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PubMed2006

Effects of estradiol on gonadotrophin release, estrus and ovulation in CIDR-treated beef cattle.

The effects of estradiol-17beta (E-17beta) or estradiol benzoate (EB) on gonadotrophin release, estrus and ovulation in beef cattle were evaluated in two experiments. In experiment 1, 16 ovariectomized cows received a previously used CIDR insert from days 0 to 7 and 1mg of EB on day 8; they also received 5mg of E-17beta on days 0 or 1, or 5mg of E-17beta+100mg of progesterone on day 0. There was only an effect of time (P<0.0001) on plasma concentrations of progesterone, estradiol, FSH, and LH. Following treatment with E-17beta, plasma FSH concentrations were suppressed for approximately 36 h, whereas plasma LH concentrations were reduced (P<0.05) for 6 h, but surged within 24 h. Injecting 1mg of EB 24 h after CIDR removal decreased (P<0.02) plasma LH concentrations for 6h, followed by an LH surge at 18 h. In experiment 2, ovary-intact heifers (n=40) received a used CIDR and 5mg of E-17beta+100mg of progesterone on day 0. On day 7, CIDR were removed, PGF given, and heifers received nothing (control) or 1mg of EB 12, 24, or 36 h later. In these groups, plasma LH peaked (mean+/-SEM) 78.0+/-23.0, 37.8+/-8.5, 44.4+/-10.3, and 51.0+/-5.1 h after CIDR removal (means, P<0.001; variances, P<0.001) and intervals from CIDR removal to ovulation were 102.0+/-6.7, 63.6+/-3.6, 81.6+/-3.5, and 78.0+/-4.1h (P<0.05). The interval from CIDR removal to ovulation was shorter and less variable in EB-treated groups; the interval from EB to ovulation was shortest (P<0.05) in the 12-h group. In summary, E-17beta or EB decreased both FSH and LH, but LH increased after 6h (despite elevated progesterone concentrations). Following CIDR removal, 1mg of EB effectively synchronized LH release, and ovulation (in intact cattle), but the interval from CIDR removal to EB treatment affected the time of ovulation.

Animals↗
PubMed1975

Biological activities of 17-phenyl-18,19,20-trinorprostaglandins.

In a number of assay systems, some 17-phenyl-trinor-prostaglandins were similar in activity and potency to the corresponding parent prostaglandin. In others, the 17-phenyl analogs appeared several times more potent. In the hamster antifertility assay, which is considered to measure luteolytic activity, 17-phenyl-18,19,20-trinor prostaglandin F2alpha was about 90-times PGF2alpha in potency. Rat blood pressure responses to 17-phenyl analogs were significant. The 17-phenyl-trinor PGF2alpha pressor potency was 5 times that of PGF2alpha. The 17-phenyl-trinor PGE2 blood pressure response was atypical since a pressor rebound phenomenon followed the expected depressor response. Lastly, 17-phenyl-trinor PGF2alpha was more potent than PGF2alpha in synchronizing the estrous cycle in beef cows.

Animals↗
PubMed1975

Control of time of ovulation in heifers treated with progesterone and gonadotrophin-releasing hormone.

The time of ovulation was determined in twenty-nine heifers by laparoscopy following treatment with progesterone. In addition, twenty-five of the animals received 100 mug Gn-RH 30 hr after the end of the progesterone treatment. Only eight of the heifers treated with Gn-RH ovulated. This contrasted with results obtained following examination of ovaries after slaughter in similar animals treated in identical fashion. Heifers which were treated with progesterone for 12 days and then slaughtered had not begun to ovulate 65 hr after the end of treatment, but five of eleven animals had ovulated 4 hr later. When Gn-RH was given, ovulation had started 60 hr after the end of progesterpme treatment, 60% of heifers had ovulated at 65 hr and 90% at 69 hr. Treatment with Gn-RH can synchronize and hasten the time of ovulation in heifers given progesterone. Possible reasons for the discrepancy between the results obtained following laparoscopy and slaughter are discussed.

