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1.
The present study was designed to determine the effect of estradiol benzoate (EB) on reproductive response following a controlled internal drug release (CIDR) protocol in crossbred (Sahiwal × Friesian) dairy heifers. In the first trial, a total of 100 crossbred dairy heifers were treated with CIDR protocol for 7 days and injected with the PGF2α on day 6. After 24 h of CIDR removal, one group (EB?=?50) was injected with estradiol benzoate whereas the other (control?=?50) remained untreated. Estrus intensity and response were recorded visually and ovulation rate was recorded by ultrasonography. All heifers were artificially inseminated at 48 and 60 h following CIDR removal. Heifers were scanned for pregnancy within days 30–40 of artificial insemination (AI). In the second trial, two subgroups of heifers were included to observe the estrus and ovulatory events. The results of the first trial revealed that estrus response was achieved 100% in both the treatment groups. Estrus intensity (2.9?±?0.1 vs. 2.0?±?0.7) and ovulation rate (100 vs. 88%) differed significantly (P?<?0.05) between the EB and control groups. However, a tendency for higher pregnancy per AI was observed (54 vs. 36%; P?=?0.07) in EB than that in control groups. The results of the second trial revealed that a significantly (P?<?0.05) shorter estrus and earlier ovulatory events were observed in EB-treated heifers. It is concluded that the incorporation of estradiol benzoate to the CIDR protocol is helpful to improve the estrus signs and enhance the ovulation and the pregnancy per AI in crossbred dairy heifers.  相似文献   

2.
Three different treatments were compared to improve pregnancy per artificial insemination (P/AI) in repeat-breeder (RB) dairy cows. All cows (n = 103) were assigned to one of four groups: (1) gonadotropin-releasing hormone (GnRH); (2) human chorionic gonadotropin (hCG); (3) once-used controlled internal drug release (CIDR) device; and (4) control. All treatments performed 5-6 days after artificial insemination (AI) and milk samples were collected just before treatment for progesterone assays. There were no significant differences in milk fat progesterone concentration among trial groups. Cows were observed for estrus signs thrice daily. Pregnancy per AI on day 45 in hCG and CIDR groups were significantly higher than GnRH and control groups (60.0% and 56.0% vs. 26.9% and 29.6%, respectively), but there were no differences in P/AI between GnRH and control groups. There were also no significant differences between hCG and CIDR groups. Milk fat progesterone concentrations were compared between pregnant and non-pregnant cows in each group and only in the hCG group it was significantly lower in pregnant cows. In conclusion, treating repeat-breeder cows with hCG or once-used CIDR 5-6 days after AI improved P/AI.  相似文献   

3.
A trial was conducted during the anestrous period in female goats to determine: (a) whether estrus can be induced in anestrous goats by administration of equine chorionic gonadotropic hormone (eCG) and PGF2α under pen conditions and (b) whether these sexually active female goats can elicit sexual arousal in sexually inactive bucks. One hundred and fifteen pluriparous, nonlactating mixed-breed female goats were randomly assigned to one of four treatment groups: (1) administration of a single dose of 240 IU of eCG, 50 μg PGF2α i.m., and 25 mg progesterone (P4) (eCG; n?=?30); (2) administration of P4 and exposure to female goats treated with eCG–PGF2α (P4; n?=?39); (3) administration of 0.5 ml saline and P4 (Sal; n?=?23); and (4) P4 plus exposure to female goats treated with saline (Con; n?=?23). After hormone administration, all goats were put together with adult sexually inactive bucks for 15 days. The percentage of goats in estrus during these 15 days was similar in eCG-treated animals and untreated animals exposed to the eCG animals (97 and 95 %). Pregnancy rate was also similar (63 vs. 64 %) between these two groups. eCG-treated goats exhibited estrus earlier (P?<?0.05) than the treated goats in contact with the eCG goats. Furthermore, eCG-treated goats had larger litters (1.9?±?0.2 vs. 1.6?±?0.1, P?<?0.05) than the untreated goats in contact with the eCG goats. These results show that fertile estrus can be induced in anestrous female goats by exposing them to female goats induced to estrus with eCG. This female–female interaction triggers the stimulation cycle leading to the sexual arousal of bucks.  相似文献   

