Luteal Diameter Research Articles

Vascular Alterations in Uterine and Ovarian Hemodynamics and Hormonal Analysis throughout Pregnancy Loss in Cows under Heat Stress.

This current study examined the ovarian (OA) and middle uterine arteries (MUA) blood flow under heat stress conditions regarding hormonal status (progesterone (P4), estradiol (E2), and nitric oxide metabolites (NOMs) assays). Eighteen pluriparous cows were examined, with twelve only being subjected to the natural mating as the other six animals were not bred. Pregnancy diagnosis was confirmed at day 30 by embryonic heartbeat and CL graviditatis (n = 6; pregnant), but some animals (n = 6) showed early embryonic death (EED), with the presence of control cows (n = 6). In the pregnant group, luteal diameter (cm) increased after mating, while in the pregnancy loss group it increased (p < 0.05) until reaching day 38 (1.41 ± 0.03), then decreased again. Luteal vascularity was declined in cows with EED after day 36 (p < 0.05) and reached its lowest level at day 50. P4 levels elevated in cows with EED until day 36 (13.64 ± 0.11) then declined. Both ipsilateral OA and MUA Doppler indices were declined in both groups except in cows who suffered from EED; both were elevated from day 38 until day 50 after mating. Ipsilateral peak systolic point (PSV cm/sec) of OA and MUA was elevated in both groups (p < 0.05), but in cows with EED this parameter was declined. E2 and NOMs levels were declined in cows with EED from day 40 and day 38 after mating (p < 0.05), respectively. This study provided novel data on the relations among the luteal diameter, E2, P4, and NOM levels, and luteal hemodynamics that predicts the amount of blood supply, which acts as a sensitive parameter to detect the alterations in luteal function during the first 50 days after mating.

100 Impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to embryo transfer

Abstract This study aimed to evaluate the impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to fixed-timed embryo transfer (FTET). Postpartum beef cows (n = 763) from 22 locations were exposed to a 7-d Select Synch + controlled internal drug releasing (CIDR) and breeding indicator patches were affixed upon CIDR removal. Estrus expression was assessed twice daily for 72 h and a 100-µg injection of gonadotropin-releasing hormone was administered to cows that failed to express estrus 72 h after CIDR removal. Brightness mode ultrasonography of the corpus luteum (CL) was conducted to select recipients for FTET 9 d after CIDR removal. Suitable recipients were assigned to receive a single fresh or frozen embryo derived from either in vitro (IVF) or in vivo (IVD) method. After embryo recipient selection, CL morphometries and blood perfusion (BP) were then assessed at the time of embryo transfer via transrectal ultrasonography. Embryo recipients were categorized according to CL area [small (&amp;lt; 3 cm²), medium (3 to 4 cm²), or large (&amp;gt; 4 cm²)] and based on the percentage of luteal area with blood perfusion signals [low (&amp;lt; 25%), medium (25 to 45%), or high (&amp;gt; 45%)]. Pregnancy diagnoses were performed between d 60 and 90 of gestation. Cows that failed to express estrus prior FTET had decreased (P ≤ 0.02) luteal area, luteal diameter, and pregnancy rates compared with cows that expressed estrus. Luteal area category had no effect (P = 0.61) on pregnancy rates. Embryo recipients that expressed estrus had similar (P = 0.12) luteal blood perfusion compared with recipients that failed to express estrus. Embryo recipients with high (P = 0.02) and medium (P = 0.05) BP had greater pregnancy rates compared with embryo recipients with low BP. There was no interaction between estrus expression and luteal BP (P = 0.84). In summary, estrus expression and luteal BP positively impacted pregnancy rates to embryo transfer and may be used to facilitate embryo recipient selection.

Evaluation of ImageJ software in ultrasonic image analysis: Follicular and luteal morphological characteristics of cattle

This study was conducted to compare the effectiveness of two methodologies in evaluating B- and Doppler-mode ultrasonic images: analysis using ultrasonic software and utilizing a computer with ImageJ software. To determine if ImageJ software utilization is an efficacious alternative to ultrasonic software device- analysis, there were comparisons of values when using the two methods for morphological and vascular characteristics of follicular dynamics and luteal function in 18 crossbred cattle. From day 8 of an ovarian dynamics synchronization treatment regimen period until the time of ovulation (Day 10), B-mode and power-flow ultrasonic cineloops were obtained every 12 h to assess follicular diameter, wall area, and wall blood perfusion area. On Day 14 after ovulation, US cineloops of ovaries were obtained in B mode and power flow to evaluate various morphological and vascular characteristics of the corpus luteum (CL), including luteal diameter, luteal area, and CL blood perfusion area. Cineloops were evaluated and analyzed using ultrasonic software, and in a computer with ImageJ software. To evaluate consistency in results between the two methods, there was evaluation utilizing paired t-test, Pearson correlation coefficient, Bland-Altman plot, and Linear Regression Test procedures to calculate proportion of bias between values for measurements of variables evaluated. Results indicated none of the values for variables before and after ovulation differed (P > 0.05). It, therefore, was concluded that utilization of ImageJ software is an efficacious biomedical technique to analyze ultrasonic images of morphological and vascular characteristics before and after ovulation in cattle.