Animals↗
PubMed1980

[Effect of the male presence on the reproductive mechanisms in female mammals].

In various physiological situations, the presence of the male may interfere with the timing of the physiological events of female reproduction. Contact with the male hastens puberty in a variety of species, provided that the female has reached a given age and weight. The male presence may induce synchronized oestrus in the adult female. In the case of seasonal or lactation anoestrus in ewes, contact with the ram increases the pulsatile release of LH within a few minutes, resulting in a preovulatory surge 24 hrs later, followed by ovulation, but usually no behavioural oestrus. However, the development of the corpus luteum is abnormal in half of the cases, leading to an abnormally short 7-day oestrous cycle. During oestrus itself, the male presence reduces markedly the duration of sexual receptivity and hastens ovulation. Direct contact is not needed to produce these effects which can be mediated by the sense of smell and also by other senses, acting in a cumulative, and possible substitutive, way. Male-induced ovulation would ensure a higher probability of fertilization in species in which the males and females are not permanently associated. Furthermore, the resulting synchronized reproduction might have an adaptative value by reducing predation at birth in wild species. Such effects could also be used for the control of domestic animal production.

Animals↗
PubMed1989

Relationship between endogenous estradiol-17 beta and estrous behavior in heifers.

Thirty-five Holstein heifers were used to examine the relationship between endogenous estradiol-17 beta and estrous traits. During a non-superovulation period (NSP), estrous cycles were synchronized and during the periovulatory stage blood samples were collected every 6 h for 120 h for subsequent determination of estradiol-17 beta and progesterone. In addition, continuous observation for estrous behavior was performed for 98 h. A gonadotropin-induced superovulation period (SP) was begun 12 d after estrus was detected during NSP. Heifers were injected with FSH twice daily for 4 d and single injections of prostaglandin were given on d 14 and 15. Beginning at d 14, blood samples were collected every 6 h for 120 h for subsequent determination of estradiol-17 beta and progesterone. Continuous observation for estrous behavior was performed for 98 h. Peak estradiol-17 beta was greater during SP than during NSP (49.0 +/- 3.1 vs 12.9 +/- 3.0 pg/ml serum). Thirty-three and 31 of the 35 heifers were in estrus during NSP and SP, respectively; duration of estrus was 2.3 h longer during SP than during NSP. However, number of behavioral interactions during estrus did not differ between NSP and SP. In conclusion, estrous traits were similar, whereas peak estradiol-17 beta concentrations were markedly different between NSP and SP.

Animals↗
PubMedDate not supplied

[Peripheral blood lymphocytes in female mice during successive phases of the sexual cycle].

The authors determined the lymphocyte count, nucleo-cytoplasmic ratio, nuclear diameter, and the number of nucleoli and their morphology in peripheral blood of female mice. The results indicate that lymphocyte count remains unchanged during the sexual cycle but changes occur in the nucleocytoplasmic ratio, nuclear diameter, the number and morphology of lymphocyte nucleoli and are synchronized with the cycle. The observations suggest that changes in the maturity and activity of lymphocytes depend on the phase of the sexual cycle.

Animals↗
PubMed1980

Effect of transportation on sexual behavior of cats.

Transportation of an established feline colony approximately 1500 miles did not inhibit the resumption of behavioral reproductive cyclicity. Estrous behavior was observed as early as 18 days following shipment and mean duration of these first post-transfer estrous periods was normal. Relocation appeared to induce a synchronizing effect on behavioral cyclicity, since 76.2% and 42.9% of the population exhibited estrous onset during Days 18--31 and Days 24--26 respectively, following transport.

Animals↗
PubMed1991

Hormonal control of proceptive and receptive sexual behavior and the preovulatory LH surge in the ewe: reassessment of the respective roles of estradiol, testosterone, and progesterone.

