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1.
Sixty-two dairy cows diagnosed as having cystic ovarian degeneration were used to study the correlation between rectal palpation findings and plasma progesterone concentrations and the response of cysts to treatment using fenprostalene, a luteolytic agent. Rectal palpation accurately determined the presence of luteal cysts as confirmed by plasma progesterone concentrations of 3 ng/mL or more. Treatment with fenprostalene was very effective for luteal cysts: a high percentage of treated cows exhibited estrus within seven days after treatment. The conception rate following artifical insemination during the induced estrus was 87.5% (21/24). Rectal palpation was much less accurate for the diagnosis of follicular cysts. Cows diagnosed as having follicular cysts had wide variations in plasma progesterone concentrations. Response to fenprostalene treatment was poor in cows with nonluteinized cystic follicles associated with low progesterone concentrations. However, cows diagnosed as having follicular cysts, but with progesterone concentrations of 1 ng/mL or more, responded better to fenprostalene treatment than cows with low progesterone concentrations.

It was concluded that, if correctly diagnosed, luteal cysts can be successfully treated with fenprostalene, and conception rates following treatment can be expected to be normal.

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2.
The objective of this experiment was to evaluate the effect of a single injection of progesterone on the lifespan of ovarian follicular cysts and to examine the fate of follicles that mature following treatment. Lactating Holstein and Jersey cows with ovarian follicular cysts were identified by rectal palpation. The ovaries of cystic cows were then examined by transrectal ultrasonography three times weekly to monitor formation of new follicular cysts. Cows with newly formed follicular cysts were treated either with a single injection of progesterone (200 mg, IM, n = 11) or corn oil vehicle (n = 7). Venous blood samples were collected daily for quantification of progesterone. Blood sampling and ultrasonography continued until ovulation or a new follicular cyst formed. Treatment reduced the lifespan of the cyst by 12 days, from 29.8 +/- 2.3 days in control cows to 17.2 +/- 1.8 days in progesterone-treated cows (P = 0.01). Progesterone treatment also tended to alter the frequency of subsequent follicular events. Ovulation occurred in 4/11 cows that were treated with progesterone whereas none of the vehicle treated cows ovulated (P = 0.07). In conclusion, a single injection of 200mg of progesterone, administered early in the life of an ovarian follicular cyst, shortened its lifespan and in some cases was followed by ovulation of a new follicle.  相似文献   

3.
The aims of this study were to assess the accuracy of different common methods of differentiating between follicular and luteal ovarian cysts, and to monitor the response of the cysts to 12 days treatment with a progesterone-releasing intravaginal device (PRID). On the basis of agreement between the different methods, 25 of the 46 cases examined were diagnosed as follicular and 14 as luteal cysts; for the other seven cases the methods disagreed. The use of ultrasound was more accurate in diagnosing follicular cysts than luteal cysts, and combined with plasma progesterone concentrations gave the most accurate assessment of cyst type (92 per cent for follicular cysts and 82 per cent for luteal cysts). The mean (se) plasma progesterone concentration was lower in the cows with follicular cysts than in those with luteal cysts (0.29 [0.05] v 3.90 [0.63] ng/ml; P<0.05). Luteal cysts had thicker walls (5.3 [0.04] v 2.5 [0.2] mm; P<0.0001), and the wall thickness of all the cysts was positively correlated with plasma progesterone concentration (r=0.52, P<0.0004). Cows with luteal cysts had more additional follicles greater than 5 mm in diameter (P<0.01). In cows with follicular cysts and other follicles greater than 5 mm in diameter, the mean oestradiol concentration was 7.9 (1.8) pg/ml compared with 24.2 (3.1) pg/ml (P=0.002) in cows without other follicles greater than 5 mm in diameter on either ovary. At the time of PRID removal, plasma progesterone concentration had increased in the cows with follicular cysts to 1.59 (0.06) ng/ml (P<0.05) and decreased in the cows with luteal cysts to 0.87 (0.01) ng/ml (P<0.05), although there was no change in original cyst structure in 45 per cent of the cases. However, new ovarian structures were frequently observed during the treatment. The overall pregnancy rate for cows with both types of cyst after treatment was 50 per cent after three inseminations, but the first service pregnancy rate was only 18 per cent for cows with follicular cysts and 28 per cent for cows with luteal cysts. After treatment, the fertility of cows with follicular cysts was similar to that of paired herdmates, whereas cows with luteal cysts took 40 days longer to calve again than healthy herdmates. However, the culling rate was higher for cows with follicular cysts (41 v 11 per cent).  相似文献   

