Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Estrus Synchronization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2005

Efficacy of either a single or split treatment of PGF2alpha after a 14 day melengestrol acetate treatment to synchronize estrus and induce luteolysis in Bos indicus x Bos taurus heifers.

Two experiments evaluated a modified delivery of prostaglandin F2alpha (PGF2alpha) after a melengestrol acetate (MGA) treatment in Angus and Bos indicus x Bos taurus (BI) heifers. Experiment 1 was replicated three times with yearling BI heifers (n = 695). Heifers received MGA (0.5 mg head(-1) day(-1)) for 14 days. In Replications 1 and 2, heifers received either 25 mg of PGF2alpha im 19 days after MGA (single) or 12.5 mg of PGF2alpha im 19 and 20 days after MGA (split). In Replication 3, heifers received the same treatments, with PGF2alpha initiated either 18 or 19 days after MGA. Estrus was detected for 72 h after PGF2alpha, with AI commencing 8-12 h after a detected estrus. Heifers not observed in estrus by 72 h were timed-AI concomitant with GnRH (100 microg im). Heifers from Replication 2 (n = 146) had blood samples collected at the initial PGF2alpha and at timed-AI to determine corpus luteum (CL) regression by evaluating plasma progesterone concentrations. The interval from MGA withdrawal to PGF2alpha did not have a significant effect on any variable in Replication 3 and there were no treatment by replication effects for any variables, therefore data were pooled. Modifying the PGF2alpha treatment from a single treatment to two treatments on consecutive days increased (P < 0.05) 72 h estrous response (43.2% versus 50.1%), timed-AI (23.9% versus 33.5%) and total-AI pregnancy rates (34.5% versus 42.5%), and CL regression (79.1% versus 92.5%), respectively. In Experiment 2, yearling Angus (n = 66) and 2-year-old BI (n = 68) heifers were synchronized as per Experiment 1 (with the initial PGF2alpha 19 days after MGA). Neither breed nor PGF2alpha treatment effected (P > 0.05) 72 h estrous response, total-AI pregnancy rate, or CL regression rate. In conclusion, treating yearling BI heifers with split treatments of PGF2alpha (given on two consecutive days) improved estrous response and pregnancy rates by increasing PGF2alpha-induced luteolysis.

Animals↗
PubMed2000

Prolonging the MGA-prostaglandin F2 alpha interval from 17 to 19 days in an estrus synchronization system for heifers.

Our objective was to determine whether extending the interval from 17 to 19 d between removal of melengestrol acetate (MGA) feed and administration of PGF2 alpha would alter conception rates, pregnancy rates and the degree of synchrony in replacement beef heifers. A commercial heifer operation in north-central Kansas purchased 591 Angus x Hereford heifers from 12 sources. Prior to the spring breeding season, 14% of the heifers were culled. The remaining heifers were assigned randomly to 2 MGA-PGF2 alpha synchronization systems. All heifers were fed MGA (0.5 mg/head/d) for 14 d, and PGF2 alpha was administered either 17 or 19 d after the completion of MGA feeding. Heifers were inseminated artificially for 30 d followed by 30 d of natural mating. Based on each source, first-service conception rates ranged from 66 to 90%, whereas overall pregnancy rates ranged from 91 to 100%. Heifers given PGF2 alpha on Day 17 after MGA had first-service conception rates of 75.9% compared with 81.4% for heifers receiving PGF2 alpha on Day 19. In response to the PGF2 alpha injection, 99% of the Day 19 heifers that were detected in estrus were inseminated artificially by 72 h after the PGF2 alpha injection, whereas 74% of the heifers in the Day 17 treatment were inseminated by that time. Average interval to artificial insemination (AI) after PGF2 alpha was greater (P < 0.01) for the Day 17 heifers (73.1 +/- 1.1 h) than for the Day 19 heifers (56.2 +/- 1.1 h). No differences in conception rates or overall pregnancy rates occurred; however, heifers receiving PGF2 alpha on Day 19 after MGA had shorter intervals to estrus, and a greater proportion was inseminated within 72 h after PGF2 alpha, thus possibly facilitating successful timed insemination of the remaining heifers not yet inseminated by that time.

Animals↗
PubMed2006

The effects of ovarian function on estrus synchronization with PGF in dairy cows.

