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PubMed2001

Use of vaginal electrical resistance (VER) to predict estrus and ovarian activity, its relationship with plasma progesterone and its use for insemination in buffaloes.

In three experiments we studied the baseline and changes in VER during different natural estrous cycle stages (n=146) in ovarian structures and in plasma progesterone during estrus induced by prostaglandin injection (n=16) and the VER at insemination (n=90) in an attempt to predict estrus, ovulation and the best VER range for inseminating buffaloes for optimum conception. The baseline VER was classified on the basis of ovarian findings and estrous cycle stages. The mean VER during estrus, metestrus, diestrus, proestrus and anestrus was 32.68 +/- 0.46, 41.26 +/- 1.17, 50.23 +/- 0.55, 43.20 +/- 0.64 and 55.86 +/- 0.57 ohms, respectively. There was a significant difference (P<0.01) between the VER except those between metestrus and proestrus. The ANOVA for VER over estrous cycle stages showed a highly significant (P<0.01) effect of stage of estrous cycle on VER in buffaloes. The percent decrease in VER was more pronounced from diestrus to estrus. In the second part of the study plasma progesterone profiles and the appearance of estrus in buffaloes induced to estrus using two dose schedules and routes of PGF2alpha administration showed that luteolysis and estrus induction was slower in the 10 mg i.v.s.m. route (Intra Vulvo Submucosal) (only 60% animals evinced estrus in 48 to 72 hours) as compared to the 25 mg i.m. route (83.33% evidenced estrus in 48 to 72 hrs). Fall in plasma progesterone was synchronous to a fall in VER, the correlation (0.65) between them being positive and significant (P<0.01). After ovulation the VER started rising, showing a distinct relationship between VER and ovulation. By using VER, an additional 36.6% of the buffaloes could be detected in estrus. In the third part of the study, insemination of buffaloes induced to estrus (n=11) and normal-estrus buffaloes (n=79) showed that the overall conception rates to single insemination when the buffaloes were inseminated at the VER range of 26 to 30, 31 to 35 and 36 to 40 ohms were 81.48, 58.97 and 16.66%, respectively. Buffaloes showing VER from 31 to 35 ohms and 36 to 40 ohms also evidenced atypical and Null fern pattern in the cervicovaginal mucus. The study proved that VER can be used successfully to predict the stage of estrous cycle, ovarian status and ovulation; and insemination at a low VER distinctly improves the conception rates in buffaloes.

Animals↗
PubMed1975

Luteinizing hormone, progesterone and the morphological development of normal and superovulated corpora lutea in sheep.

The development of granulosa-lutein cells was studied in 27 normal and 32 superovulated ewes between days 0-4(day 0 began with the preovulatory LH peak in normal animals and the HCG injection in superovulated ewes). The pattern of differentiation was similar in both groups. Following initial hormonal stimulation (0-12 hours after LH or HCG), granulosa cells were approximately 100 mu2 and contained small, pleomorphic nuclei with large amounts of clumped chromatin. Elongate cells lining the basement membrane possessed large, heterogeneous dense bodies, and a well-developed Golgi apparatus. Mitotic figures were observed up to 6 hours prior to ovulation. Sixteen to 20 hours following the LH surge or HCG injection, hypertrophy of granulosa cells was evident. Nuclei contained definitive nucleoli. Blood vessels in the theca interna were abundant and highly dilated. Ovulation occurred approximately 24 hours after the LH peak or HCG injection. Visible signs of luteinization were evident 6-12 hours after ovulation. A slight increase in serum progesterone levels was detected. The second post-ovulatory day was characterized by continuing hypertrophy of granulosa cells and extensive proliferation of smooth endoplasmic reticulum and mitochondria. Nuclei of granulosa cells were larger and possessed extremely large nucleoli. Numerous mitotic figures were apparent within the corpus luteum. Serum progesterone concentrations began increasing at 60-72 hours after hormone stimulation. By the end of the third post-ovulatory day, the corpus luteum consisted of large, pleomorphic, parenchymal cells, interspersed between capillaries and connective tissue elements. Only an occasional mitotic figure was apparent within the corpus luteum at 100 hours. Light microscopic autoradiography of 5, 10, and 15 day corpora lutea taken from ewes pulsed with 3H thymidine at specific times before and after ovulation revealed that granulosa cells did not undergo secondary mitoses following ovulation. In contrast, thecal, mesenchymal and endothelial cells did mitose on day 3.