4.
Several studies have clarified that the follicular cysts degenerate and are replaced by newly growing follicles that develop into new follicular cysts without ovulation, i.e., turnover of ovarian follicular cysts in cows. However, the relativity of endocrinological changes, including the inhibin profile during turnover of spontaneous follicular cysts in dairy cows, is still unclear. In the present study, the relationship between turnover of follicular cysts and changes in the peripheral blood concentrations of progesterone (P), estradiol-17beta (E(2)), luteinizing hormone (LH), follicle stimulating hormone (FSH) and inhibin were examined in lactating dairy cows. Five cows diagnosed with follicular cysts (follicles of more than 25 mm in diameter in the absence of a corpus luteum) were investigated. Their ovarian dynamics were monitored using ultrasonography, and blood samples were collected at 2- or 3- day intervals throughout the experiment. The day when a follicle fated to become a follicular cyst reached more than 8 mm in diameter was defined as the start of a cystic follicular wave. Four of the 5 cows exhibited a similar patterns of cystic follicular changes and hormone profiles. The data from the 4 cows was used for analysis of the relationships between turnover of cystic follicles and the hormone profiles. Two or three new cystic follicular waves occurred in each cow during the experimental period. The mean diameter of the cystic follicles was more than 25 mm 13 to 15 days after the start of the cystic follicular wave, and it began to decrease 1 to 6 days before the start of the subsequent cystic follicular wave. The levels of E(2) and inhibin tended to decrease for 7 to 9 days before the start of a new cystic follicular wave and to increase concomitantly with new follicular cyst growth. The levels of FSH rose for 1 to 3 days before the start of a new cystic follicular wave. The present study clarified the relationship between FSH and inhibin during turnover of spontaneous follicular cysts in dairy cows and found that it was very similar to previous results for cows. The present results suggest that an increase in FSH secretion following a reduction in inhibin secretion triggers turnover of cystic follicles in cows with spontaneous follicular cysts.  相似文献   

5.
The aim of the present study was to clarify the ovarian and hormonal dynamics after the aspiration of follicular fluid in cows with follicular cysts. Follicular fluid was aspirated from the follicular cysts and follicles that were fated to become cystic follicles and other coexisting normal follicles, respectively, in lactating cows (n = 3). After the aspiration procedure, new follicles developed and reached a diameter of 25 mm without ovulation within 13–19 days. The plasma concentrations of inhibin decreased and follicle-stimulating hormone increased rapidly after the aspiration procedure, and subsequently increased and decreased, respectively, as a new follicle grew. No luteal structures developed after the aspiration procedure, and the animals’ plasma progesterone levels remained low. The present study indicates that the cystic follicles are never luteinized by the aspiration of follicular fluid, and consequently, new follicular cysts are observed to repeatedly develop.  相似文献   

6.
The goals of the present study were to investigate whether colour Doppler sonography can be used to differentiate temporary from persistent ovarian follicles and follicles with luteal tissue from follicles without luteal tissue and to assess the response of follicular cysts to administration of a gonadotropin releasing hormone (GnRH) analogue. Fifty-four cows having ovarian follicular structures with a diameter of >15 mm but no corpus luteum were included. These cows were examined via B-mode and colour Doppler sonography. The same examinations were repeated 10 to 12 days later, and the cows with follicular cysts (n=17) received a GnRH analogue. Blood flow was measured before and 30 min after treatment. Ten to 12 days later, the response to treatment was assessed using B-mode sonography. While 31 of 54 follicles disappeared spontaneously (temporary follicles), 23 follicles persisted and were diagnosed as cystic ovarian follicles (COFs). There was no difference between temporary follicles and COFs in regard to total area, wall thickness or the perfused area. In the luteinized follicles (n=13), based on the plasma progesterone concentration, total area was twice as large, wall thickness was three times greater and the perfused area was 4.5 times larger than those of the non-luteinized follicles (n=41). The sensitivity of diagnosing luteinized follicles was 61.5% using B-mode sonography and 92.3% using colour Doppler sonography. Twelve cows responded to GnRH, and five cows did not. There was a trend (P=0.07) toward higher (59.3%) blood flow in the cyst wall 30 min after treatment in the responding cows compared with the non-responding cows. Our results showed that the perfused area more accurately reflects active luteal tissue than wall thickness. Thus, colour Doppler sonography is superior to B-mode sonography for differentiating follicular and luteal cysts and aids in the selection of treatment. However, exact prediction of COFs destined to regress or persist and the response of COFs to treatment with a GnRH analogue were not possible using colour Doppler sonography.  相似文献   