Milk progesterone concentration (P4), milk yield, milk composition, ovarian structures and pregnancy status were studied in 108 cows treated with two doses of PGF 14 days apart and inseminated at fixed time (TAI) 80-82 h later. The synchronization protocol was started at 70+/-1.4 days after parturition. Milk P4 profiles revealed that anestrus, failure of luteolysis following treatment with PGF and failure to ovulate following luteolysis were the main reasons for low pregnancy rate with TAI. Anestrous cows had a higher percentage of milk fat (P<0.05) and higher fat to protein ratio (P<0.01), and cows that did not undergo luteolysis had higher milk yield (P<0.05) and lower percentage of milk protein (P<0.05) than cows that responded to PGF treatment. Cows that did not undergo luteolysis and cows that did not ovulate following luteolysis had lower milk P4 during the luteal phase preceding the second PGF injection (P<0.01 and P<0.05, respectively). Pregnancy rates 24 and 47 days after TAI in cows that responded as expected to the synchronization treatment were 62% and 54%, respectively. Pregnancy was precluded in non-responsive cows. The largest follicle at the time of TAI in cows experiencing late embryonic mortality was smaller (P=0.02) than in cows that successfully maintained pregnancy. Results suggest that a primary reason for low pregnancy rate in dairy cows after administration of PGF and TAI is inappropriate ovarian function prior to, or following treatment.

Animals↗
PubMed1979

[Estrus synchronization in sheep with ICI 80 996].

An experiment was carried out including 96 experimental and 126 control sheep of a herd with the aim to study the synchronizing effect of ICI 80.996 in respect to their sex cycle and to the changes occuring in 17 beta-estradiol and progesteron content and dynamics in the blood plasma at the time of induced oestrus. In the course of three days following the application of the preparation synchronous oestrus was induced in 80.2% of the sheep. The percentage of fertilization of the first and second insemination was 44.8 in the experimental group of sheep and 43.2 in the control group, while the percentage of fertility was 101.0 and 73.6, respectively. The rate of the changes occuring in 17 beta-estradiol and progesteron concentration in peripheral blood during the period of ICI 80.996 induced oestrus reveals no deviations from the normal physiological values, typical of that period.

Animals↗
PubMed1981

[Selection of laboratory rats for fertility components under conditions of estrus synchronization with Suisynchron-Praemix. 3. Results of puberty parameters].

The following results, in the context of puberty parameters, were recorded from laboratory rats, eight generations after Suisynchron-Prämix was begun to be used for synchronisation of oestrus, in studies on selection for fertility: -- Correlated success of selection in terms of earlier onset of puberty were found to exist in both oestrussynchronised and unsynchronised populations selected for fertility. The timing of both vaginal opening and first oestrus as well as weight parameters were affected. -- Earlier onset of puberty was interpreted as a consequence of elevated oestrogen level resulting from selection for fertility. -- Puberty characteristics were not influenced by synchronisation of oestrus.

Aging↗
PubMed1975

[Dynamics of changes in the uterine glands of ewes during chlorsuperlutine-synchronized estrus].

Dynamics of uterine glands was studied in ewes after oestrus synchronization. Full-value oestrus was obtained in the ewes under study after the introduction of polyurethane vaginal tampons impregnated with 20 mg Chlorsuperlutine Spofa. Endometrium biopsy was used to collect samples after laparotomy. The number of uterine glands showed a significant increase, especially after the application of PMSG; the percentual proportion of glandular tissue in endometrium tree increases. There is an insular-type extension of glands. After ovulation there appear broadly luminized glands with numerous extension reaching up to the cellular layer of endometrium.

Animals↗
PubMed1977

[Studies on the use of megestrol acetate for estrus synchronization in heifers].

Megestrol acetate has been tested for its applicability to synchronisation of oestrus in 463 mature heifers in the framework of preclinical and clinical experiments. Clinical tests and studies in the context of laboratory diagnostics have shown that 40 mg/die megestrol acetate, administered in two applications with twelve hours in-between and over 15 days, are necessary for maximum synchronisation effect. The resulting oestrus was found to be prolonged, with ovulations taking place within two or three days. Technological requirements in this context are discussed. Megestrol acetate is found to be suitable for oestrus synchronisation in heifer. Tests conducted under industrialised conditions have shown conception rates to be identical with those obtained by administration of chloromadinone acetate.

Animals↗
PubMed1977

[Use of megestrol acetate in estrus synchronization of heifers under industrialized conditions of cattle breeding].