Effect of various hCG treatment protocols on luteal characteristics, plasma progesterone concentration, and pregnancy in normal cyclic Indian crossbred dairy cows.

Limited information exists on the application of human chorionic gonadotropin (hCG) post insemination in the Indian crossbred dairy cows. This study aimed to evaluate the effect of four hCG administration protocols on luteal characteristics and pregnancy outcomes following artificial insemination (AI). Using block randomization, 50 healthy lactating crossbred cows were allocated in equal numbers (n = 10 cows per group) to receive either 5 mL normal saline (control) or 1500 IU hCG on the day of AI (hGG-0), day 7 post AI (hCG-7), day 14 post AI (hCG-14), or days 0, 7, and 14 post AI (hCG-0,7,14). All cows were scanned using sequential transrectal ultrasound examinations to evaluate primary luteal parameters, development of accessory corpora lutea, and pregnancy. Serial blood samples were collected to measure plasma progesterone concentrations. Data were analyzed using repeated measures ANOVA and Fisher's exact tests. The mean primary luteal area, total luteal area, and total luteal diameter values were significantly greater in the hCG-treated cows. Compared to the control, the hCG-14 group had a significantly higher percentage of cows with an accessory corpora luteum. However, there were no significant differences in the mean progesterone concentrations or the first service conception rates between any of the groups. Overall, the results of this study indicate that while hCG administration post AI in healthy Indian crossbred cows may enhance primary luteal dimensions or induce the formation of accessory corpora lutea, it does not appear to have any beneficial effect on luteal function or pregnancy.

The Opuntia effect upon the out-of-season embryo implantation rate in goats: Corpus luteal number, corpus luteal diameter and serum progesterone concentrations

We evaluated the possible effect of targeted supplementation of protein enriched Opuntia megacantha Salm-Dyck cladodes, the flat leaf-like stem of cactus species, upon corpus luteum number (CLN), corpus luteum diameter (CLD), serum progesterone concentrations (P4) and embryo implantation rate (EIMPL) in anestrous goats exposed to sexually active males. During the non-breeding season (May-Jun, 25°LN), anestrus Alpine-Saanen-Nubian × Criollo adult goats (n = 45) homogeneous regarding live weight (LW, kg) and body condition score (BCS, units) were randomly assigned to the supplement treatments: 1). Protein-enriched Opuntia (PEO;n = 15; 43.8 ± 1.5 kg LW, 2.48 ± 0.10 BCS; 29.8% CP, 2.2 Mcal ME kg−1), 2). Non-enriched Opuntia (NEO; n = 15; 43.8 ± 1.5 kg LW, 2.47 ± 0.10 units BCS; 6.4% CP, 2.1 Mcal ME kg−1), compared with 3). Control (CONT; n = 15; 45.41 ± 1.5 kg LW, 2.54 ± 0.10 units BCS). Both NEO and PEO goats were individually supplemented with cladodes (160 g d−1; 0900–1000 h) and then goats grazed in a marginal rangeland (1000–1800 h). PEO was bio-fortified in a fermentation bioreactor (1% of Scaromices cereveciae, + 1% urea + 0.1% of ammonium sulphate). Three transrectal ultrasonographic scans (US) were performed during the supplement adaptation period (20d) to confirm the goat´s anovulatory status and then (May 20) exposed to males during a 10d breeding period. A 4th-US quantified CLN and CLD 20 d post-male introduction (PMI), while a 5th-US evaluated EIMPL (47 d, PMI); supplementation lasted up to June 30. No differences (P > 0.05) in LW and BCS occurred either at the onset (44.38 ± 1.5 kg, 2.49 ± 0.10 units) or at the end (45.03 ± 1.5 kg, 2.60 ± 0.20 units) of the experiment, neither concerning P4-average (3.73 ± 1.6 ng mL−1) nor related to the treatment x time interaction. Although no differences in the reproductive response (P > 0.05) regarding CLN, CLD and EIMPL occurred in the PEO and NEO, an amplified response (P < 0.05) was observed in the PEO-group compared to the CONT goats [CLN: 1.33, 0.71 & 0.43 ± 0.7 units; CLD: 1.66, 0.92 & 0.61 ± 0.30 mm; and EIMPL: 86, 53 & 18 ± 14%, respectively]. Targeted supplementation with protein-enriched Opuntia cladodes (i.e. the “Opuntia Effect”) during the conception-to-implantation period to anestrous goats exposed to males increased out-of-season reproductive outcomes; this strategy could be potentially important to uphold the sustainability of goat production systems under semiarid conditions.

