average 5 days before a rise in plasma progesterone values. The proportion of epithelial cells in vaginal smears varied throughout the cycle, with a high percentage of superficial epithelial cells observed during the follicular phase. During periods when progesterone concentrations were high, a greater percentage of parabasal–intermediate cells was observed. In conclusion, this study has characterised the oestrous cycle of the southern hairy-nosed wombat and confirmed that changes in vaginal smears together with pouch and urogenital sinus details could be used to determine signs of oestrus in this species.

Effect the administration of human chorionic gonadotrophin (hCG) hormone following superovulation treatment in buffalo

A numbers of studies had been reported to evaluate the effect of hormone for superovulation treatment in buffaloes, however the numbers of embryo recovered is still very small. One of the limiting factors which affect the numbers of embryo recovered is preovulatery LH concentration. The experiment was carried out to study the effect of hCG following superovulation treatments in buffaloes as an effort to increase the embryo recovered. Ten (10) buffaloes in three different genotypes (Riverine, swamp and its crosses) were superovulated using follicle stimulating hormone (FSH). A total of 12 ml FSH (Folltropin) was injected intramuscularry twice a day with 12 hours interval in a decreasing doses for 4 days (2.5, 2.5; 2.0, 2.0; 1.0, 1.0 and 0.5, 0.5 ml). Prostaglandin was injected intramuscularry 2 days after the first injection of FSH followed by administration of 500 IU hCG two days later. At the same days of administration of hCG, artificial insemination (AI) using frozen semen was conducted and repeated again after 12 and 24 hours. Blood collecting was conducted 3 times a week for obtaining the progesteron level of plasma blood. Embryo was collected by non-surgically technique on day 6 of estrus cycle by flushing each horn of uterus with 500 ml Dubelco's Phosphat Buffer Saline (DBPS). Parameter recorded were diameter of ovary (DO), total corpus luteum (TCL), number of embryo collected (NE), percentage of recovery rate (%RR) and peak progesteron level (PP). Administration of hCG significantly increase the response of buffalo to superovulation treatment. The mean of DO (cm), TCL, NE and RR (%) was 4.0, 6.3, 2.1 and 37.2 and 4.5, 7.5, 3.9 and 48.1 for controll and 500 IU hCG respectively. The mean NE was significantly higher (P<0.05) in hCG than those control. The peak progesterone concentration was highly significant higher (P<0.01) in hCG (8.9 ng/ml) than those control (6.8 ng/ml). Both left and right ovary gave a similar response to superovulation treatments. In conclusion the admission of hCG following superovulation treatments using folltrophin increase the number of embryos recovered. Key Words: hCG, Superovulation, Buffalo, Embryo

Effect of exogenous progesterone and eCG treatment on ovarian follicular dynamics in vicunas ( Vicugna vicugna)

The aim of the present study was two-fold. First, to evaluate the effect of exogenous progesterone on ovarian follicular dynamics in order to assess its ability to synchronize ovarian activity in the vicuna. Secondly, to evaluate the ovarian response to the treatment with eCG through the observation of the structures developed in the ovaries. Follicular dynamics was monitored daily by transrectal ultrasonography in 12 adult, non-pregnant vicunas. Plasma progesterone and estradiol-17β concentrations were measured in blood samples collected daily. In experiment 1, intravaginal devices containing 0.33 g of progesterone were inserted into the vagina and kept in place for 5 days (treatment group, n = 8). After progesterone withdrawal, five animals were further monitored in order to evaluate the efficacy of the CIDR ® to synchronize the emergence of a dominant follicle. In experiment 2, four females received 750 IU of eCG IM. Two were previously monitored ultrasonographically to confirm the absence of a dominant follicle at the beginning of the superstimulatory treatment (group A). The other two animals had a CIDR ® inserted into the vagina for 5 days and the superstimulatory treatment was applied 24 h after device withdrawal (group B). Females from both groups were surgically explored 96 h after eCG injection; the ovaries were exposed and the number of newly formed structures produced by each ovary was counted. Peak progesterone concentrations (25.9 ± 5.29 nmol l −1, mean ± S.E.M.) were attained on day 1 after device insertion, remained high until the day of device withdrawal (9.7 ± 1.98 nmol l −1) and decreased to 5.5 ± 1.13 nmol l −1 the day after. There was no follicle development to the state of dominance after device insertion. Moreover, mean follicle diameter steadily decreased after insertion of the device until the minimum mean value (1.85 ± 0.17 mm) was recorded on day 5 ( P = 0.006). Similarly, plasma concentrations of estradiol-17β remained below 35 pmol l −1 during the period of progesterone treatment in all animals and the mean estradiol-17β declined with the lowest value (22.1 ± 2.19 pmol l −1) being recorded on day 4 after device insertion. After superstimulation of follicular development with eCG, the total number of follicles that developed was 33 in group A and 58 in group B and the mean number of newly developed ovarian structures per female was 22.75 ± 4.26. In conclusion, progesterone released by the CIDR ® exerts a negative effect on ovarian follicular development and function suggesting intravaginal devices could be used to synchronize the beginning of follicular waves during a superstimulatory treatment. There was also a tendency for greater ovarian follicular development when the animals were previously treated with progesterone.