Daily doses between 30 and 35 mg megestrol acetate were administered to 4,000 heifers over roughly two weeks and produced highly synchronising effects which, however, were lower in response to lower doses. Rectal checks were applied to the ovaries of heifers which had received megestrol acetate and showed that here the number of mature follicles was higher than recorded from animals that had been given chlormadinone acetate. Megestrol acetate, applied in granular form blended into mixed fodder, proved to be the most favourable variant of application. Synchronisation of oestrus on the basis of the above approach was found to yield per animal savings between 4.30 and 22.70 roubles under practice conditions.

Animals↗
PubMed1977

[Studies on the determination of optimal insemination time using electrometric resistance measurements in heifers and young cows after estrus synchronization].

Studies were conducted on how to use under the conditions of industrialised production in the GDR an electrometric method proposed by Soviet scientists to determine oestrus and ovulation date in oestric-synchronised heifers and cows. "Oestrometer-2", an instrument developed in the USSR, was used for 4,818 measurements of electric resistance in 700 oestric-synchronised heifers and 39 oestric-synchronised cows. The typical course of the resistence curve was confirmed by the results. Individual data variation together with unsatisfactory data reliability of the instrument, when applied to measurement at vaginovestibular mucosa, were likely to suggest that the method could not be used with good effect for high-accuracy determination of the ovulation date and therefore, was not useful in helping to save semen pellets after oestric synchronisation.

Animals↗
PubMed1977

[Use of norgestagens for estrus synchronization if farm animals].

The action of norsteroid type preparations and their capability of synchronising oestrus in heifer and sheep were studied at laboratory and clinical levels. The effectiveness of norethysterone acetate in heifer was tested by subcutaneous injections of 5 mg and 10 mg and did not exceed the order of 50 per cent. Combination of norsteroids with serum of pregnant mares increased slightly the number of animals with synchronised oestrus and improved the rate of fertilisation. Studies conducted into sheep revealed that no complete inhibition of the sexual function was ensured by injection of norgestrol acetate with prolongator in intervals of four days. Implantation of norgestrol acetate was not effective either. Further studies are required, before the above preparations can be applied to farm animals on a large scale.

Animals↗
PubMed1995

[Dynamic changes in hematologic parameters in the blood of sheep during estrus synchronization and in the subsequent early pregnancy].

Observation of hematological indices which are a reflection of physiological processes in the individual phases of the reproductive cycle, presents one of the methods of controlling the homeostasis of the ewe's organism. This work focused on the observation of selected indices during synchronization treatment and in the first days of pregnancy The experiment included 10 conventionally bred animals. Blood was obtained from the v. jugularis into an oxalate mixture on days 0 (date of synchronization), 3, 7 and 14 of Agelin implantation, on the day of oestrus and days 7, 14, 17 and 34 of pregnancy. Erythrocyte counts were determined by the Bürker flask method, hemoglobin concentrations by spectrophotometry and packed cell volume (PCV) by the method of Janetzki. For leucocyte count determination the Bürker flask method with Turk's solution was used; the percentual proportion of leucocytes was stated by the leucogram. During synchronization treatment and pregnancy the mean erythrocyte counts ranged from 9.16 +/- 0.81 to 9.74 +/- 0.61 T/l and from 9.09 +/- 0.84 to 9.47 +/- 1.11 T/l, respectively. Hemoglobin concentrations oscillated between 10.71 +/- 1.02 and 11.83 +/- 1.01 g/l. PCV values reached between 32.44 +/- 2.18 and 39.33 +/- 2.73 l/l with a significant increase on day 14 of Agelin implantation and days 17 and 34 of pregnancy (P < 0.05). This dynamics of the red blood components points to the occurrence of functional-morphological changes in the sexual apparatus during oestrus and Agelin treatment. Through mediation by the vascular system a change in the mean values may also occur (Kresan et al., 1979).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Changes in the biometry of the sex organs of sheep after estrus synchronization and superovulation in the breeding period].