Ultrasonography-accessed luteal size endpoint that most closely associates with circulating progesterone during the estrous cycle and early pregnancy in beef cows

The aim was to evaluate the associations between circulating P4 concentrations, corpus luteum (CL) size (diameter, area or volume) and blood perfusion (BP) in cows. In Experiment 1, Pearson’s correlations (P < 0.05) with P4 concentrations were observed during CL development (D8) for total area (TA; r = 0.76), luteal area (ACL; r = 0.72), total and luteal diameter (TD and DCL respectively; r = 0.46). During mid-late diestrus, there was a positive correlation (P < 0.05) only at D15 with TA and ACL (r > 0.60), TD, total volume (TV) and luteal volume (VCL; r > 0.434). During luteal regression, the correlation was only observed at D18 for ACL (r = 0.478) and D20 with several variables. In Experiment 2, CL weight and ACL had the greatest correlation with P4 (r > 0.6). In Experiment 3, TA and ACL were the variables that were most closely correlated with serum P4 concentrations at D7 in recipient cows. Correlation coefficients were greater for luteal measurements when there were compact compared with cavitary CLs. In Experiment 4, there was no correlation (P > 0.05) between P4 and any of the variables measured on D4 and D7 in recipient cows detected in estrus. On D18 to D20, all CL characteristics were correlated (P < 0.05) with plasma P4, and luteal BP and BP area were more closely (P < 0.05) correlated than ACL. In conclusion, CL perimeter area measurements had the greatest association with luteal function during CL development; whereas for BP there was a greater correlation with P4 than luteal size during luteolysis.

Early luteal development in Santa Inês ewes superovulated with reduced doses of porcine follicle-stimulating hormone.

The aim was to compare the early luteal development in ewes superovulated with different doses of pFSH. Twenty-nine Santa Inês ewes received a progesterone device (CIDR®) for 8days. Gonadotrophic treatment started on Day 6: G200 (control, n=9, 200mg); G133 (n=10, 133mg); and G100 (n=10, 100mg of pFSH). On Day 6, all females received eCG (300IU). B-mode and spectral Doppler ultrasonography were performed daily during the early luteal phase (Days 11-15) to monitor the development of corpora lutea (CLs; dimensions) and ovarian arteries indices. CLs were also classified as normal or prematurely regressed (PRCL) on Day 15 by videolaparoscopy. Ewes from G100 and G133 showed gradual increase in luteal diameter during the early luteal phase (p<0.001), whereas G200 animals presented increase from Day 11 to Day 13, and then decrease on Days 14 and 15 (p<0.001). The G200 females showed greater percentage of PRCL (45.20%) than those of the other groups (p<0.001). The normal CLs number was greater in G100 than in G133 (p=0.04), while the PRCL number was greater in G200 than in the other groups (p=0.03). Resistive index (RI) was greater in G200 than in G100 (p=0.02). RI was lower in Day 12 than Day 15 (p=0.02). Pulsatility index (PI) was greater on Days 14 and 15 (p<0.01). In conclusion, the lowest dose of pFSH (100mg) can be considered sufficient for an efficient superovulatory response in sheep, producing better CLs development dynamic in early luteal phase and ovarian blood perfusion and smaller number of PRCL than the traditional (200mg) pFSH dose.

Age-related changes in luteal dynamics: preliminary associations with antral follicular dynamics and hormone production during the human menstrual cycle.