When estrous behavior is induced in ovariectomized ewes by subjecting them to progestagen priming followed by a dose of estrogen large enough to guarantee estrus in all animals, an abnormally long period of estrus in induced, suggesting that the regime of steroid replacement needs modification. Using quantitative tests for proceptivity and receptivity, we studied the patterns of sexual behavior of intact ewes and then attempted to reproduce them in the same animals after they had been ovariectomized. We used various combinations of exogenous estrogen, androgen, and progestagen and compared the behavioral responses with an endocrine response, the preovulatory surge of luteinizing hormone (LH). In intact ewes, sexual behavior and the LH surge were closely synchronized and their characteristics differed slightly between the middle and the end of the breeding season. Proceptive behavior was not greatly affected by the frequency of tests, but the duration of receptivity was significantly reduced by frequent testing. In ovariectomized ewes, we found that: (a) progesterone priming is essential for normal patterns of receptive and proceptive behavior, and for synchronizing the behavioral and endocrine responses to estrogen; (b) androgens do not play a major role in the control of either receptive or proceptive behavior; and (c) the inclusion of a low dose of estrogen with the progestagen in the 'priming' regime improves the responses to estradiol-17 beta. Under these conditions, the timing, intensity and duration of the behavior are very close to those observed in the same ewes when they were intact and cycling spontaneously.

Animals↗
PubMed2002

Stage of the estrous cycle at the time of pregnant mare's serum gonadotropin injection affects the quality of ovulated oocytes in the mouse.

The present study aims to analyze the effect of the stage of the estrous cycle at the time of pregnant mare's serum gonadotropin (PMSG) injection on number and quality of mouse oocytes retrieved from oviducts after exogenous ovarian stimulation. Cellular and morphological traits of ovulated oocytes from hybrid (C57Bl/6JIco female X CBA/JIco male) female mice of 12, 40-42, 50-52 or 57-62 weeks of age were analyzed. Superovulation was induced by a priming injection of PMSG at different stages of the estrous cycle followed after a 48-hr interval by human chrorionic gonadotropin. Injection of PMSG at diestrus-1 was associated with: (1) increased percentage of cumulus-free oocytes; (2) raised total percentage of oocytes without polar body; (3) increased total percentage of oocytes with intracytoplasmic mitochondrial aggregates; (4) decreased percentage of oocytes with a normal distribution of chromosomes in the metaphase II plate; and (5) raised percentage of oocytes with chromosome scattering when compared to injection at estrus, diestrus-2, and proestrus stage. On the contrary, estrus females displayed the highest percentage of oocytes with a normal distribution of chromosomes in the metaphase II plate and the lowest percentage of oocytes denuded of cumulus cells, without polar body, with intracytoplasmic mitochondrial aggregates and/or with chromosome scattering. These data suggest that administration of gonadotropins in mice should be synchronized with the innate estrous cycle of females to optimize the quality of oocytes collected from oviducts.

Animals↗
PubMedDate not supplied

Gonadotrophin-induced ovulation in melengestrol acetate treated female goat.

Adult, Black Bengal goats synchronized to oestrus with Melengestrol Acetate (MGA) could be subjected to superovulation with 1000 IU of the Pregnant Mare Serum Gonadotrophin (PMSG). However, with 500 IU of PMSG higher rate of ovulation observed only in goats above one year age was not significant. Results indicate that the successful superovulation in MGA synchronized goats depend both on the dosage of the PMSG, as well as upon the age of the treated animal.

Aging↗
PubMed1996

Evaluation of timed insemination using a gonadotropin-releasing hormone agonist in lactating dairy cows.

