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 1,495 records · Page 83Linked to original sources
PubMed2006

Survey of management practices on reproductive performance of dairy cattle on large US commercial farms.

A survey regarding general management, sire selection, reproductive management, inseminator training and technique, heat abatement, body condition scoring, facility design and grouping, nutrition, employee training and management, and animal health and bio-security was carried out from March to September of 2004 in 153 herds in the Alta Genetics (Watertown, WI) Advantage Progeny Testing Program. A total of 103 herds (67.3%) completed the survey. Herd size was 613 +/- 46 cows, with herds located in Wisconsin (26), California (12), New York (11), Minnesota (10), Michigan (7), Washington (6), Pennsylvania (6), Iowa (5), Idaho (5), Texas (4), Ohio (4), and other states (7). These farms sold 34.5 +/- 0.3 kg of milk/d per cow, with an annual culling rate of 34 +/- 1% and a calving interval of 13.8 +/- 0.1 mo. Cows were observed for estrus 2.8 +/- 0.3 times/d, for a duration of 27 +/- 4 min, but 78% of the respondents admitted that detection of estrus was not the employee's sole responsibility at that time. Managers tried to achieve pregnancy until 8.8 +/- 0.9 failed inseminations, 300 +/- 26 d postpartum, or milk yield <17.7 +/- 0.5 kg/d. Nonpregnant cows were culled at 326 +/- 36 d postpartum or milk yield <16.4 +/- 0.3 kg/ d. Mean durations of the voluntary waiting period were 52 +/- 1.3 and 53 +/- 1.4 d for primiparous and multiparous cows, respectively. Hormonal synchronization or timed artificial insemination programs were used in 87% of the herds, with 86% synchronizing first services, 77% resynchronizing repeat services, and 59% treating cystic, anestrous, or anovular cows. Finding good employees was identified as the greatest labor challenge, followed by training and supervising employees. Mastitis and hairy heel warts were noted as the greatest animal health concerns, followed by lameness, abortions, and death losses, whereas the greatest reproductive challenges were artificial insemination service rate, conception rate, twinning, and retained placenta or metritis. Results of this study can provide a useful benchmark or reference with regard to commonly used management practices on large commercial US dairy farms at the present time.

Animals↗
PubMed2005

Endocrine and ovarian changes in response to the ram effect in medroxyprogesterone acetate-primed Corriedale ewes during the breeding and nonbreeding season.

Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4-6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17beta were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17beta concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17beta, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17beta levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17beta concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect.

Animals↗
PubMed1980

Non-surgical embryo transfer in cattle.

Embryos collected surgically from donors superovulated with PMSG and synchronized with either prostaglandin F(2)alpha or progestagen impregnated sponges were transferred non-surgically to prostaglandin or progestagen synchronized recipients. One embryo was transferred to the uterine horn ipsilateral to the corpus luteum either through a flexible catheter introduced through a steel tube and passed to the uterine tip, or through a Cassou inseminating gun passed approximately 6 cm into the horn. Of 16 recipients receiving 5 or 6 day old embryos through the catheter (1976), 6 (38%) were palpated pregnant at 42 days and 4 (25%) subsequently calved. Of 16 recipients receiving 7 or 8 day old embryos through the straw and 16 through the catheter (1977), 10 (63%) and 3 (19%), respectively, were palpated pregnant (P<0.05) and 8 (50%) and 3 (19%), respectively, had normal embryos at slaughter 4 to 29 days after palpation (P reverse similar0.10 ). Forty 7 to 9 day old embryos were transferred through the straw in 1978. Eighteen (45%) of the recipients were palpated pregnant and 16 (40%) had normal embryos at slaughter 98 to 168 days after palpation. The success of the transfers in 1978 was affected by embryo quality [good vs poor embryos; 64% vs 22% recipients pregnant (P<0.01) and 59% vs 17% embryos surviving to slaughter (P<0.05)]. Also, in 1978, pregnancy rate was affected by the time taken to transfer the embryo with the highest rate achieved with the fastest transfers (P<0.10, b = -0.47). Injection of Indomethacin near the time of transfer, synchronization between donor and recipient onset of estrus and embryo age did not affect pregnancy rates. The pregnancy rate achieved after the transfer of good quality embryos by the straw technique was equal to that expected from surgical techniques.