The aim of the study was to test the hypothesis that the development of luteal phase dominant follicles (LPDFs) as women age is associated with abnormal luteal function. Luteal and antral follicle diameter were quantified in ovulatory women of midreproductive age (MRA; 18-35 y; n = 9) and advanced reproductive age (ARA; 45-55 y; n = 16) every 1 to 3 days during one complete interovulatory interval. Blood was drawn at each visit and assayed for progesterone, estradiol, inhibin A, follicle-stimulating hormone, and luteinizing hormone. Luteal diameter and hormone profiles were compared within MRA and ARA women with versus without LPDFs. Luteal growth and regression profiles were similar in MRA women with typical versus no LPDFs (13.9, 14.8 mm; P > 0.1); however, luteal phase estradiol and progesterone were greater in MRA women with typical (91.1 ng/L, 8.81 μg/L) versus no (48.8 ng/L, 7.32 μg/L) LPDFs, respectively (LPDF effect, P < 0.1). In the ARA group, mean luteal diameter was lowest in women with atypical LPDFs (12.3 mm), greatest in those with typical LPDFs (16.0 mm), and moderate in those with no LPDFs (13.6 mm), (P < 0.1). Reduced luteal growth in ARA women with atypical versus typical and/or no LPDFs occurred simultaneously to greater luteal phase estradiol (199 vs 69.0, 78.4 ng/L) lower progesterone (7.38 vs 10.7, 13.8 ug/L), and lower inhibin A (36.3, 35.6, 51.2) (P < 0.1). The development of LPDFs as women age was associated with reduced luteal growth, greater estradiol, lower progesterone, and lower inhibin A. These findings provide preliminary evidence that variations in antral folliculogenesis contribute to luteal insufficiency during the menopausal transition.

Luteal dynamic and functionality assessment in dairy goats by luteal blood flow, luteal biometry, and hormonal assay

This study aimed to assess the luteal dynamics of pregnant and non-pregnant Saanen goats throughout an estrous cycle by B-mode and color Doppler ultrasonography (US) associated with a P4 hormonal assay. Furthermore, a cutoff point was chosen to determine the corpus luteum (CL) functionality by luteal biometry (LB) measurement and luteal blood flow (LBF) assessment. Ultrasound assessment was carried out daily throughout an entire estrous cycle (21 days) in 23 Saanen goats pre-synchronized and inseminated in the breeding season. The plasmatic P4 concentration was determined daily by radioimmunoassay. LB parameters (diameter, area, and volume) were measured using the maximum area of a cross-section of the CL. LBF assessment was performed subjectively by percentage of area of colored pixels and objectively by calculating the number of the colored pixels. Eventually, 45.0% (9/20) and 55.0% (11/20) of goats became pregnant and or remained non-pregnant, respectively. The LB and LBF demonstrated value stabilization on the 9th day of the estrous cycle and maximum values on the 12th and 13th days of the estrous cycle, respectively. LB presented a progressive decrease in the luteal regression phase, whereas the LBF decreased abruptly in association with P4. The LBF values were more reliable in predicting the luteal functionality when compared to the LB data. The number of colored pixels accurately predicted values of P4 >1.0 ng/mL, reaching only 17% of the maximum values, and 1200 colored pixels as a minimum cutoff point when compared to the use of 53% of the maximum values and a minimum luteal diameter of 9.0 mm as cutoff point for P4 >1.0 ng/mL. The LBF assessment was more informative about the CL functionality throughout the complete luteal phase when compared to the LB. The use of the number of colored pixels is indicated for research regarding luteal functionality due to their greater correlation with P4 values. In addition, the luteal subjective evaluation can be used under field conditions due to greater convenience and similar pattern of correlation with P4.

An administration of TAK-683 at a minimally effective dose for luteinizing hormone stimulation under the absence of the ovary induces luteinizing hormone surge in ovary-intact goats.

The present study aimed to evaluate hormonal responses and their association with the TAK-683 blood concentrations in goats administered TAK-683 at a low dose, which had been previously determined as the minimally effective dose for luteinizing hormone (LH) stimulation in ovariectomized goats. In Experiment 1, 5 µg of TAK-683 treatment had no significant stimulatory effect on LH secretion in ovariectomized Shiba goats (n = 4). In Experiment 2, cycling goats received the treatment of prostaglandin F2α and progesterone-releasing controlled internal drug releasing (CIDR) to induce the follicular phase, then they were treated with 5 µg of TAK-683 (hour 0) intravenously (n = 4, IV) or subcutaneously (n = 3, SC) or with vehicle intravenously (n = 4, control) at 12 h after CIDR removal. Blood samples were collected at 10-min (–2–6 h), 2-h (6–24 h), or 6-h (24–48 h) intervals. Ovarian ultrasonographic images were assessed daily to confirm ovulation after the treatment. A surge-like release of LH was immediately observed after injection in all animals in the IV (peak time: 4.2 ± 0.6 h, peak concentration: 73.3 ± 27.5 ng/ml) and SC (peak time: 4.6 ± 0.4 h, peak concentration: 62.6 ± 23.2 ng/ml) groups, but not in the control group. Ovulation was detected within 3 days after TAK-683 injection in all animals in the IV and SC groups, and the interval period from TAK-683 administration to ovulation in the IV group was significantly (P < 0.05) shorter than that of the control group. No significant changes were observed between the IV and SC groups in terms of luteal diameter and blood progesterone levels after ovulation. The present findings suggest that the involvement of one or more ovarian factor(s) is indispensable for a TAK-683-induced LH surge leading to ovulation in goats.