An experiment compared the effectiveness of a timed AI and an AI at observed estrus. Lactating dairy cows were injected with PGF2 alpha at 30 +/- a range of 3 d postpartum, with a GnRH agonist at 65 +/- a range of 3 d, and with PGF2 alpha 7 d later; control cows (n = 128) were inseminated at detected estrus, but cows in the timed AI group (n = 171) received a second injection of GnRH agonist 48 h after the injection of PGF2 alpha and were inseminated 16 h later. Control cows that were not inseminated within 7 d were resynchronized with GnRH agonist, followed 7 d later with an injection of PGF2 alpha. Pregnancy rate was 30.5% for control cows and 29.0% for cows in the timed AI group, and conception rate was 41.5% for control cows and 26.5% for cows in the timed AI group. Days open for cows that conceived by 120 d postpartum was 83.6 d for control cows and 79.2 d for cows in the timed AI group. Treatment by month interactions indicated that pregnancy and conception rates and days open for cows that conceived were more consistent across months for cows in the timed AI group. Differences (control vs. timed AI) were not detected for overall pregnancy rate by 120 d postpartum (58.8 +/- 4.7% vs. 56.2 +/- 4.4%). Conception and pregnancy rates at first synchronization were influenced positively by body condition and plasma concentrations of progesterone at 65 d postpartum. Timed AI was an effective alternative for reproductive management.

Animals↗
PubMed1997

LH profile and advancement of ovulation after transcervical infusion of seminal plasma at different stages of oestrus in gilts.

The influence of a transcervical infusion of seminal plasma on preovulatory LH profiles and the advancement of ovulation after seminal plasma infusion for different times during oestrus were investigated using the single uterine horn infusion technique (Mariensee model), in combination with transcutaneous sonographic monitoring of the ovaries. Preparative surgery in 23 German Landrace gilts comprised the detachment of the left uterine horn from the corpus, leaving the caudal end open to the peritoneal cavity but sealing the corpus wound. In six gilts fitted with a permanent jugular vein catheter the patent horns were administered a transcervical infusion of seminal plasma (n = 5 cycles) or PBS (n = 4 cycles) immediately after the detection of oestrus by a teaser boar. In addition, 17 non-catheterized gilts received infusions of seminal plasma either 0 h (n = 3 gilts), 16 h (n = 7 gilts) or 24 h (n = 7 gilts) after the detection of oestrus. Seminal plasma infusion at the onset of oestrus provoked ovulation in the ipsilateral ovary of the treated horn 8.5 +/- 0.9 h earlier than in the contralateral (control) ovary. Seminal plasma did not influence the LH profile compared with PBS (P > 0.05), but shortened the interval between the LH peak and ipsilateral ovulation to 23.4 +/- 4.0 h compared with 31.8 +/- 3.4 h in the contralateral ovulation (P < or = 0.01). Infusion 16 h after the onset of oestrus reduced the effect to 4.6 +/- 3.8 h with a wide range of 0-8 h (P < 0.01). The effect was more pronounced in gilts with long intervals between the onset of oestrus and contralateral ovulation compared with earlier ovulation on the control ovary. Seminal plasma infusion less than 16 h before contralateral ovulation and 24 h after the detection of oestrus had no effect. It is concluded that transcervical infusion of seminal plasma early in oestrus synchronizes the variable intervals between the onset of oestrus and ovulation in sows by a locally active mechanism.

Animals↗
PubMed1983

Estrous behavior and circadian discharge of luteinizing hormone in the prepubertal gilt in response to exogenous estrogen.

The influence of varying doses of estradiol benzoate (EB) on the induction of estrus and luteinizing hormone (LH) discharge was studied in crossbred prepubertal gilts of 135 to 150 days of age. Five gilts were assigned randomly to each of 6 groups and treated with 0, 10, 20, 100 or 200 micrograms EB/kg body weight (BW) at 1200 h or with 10 micrograms/kg at 2400 h. The characteristics of the estrous and endocrine responses of the prepubertal gilts to EB were compared to the responses of 4 ovariectomized, adult gilts treated with EB. Dose of EB administered to prepubertal gilts had no influence on the interval from injection to estrus. Amount of EB administered, however, was correlated positively (r = 0.82, P less than 0.001) with the duration of estrus. Increasing the dose of EB tended to increase (0.05 less than P less than 0.10) the proportion of prepubertal gilts in estrus. Ovariectomized adult gilts treated with 10 micrograms EB/kg BW were in estrus for a duration similar to that of prepubertal gilts treated with that dose of EB. All doses of EB induced at least one surge of LH in each prepubertal gilt. As the dose of EB was increased, a greater proportion of prepubertal gilts showed 2 surges of LH at a 24-h interval. Dose had no influence either on the magnitude or the duration of LH surges. In all gilts, whether prepubertal or mature, surges of LH occurred at either 2400 or 0600 h. Thus, gilts treated with EB at either 2400 or 1200 h were asynchronous with respect to time after treatment until LH peak but were synchronous relative to the time during the day of LH surge. Ovariectomized adult gilts treated with EB had a single surge of LH that was similar in magnitude and duration to the first surge of LH observed in prepubertal gilts.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