Journal Article↗
PubMed1982

The use of FSH and GnRH as alternative compounds to PMSG for springtime breeding of ewes.

During early springtime, ewes were treated with a single injection of PMSG (500 IU) administered at the time of progesterone sponge withdrawal (Group I) or four, twice daily injections of FSH (2 mg each) administered from twelve hours before, to 24 hours after sponge withdrawal (Group II). One hundred mug of GnRH was administered 36 hours after sponge withdrawal in Group II. The two groups were compared with respect to estrous display, conception rate and other reproductive parameters. There were no significant differences (p>.05) between the two treatment group in any of the reproductive parameters measured. The occurrence of estrus during the first 96 hours after synchronization was low (X = 45% of all treated ewes). Conception of all treated ewes during this estrous period was also low (X = 32% of all treated ewes). The potential use of FSH and GnRH in estrous synchronization regimes was discussed. Possible reasons for the poor estrous and conception rates in present experiment were also considered.

Journal Article↗
PubMed1996

Artificial insemination, hybridization and pregnancy detection in sika deer (Cervus nippon ).

Artificial insemination (AI) was performed on sika hinds (Cervus nippon ) receiving various dosages of pregnant mare serum gonadotropin (PMSG; Year 1: 0, 50 and 100 IU; Year 2: 100 and 150 IU) and using semen collected from elk and 1 2 elk x 1 2 sika stags. The time from synchronization device removal (CIDR vs norgestomet) to estrus was determined through observations of mounting activity. Methods for pregnancy detection, serum progesterone (P4), estrone sulfate (E1S), pregnancy-specific protein B (PSPB) and ultrasonography, following AI (Year 1: AI, Days 28 and 48 after AI; Year 2: AI, Days 42, 53 and 100 after AI) and a 90-d natural breeding season were investigated. From available production data, body weights were compared among sika and 1 4 elk x 3 4 sika hybrids relative to age. Pregnancy rates tended (P < 0.10) to differ relative to PMSG treatment and sire; administration of 0 IU PMSG resulted in fewer hinds becoming pregnant to AI than 50 or 100 IU of PMSG. Hinds receiving 100 IU of PMSG had higher (P < 0.05) pregnancy rates than hinds receiving 150 IU PMSG. Time to standing estrus did not differ (P > 0.10) between the CIDR and norgestomet groups. Pregnancy rates 50 d after a 90-d breeding season were similar (P > 0.10) between ultrasound (70.9%) and PSPB (61.6%). Serum P4 after 90 d in breeding groups and 50 d after stag removal were higher (P < 0.05) for pregnant than open hinds. Pregnancy rates (Year 1) 48 d after AI were similar (P > 0.10) between ultrasound (49.0%) and PSPB (37.3%). Serum P4 28 and 48 d after AI were higher (P < 0.05) for pregnant than open hinds. Serum E1S was higher (P < 0.01) for pregnant than open hinds 48 d after AI. Pregnancy rates (Year 2) 100 d after AI did not differ (P > 0.10) between ultrasound and PSPB (66.7%). Serum P4 was higher (P < 0.03) in pregnant than open hinds at 42, 53 and 100 d after AI. At 100 d after AI, pregnant hinds had higher (P < 0.002) serum E1S than open hinds. At 6 to 8 and 11 to 13 mo of age, 1 4 elk x 3 4 sika males tended (P < 0.08) to be heavier than sika males, while 1 4 elk x 3 4 sika females were heavier (P < 0.05) than sika females at all ages. In summary, this study documents the use of AI and methods for pregnancy detection in sika hinds as well as preliminary information regarding the production of elk-x-sika hybrids.

Journal Article↗
PubMed1997

Distribution of mucus and sperm in bovine oviducts after artificial insemination: the physical environment of the oviductal sperm reservoir.