Synchrotron Imaging of Ovaries Ex Vivo

Background: Conventional 2-dimensional ultrasonography is limited in its ability to detect ovarian microanatomy. The objective of this study was to determine if biomedical synchrotron techniques would be effective for imaging ovarian microanatomy, including ovarian follicles, corpora lutea, and the oocyte. Methods: A prospective, observational study was conducted at the Canadian Light Source to compare ovarian imaging ex vivo using propagation-based computed tomography (PB-CT) synchrotron imaging, ultrasonography, and histology. Bovine (n=4) and human (n=4) ovaries were imaged fresh or formalin-fixed. The effectiveness of Talbot grating interferometry computed tomography (TGI-CT) synchrotron imaging to image preserved bovine (n=1) and human (n=1) ovaries was evaluated at the SPring-8 synchrotron, Japan. Results: All antral follicles ≥ 2 mm and corpora lutea detected with ultrasonography were identified with PBCT. Mean follicle and luteal diameters did not differ among PB-CT, ultrasonography, and histology. The smallest follicle detected was superior with PB-CT (0.9 ± 0.4 mm) than ultrasonography (2.2 ± 0.2 mm, P<0.05). PB-CT, but not ultrasonography, allowed the detection of follicle wall cell layers (P<0.05). TGI-CT provided greater contrast for evaluating follicles, corpora lutea, and vasculature than PB-CT and ultrasonography. High contrast spherical structures resembling cumulus oocyte complexes were detected with PB-CT and TGI-CT; oocytes were only detected with TGI-CT. Conclusion: PB-CT was as effective as ultrasonography for measuring follicle and luteal diameters and superior to ultrasonography for visualizing follicles <2 mm, follicle wall cell layers, and cumulus oocyte complexes. TGI-CT appears to provide the greatest resolution for imaging ovarian anatomy compared to ultrasonography and PB-CT. Phase contrast CT Synchrotron can be used as a model for developing high resolution tools for imaging human ovaries.

Follicular dynamics, corpus luteum growth and regression in multiparous buffalo cows and buffalo heifers

ABSTRACTObjective. Characterize the follicular dynamics and luteal growth and regression pattern of multiparous (MB) and heifer (BH) Murrah buffaloes in Colombian tropical conditions. Material and methods. Ten MB and ten BH were synchronized with a progesterone-releasing intravaginal device. No artificial insemination was performed during the estrous and daily ultrasound examinations were performed 15 days later to determine the number and diameter of the structures present in both ovaries in the subsequent natural estrous cycle. The Student’s T test was used to evaluate differences between MB and BH. All data are presented as mean ± standard deviation. Results. The length of the estrous cycle was 22.00±4.50 days for MB and 22.00±2.70 days for BH. Follicular growth occurs in one (n=1; 5.89%), two (n=14; 82.35%) or three waves (n=2; 11.76%). The first wave initiated the day after ovulation with the recruitment of 8.33±2.06 and 10.00±2.72 follicles in MB and BH, while the second wave started on day 11.00±2.00 and 10.50±2.82, presenting 8.37±2.26 and 8.00±1.51 follicles. The third wave began on day 16.21±3.10 showing 6.50±1.70 follicles, only BM had three waves. The maximum luteal diameter was 19.58±4.16 mm and 17.74±3.32 mm respectively. There were no significant differences between the groups for these variables. Conclusions. These results show that the follicular development in buffaloes occurs in waves, where two waves is the most common pattern, as previously reported by other authors.

Relationships Between the Appearances and Changes of Estrous Signs and the Estradiol-17β Peak, Luteinizing Hormone Surge and Ovulation During the Periovulatory Period in Lactating Dairy Cows Kept in Tie-stalls

Lactating Holstein-Friesian cows kept in tie-stall barn were used as subjects in this study. Rectal examination, ultrasonography and blood sampling were conducted every other day and then daily after the day on which diameter of the corpus luteum decreased. After the luteal diameter decreased for 2 consecutive days, rectal and ultrasound examinations, blood sampling, and observation of estrous signs were conducted at 6-h intervals. Most of the estrous signs became obvious with the increase in estradiol-17β (E2) and became most remarkable 24 to 30 hours before ovulation, at which point the E2 peak and luteinizing hormone (LH) surge were achieved, and then weakened which progression to ovulation. The correlation between the intensity of four estrous signs (hyperemia and swelling of the intravaginal part of the uterus, opening of the external uterine orifice and viscosity of the cervical mucus) and the plasma E2 concentration was higher than that of three estrous signs (swelling of the vulva, contraction of the uterus, diameter of uterine horn) and the plasma E2 concentration. The relaxation of the intravaginal part of the uterus showed a unique change compared with the other estrous signs, and it became most obvious 6, 12 and 18 h before ovulation; this obviously relaxed period was consistent with the generally accepted theoretical optimal time for artificial insemination (AI), i.e., 6 to 24 h after initiation of estrus. These results suggest that observation of estrous signs by vaginoscopic examination gave useful information for detection of the optimal timing of AI in the periovulatory period in lactating dairy cows kept in a tie-stall barn.