7.
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8.
The purpose of this study was to determine by immunohistochemistry the expression of estrogen and progesterone receptors in ovarian follicular structures from cows with cystic ovarian disease (COD) and to compare these with normal ovarian structures. Secondary, tertiary, atretic, and cystic follicles were evaluated. The follicular cysts of animals with COD presented a significantly higher expression of estrogen receptor alpha in all follicular layers than secondary, tertiary, and atretic follicles in both groups (P < .05). The intensity of estrogen receptor beta in the granulosa cell layer was stronger in tertiary than in secondary and atretic follicles in normal animals (P < .05) and in growing and cystic follicles in animals with COD (P < .05). Theca cells were scarcely stained in the 2 groups. Growing follicles and cysts from COD animals were less stained than tertiary follicles from normal animals (P < .05). Differences did not exist between the 2 groups with regard to the progesterone receptor. Ovaries of animals with COD exhibited altered estrogen receptors expression compared with that in normal animals.  相似文献   

9.
In 160 cows with ovarian cysts as determined by rectal palpation, differentiation was made of follicular cyst, luteal cyst, and cystic corpus luteum on the basis of milk progesterone concentrations estimated by an enzyme immunoassay before and at 10 days after cows were treated with gonadotropin-releasing hormone. Cows having a progesterone concentration in skim milk less than 1.0 ng/ml were considered to have follicular cysts and those with concentrations of 1.0 ng/ml or higher were regarded as the cases of luteal cyst or cystic corpus luteum. Luteal cyst was characterized by progesterone values remaining high in the cows for 10 days after treatment, and cystic corpus luteum was characterized by a decrease in progesterone concentration after cows were treated. By the rectal palpation procedure it was impossible to differentiate luteal cyst and cystic corpus luteum from follicular cyst. The frequencies of follicular cyst, luteal cyst, and cystic corpus luteum were 65%, 19%, and 16%, respectively. Of 104 cows with follicular cysts as defined by milk progesterone assay result, 73 (70%) responded to the treatment with gonadotropin-releasing hormone, the milk progesterone concentration increasing from 0.7 +/- 0.2 ng/ml (mean +/- SD) to 1.8 +/- 1.1 ng/ml. The accuracy of rectal palpation 10 days after treatment for judgment of luteinization of follicular cyst confirmed by milk progesterone analysis was only 30% (48 cows of 160).  相似文献   

10.
The objective of this research was to determine changes in IGF-I levels in serum and follicular fluid, and immunoreactivity of the follicle wall of cows with spontaneous (slaughter specimens) or ACTH-induced follicular cysts, and to compare results to normal cycling (control) cows after selection of the ovulatory follicle. Concentrations of IGF-I in serum did not differ between control and cystic animals (p=0.76). Fluid from the ovulatory follicle in control cows had 41% higher concentrations of IGF-I than that from cystic follicles collected at slaughter (spontaneous cysts; p<0.05) and 70% higher than that in induced follicular cysts (p<0.05). An intense positive immunostaining with anti-IGF-I was observed in granulosa cells (p<0.05) and in the theca interna (p<0.05) of secondary and tertiary follicles in all three groups of animals, but staining was less intense in cystic (p<0.05) and atretic follicles (p<0.05). This study provides evidence to suggest that cystic ovarian disease in cattle is associated with decreased concentrations of IGF-I in follicular fluid, but not in serum, and decreased production of IGF-I in the follicular wall. These data support the notion that IGF-I plays a role in the regulation of folliculogenesis, and may participate in the pathogenesis of cystic ovarian disease in cattle.  相似文献   

11.
Ovarian function in 91 dairy cows with cystic ovarian disease was assessed by rectal palpation and by plasma hormone analysis before and after treatment. Plasma analysis showed that 84% of the cysts were correctly classified clinically and only these cows are considered further. Luteinised cysts occurred in 59 cows whereas only 18 had non-luteinised cysts. The mean plasma concentrations of luteinising hormone (LH), follicular stimulating hormone (FSH), progesterone, oestradiol and testosterone were not significantly different when compared with values at relevant stages of the oestrous cycle in normal cows. Success of treatment with progesterone, a synthetic prostaglandin, human gonadotrophin (HCG), or gonadotrophin releasing hormone (GnRH) was not dependent upon prior hormone concentrations, except for the prostaglandin which required active luteal tissue. LH and FSH concentrations in cows with luteinised cysts were not significantly different before and after successful treatment with GnRH or progesterone. Normal luteal function was not always established after treatment of non-luteinised cysts with GnRH.  相似文献   