Failure of the orally active progestin, Regu-mate, to overcome confinement-induced delayed puberty in gilts.

Thirty-three crossbred gilts that were raised in total confinement were randomly allotted to two adjacent pens in a finishing unit at 144.7 +/- .5 days of age and 58.0 +/- 1.7 kg body weight. At approximately 253 days of age, 16 gilts were group fed a daily dose of 20 mg of Regu-mate per gilt for 18 days and 17 control gilts were group fed the same diet without Regu-mate for 18 days. Ovarian morphology was examined on 11 or 12 days after the last feeding of Regu-mate. Based on estrous behavior and ovarian morphology only one Regu-mate gilt displayed an estrus but did not ovulate and only three of the control gilts displayed estrus and ovulated at least once before the start of treatment. Three of the 16 Regu-mate gilts displayed estrus and ovulated 7.3 +/- .3 days after the last feeding and within the same time period the 3 control gilts, which previously displayed estrus, continued to have estrous cycles. One additional control gilt displayed estrus and ovulated 5 days after the last feeding of the control diet. Therefore, the proportion of gilts that displayed estrus and ovulated by the end of the experimental period were similar for the treated (25.0%) and control (23.5%) groups. Based on these results we conclude that treatment of gilts in a state of confinement-induced delayed puberty with 20 mg Regu-mate daily for 18 days failed to result in a synchronized onset of puberty in a significant proportion of gilts.

Journal Article↗
PubMed2002

Embryo recovery and pregnancy rates after the delay of ovulation and fixed time insemination in superstimulated beef cows.

The aim of this study was to evaluate the effect of delaying ovulation subsequent to superstimulation of follicular growth in beef cows (Bos indicus) on embryo recovery rates and the capacity of embryos to establish pregnancies. Ovulation was delayed by three treatments using either progesterone (CIDR-B) or a GnRH agonist (deslorelin). Multiparous Nelore cows (n = 24) received three of four superstimulation treatments in an incomplete block design (n = 18 per group). Cows in Groups CTRL, P48 and P60 were treated with a CIDR-B device plus estradiol benzoate (EB, 4 mg, i.m.) on Day-5, while cows in Group D60 were implanted with deslorelin on Day-7. Cows were superstimulated with FSH (Folltropin-V, 200 mg), from Day 0 to 3, using twice daily injections in decreasing amounts. All cows were treated with a luteolytic dose of prostaglandin on Day 2 (08:00 h). CIDR-B devices were removed as follows: Group CTRL, Day 2 (20:00 h); Group P48, Day 4 (08:00 h); Group P60, Day 4 (20:00 h). Cows in Group CTRL were inseminated at 10, 20 and 30 h after first detected estrus. Ovulation was induced for cows in Group P48 (Day 4, 08:00 h) and Groups P60 and D60 (Day 4, 20:00 h) by injection of LH (Lutropin, 25 mg, i.m.), and these cows were inseminated 10 and 20 h after treatment with LH. Embryos were recovered on Days 11 or 12, graded and transferred to synchronized recipients. Pregnancies were determined by ultrasonography around Day 100. Data were analyzed by mixed procedure, Kruskal-Wallis and Chi-square tests. The number of ova/embryos, transferable embryos (mean +/- SEM) and pregnancy rates (%) were as follows, respectively: Group CTRL (10.8+/-1.8, 6.1+/-1.3, 51.5), P48 (12.6+/-1.9, 7.1+/-1.0, 52.3), P60 (10.5+/-1.6, 5.7+/-1.3, 40.0) and D60 (10.3+/-1.7, 5.0+/-1.2, 50.0). There were no significant differences among the groups (P > 0.05). It was concluded that fixed time AI in association with induced ovulation did not influence embryo recovery. Furthermore, pregnancy rates in embryos recovered from cows with delayed ovulation were similar to those in embryos obtained from cows treated with a conventional superstimulation protocol.