There is a sperm reservoir in the caudal oviduct of cattle and other mammals. We had observed trapping of sperm by mucus produced by explants of bovine oviductal epithelium in vitro; therefore, we used techniques designed for preserving mucus and luminal dimensions to determine whether mucus is associated with the reservoir in vivo. Heifers were synchronized by prostaglandin injections and inseminated during estrus. Oviducts on the side of ovulation were surgically removed either 8-10 h after insemination (preovulatory) or 50-55 h after insemination (postovulatory). Segments (1 cm) taken from the uterotubal junction (UTJ), caudal 3 cm of isthmus, and mid ampulla were snap frozen. Frozen sections were coated with collodion and postfixed in phosphate-buffered formaldehyde containing cetyl-pyridinium chloride. Sections were alternately stained with periodic acid-Schiff stain (PAS) or alcian blue/PAS. Most of the oviductal lumen was highly branched with passages that measured only a few microns across and were filled with mucus. In limited areas, the lumen opened to 100 microm across and was only lightly stained for mucus. Overall, the lumen was much narrower than in sections prepared by standard fixation and paraffin embedding. Sperm were found scattered throughout the lumen of the UTJ and isthmus, in both the narrow, deeply stained luminal areas and the wider, lightly stained areas. The numbers tapered off cranially, especially prior to ovulation. In conclusion, the combination of narrow passages and mucus would appear to impede sperm progress, contributing to the creation of a reservoir.

Alcian Blue↗
PubMed2004

Estrous synchronization using an intravaginal progesterone device in combination with gnrh or estradiol benzoate characterized by the initial ovarian conditions in Japanese black cows.

Estrous synchronization using a Controlled Internal Drug Releasing device (CIDR) in combination with GnRH or estradiol benzoate (EB) treatment was investigated in Japanese black cows characterized with initial ovarian conditions. A total of 142 cows were allocated to one of four treatments: insertion of CIDR for eight days (Group A: n=34), CIDR with 100 microg of GnRH on d 0 (Group B: n=54, d 0=CIDR insertion), CIDR with GnRH on d 0 and 1 mg of EB on d 10 (Group C: n=20) or CIDR with 2 mg of EB on d 0 and 1 mg of EB on d 9 (Group D: n=34). All cows received 25 mg of PGF(2alpha) on d 7 and blood was collected for progesterone (P4) analysis on d 0, 8, and 21. AI was performed at estrus, but in Group D timed AI was set following a day of EB treatment. Estrus was induced in 141/142 cows, and the majority of which occurred on d 10 and 11 (98 cows, 34 cows). GnRH treatment induced more intermediate ovulation than EB treatment in cows with CL on d 0 (19.0% vs. 0%). Ovulation after CIDR removal was significantly higher in cows with CL on d 0 compared to those without CL (87.0% vs. 71.4%). Group B showed higher conception rates than those combined with Groups C and D where EB was injected after CIDR removal (51.1% vs. 38.9%). Conception had no correlation with either CL existence on d 0 or intermediate ovulation on d 8. P4 concentrations on d 8 were significantly lower compared to those on d 0 or d 21. On d 21 in cows without intermediate ovulation, Group A showed significantly lower P4 concentrations than the other 3 groups. The data suggests that CIDR insertion with PGF(2alpha) treatment is an effective method for estrous synchronization irrespective of initial ovarian conditions, and GnRH treatment at CIDR insertion induces intermediate ovulation and improves the conception rate in Japanese black cows.

Administration, Intravaginal↗
PubMed1991

Luteal function, estrous response, and pregnancy rate after treatment with Norgestomet and various dosages of estradiol valerate in suckled cows.