Animals↗
PubMed2002

Seasonal effects on estrous behavior and time of ovulation in nonlactating beef cows.

Estrous behavior and time of ovulation relative to the onset of estrus were determined in mature Angus x Hereford cows (n = 17 to 21 each season) during summer, winter, and spring for 2 yr. Estrous behavior was evaluated during the first of two consecutive estrous periods, and time of ovulation was determined during the second estrus. Concentrations of progesterone were quantified in twice weekly blood samples to ensure all cows had normal estrous cycles. The HeatWatch system was used to measure the duration of estrus, number of mounts received per estrus, and duration of the longest interval between mounts received. Commencing 16 h after the onset of the second estrus, transrectal ultrasonography was performed every 4 h until the dominant follicle was no longer present on the ovary, and time of ovulation was defined as 2 h preceding the absence of the dominant follicle. There was a seasonal effect on the duration of estrus; cows were estrus longer in summer (17.6 +/- 0.8 h) than in winter (15.5 +/- 0.8 h; P = 0.07) or spring (13.9 +/- 0.9 h; P < 0.05). Cows were mounted more times per estrus (P < 0.05) in winter (59.0 +/- 5.3) than in summer (43.6 +/- 5.3) or spring (38.2 +/- 5.8). Intervals between mounts of estrous cows were longer (P < 0.05) in summer (4.1 +/- 0.4 h) than in spring or winter (2.7 +/- 0.4 h). During all seasons, cows were mounted more times (P < 0.01) between 0600 to 1200 (3.2 +/- 0.2 mounts received/h of estrus) than during other times of the day (2.1 +/- 0.2 mounts received/h of estrus). Cows ovulated 31.1 +/- 0.6 h after the onset of estrus, and time of ovulation was not influenced by season. We conclude that season influences estrous behavior of beef cows; cows are mounted more times per estrus in winter than in summer or spring. Time of ovulation relative to the onset of estrus is constant during all seasons and averages 31.1 h.

Animals↗
PubMed1993

[Pulsatile gonadotropin releasing hormone treatment following previous ovarian hyperstimulation].

Physiological follicular maturation was achieved by pulsatile gonadotrophin releasing hormone treatment in ovarian hyperstimulatory cases induced previously by other ovulation induction methods (clomiphene, clomiphene + hCG, clomiphene + hMG + hCG). The follicular development was detected by vaginal ultrasound examination (Hitachi-3000, 6.5 MHz) in 8 cycles treated with gonadotrophin releasing hormone. During the pulsatile gonadotrophin releasing hormone treatment ovulation was found in all cases and 2 pregnancies occurred. Ovarian hyperstimulation was not noticed. Physiological follicular maturation can be induced with the pulsatile administration of gonadotrophin releasing hormone after previous ovarian hyperstimulation because using this method the hypophyseal-ovarian steroid feed back mechanism remains unchanged.

Adult↗
PubMed2001

Ovulation induction disrupts luteal phase function.

Abnormalities in the luteal phase have been detected in virtually all the stimulation protocols used in in vitro fertilization, on both the hormonal and endometrial levels. Supraphysiological follicular or luteal sex steroid serum concentrations, altered estradiol: progesterone (E2/P) ratio, and disturbed luteinizing hormone pituitary secretion leading to corpus luteum insufficiency or a direct drug effect have been postulated as the main etiologic factors. Luteinizing hormone supports corpus luteum function, and low LH levels have been described after human menopausal gonadotropin treatment, after gonadotropin-releasing hormone (GnRH)-agonist treatment, or after GnRH-antagonist treatment. These low luteal LH levels may lead to an insufficient corpus luteum function and consequently to a shortened luteal phase or to the low luteal progesterone concentrations frequently described after ovulation induction. A direct effect of the GnRH agonist or GnRH antagonist on human corpus luteum or on human endometrium and thus on endometrial receptivity cannot be excluded, as GnRH receptors have been described in both compartments. Endometrial histology has revealed a wide range of abnormalities during the various stimulation protocols. In GnRH-agonist cycles, mid-luteal biopsies have revealed increased glandulo-stromal dyssynchrony and delay in endometrial development, strong positivity of endometrial glands for progesterone receptors, decreased alphavbeta3-integrin subunit expression, and earlier appearance of surface epithelium pinopodes. These factors suggest a shift forwards of the implantation window. Progesterone supplementation improves endometrial histology, and its necessity has been well established, at least in cycles using GnRH agonists.