Effects of d-cloprostenol dose and corpus luteum age on ovulation, luteal function, and morphology in nonlactating dairy cows with early corpora lutea

Luteolysis is a key event in cattle reproduction. A standard dose of exogenous PGF2α will induce full luteolysis in the majority of cows with a matured corpus luteum (CL). However, this will not occur in cows with a CL <5d old. To date, it is not known whether a larger dose will have a more potent luteolytic effect in cows during early diestrus. The objective of this study was to characterize the effect of 2 doses of d-cloprostenol (150 and 300μg) on the progesterone concentration, luteal diameter, and ovulation rate in nonlactating dairy cattle 96 to 132h postovulation. Twenty nonlactating dairy cows were included in the study. Each cow received 2 treatments of d-cloprostenol in 2 consecutive cycles: a standard dose of 150μg and a double dose of 300μg. The cows were allocated randomly to 1 of 4 groups (5 cows in each group) according to the age of the CL at the time of treatment: 96, 108, 120, and 132h. The exact time of ovulation was known within 12h, because of twice per day ultrasound examination. The CL diameter and progesterone concentration were measured before treatment (d 0) and 2 and 4d after treatment. Within each CL age group, the effect of d-cloprostenol dose on luteolysis was determined. More cows treated with double dose tended to have full luteolysis compared with the standard dose (8/10 vs. 4/10, respectively). This effect was only apparent in cows with CL of 120 and 132h but not in earlier CL. The interval from treatment to ovulation was shorter (3.3±0.1d) in cows treated with a double dose than in cows treated with the standard dose (4.5±0.4d).

Local versus systemic effect of ovulation-inducing factor in the seminal plasma of alpacas

BackgroundCamelids are induced (reflex) ovulators. We have recently documented the presence of an ovulation-inducing factor (OIF) in the seminal plasma of alpacas and llamas. The objective was to test the hypothesis that OIF exerts its effect via a systemic rather than a local route and that endometrial curettage will enhance the ovulatory response to intrauterine deposition of seminal plasma in alpacas.MethodsFemale alpacas were assigned randomly to 6 groups (n = 15 to 17 per group) in a 2 × 3 factorial design to test the effect of seminal plasma versus phosphate-buffered saline (PBS) given by intramuscular injection, by intrauterine infusion, or by intrauterine infusion after endometrial curettage. Specifically, alpacas in the respective groups were given 1) 2 ml of alpaca seminal plasma intramuscularly, 2) 2 ml of PBS intramuscularly (negative control group), 3) 2 ml of alpaca seminal plasma by intrauterine infusion, 4) 2 ml of PBS by intrauterine infusion (negative control group), 5) 2 ml of alpaca seminal plasma by intrauterine infusion after endometrial curettage, or 6) 2 ml of PBS by intrauterine infusion after endometrial curettage (negative control group). The alpacas were examined by transrectal ultrasonography to detect ovulation and measure follicular and luteal diameters.ResultsIntramuscular administration of seminal plasma resulted in a higher ovulation rate than intrauterine administration of seminal plasma (93% versus 41%; P < 0.01), while intrauterine seminal plasma after endometrial curettage was intermediate (67%). None of the saline-treated controls ovulated. The diameter of the CL after treatment-induced ovulation was not affected by the route of administration of seminal plasma.ConclusionWe conclude that 1) OIF in seminal plasma effects ovulation via a systemic rather than a local route, 2) disruption of the endometrial mucosa by curettage facilitated the absorption of OIF and increased the ovulatory effect of seminal plasma, and 3) ovulation in alpacas is not associated with a physical stimulation of the genital tract, and 4) the alpaca represents an excellent biological model to evaluate the bioactivity of OIF.