Two experiments were conducted to determine whether dosage of estradiol valerate (EV) or day of estrous cycle when treatment was administered affected response to Syncro-Mate-B (SMB). Suckled beef cows received a 6-mg Norgestomet (NOR) ear implant (in situ 9 d) and a 3-mg NOR i.m. injection. In Exp. 1, 74 cows received NOR treatments concurrently with either 5 or 6 mg of EV administered i.m. on either d 1, 3, or 5 of an estrous cycle (estrus = d 1). In Exp. 2, 169 cows received NOR treatments concurrently with either 5, 7, or 9 mg of EV administered i.m. on either d 3 or 9 of an estrous cycle. In Exp. 1, 67, 50 and 92%, respectively, of cows receiving 5 mg of EV on d 1, 3, or 5 had functional corpora lutea (CL) at implant removal, whereas 42, 75, and 77%, respectively, of cows receiving 6 mg of EV had functional CL at implant removal (dosage P greater than .10; day P less than .05). Synchronized estrous responses were 50, 33, and 23%, respectively, when cows received 5 mg of EV on d 1, 3, or 5, and 67, 33, and 38%, respectively, when cows received 6 mg of EV (dosage P greater than .10; day P less than .05). First-service pregnancy rate was decreased (P less than .05) in cows treated on d 5 (33%) compared with cows treated on d 1 (63%), but dosage of EV had no effect on pregnancy rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Synchronization of ovulation using GnRH or hCG with the CO-Synch protocol in suckled beef cows.

The objectives of this study were to evaluate replacing GnRH with hCG and the effects of 48-h calf removal (CR) on pregnancy rates of cows synchronized with the CO-Synch protocol. Suckled beef cows (n = 467) at two locations were assigned to treatment by breed, age, and calving date. Treatment included either GnRH with (n = 121) or without CR (n = 117) or hCG with (n = 115) or without CR (n = 114) using the CO-Synch protocol. On d 0 and 9, cows received either hCG (2,500 IU, i.m.) or GnRH (100 microg, i.m.), and on d 7 all cows received PGF2alpha (25 mg). At one location, blood samples were collected from all cows (n = 203) on d -14, -7, 0, 7, 9, and 16. Calves were removed on d 7 and returned on d 9 (48 h) from approximately half of the cows that received GnRH or hCG. Cows that were detected in estrus between d 6 and 9 were bred approximately 12 h later and received no further injections. Cows not observed in estrus by d 9 received a second injection of either GnRH or hCG and were timed-inseminated. The AI pregnancy rates for GnRH-treated cows with or without CR and hCG-treated cows with or without CR were 46, 49, 35, and 34%, respectively (P = 0.44). Pregnancy rates of cows differed by treatment x age interaction (P = 0.07), hormone (P = 0.09), and hormone x age (P = 0.01) but not by CR (P = 0.66) or CR x age (P = 0.33). Among 2-yr-olds, pregnancy rates were higher for cows treated with hCG without CR than for cows that received GnRH with calf removal, whereas cows treated with hCG with CR and GnRH without CR were intermediate. In addition hCG-treated 2-yr-olds had higher pregnancy rates than GnRH-treated 2-yr-olds regardless of calf presence, but the reverse was true for older cows. Overall, GnRH-treated cows (48%) had a higher (P = 0.09) pregnancy rate than hCG-treated cows (34%). Among anestrous cows, GnRH and hCG were similar (P = 0.40) in their ability to induce ovulation and corpus luteum formation after the first and second injections of GnRH (31 and 76%, respectively) or hCG (39 and 61%, respectively). More (P = 0.001) hCG-treated cows exhibited short estrous cycles following timed AI. We conclude that hCG is not a suitable replacement for GnRH to synchronize ovulation with the CO-Synch protocol in multiparous cows, although further evaluation among primiparous cows is warranted using hCG with the CO-Synch protocol.

Age Factors↗
PubMed2001

Estradiol-17beta and progesterone in the peripheral blood plasma of goats following superovulation with a single dose of pFSH, hMG or eCG.

During the breeding season, 42 adult German Improved Fawn nanny goats were superovulated with a single dose of pFSH, hMG or eCG at the end or a single application of pFSH 36h before the end of synchronization treatment using flugestone acetate (FGA). Plasma sampling was performed immediately before and 1h after gonadotrophin treatment, twice daily during pre-estrus and estrus and once daily during post-estrus in order to determine peripheral estradiol-17beta and progesterone levels. During that period, ovarian dynamics was followed by serial ultrasound scans (8h interval during pre-estrus and estrus and once daily during post-estrus). Estradiol-17beta profiles differed between the treatment groups exhibiting significantly positive correlations between the mean estradiol-17beta concentrations and the numbers of developing large and medium-sized follicles during estrus. The early bolus application of FSH 36h before the end of synchronization treatment induced an additional advanced estradiol-17beta peak during gestagen dominance. A sharp decrease of estradiol-17beta at the end of estrus seems to play a major role for normal luteal development. Progesterone profiles during the early luteal phase revealed high premature luteal regression. An early progesterone increase was accompanied by low premature regression rates.Although simple B-mode ultrasonography is suitable to follow follicular growth patterns and to determine the ovulation rate following different superovulation regimen endocrinological supervision is required in order to detect a premature corpus luteum insufficiency.