Endometrium↗
PubMed1985

Altrenogest and fat for summer breeding of primiparous sows.

Delaying the onset of estrus after weaning and adding fat to the postweaning diet were studied for their effects on estrus and fertility in 232 crossbred primiparous sows on a commercial swine farm. Sows were assigned randomly to the following treatments after weaning in June, July, August, or September, 1983: 1) altrenogest (20 mg/d) was fed for 7 d after weaning (n = 76), 2) altrenogest was fed for 7 d plus .53 kg dried animal and vegetable fat product (.45 kg actual fat/d) for 14 d after weaning (n = 78), or 3) no treatment (controls, n = 78). While a similar proportion of sows came into heat after weaning (lactation length = 4 wk), sows fed altrenogest (14.4 +/- .2 d) returned to estrus about 9 d later (P less than .01) than controls (5.6 +/- .2 d). Serum progesterone concentration was assayed in blood samples collected from a subgroup (74%) of the cows not observed in estrus by 3 wk after weaning to determine possible causes of anestrus. If serum progesterone (greater than 5 ng/ml) was elevated, we assumed that sows had ovulated without expressing estrus (behavioral anestrus) or ovulated with undetected estrus (less overt estrus or error in estrous detection), whereas low progesterone (less than or equal to 5 ng/ml) indicated that sows were anovulatory. About 53% of the sows not observed in estrus across all treatments had luteal function, probably resulting from post-weaning ovulation. Incidence of anovulation without estrus was 47%. Farrowing rate was higher (P less than .05) for sows fed only altrenogest (64%) compared with controls (46%), but similar to fat supplemented, altrenogest-treated sows (52%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Preimplantation embryo development in ICR mice after streptozotocin treatment.

To investigate the significance of impaired insulin secretion on preimplantation embryo development, outbred ICR female mice received a single injection of streptozotocin 130 mg (low) and 160 mg (subdiabetic) kg(-1), 14-17 days before fertilization. Preimplantation embryos were collected on day 3 of pregnancy, four to eight-cell embryos were cultured in vitro 48 h (day 5) and their cell number was estimated. After spontaneous ovulation, the significantly different distribution pattern in comparison with the controls was detected only in preimplantation embryos isolated from subdiabetic (160 mg x kg(-1) streptozotocin) mice. Furthermore, the incidence of degenerated embryos was significantly increased after 48 h in vitro cultivation. The analysis of cell number distribution in embryos after cultivation in vitro indicated a significant delay in cell proliferation in both experimental groups (130 and 160 mg x kg(-1) streptozotocin) in comparison with control mice. After superovulation, the only significant difference was found in the distribution pattern of embryos isolated on day 3 of pregnancy from subdiabetic (160 mg x kg(-1) streptozotocin) mice. No significant differences were found after embryo cultivation in vitro. It could be concluded that, in outbred ICR mice, lower streptozotocin treatment (130 mg x kg(-1)) influenced only cell distribution of in vitro cultured embryos after spontaneous ovulation. In ICR mice, marked changes in preimplantation embryo development were detected only after subdiabetic (160 mg x kg(-1)) streptozotocin treatment. During in vitro cultivation delayed effects of impaired insulin secretion resulted in an increase of embryo degeneration at the time after the third mitotic cleavage. Our results indicate that the effects of impaired maternal insulin secretion on preimplantation embryo development in mice are marked and consistent after spontaneous ovulation. Superovulation apparently disguises subtle changes in preimplantation embryo development after low and subdiabetic streptozotocin treatment.

Animals↗
PubMed1982

Luteal function in hypophysectomized rhesus monkeys.