Incidence of spontaneous ovulation and development of the corpus luteum in non-mated dromedary camels ( Camelus dromedarius)

The occurrence of spontaneous ovulation in dromedaries was examined in two separate studies including 20 non-lactating, barren and 12 lactating dromedaries, respectively. Lactating camels were milked twice a day with an automatic bucket milking machine. Ovarian activity was monitored by repeated ultrasonography. Blood samples for progesterone were collected daily or two to three times a week. To compare CL development after spontaneous and induced ovulations, ovulation was induced by a GnRH analogue in eight lactating dromedaries. Spontaneous ovulation was observed in one non-lactating camel (1 of 20 camels, 5%; 1 of 70 follicular waves, 1.4%), whereas, spontaneous ovulation was detected more frequently in lactating dromedaries (5 of 12 camels, 41.7%; 13 of 91 follicular waves, 14.3%). In one lactating camel, spontaneous ovulation occurred repeatedly for nine times. There was a significant effect of type of ovulation (spontaneous versus induced, P < 0.05) and day ( P < 0.001) on serum progesterone concentration. Mean serum progesterone levels and total progesterone production (AUC) were higher after induced ovulation. Luteal diameter and serum progesterone concentration were positively correlated ( r = 0.71, P < 0.001), but there was a significant difference between morphological and functional development of the CL. In dromedaries, morphological development starts earlier, morphological regression starts later and last longer than functional development and regression of the CL. Compared to induced ovulation, functional development of the CL after spontaneous ovulation might be altered but the morphological development is not affected.

268. Experimentally induced hypoglycemia: a model to examine the effects of lactation on reproductive function in dairy cows?

The metabolic changes subsequent to lactogenesis have been associated with poor reproduction in high-producing dairy cows.1,2 Periods of hypoglycaemia reflect severe energy deficit and are associated with changes in plasma levels of growth hormone (GH), insulin-like growth hormone-I (IGF-I) and insulin-like growth hormone-II (IGF-II). Somatotropic activity has been shown to influence reproductive functions.3–5 This study evaluated the effects of experimentally induced hypoglycaemia in seven non-lactating cows, over a 7-day period. Phloridizin treatment (8 g/d) resulted in urinary glucose loss (control: 3.5 ± 1.0 g/d and phloridizin: 468 ± 46 g/d) and decline in plasma glucose (control: 60.6 ± 0.6 mg/dL and phloridizin: 71.8 ± 0.4 mg/dL; P &lt; 0.001). Treatment increased plasma beta hydroxybutyrate (BOH), non-esterified fatty acids (NEFA) and IGF-I concentrations (P &lt; 0.001). Plasma insulin and GH concentrations did not differ. During treatment, expression of mRNA for total growth hormone receptor (GHR(tot); P = 0.012) and GHR(1A) (P &lt; 0.001) in liver tissue declined. Luteal and follicle diameters in ovaries recovered after treatment did not differ. Expressions of mRNA for IGF-I (P = 0.052) and interleukin-1β (IL-1β) in corpus luteum and for 3β-hydroxysteroid dehydroxyenase (3β-HSD) within dominant follicles were significantly elevated, while mRNA for GHR(tot), cytochrome P450 cholesterol side chain cleavage enzyme (P450-SCC), and steroidogenic acute regulatory protein (StAR) tended to increase (P &lt; 0.1) with treatment. The treatment resulted in changes similar to those of nutritional stress or the initiation of lactogenesis. Phloridizin-induced hypoglycaemia may be a model to investigate mechanisms linking glucose metabolism, and the somatotropic axis to reproductive function. The advantages of such a model, is that it allows for strict control of the level of hypoglycaemia. The use of non-lactating cows also removes the feedback mechanisms that modulate mammary gland requirements, and therefore will minimize the between cow variance when using lactating cows. This work was completed with the help from Dexcel Farms and the Dairy Cattle Fertility team. This study was funded by the New Zealand Foundation for Research, Science and Technology (DRCX 0202). (1)Roberts et al. (1997) Journal of Animal Science 75, 1909–1917.(2)Thatcher et al. (1996) Reproduction, Fertility and Development 8, 203–217.(3)Royal et al. (2000) Animal Science 70, 487–501.(4)Butler (2000) Animal Reproduction Science 60, 449–457.(5)Lucy (2000) Journal of Dairy Science 84, 1635–1647.