12.
We investigated the therapeutic effects of a progesterone releasing intravaginal device (PRID) on cystic ovarian disease (COD) and reproduction performance of cows. The possible influence of PRID on metabolic and/or health status was also examined. A total of 40 Holstein-Friesian cattle, with ovarian cystic structures, > or =2.5 cm in diameter, persisting for more than 7-14 days, without a corpus luteum (CL) were used for the study. PRID or placebos were inserted into the vagina for 12 days. Five animals lost the intravaginal device before removal and one was culled. Based on plasma progesterone concentration on the day of treatment, 20 (17 PRID and 3 placebos) of the remaining 34 cows had follicular cysts (progesterone < or =1 ng/ml) and 14 (10 PRID and 4 placebos) had luteal cysts (progesterone >1 ng/m l). Fourteen (82%) of the PRID-treated follicular cystic cows responded with formation of a CL within 14 days after treatment, and an overall conception rate of 53.8%. Likewise, 70% of the treated luteal cystic cows responded with CL formation and 71.4% conception rate. No significant differences were observed in hematocrit (Ht), white blood cell count and serum levels of glucose, blood urea nitrogen, aspartate aminotransferase, and alanine aminotransferase, between the day of PRID insertion and removal, in animals with follicular and luteal cysts. PRID treatment resulted in ovulation 2-4 days later and formation of a CL in cows that recovered.  相似文献   

13.
Cows with ovarian follicular cysts were treated with progesterone to determine whether a reduction in LH concentrations and initiation of ovulatory follicular waves would occur. Cysts were diagnosed using transrectal ultrasonography when single follicular structures > 20 mm or multiple structures > 15 mm in diameter were present for 7 d in the presence of low progesterone concentrations. Three groups were studied: 1) cows with normal estrous cycles (CYC, n = 8); 2) cows with untreated cysts (CYST, n = 7); and 3) cows with cysts treated with two progesterone-releasing intravaginal devices (PRID, n = 8) for 9 d. Ovaries were examined with transrectal ultrasonography, and blood samples were collected daily for analysis of progesterone and FSH. Serial blood samples for determination of mean LH and LH pulse frequency were collected on d 0 (CYST and PRID cows only), 1, 5, 9, and 10. Progesterone concentrations were higher in PRID cows than in CYST cows throughout the PRID treatment period (P < .002). On d 0, LH pulse frequency was similar (P = .10) in PRID (6.6+/-.6 pulses/8 h) and CYST cows (5.1+/-.6 pulses/8 h), but mean LH tended to be higher (P = .054) on d 0 in PRID cows (2.5+/-.2 ng/mL) than in CYST cows (1.9+/-.2 ng/mL). Mean LH and LH pulse frequency decreased (P < .002) by d 1 in PRID cows (1.1+/-.2 ng/mL, 1.8+/-.6 pulses/8 h) compared with CYST cows (2.1+/-.2 ng/mL, 5.6+/-.6 pulses/8 h) and remained lower throughout most of the experimental period. The FSH concentrations were higher (P < .01) in PRID cows than in CYC and CYST cows on d 3 and 4. The increase in FSH concentrations preceded emergence of the PRID-induced follicular wave. All PRID cows and four of seven CYST cows initiated new follicular waves during the period of PRID treatment. Follicular waves were initiated later (P < .05) in CYST cows (d 5.2+/-1.7) and PRID cows (d 5.5+/-.6) than in CYC cows (d 1.8+/-.3). Cysts were smaller (P < .01) at the end of the treatment period in PRID cows compared with CYST cows. No CYST cows ovulated, but all PRID cows ovulated newly developed follicles 3 or 4 d after PRID removal. Treatment with exogenous progesterone reduced LH in cows with cysts, and this was followed by development of normal ovulatory follicles.  相似文献   