Experiments were designed to study the maintenance of corpus luteum function in the rhesus monkey. The experiments used a transfrontal microsurgical approach for total hypophysectomy. This proved to be a reliable and safe procedure for the complete removal of the pituitary gland. Luteal function was not affected by either complete hypophysectomy or sham surgery performed 1 day after ovulation. The concentrations of PRL in serum became undetectable during the luteal phase in hypophysectomized animals. Serum LH levels in the first postoperative cycle were detectable, but were just above the lower limits of sensitivity of the bioassay. Ovulation was induced with human menopausal gonadotropin and hCG or human menopausal gonadotropin and human LH at least 6 months after hypophysectomy, at which time endogenous LH was undetectable. These animals displayed normal luteal function, for approximately 10 days suggesting that the corpus luteum, once formed, can function independently of circulating LH and in the absence of the pituitary gland.

Animals↗
PubMedDate not supplied

Effects of paraquat on development of preimplantation embryos in vivo and in vitro.

Paraquat can cause oxidative stress through redox cycling, and preimplantation embryos are sensitive to oxidative stress in vitro. In this study, the effects of paraquat on preimplantation embryo development were examined. Exposure of preimplantation embryos (collected on the day after ovulation) to paraquat in vitro for 24 h at concentrations as low as 8 microM caused a significant decrease in the percentage of 8-cell embryos and an increase in the percentage of compacted morulae, but the content of reduced glutathione (GSH) in embryos was not changed. Altered embryo development was most likely due to premature compaction because a 42% decrease in cell number per compacted morulae was observed in embryos exposed to paraquat at 1 mM. Exposure of preimplantation embryos to paraquat in vitro for 4 days at 200 microM or higher eliminated development beyond the blastocyst stage. Exposure of bred female mice to paraquat at 30 mg/kg on day 2 after ovulation led to a small but significant decrease in the percentage of 8-cell embryos on day 3 without a detectable increase in the percentage of compacted morulae. No detectable change in preimplantation embryo development was found following paraquat exposure on the day of ovulation (day 0), although a significant decrease in embryo GSH was found on day 1. These data indicate that paraquat can adversely impact the development of preimplantation embryos in vitro and in vivo without consistent modulation of GSH level.

Animals↗
PubMed1996

Differential effects of indomethacin on the sheep ovary: prostaglandin biosynthesis, intracellular calcium, apoptosis, and ovulation.

Cells of the apical wall of the dominant follicle and contiguous ovarian surface epithelium become apoptotic with the approach of ovulation in the sheep. It was hypothesized that indomethacin, an established inhibitor of prostaglandin biosynthesis and ovulation, would protect apical ovarian cells from programmed death. The anovulatory potencies of two systemic doses of indomethacin (200 and 800 mg) were tested in gonadotropin-stimulated ewes. A complete blockade of ovulation occurred at the higher dose of indomethacin. Ovulation was not inhibited by 200 mg indomethacin. Both doses of drug suppressed follicular prostaglandin production below pregonadotropin levels. Immunofluorescence detection of digoxigenin end-labeled (fragmented) DNA was used as a marker of apoptosis among ovarian surface epithelial and granulosa cells recovered from the optical hemisphere of preovulatory ovine follicles. Cellular DNA fragmentation was averted in animals given 800 mg indomethacin, whereas apoptosis ensued after 200 mg. A sustained increase in cytosolic calcium is generally a prerequisite to apoptotic DNA fragmentation and cell death. Indeed, intracellular calcium, detected by fluorescence of fura-2, was elevated in ovarian cells of animals destined to ovulate (controls, 200 mg indomethacin) in comparison to (safeguarded) cells of anovulatory ewes (800 mg indomethacin). These observations provide circumstantial evidence that apical ovarian cell degeneration by calcium-mediated apoptosis is a determinant of follicular instability and rupture, but that these events are unrelated to the gonadotropin-induced rise in prostanoid production characteristic of preovulatory follicles.

Animals↗
PubMed2001

Level of dietary energy during prepubertal growth and reproductive development of gilts.