Quantitative echotexture analysis of bovine corpora lutea

A study was designed to evaluate the attributes of ultrasound images of bovine ovarian CL throughout the estrous cycle. The ovaries of 8 heifers were examined daily by transrectal ultrasonography for 2 interovulatory intervals (ovulation = Day 0). Ultrasonographic examinations of the ovaries were videotaped daily, and recorded images of the CL were digitized for computer analysis of echotexture (mean pixel value and heterogeneity). Blood samples were taken daily and to determine plasma progesterone concentrations. Corpora lutea were of 2 morphological types, those with a central fluid-filled cavity (n = 6) and those without (n = 9). No differences were detected between CL with or without a fluid-filled cavity; therefore, data were combined. Mean pixel values of ultrasound images of the CL changed (P = 0.0001) during the interovulatory interval; values decreased (P < 0.05) from Day 0 to Day 3 during early growth of the CL, reached a plateau when increases in luteal diameter ceased, and decreased (P < 0.05) to minimal levels at the onset of regression of the CL. The mean pixel value subsequently increased (P < 0.05) after Day 17 to values similar to those at the beginning of the interovulatory interval. A time-dependent effect was not observed for heterogeneity of images of the CL (P > 0.5). The results supported the hypothesis that quantitative changes in luteal echotexture are reflective of changes in the physiologic status of the CL.

Form and function of the corpus luteum in llamas

In Part 1, the presence and diameter of the corpus luteum was monitored daily by transrectal ultra-sonography for a minimum of 30 days in 39 llamas. Animals were categorized as non-lactating or lactating and randomly allotted to the following groups (reproductive status), (1) non-mated (anovulatory); (2) mated by a vasectomized male (ovulatory non-pregnant); (3) mated by an intact male (pregnant). In Part 2, luteal diameter was monitored by transrectal ultrasonography in 68 pregnant llamas to characterize its diameter profile for the first 60 days of pregnancy. Results indicated that measurement of the diameter of the corpus luteum by transrectal ultrasonography was an accurate method of assessing luteal function (plasma progesterone concentration) in llamas ( r = 83%, P < 0.0001). Corpora lutea were not detected and the plasma progesterone concentration did not exceed 0.4 ng ml −1 in anovulatory (non-mated) llamas. The corpus luteum was first detected on mean Day 3.1 ± 0.2 for ovulatory non-pregnant and pregnant llamas, and reached the maximum diameter on mean Day 5.9 ± 0.3 and 21.4 ± 1.2, respectively ( P < 0.0001); the maximum diameter was 12.8 ± 0.3 and 16.3 ± 0.3 mm, respectively ( P < 0.0001). Except for the first day of detection of the corpus luteum, lactational status did not affect luteal growth and regression. Reproductive status (ovulatory non-pregnant vs. pregnant) did affect luteal growth and regression ( P < 0.0001); the profiles were the same until Day 9 at which time the corpus luteum was regressing in non-pregnant llamas and still growing in pregnant llamas. The corpus luteum was not detected after Day 12 in non-pregnant llamas and was detected to Day 60 (end of observations) in pregnant llamas. A prolonged luteal phase (pseudopregnancy) was not observed in any non-pregnant (non-mated or vasectomy-mated) llamas. The plasma progesterone concentration fell ( P < 0.05) on Day 8 in pregnant llamas, similar to non-pregnant llamas, but there was a resurgence of luteal function in pregnant animals after Day 10 (Day 6, 5.6 ng ml −1; Day 10, 3.1 ng ml −1; Day 12, 6.3 ng ml −1). Results demonstrated, (1) a close temporal relationship between ultrasonically determined luteal diameter and circulating progesterone concentration, except that progesterone decreased 1–3 days before the morphologic decrease; (2) regression of the corpus luteum between Days 9 and 11 in non-pregnant llamas versus a continued gradual increase until a plateau at Day 25 in pregnant llamas; (3) a fall in circulating progesterone in both non-pregnant and pregnant llamas on Day 8, but with rescue and resurgence of the corpus luteum in pregnant llamas after Day 10. The latter observation was unexpected and requires confirmation.

The predictive value, sensitivity and specificity of palpation per rectum and transrectal ultrasonography for the determination of bovine luteal status

Luteal status (classifications 1 and 3 = high progesterone levels, 2 and 4 = low progesterone levels) was diagnosed in randomly cyclic Holstein cows, using palpation per rectum and B-mode transrectal ultrasonography, respectively. The results were compared in 2×2 contingency tables with radioimmunoassay (RIA) classifications. Cows with milk progesterone levels of 5.0 ng/ml or higher were classified high and cows with levels below 5.0 ng/ml of progesterone were low. The predictive value, sensitivity and specificity results were 1) 88.2, 68.2 and 88.9% for Classification 1; 69.6, 88.9 and 68.2 for Classification 2; 90.9, 83.3 and 87.5 for Classification 3; and 77.8, 87.5 and 83.3 for Classification 4. Within each test, the diagnosis of high progesterone status was more accurate than of low status. The types of errors are discussed. A correlation coefficient of 0.68 resulted between RIA progesterone concentration and ultrasonographic luteal diameter. Ultrasonography was a better diagnostic test than palpation per rectum.