In twenty ewes of the Slovak Merino breed coming from a demonstration farm at Zemplínska Teplica, to the age of two-three years biometrical variations of the sex organs and overall follicular response to PMSG and PGF2 alpha administration were investigated in the autumn period (October-November). In the ewes of all groups the heat was synchronized by i. m. administration of PGF2 alpha (Oestrophan Spofa) at a dose of 125 micrograms in the interval of 11 days. On the ninth day the ewes of the second and fourth group were given 1000 i. u. of PMSG (Antex Leo, Denmark), the ewes of the third group 750 i. u. of PMSG. The ewes of the third and fourth group were administered at the same time 50,000 i. u. vitamin A (Axerophtol Spofa) (each group). The weight and dimensions of the sex organs were investigated. The results demonstrate that the administration of PMSG in the mating period increases significantly the weight of oviducts and horns of uterus in the ewes while there are no variations of the weight of the other sex organs and of their length, or it is lower than in the ewes of the control group. The overall follicular response was not influenced by the higher weight of ovaries.

Animals↗
PubMed1978

[Insertion and removal of intravaginal tampons during estrus synchronization in heifers].

In eight trials, 197 heifers were synchronized with gestagen chlorsuperlutin (CSL). The intravaginal tampons soaked with chlorsuperlutin were introduced in the vagina by means of an applier by a vaginal speculum. Silon threads were attached to the tampons, by which they were pulled out after treatment. The mentioned method of application removes the great physical exertion needed for manual application and increases labour productivity in tampon application by about 200%. The hazard of tampon contamination is reduced to the minimum. Of the two tampon types tested (ester and ether type) the ester type was found to be better for not needing sterilization if the disinfectant Aseptin is dropped upon it prior to application. The retention of the tampons was 94.9%. Eighty-four per cent of the retained tampons could be removed by pulling the silon threads. About 40 to 60% of CSL is excreted from the tampons during the treatment. If the initial content of CSL is increased, its excretion is raised as well.

Animals↗
PubMed1993

[Estrus synchronization and insemination results in Arabian mares in the Eskisehir stud].

An Arab broodmare herd of 30 mares age ranging from 4 to 12 years was grouped into 3 groups (group A, B, C) with 10 mares each and exposed to three different methods of cycle synchronisation. Group A mares received two PGF2 alpha injections 14 days apart. Group B mares got additionally 2,500 IU of hCG 5 days after second prostaglandin application. Group C consisted of mares which had foaled in a synchrony of one week and got a PGF2 alpha injection 3 weeks after parturition. All the mares responding to synchronisation were inseminated closely to ovulation detected by serial rectal palpations with an insemination doses of 0.5 billion of progressively motile spermatozoa. Conception control was performed on the 18th day after ovulation to be continued up to pregnancy confirmation on day 60. Synchronisation response in the different groups A, B, C was 60, 80, 80% starting first oestrus signs between 24 to 36 hours and ovulation time between 5 to 6.5 days post last PGF2 alpha application. Pregnancy rate (first cycle) was 66.7% (A), 75% (B) and 87% (C) basing on the number of mares who responded to synchronisation exposure.

Animals↗
PubMed1984

[Histology of the oviduct epithelium of dairy cows after estrus synchronization with cloprostenol].

After fading away of the effect of cloprostenol contained in the Oestrophan inj. Spofa preparation, the qualitative and quantitative changes in the epithelium of oviduct ampulla and isthmus of dairy cows were studied. Three dairy cows in the fourth to fifth day after heat were used as control, three cows with the rectally palpated active corpus luteum were given 0.5 mg cloprostenol i. m. On the eighth day after treatment, samples were taken from ampulla and isthmus by means of necropsy. After histological treatment, the samples were evaluated microscopically. Histological staining with hematoxylin-eosine, PAS reaction and PAS reaction with nucleus staining with Harris hematoxylin were used to describe the occurrence of the so-called pale cells. In accordance with the literary data, these cells are believed to be intraepithelial lymphocytes, the function of which will have to be further researched and determined objectively. On the eighth day after cloprostenol administration or on the fourth to fifth day after ovulation in the ipsilateral ovary, a significant decrease in epithelium thickness close to infundibulum and in the depth of ampulla (P less than 0.001) was observed. The changes in the contralateral left side were not significant. After cloprostenol application, the multiplication of nail-like cells in the right-side oviduct ampulla was statistically significant (P less than 0.05).

Animals↗
PubMed2000

Reproductive efficiency of three estrus synchronization schemes comprising fixed-time insemination in dairy cows.