Journal Article↗
PubMed2004

Fertility following fixed-time AI or insemination at observed estrus in Ovsynch and Heatsynch programs in lactating dairy cows.

The objective of this study was to compare the conception rate for fixed-timed artificial insemination (FTAI) and observed heat artificial insemination (HAI) prior to the scheduled FTAI in Ovsynch and Heatsynch synchronization protocols. In Experiment 1, lactating dairy cows (n=535) received two set-up injections of 25mg prostaglandin F(2alpha) (PGF(2alpha)) i.m., 14 days apart starting at 36+/-3 days in milk (DIM). Cows were blocked by parity and were randomly allocated to either Ovsynch or Heatsynch groups. All cows received 100 microg of GnRH i.m. 14 days after the second set-up injection of PGF(2alpha), followed by a third injection of 25mg PGF(2alpha) i.m., 7 days later. In the Ovsynch group, HAI cows (n=29) were bred on standing estrus after the third PGF(2alpha) before the scheduled second GnRH, whereas FTAI cows (n=218) that were not observed in estrus, received a second injection of 100 microg of GnRH i.m., 48 h after the third PGF(2alpha) and received TAI 8 h after the second GnRH. In the Heatsynch group, all cows (n=288) received 0.5 mg of estradiol cypionate (ECP) 24 h after third PGF(2alpha) and HAI cows (n=172) were bred on standing estrus and FTAI cows (n=116) that were not observed in estrus, received TAI 72 h after the third PGF(2alpha). In Experiment 2, repeat breeder cows (n=186) were randomly assigned to either Ovsynch or Heatsynch groups. The FTAI and HAI cows were inseminated similar to Experiment 1. All cows were observed for estrus three times daily. The associations with the conception rate were modeled with logistic regression separately for Experiments 1 and 2. Of all the variables included in the model in Experiment 1, type of AI (HAI versus FTAI, P=0.0003) and parity (primiparous versus multiparous, P=0.05) influenced the first service conception rate. Over-all conception rate and first service conception rate for HAI cows were higher compared to FTAI cows (33.8% versus 21.3%, and 35.3% versus 21.0%; P=0.001). In the Heatsynch group, cows that received HAI had significantly higher over-all conception rate and first service conception rate compared to FTAI (35.2% versus 17.3% and 36.0% versus 15.5%; P=0.0001). The conception rates in repeat breeder cows for HAI and FTAI (30.1% versus 22.3%) were not different (P>0.1). In conclusion, it was recommended to include AI at observed estrus and fixed-time AI for cows not observed in estrus in order to improve the conception rate in synchronization protocols.

Animals↗
PubMed2006

Evaluation of a contract breeding management program in selected Ohio dairy herds with event-time analysis I. Cox proportional hazards models.