Development of gilts that conceive early and continue to produce offspring is a primary objective of swine production. The objective of this study was to determine the degree of feed restriction during development required to optimize reproductive performance and efficiency in gilts. The effects that various patterns of growth had on reproductive development and performance of gilts through d 30 of gestation were investigated. At 13 wk of age and 41 kg BW, 192 white crossbred gilts were penned individually and assigned to receive 87.5%, 75%, 62.5%, and 50% of predicted ad libitum energy intake. The study was replicated in two seasons. At 25 wk of age, gilts were moved to group pens and allowed ad libitum access to feed, and estrous detection was initiated. Gilts were inseminated at first observed estrus and those recycling were remated. Post-mating gilts were fed 1.5x maintenance in stalls. Gilts that did not return to estrus 17 to 30 d after mating were slaughtered at 30 d of gestation. Reproductive tracts were collected and numbers of corpora lutea and live embryos were recorded. Feed restriction during development resulted in differences in BW and backfat thickness at the start of the breeding period and differences in feed intake during breeding. Gilts subjected to the greatest feed restriction during development consumed the greatest quantity of feed during breeding. Feed intake during breeding was associated with BW and backfat gain during breeding. The treatment group that entered breeding lightest and leanest (50% of predicted ad libitum intake) had the least number of days to first estrus, followed by the fattest, heaviest group (87.5% of predicted ad libitum intake). Treatment groups did not differ (P > 0.38) in ovulation rate or live embryo numbers. Significant relationships between quantity of GE consumed during development and variables considered important in reproductive development and performance were evident, such as BW and fatness at start of breeding and first detected estrus, and ovulation rate. Variation in dietary energy during the development period impacted many aspects of reproductive development and performance. However, coupling restricted energy intake during development with ad libitum intake during breeding negated many of the effects of feed restriction during the development period.

Animal Feed↗
PubMed1982

Influence of energy intake during lactation on the interval from weaning to first estrus in sows.

A total of 191 crossbred sows were used to determine the effect of energy intake during one lactation on (1) sow and pig performance and (2) the percentage of sows in estrus by 7, 14, 21 and 70 d postweaning. Sows received 8 (Lo) or 16 (Hi) Mcal of metabolizable energy (ME)/d (Exp. 1 and 2) and 8 (Lo), 12 (Md) or 16 (Hi) Mcal of Me/d (Exp. 3) during a 28-d lactation period. All sows were fed an equal amount of crude protein, vitamins and minerals that met or exceeded the recommendations of the National Research Council. Each day after weaning, sows were fed 1.8 kg of a 14% crude protein diet and checked for estrus using boars. Serum samples were obtained weekly from sows not detected in estrus by 15 d postweaning for progesterone analysis. In Exp. 1 sows fed Lo lost more (P less than .01) weight and backfat, and weaned lighter weight (P less than .01) pigs than sows fed Hi. Fewer sows fed Lo exhibited estrus (P less than .01) by 7, 14, 12 and 70 d postweaning than sows fed Hi. In Exp. 2, sows fed Lo lost more (P less than .01) weight and backfat than sows fed Hi, but pig weaning weights did not differ. Fewer sows fed Lo expressed estrus by 7 d (P less than .01) postweaning than those fed Hi. In Exp. 3 sow weight and backfat loss decreased (P less than .01) linearly as energy intake increased. Pig weaning weights were not affected by energy intake. Fewer sows fed Lo expressed estrus (P less than or equal to .05) by 7, 14, 21 and 70 d postweaning than those fed Md and Hi. There was no difference in the percentage of sows fed Md or Hi that exhibited estrus by these time periods. Blood samples collected on d 110 of gestation and d 14 and 26 of lactation, indicated that energy intake did not influence hematocrit values, total serum protein or albumin concentrations. A significant energy intake by time interaction was observed for serum blood urea N. Three of the 25 sows bled for progesterone analysis had luteal tissue activity suggesting ovulation had occurred even in the absence of a detected behavioral estrus.

Animals↗
PubMed1986

Mechanisms by which 5HT stimulates ovulation in the immature rat treated with pregnant mare serum gonadotrophin.

Pregnant mare serum gonadotrophin (PMS) normally induces a pre-ovulatory immunoreactive LH surge followed by ovulation in 27 day old rats provided they weigh more than 60 g; ovulation does not occur in the lighter rats although a pre-ovulatory LH surge can still be measured. 5HT injected into the paraventricular nucleus (PVN) can induce ovulation in these smaller rats treated with PMS and does so without appearing to stimulate extra immunoreactive LH. The LH secreted in the under 60 g PMS-treated rats is a pleiomorphic form since it cannot be detected by cytochemical bioassay, indicating abnormal biological activity, which may account for its failure to induce ovulation. After unilateral injection of 5HT into PVN, the LH was detectable by the bioassay. Injection of 5HT also stimulated the release of growth hormone and prolactin but had no significant effect on the plasma concentration of the gonadotrophins or corticosterone. Since an injection of exogenous GH converted the LH to a fully bioactive form it is suggested that GH is important in inducing the secretion of an "adult' form of LH in the peripubertal rat necessary for first ovulation and that 5HT exerts its ovulatory effect via stimulating the release of this hormone.