14.
Ovarian function was assessed from milk progesterone profiles in 236 cows that were presented for clinical examination after parturition and in 227 unexamined herdmates. By 30 days after calving, 81 per cent of the cows had ovulated and by 42 days 92 per cent had resumed cycling. On average milk samples were taken for 155 days, and during this period 67 luteal cysts or cystic corpora lutea and 24 follicular cysts were recorded, and 88 cows were anoestrus for more than 30 days. Luteal cysts, follicular cysts and prolonged anoestrus all occurred twice as frequently in the cows which were clinically examined as in those which were not examined. Progesterone profiles indicated that at the time of clinical examination 72.4 per cent of the cows examined were cycling normally, 11.3 per cent were anoestrus, 6.7 per cent had follicular cysts, 8.0 per cent had luteal cysts and 1.6 per cent were pregnant. Rectal palpation correctly identified ovarian function in only 63.5 per cent of examinations, with 29.8 per cent of cows that were cycling normally, 58.1 per cent that were anoestrus, 70.3 per cent with follicular cysts and 25 per cent with luteal cysts being incorrectly diagnosed. Progesterone profiles confirmed normal oestrous cyclicity in 81.9 per cent of these cows diagnosed as cycling normally by the clinician. The clinical treatments administered included prostaglandin, gonadotrophin-releasing hormone (GnRH), progesterone (PRID) and the physical expression of ovarian structures. Cows diagnosed as cycling normally were left untreated. At the time of treatment, 28.8 per cent of prostaglandin-treated cows had low progesterone concentrations indicating that no luteal tissue was present.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
The purpose of this study was to determine and compare the accuracy of palpation per rectum and linear-array ultrasonography for diagnosing follicular vs luteal ovarian cysts in cows. Forty-seven examinations of ovarian cysts from 28 cows were diagnosed by palpation per rectum as either a firm, thick-walled structure (luteal cyst) or a soft, thin-walled structure (follicular cyst) during weekly herd examinations. The ovaries of each cow were then examined by ultrasonography. Ultrasonograms of cysts greater than 25 mm in diameter were diagnosed as luteal or follicular cysts and were recorded on videotape for evaluation by a second clinician. Serum progesterone concentrations at the time of examination were determined by radioimmunoassay and used to classify luteal (greater than 0.5 ng/ml) or follicular (less than or equal to 0.5 ng/ml) cysts. Selection of this discriminatory level was based on response of a proportion of cows with luteal cysts that were given 25 mg of prostaglandin F2 alpha at the time of diagnosis by ultrasonography. Sensitivity and specificity of palpation per rectum for diagnosis of type of ovarian cyst were low (43.3 and 64.7%, respectively). In contrast, sensitivity and specificity of ultrasonography were considerably higher (86.7 and 82.3%, respectively). Agreement between the 2 methods of diagnosis was 57.4%. Overall agreement between the 2 clinicians' diagnoses by ultrasonography was 85.1%. On the basis of our findings, we confirm that luteal and follicular cysts cannot be accurately differentiated by palpation per rectum alone. These data suggest that linear-array ultrasonography is more effective than palpation per rectum for diagnosing type of ovarian cyst in cows.  相似文献   

16.
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17.
The fate of cystic ovarian follicles that developed spontaneously during the early postpartum period of 50 lactating dairy cows was traced by ultrasonography to characterise the follicular dynamics in relation to the fertility of the cows. The absence of postpartum ovulations caused by repeated waves of anovulatory large follicles was also characterised and evaluated. Fifteen of the 50 cows developed cystic follicles, and these follicles became follicular cysts in five of the 15 cows. Most of the cystic follicles emerged before the first postpartum ovulation of the cows. The transition from cystic follicles to follicular cysts delayed the cows' first ovulation, oestrus and insemination, but had less influence on their fertility after they had recovered spontaneously. In addition to the 15 cows that developed cystic follicles or follicular cysts, six of the cows had five to 13 waves of follicles before their first ovulation. These repeated waves of follicles caused a more severe delay in the early postpartum reproductive events but did not affect the cows' fertility.  相似文献   