An observational study was conducted in order to assess the impact of a contract breeding program on the reproductive performance in a selected group of Ohio dairies using event-time analysis. The contract breeding program was offered by a breeding co-operative and featured tail chalking and daily evaluation of cows for insemination by co-operative technicians. Dairy employees no longer handled estrus detection activities. Between early 2002 and mid-2004, test-day records related to production and reproduction were obtained for 16,453 lactations representing 11,398 cows in a non-random sample of 31 dairies identified as well-managed client herds of the breeding co-operative. Of the 31 herds, 15 were using the contract breeding at the start of the data acquisition period, having started in the previous 2 years. The remaining 16 herds managed their own breeding program and used the co-operative for semen purchase. Cox proportional hazards modeling techniques were used to estimate the association of the contract breeding, as well as the effect of other significant predictors, with the hazard of pregnancy. Two separate Cox models were developed and compared: one that only considered fixed covariates and a second that included both fixed and time-varying covariates. Estimates of effects were expressed as the hazard ratio (HR) for pregnancy. Results of the fixed covariates model indicated that, controlling for breed, herd size, use of ovulation synchronization protocols in the herd, whether somatic cell score exceeded 4.5 prior to pregnancy or censoring, parity, calving season, and maximum test-day milk prior to pregnancy or censoring, the contract breeding program was associated with an increased hazard of pregnancy (HR=1.315; 95% CI 1.261-1.371). The results of the time-varying covariates model, which controlled for breed, herd size, use of ovulation synchronization protocols, somatic cell score above 4.5, parity, calving season, and testing season also found that the program was associated with an increased hazard of pregnancy (HR=1.387; 95% CI 1.327-1.451). The fixed and time-varying covariates models both found similar sets of predictors when analyzing the association of the contract breeding program with hazard of pregnancy. Both models identified a 30% or greater increase in hazard of pregnancy associated with use of the contract breeding program, suggesting that herds subscribing to the program achieved pregnancies in a more timely fashion.

Animals↗
PubMed2003

Effects of pre-synchronization using combinations PGF(2alpha) and (or) GnRH on pregnancy rates of Ovsynch- and Cosynch-treated lactating Holstein cows.

In Experiment 1, the effects of two pre-synchronization treatments on synchronized AI pregnancy rates of lactating dairy cattle were compared. Lactating Holstein cows (n=159) received 100 microg of GnRH (im) on day -7 and 25mg of PGF(2alpha) (im) on day 0 and were observed once daily for signs of estrus from day -3 to day 3. Cows detected in standing estrus and those that had lost significant amounts of tail-chalk in the previous 24h were immediately inseminated in a once-daily observation/AI program. Cows not detected in estrus by 72 h after PGF(2alpha) received fixed-time AI (TAI) and a concurrent 100 microg injection of GnRH (im). Cows were randomly assigned by parity and calving date to receive one of the following pre-synchronization treatments: (1) 25mg of PGF(2alpha) (im) on day -35 and day -21 (PGF-PGF) or (2) 100 microg of GnRH (im) on day -14 (GnRH). Fewer (P<0.05) GnRH- (49%, 41/84) than PGF-PGF-pretreated cows (65%, 49/75) were detected in estrus, however, overall pregnancy rates were not affected by pre-synchronization treatment (30 versus 32%, respectively). In Experiment 2, lactating Holstein cows received 100 microg of GnRH (im) on day -7, 25mg of PGF(2alpha) (im) on day 0 and TAI at 60-64 h after PGF(2alpha). Cows were randomized by parity and postpartum interval into pre- and post-synchronization treatments in a 2 x 2 factorial design. Pre-synchronization treatments included: (1) 25mg of PGF(2alpha) (im) on day -35 and on day -21 (PGF-PGF; n=168) or (2) 25mg of PGF(2alpha) (im) on day -21 and 100 microg of GnRH (im) on day -14 (PGF-GnRH; n=180). Within each pre-synchronization treatment, cows were further allocated by parity and postpartum interval to receive as a post-synchronization treatment 100 microg of GnRH (im) at either 48 h (Ovsynch; n=175) or 60-64 h (Cosynch; n=173) after PGF(2alpha). Pregnancy rates at TAI were not affected by pre- (PGF-PGF=26%, 44/168 versus PGF-GnRH=24%, 44/180) or post-synchronization treatments (Ovsynch=29%, 50/175 versus Cosynch=22%, 38/173). However, the numeric shift towards reduced pregnancy rates in Cosynch-treated cows suggests the 12h interval between GnRH and AI may be important to optimize conception rates in GnRH-PGF(2alpha)-based TAI protocols in dairy cattle. In conclusion, each of the pre-synchronization protocols evaluated in present study performed with comparable efficacy. Although the Cosynch protocol facilitates more efficient labor utilization, numeric trends toward reduced conception warrants further investigation.

Animals↗
PubMed2004

[Suppression of cycling activity in sheep using parenteral progestagen treatment].