Animals↗
PubMed1995

Early pregnancy factor (EPF) as a marker for detecting subclinical embryonic loss in clomiphene citrate-treated women.

PROBLEM: A discrepancy exists between the apparently normal ovulation and the pregnancy rates in women treated with clomiphene citrate (CC). Our previous studies have indicated that immuno-suppressive "early pregnancy factor" (EPF) is a novel marker to detect subclinical embryonic loss in infertile women. METHOD: In the present study EPF was used as a marker to detect subclinical embryonic loss in women treated with CC with/without gonadotropins. In some of the women treated with CC, conception was assisted by artificial insemination with husband's semen (AIH). RESULTS: Our results have indicated that fertilization occurred (EPF + ve) in 47.7% (52/109) of women treated with CC with/without gonadotropins; 13.46% (7/52) retained the fetus and continued pregnancy till full term, whereas 78.9% (41/52) did not retain the fetuses. In the group where after stimulation, conception was assisted by AIH, fertilization was observed in 38.24% (26/68), retention in 11.54% (3/26) but subclinical embryonic loss was observed in 80.8% (21/26) cases. CONCLUSION: Thus, our results have indicated that subclinical embryonic loss may account for some of the discrepancy observed between the apparently normal ovulation and the pregnancy rates in women treated with clomiphene citrate.

Adult↗
PubMed1984

The effects of chlorpromazine, mianserin and Org GC94 on reproductive function in the rat.

In the assessment of drug safety with respect to mammalian reproductive function chlorpromazine and two serotonin antagonists, mianserin (Org GB94 ) and Org GC94 were studied for their effects on ovulation and ovum transport. In addition, the effect of coitus on drug-induced ovulation inhibition was investigated. The compounds were intragastrically administered to Charles River CD rats in a single dose or in consecutive daily doses for one or two weeks. The incidence of ovulation and the number of eggs were recorded. The compounds blocked ovulation in pro-oestrous rats after a single dose. Ovulation was restored by coitus in drug-treated animals. The compounds appeared to become less effective in blocking ovulation after multiple dosing. No effects on ovum transport were detected. From the results obtained in this study, it is concluded that the CNS-active drugs investigated did not adversely affect reproductive function in the rat.

Animals↗
PubMed1999

Changes in nitric oxide synthase activity in the ovary of gonadotropin treated rats: the role of nitric oxide during ovulation.

Immature rats receiving equine chorionic gonadotropin (eCG) and human CG (hCG) were used to study the time course changes in nitric oxide synthase (NOS) activity in the ovary during ovulation. To study the role of NO in ovulation, the effects of intrabursal injection of L-N(G)-monomethylarginine (L-NMMA, 125 microg/20 microl/bursa), a NOS inhibitor, on the number of ova shed were also examined. Rats were sacrificed at -48, 0, 3, 6, 9, 12, and 24 h after hCG injection, and the ovaries were collected for the NOS activity assay, Western blotting, NADPH-diaphorase histochemistry and immunohistochemistry. Total NOS and constitutive NOS activities in the ovary increased significantly at 9 h after hCG injection and the values remained high thereafter. Inducible NOS (iNOS) activity was detectable as a small peak at 3 and 6 h after hCG injection. Endothelial NOS (eNOS) protein production increased after hCG injection with a peak at 12 h, whereas iNOS protein production decreased at 12 and 24 h after hCG injection. NADPH-diaphorase positive cells increased at the thecae of growing follicles after hCG injection, appeared at mural granulosa cells before ovulation, and were detected in newly formed corpora lutea, which coincided with the results in eNOS positive cells by immunohistochemistry. L-NMMA given to rats at 5 or 7 h after hCG was most effective in reducing the number of ova shed. These results indicate that the NOS activity and NOS positive cells increased after hCG injection, and that eNOS was likely the main NOS increasing in the ovary during ovulation. It is concluded that NO produced between 5 and 9 h after hCG might play a supportive role in ovulation.