18.
Comparisons of numbers of antral ovarian follicles and corpora lutea (CL), of blood hormone concentrations, and of follicular fluid steroid concentrations and IGFBP activity were conducted between cows selected (twinner) and unselected (control) for twin births to elucidate genetic differences in the regulation of ovarian follicular development. Ovarian follicular development was synchronized among cows by a single i.m. injection of PGF2alpha on d 18 of the estrous cycle; six cows per population were slaughtered at 0, 24, 48, and 72 h after PGF2alpha. Jugular vein blood was collected from each animal at PGF2alpha injection and at 24-h intervals until slaughter. Ovaries of twinner cows contained more small (< or = 5 mm in diameter, P < 0.05), medium (5.1 to 9.9 mm, P < 0.05), and large (> or = 10.0 mm, P < 0.01) follicles and more (P < 0.01) CL than ovaries of controls. Follicular fluid concentrations of estradiol, androstenedione, testosterone, and progesterone reflected the stage of follicular development and were similar for twinner and control follicles at the same stage. Earlier initiation of follicular development and/or selection of twin-dominant follicles in some twinner cows resulted in greater concentrations of estradiol in plasma at 0, 24, and 48 h and of estradiol, androstenedione, and testosterone in follicular fluid of large follicles at 0 h after PGF2alpha for twinner vs. control cows (follicular status x time x population, P < 0.01). Binding activities of IGFBP-5 and -4 were absent or reduced (P < 0.01) in follicular fluid of developing medium and large estro-gen-active (estradiol:progesterone ratio > 1) follicles but increased with atresia. Only preovulatory Graafian follicles lacked IGFBP-2 binding, suggesting a possible role for IGFBP-2 in selection of the dominant follicle. Concentrations of IGF-I were twofold greater (P < 0.01), but GH (P = 0.10) and cholesterol (P < 0.05) were less in blood of twinners. Three generations of selection of cattle for twin ovulations and births enhanced ovarian follicular development as manifested by increased numbers of follicles within a follicular wave and subsequent selection of twin dominant follicles. Because gonadotropin secretion and ovarian steroidogenesis were similar for control and twinner cattle, enhanced follicular development in twinners may result from decreased inhibition by the dominant follicle(s), increased ovarian sensitivity to gonadotropins, and/or increased intragonadal stimulation, possibly by increased IGF-I.  相似文献   

19.
In 7 instances, cystic ovarian follicles resulted when adrenocorticotropin (ACTH) was administered daily during the follicular phase of the estrous cycle in cows. Two cows given daily injections of hydrocortisone (cortisol) during the follicular phase of the estrous cycle did not develop cystic ovaries. Plasma concentrations of estradiol in cows with induced cystic ovarian follicles were similar to the peak values observed at estrus and were between 6 and 12 pg/ml. Progesterone concentrations in plasma of cows with cystic ovaries were low, between 1 and 2 ng/ml. Ovulation occurred when 2 cows were given human chorionic gonadotropin (HCG) during the period of ovarian cyst development with ACTH administration. Several days of administration of ACTH was required to cause cyst development. Ovulation occurred at the expected time in 1 cow when injections began on day 19, that is, late in the follicular period. In another cow, when treatment was stopped on day 3, after the expected time of estrus a delayed ovulation occurred. In 2 cows with induced cystic ovarian follicles, cyst atresia occurred spontaneously about day 13 to 17 of the cycle. In these cows, new follicular growth and ovulation followed (although delayed in 1 cow). The time of atresia of cystic follicles was not influenced by the intrauterine injection of 10 ml of sterile saline solution on days 8, 9, and 10 in 1 cow. When 5 mg of prostaglandin F2alpha in 10 ml of sterile saline solution was given (uterine injection) in 2 cows on days 8, 9, and 10, cyst atresia occurred earlier than the time of spontaneous atresia. Intrauterine administration of 100 mg of indomethacin in 10 ml of sterile saline solution daily for 13 or 14 days to 2 cows, starting on day 12 or 13 of the cycle, resulted in persistence of the induced cystic ovarian follicles. After cessation of indomethacin treatment, atresia of cysts followed and new follicular growth and ovulation occurred.  相似文献   

20.
The objective of this study was to test the hypothesis that supra-basal concentrations of progesterone during the follicular phase are associated with the development of follicular cysts. Twenty-five non-lactating dairy cows were used in the study, which was performed over five identical replicate trials. Luteolysis was induced during the mid-luteal phase. Transrectal ultrasonography was performed daily to determine the occurrence/timing of ovulation. Plasma samples were collected for progesterone, oestradiol and luteinizing hormone (LH) analysis. Three cows failed to ovulate (cystic anovulatory) but did ovulate in a subsequent replicate (cystic ovulatory). Eight cows from the appropriate replicates were used as control cows (normal group). Follicular growth patterns and plasma oestradiol concentrations were similar between the three groups. However, the plasma progesterone concentrations during the follicular phase were twofold higher in the cystic anovulatory group (P < 0.01). Furthermore, no LH surge was detected in these animals. While LH pulse amplitude was similar between groups, LH pulse frequency in the cystic anovulatory group was attenuated (P < 0.05). In conclusion, the formation of follicular cysts were preceded by elevated plasma progesterone concentrations and the suppression of the LH surge.  相似文献   

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