Development of a model for inducing transient insulin resistance in the mare: preliminary implications regarding the estrous cycle.

Peripheral insulin resistance is the failure of proper cellular glucose uptake in response to insulin. Insulin resistance and hyperinsulinemia are associated with several disease states in the horse and reproductive function disturbances in humans, including polycystic ovarian syndrome. To test the hypothesis that insulin resistance (IR) and hyperinsulinemia disrupt the estrous cycle in mares, two experiments were conducted to first develop a model to induce IR and to then examine the effect of this model on the duration of the estrous cycle. In Exp. 1, a hyperinsulinemic-euglycemic clamp (HEC) procedure was performed on seven mares to determine insulin sensitivity before and immediately following infusion of a heparinized lipid solution. The HEC procedure was repeated 1 wk after lipid infusion. Mares developed IR following the lipid infusion (P < 0.05), and some individuals maintained IR for up to 1 wk. Mares also exhibited increased blood insulin both immediately following treatment and 1 wk later (P < 0.05). In Exp. 2, induction of insulin resistance by lipid solution was not accompanied by changes in circulating concentrations of luteinizing hormone, and duration of the luteal phase, compared with the duration of untreated luteal phases. Nonetheless, lipid infusion and the resultant insulin resistance were associated with an increased interovulatory period (P < 0.05), and peak concentrations of progesterone (P < 0.05) were higher during the treated vs. untreated luteal phases of the estrous cycle. The results from the preliminary study suggest that infusion of a lipid solution may induce transient insulin resistance and hyperinsulinemia. The resulting insulin resistance and hyperinsulinemia may modify characteristics of the estrous cycle, perhaps at the level of the ovary.

Luteal function and conception in lactating cows and some factors influencing luteal function after first insemination

The objective of this study was to investigate the types and incidence of luteal sub-function in lactating cows after artificial insemination (AI) and their relationship with pregnancy, and to clarify the relationship between luteal function and parity, body condition score (BCS), milk yield, and dietary intake. In 19 cows, milk samples were collected daily from AI to confirmation of pregnancy. Milk progesterone concentrations were determined by EIA. Based on peak progesterone concentration and the day of onset of luteal phase, 15 of 30 progesterone profiles (50%) were normal, with progesterone concentration reaching 1.0 ng/ml within 5 days after insemination and ≥2.0 ng/ml thereafter. In addition, 6 (20%) were insufficient, (progesterone concentration remained <2.0 ng/ml), 5 (17%) were delayed (progesterone reached 1.0 ng/ml after 5 days), 2 (7%) were both delayed and insufficient, one (3%) was short (progesterone >1.0 ng/ml for only 7 days), and one (3%) remained basal. Cows with a normal profile had a higher ( P<0.05) pregnancy rate than those with an abnormal profile (87% versus 33%, respectively). The amount of progesterone secreted in milk after first AI, as indicated by progesterone area under curve (AUC), was negatively correlated with milk yield ( r=−0.83, P<0.01), dry matter intake ( r=−0.81, P<0.05), total digestible nutrients ( r=−0.82, P<0.05), and digestible crude protein ( r=−0.79, P<0.05). Cows that produced more milk and consumed more dry matter had less progesterone during the luteal phase. In conclusion, abnormal luteal function was associated with reduced pregnancy rates and high milk production and increased dietary intake during breeding were associated with reduced progesterone concentrations.