Animals↗
PubMed2000

Comparison of synchronization of ovulation and induction of estrus as therapeutic strategies for bovine ovarian cysts in the dairy cow.

The benefit of using timed-insemination in lactating dairy cows for the treatment of ovarian cysts lies in the fact that cows do not have to be detected in estrus for insemination and achieving pregnancy. We compared the effectiveness of synchronization of ovulation with timed-insemination and induction of estrus with insemination at estrus in the treatment of bovine ovarian cysts in lactating dairy cows. After Day 65 post partum, a total of 368 lactating dairy cows was divided into 3 groups. Cows in Group 1 (n = 209, normal, noncystic) were treated with 100 ug, i.m. GnRH on Day 0; 25 mg, i.m. PGF2 alpha on Day 7; and 100 ug, i.m. GnRH on Day 9 and then were time-inseminated 16 h later. Cows in Group 2 (n = 76, abnormal, cystic) were treated with 100 ug, i.m. GnRH on Day 0; 25 mg, i.m. PGF2 alpha on Day 7; and 100 ug, i.m. GnRH on Day 9 and time-inseminated 16 h later. Cows in Group 3 (n = 83, abnormal, cystic) were treated with 100 ug, i.m. GnRH on Day 0; 25 mg, i.m. PGF2 alpha on Day 7; and inseminated at induced estrus within 7 d after treatment with PGF2 alpha. Day 0 was the day of initiation of the study. Conception and pregnancy rates among groups were compared using logistic regression and adjusted for parity, time of year and days in milk. Conception and pregnancy rates of Group 1 cows (31.5%) were not significantly different from those of Group 2 cows (23.6%). However, the pregnancy rate in normal cows (Group 1) was higher (P < 0.01) than in cystic cows (Groups 2 and 3). Cows in Group 3 had a higher conception rate than cows in Group 2 (51.7% > 23.6%; P < 0.01). However, pregnancy rates for cows in Groups 2 (23.6%) and 3 (18%) were not significantly different. The finding indicated that synchronization of ovulation and timed-insemination resulted in pregnancy rates similar to those of synchronization of estrus and insemination at an induced estrus within 7 d for the treatment of ovarian cysts in lactating dairy cows.

Animals↗
PubMed2000

Oviductal isthmic motility in relation to ovulation and endocrine changes in unrestrained sows.

This study was designed to characterize changes in the motility of the oviductal isthmus in relation to endocrine changes around ovulation in unrestrained sows in their normal environment. Oviductal isthmic motility was monitored on Polyview from 11 h prior to and up to 36 h after ovulation in 13 unrestrained multiparous sows during their second estrus after weaning, using a pressure microtransducer implanted 3 cm into the isthmus. Both the maximum, minimum and mean pressures and the frequency of phasic pressure fluctuations were high prior to ovulation but declined significantly (P<0.05) at 9 to 12 h, 13 to 16 h, 13 to 16 h and 5 to 8 h after ovulation, respectively. Plasma estradiol-17beta and prostaglandin F2alpha metabolite levels declined significantly (P<0.05) at 4 to 7 h prior to ovulation while progesterone levels increased significantly (P<0.01) at 5 to 8 h after ovulation. The decrease in the plasma estradiol-17beta levels was correlated to the decrease in maximum and mean pressures and the frequency of phasic pressure fluctuations (n=113; r=0.30, 0.25, 0.25, respectively; P<0.01) but not to the decrease in minimum pressure (n=113; r=0.17, P>0.05). Similarly, the decrease in PGF2alpha metabolite levels was correlated to the decrease in minimum, maximum and mean pressures and the frequency of phasic pressure fluctuations (n=112; r=0.43, 0.35, 0.38, 0.32, respectively; P<0.001). Conversely, the increase in plasma progesterone levels was correlated to the decrease in minimum, maximum and mean pressures and the frequency of phasic pressure fluctuations (n=113; r=-0.56, -0.70, -0.68, -0.60, respectively; P<0.001). Therefore, the pressure parameters seem to be influenced by changes in the levels of estradiol-17beta, prostaglandin F2alpha and progesterone with respect to ovulation.

Animals↗