The objective of this study was to evaluate the effect of two synthetic progestagen preparations Chlormadinone acetate (CAP, Chronosyn, Veterinaria AG Zürich) and Medroxyprogesterone acetate (MPA, Nadigest, G Streuli & Co. Uznach) on cycling activity and fertility in sheep. A flock of 28 non pregnant white alpine sheep was randomly divided into three groups, A (n = 10), B (n = 9) and C (n = 9). During a period of 4 weeks the cycling activity was confirmed by blood progesterone analysis. Thereafter, the animals of group A were treated with 50 mg CAP, those of group B with 140 mg MPA and those of group C with physiological saline solution. All injections were given intramuscularly. Suppression of endogenous progesterone secretion lasted from 28 to 49 days (mean = 39 days) in group A and from 42 to 70 days (mean = 50 days) in group B. The synchronization effect of both preparations was unsatisfactory as the occurrence of first estrus was distributed over a period of 3 weeks in group A and 4 weeks in group B. These findings could also be confirmed by the lambing period which lasted 52 days in group A and 36 days in group B. Control animals lambed within 9 days due to the synchronizing effect of the ram. The first fertile estrus was observed 36 days (group A) and 45 days (group B) after the treatment. In group A all 10 animals and in groups B and C 8 of 9 ewes each became pregnant. Parenteral progestagen application with CAP and MPA is a simple, safe and reversible method of estrus suppression in the sheep. The minimal suppressive duration of 4 (CAP) and 5 weeks (MPA) is not sufficient when a period of 3 months (alpine pasture period) is desired.

Animals↗
PubMed1988

[The effect of vitamin A on trypsin inhibition activity of the blood and cervical mucus after the effects of hormones on the ovaries of sheep in the estrus period].

Vitamin A (50,000 I. U.), administered after oestrus synchronization by PGF2 alpha (2 X 125 micrograms; 1st and 11th day) together with PMSG (750 and 1000 I. U.), had a stronger influence on the changes in the trypsin-inhibition activities (TIA) of the blood plasma, as compared with the effect of PMSG. The changes in the average TIA values within 120 hours after the administration of the stimulating dose were also observed more frequently to depend on vitamin A. After administration of 1000 I. U. PMSG, an increase was recorded only in the values of the fraction of low-molecular TIA, whereas the administration of the combinations of PMSG + vitamin A resulted in an increase of all the TIA's under study. This increase was directly correlated with an increased number of non-atretic tertiary follicles, with an increased number of ovulations (at the same dose of PMSG), and with a reduced ratio of changes in the concentration of progesterone (P) and 17-beta oestradiol (E): P/E = 1.1 after the administration of 1000 I. U. PMSG, P/E = 0.81 after I. U. PMSG + vitamin A, and P/E = 0.90 after 1000 I. U. PMSG + vitamin A. The increase in the average TIA of the cervical mucus is due to the increased secretory activity of the cervical glands rather than to the multiplication of these glands after ovary stimulation.

Animals↗
PubMed1981

Luteolysis and cycle synchronization with a new prostaglandin analog for artificial insemination in the mare.

Over a period of three years, 165 cyclic or anestrous Hanoverian mares received 177 treatments with 2, 3 or 4 mg of a novel luteolytic prostaglandin analog, K 11941. Heat and ovulations, indicating luteolysis, were observed after an average of 3.98 and 7.62 days, respectively, in 88.04% of 142 treated cyclic, postpartum and anestrous mares, and mares after an early loss of the conceptus. All doses tested were effective in inducing luteolysis as confirmed by determination of progesterone blood levels in samples collected daily, in 70 of 80 mares studied (87.5%). Attempts to achieve control of the cycle by various methods revealed that with K 11941 given once or twice, alone or in combination with hCG and/or an GnRH analog (Hoe 766), one can effectively concentrate estrus periods and follicular growth patterns, but can neither synchronize nor concentrate ovulations. Since most of the mares treated were confirmed problem mares, the pregnancy rate of 40.0% from first insemination at drug induced estrus, was regarded as satisfactory when compared to a pregnancy rate of 43.8% obtained with natural breeding in the same population. No drug related clinical signs of side-effects were observed.