The objective of this field trial was to compare the odds of pregnancy at 25 days (P25) and at 60 days (P60), of embryonic death (ED) between 25 and 60 days, and of non-pregnant cows returning to heat 20-25 days after artificial insemination (AI). Three fixed-time insemination protocols involving combined administration of either double gonadotrophin-releasing hormone (GnRH) and prostaglandins (A) or GnRH, human chorionic gonadotrophin (hCG) and prostaglandins (B), or double treatment with prostaglandins (C) were used. Cows included in the trial were selected from five herds, comprising a total of 735 (herd size range 85-250, median 120) Holstein dairy cows. Animals used for the study were multiparous, 4-7 years of age, had expressed at least one overt postpartum heat, were between 60 and 120 days of lactation and had at least one palpable corpus luteum and no gross morphological anomalies of their reproductive tracts. They were randomly allocated to receive treatment A (n = 89), B (n = 93), or C (n = 65). Pregnancy of cows not observed in heat 18-24 days post AI was diagnosed by transrectal ultrasonography at 25-30 days and confirmed by rectal palpation at 60-75 days post AI. Those that were detected in heat in the normal period post AI were re-inseminated. No differences were detected among the three treatment groups concerning the odds of P25 (P = 0.5), P60 (P = 0.2) and ED (P = 0.13). In contrast, non-pregnant cows that were administered treatment A were less likely to exhibit estrous signs in the normal period post AI than those administered treatments B (P = 0.02) or C (P = 0.005).

Animals↗
PubMed1993

[Levels of total lipids, cholesterol and progesterone during estrus synchronization and pregnancy in sheep].

Our investigations were concerned with dynamic changes in total lipids (CL), cholesterol (CHOL) and progesterone (P4) in blood serum of sheep in the period of oestrus synchronization treatment and during mating and gravidity. Our experiment was carried out using 10 animals housed under the conditions of productive rearing. Blood samples were taken from v. jugularis on day of swab application (day 0) and on days 3 and 7 of the action of Agelin vaginal swabs, on day of insemination, and on days 7, 14, 17 and in the 2nd, 3rd and 4th month of gravidity. Blood serum was used to determine total lipids and cholesterol by means of Bio-Lachema tests, and P4 concentrations employing RIA-test-Prog kits (URVJT, Kosice). A statistically significant decrease in concentrations of total lipids (Fig. 1, Tab. I) in sheep blood serum was recorded on day of insemination (P < 0.05) compared to day 0, with the value 1.59 +/- 0.31 g/l of serum, and in the 3rd month of gravidity (P < 0.01), at concentrations 1.36 +/- 0.38 g/l of serum. The determined decrease in their values in the mentioned period can be modulated by the mutually changing ratio of steroid hormones or by inhibition of synthesis of lipoproteins responsible for changes in total plasma lipids. Changes in cholesterol concentrations (Fig. 2, Tab. I) during the introduction of swabs were insignificant and ranged from 1.60 +/- 0.42 to 1.73 +/- 0.33 mmol/l of serum. An insignificant increase in cholesterol concentrations (P < 0.05), with its highest levels 1.98 +/- 0.43 mmol/l of serum, was recorded in the 3rd month of gravidity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[The follicular system of bovine ovaries after estrus synchronization using the luteolytic action of cloprostenol].

Oestrus synchronization was studied in samples from six cows of the Black-Pied Lowland breed. Three cows four to five days from oestrus were used as the control; three animals with marked periodic corpora lutea were given an i. m. injection of 0.5 mg cloprostenol. The eighth day from the administration of the preparation, the ovaries of the cows were excised and, after histological processing in a simultaneous series in a 4mm interval, the preparations were subjected to qualitative and quantitative microscopic evaluation. The structure of non-atretic and atretic follicles was described in different stages of the atretic process. The lymphoid cells of atretic follicles were observed to penetrate into the granulosa membrane. A multiplication of non-atretic tertiary follicles was observed after the administration of cloprostenol. This multiplication was more pronounced on the right ovary where the preceding ovulation had taken place (P less than 0.01). The treated animals, compared with the controls, showed a significant multiplication of tertiary follicles at early atresia and at total collapse atresia (P less than 0.001), whereas the number of follicles with contractive atresia showed a significant decrease (P less than 0.001). The results suggest that cloprostenol can influence follicle population mostly through the stimulation of the growth and ripening of tertiary follicles; its modulation effect seems manifest itself in cooperating relation with gonadotrophic hormones, mainly with the follicular secondary hormone (FSH), in the theory of the complex effect of proteohormones .

Animals↗