Animals↗
PubMed1991

Evidence for relaxin and progesterone synchronous secretion on days 13 to 17 of the oestrous cycle in sows.

Concentrations of relaxin in both the utero-ovarian vein (UOV) and jugular vein (JV) as well as those of progesterone and prostaglandin F2 alpha in the UOV were studied on Days 13-17 of the oestrous cycle in sows. Mean relaxin plasma concentrations in the UOV and JV were correlated (r = 0.55; P less than 0.001) and were significantly higher (P less than 0.01) in the UOV (1.67 +/- 0.07 ng/ml), than in the JV (0.59 +/- 0.1 ng/ml). The great similarity between relaxin and progesterone profiles was ascertained (r = 0.57; P less than 0.001). The steep decrease of progesterone plasma concentration on the day of luteolysis was observed together with synchronous relaxin concentration decline. A significant correlation between relaxin and PGF2 alpha plasma concentration was demonstrated one day before luteolysis (r = 0.41; P less than 0.001).

Animals↗
PubMed1999

Effect of acute nutritional restriction on incidence of anovulation and periovulatory estradiol and gonadotropin concentrations in beef heifers.

The effects of acute nutritional restriction on follicular dynamics, incidence of anovulation, and periovulatory estradiol and gonadotropin concentrations were studied in two replicates using beef heifers exhibiting regular estrous cycles. Heifers fed a diet supplying 1.2 maintenance (1.2 Mn) were synchronized using an intravaginal progesterone-releasing device for 8 days. One day before device removal, heifers were allocated randomly, within replicate, to a diet supplying 0.4 Mn (n = 20), or kept at 1.2 Mn (n = 21). On the sixth day after detected ovulation, heifers received 500 microg of synthetic prostaglandin F(2alpha) (PGF(2alpha)) to induce luteolysis, estrus, and ovulation of the first dominant follicle (DF). Animals were inseminated and returned to a diet of 1. 2 Mn. Pregnancy diagnosis was performed 30 days later. The maximum diameter subsequently attained by the DF present at progesterone withdrawal was smaller (P < 0.01) in heifers fed 0.4 Mn. Two heifers fed 0.4 Mn failed to ovulate this DF (P > 0.10). Growth rate (P < 0. 01) and maximum diameter (P < 0.001) of the DF in the first follicular wave of the next estrous cycle was also reduced in heifers fed 0.4 Mn. After prostaglandin administration, a further 10 heifers fed 0.4 Mn failed to ovulate the first DF of this cycle, and it regressed (P < 0.001), causing anovulation in 12 of 20 heifers within 13-15 days (P < 0.001). Anovulation of the DF present at progesterone withdrawal was preceded by a proestrous estradiol increase but absence of a gonadotropin surge (2 of 2 heifers), while neither endocrine event was detected before anovulation of the DF of the first new follicular wave (2 of 2 heifers). In cases in which ovulation of the first DF of the new cycle occurred, fertility was similar (P > 0.10) in heifers fed either 0.4 (n = 7) or 1.2 Mn (n = 20). In conclusion, acute nutritional restriction of cyclic heifers from 1.2 to 0.4 Mn decreased the growth rate and maximum diameter of DFs and induced failure of the DF to ovulate in 60% of heifers, but, within the confines of limited animal numbers, did not compromise fertility in heifers that ovulated.

Animal Nutritional Physiological Phenomena↗