Journal Article↗
PubMed1999

The effect of spermatozoa and seminal plasma on leukocyte migration into the uterus of gilts.

Yorkshire x Landrace gilts were used to determine the effect of spermatozoa and seminal plasma on postbreeding uterine leukocyte influx. Estrus detection was performed with a boar at 12-h intervals following synchronization with 400 IU eCG and 200 IU of hCG. All gilts were AI once, 24 h after the detection of estrus following random assignment to a 2x2x3 factorial arrangement of treatments (sperm or sperm-free AI doses), AI dose medium (seminal plasma or PBS), and lavage time following AI. Gilts were treated with sperm (5x10(9) spermatozoa; SPZ; n = 30) or sperm-free (SF; n = 30) doses containing either 100 mL of seminal plasma (SP; n = 15/treatment) or PBS (n = 15/treatment). Uterine lavage was performed once on each gilt (n = 20/time) at one of three times after AI (6, 12, or 36 h) to determine the total number of uterine leukocytes. The leukocytes consisted predominately (92 to 99%) of polymorphonuclear neutrophilic granulocytes (PMN). There was an AI x medium interaction on uterine PMN numbers. The number of uterine PMN recovered from gilts inseminated with sperm suspended in PBS was greater than the number of PMN recovered from the uterine lumen of gilts inseminated with sperm in SP, SP alone, or PBS alone (P<.05). Furthermore, SP accelerated the rate of uterine clearance when suspended with sperm cells during the first 36 h following AI (P<.05). These results indicate that seminal plasma suppresses PMN migration into the uterus following breeding and enhances the rate of disappearance of uterine inflammation.

Animals↗
PubMed1982

Pregnancy rate in peripuberal beef heifers following treatment with syncro-mate-B and gonadotropin releasing-hormone.

A study was conducted to evaluate the effectiveness of treatment with Syncro-Mate-B (SMB) and gonadotropin releasing-hormone (GnRH) on inducing a fertile estrus and/or ovulation in peripuberal beef heifers. Two hundred and twenty-three, 13 to 15 month peripuberal beef heifers, primarily of Angus or Simmental breeding, were alternately allotted by weight and age within breed to a non-treated control group (C) and three groups which received the SMB treatment regime. Treated groups differed in that one group was inseminated approximately 12 hr after detected in estrus (T) while two other groups were inseminated at a fixed time after implant removal (T-G-I42, T-I48). Heifers in group T-G-I42 received 125 mug GnRH at 30 hr, and were inseminated 42 hr after implant removal. The remaining group of SMB-treated heifers received no additional hormone therapy but were inseminated 48 hr after implant removal (T-I48). Age had no significant effect on estrous response or pregnancy rate nor were there significant age by weight interactions on these parameters. Weight was a significant source of variation on interval from start of breeding to pregnancy (P<.01) and the effect on interval to estrus approached statistical significance (P<.0.9). In control heifers, increased weight had a positive effect on estrous response during the first 21 days of breeding (P<.05). Conversely, weight had no effect on estrous response during the 5-day synchronized period in heifers treated with SMB and observed for estrus (group T). Cumulative estrous response in control heifers was 10, 47, 48 and 55% in 5, 21, 27 and 45 days of breeding, respectively. Cumulative estrous response in SMB-treated heifers obsrved for estrus (group T) was 88, 91, 91 and 91% in 5, 21, 27 and 45 days of breeding, respectively. Pregnancy rate after 5 days of breeding was 9, 27, 18 and 30% for heifers in groups C, T, T-G-I42 and T-I48, respectively. Pregnancy rate after 21 days of breeding for heirfers in groups C, T, T-G-I42 and T-I48, respectively, was 33, 38, 21 and 41%; after 27 days of breeding was 36, 43, 40 and 48%; after 45 days of breeding was 48, 61, 51 and 69% and after the total 88-day breeding season was 59, 68, 71 and 72%. While a large percentage of peripuberal beef heifers with adequate age but insufficient weight were induced into estrus with the SMB treatment, pregnancy rates were low. Timed insemination programs with or without GnRH do not appear to be effective in improving pregnancy response in non-cyclic beef heifers.

Journal Article↗