4.
A serial ultrasonographic study was conducted on nine jennies aged 5–15 years from January to April 2008 with the objective of studying ovarian follicular dynamics and estrus manifestations under controlled management. Ovarian follicular activity was determined from the number and size distribution of follicles, length of interovulatory interval (IOI), growth rate of preovulatory follicles, diameter of follicles at the onset of estrus, and incidence of ovulation. Estrus manifestations were characterized using length of estrus and estrous cycle. The mean (±SD) number of follicle detected per ovary was 5.45?±?2.3 (range, 1–16) with sizes ranging from 2.9 to 44 mm. The mean (±SD) size of follicle encountered at the onset of estrus was 25.9?±?3.7 mm (range, 20.9–34.4) while that of the preovulatory follicles at ?1 day before ovulation was 36.81?±?3.78 mm. The mean (±SD) IOI, estrus, and estrous cycle length were 25.4?±?3.6, 7.9?±?2.9, and 24.2?±?7.4 days, respectively. The mean (±SD) growth rate of the preovulatory follicle after the day of divergence was 1.9?±?0.3 mm/day. Serum progesterone profile followed the same patterns of ovarian dynamics with maximum values being detected during midluteal phase. Serum progesterone assay revealed blood progesterone profiles of <1.0 ng/ml during estrus and up to 11 ng/ml during midluteal phase with a pattern following follicular dynamics. Body condition of the study jennies steadily increased and was positively correlated (r?=?0.52, p?<?0.001) with the diameter of the preovulatory follicle. In conclusion, the ultrasonic evaluation has revealed that follicular dynamics of jennies were generally related with body condition which might have been influenced by the type of management.  相似文献   

5.
The objective was to determine the effects of giving prostaglandin F2alpha (PGF) concurrent with, or 24 h before, removal of an intravaginal, progesterone-releasing (controlled internal drug release [CIDR]) device, on luteolysis, the synchrony of estrus and ovulation. Eighteen postpubertal Holstein heifers were given a CIDR and 100 microg gonadotropin releasing hormone (GnRH) and equally allocated to 3 groups. The PGF was given concurrently with CIDR removal after 7 or 8 d (groups D7/D7 and D8/D8, respectively) or given 1-d before removal of CIDR after 8 d (group D7/D8). There was no difference (P > 0.75) among groups in the intervals (h) from CIDR removal to onset of standing estrus and to ovulation (49.3 h+/-6.2 h and 77.5 h+/-9.0 h, respectively; least squares means+/-standard error of means). We also determined if stage of the estrus cycle influenced the synchrony of estrus or ovulation. In heifers in metestrus at CIDR insertion (versus those at estrus or diestrus), intervals from CIDR removal to estrus and to ovulation were longer by 33.4 h (P < 0.05) and 38.5 h (P = 0.01), respectively. However, the interval from standing estrus to ovulation was not affected. Giving PGF concurrent with CIDR removal did not affect luteal regression, the synchrony of estrus, and ovulation; but heifers in metestrus at the initiation of treatment had longer intervals from CIDR removal to estrus and ovulation.  相似文献   

6.
This study aimed to investigate the influence of growth rate and onset of boar contact on age at first observed estrus of the replacement gilts raised in Thailand. In total, 766 gilts were measured for body weight and backfat thickness prior to insemination. Body weight was further calculated for growth rate. Estrus detection was performed twice a day by back pressure test with an existence of mature boars with high libido. The first date of boar exposure and that of first observed estrus were individually recorded. Due to growth rate, they were classified into three groups: high (>700 g/day), moderate (600–700 g/day), and low (<600 g/day). According to onset of boar contact, the gilts were grouped into two categories: early (<150 days) and late (≥150 days). The results revealed that the gilts expressed first observed estrus, averagely, at age 205.1?±?34.1 days, had a growth rate of 615.5?±?57.6 g/day, and first contact with boars at 160.7?±?19.9 days of age. The gilts with low growth rate expressed first estrus later than those with moderate (208.6?±?2.0 vs 198.0?±?3.2 days, P?=?0.033) and high growth rate (208.6?±?2.0 vs 193.9?±?6.7 days, P?=?0.005) groups. Together with the influence of boar exposure, the gilts contacted boar earlier with high growth rate showed first estrus at age 180.3?±?10.1 days, whereas those with later boar contact with low growth rate showed first estrus at age 197.9?±?3.2 days. In summary, the replacement gilts should have high growth rate and contact boar early to attain puberty faster and possess decent subsequent reproductive performance.  相似文献   

7.
The Girolando breed is used in pasture-based dairy production systems in Brazil to associate the high production of Bos taurus to the rusticity and thermal adaptation of Bos indicus. This study was designed to evaluate the physiological response to a gonadotropin-releasing hormone (GnRH)–prostaglandin F2α (PGF2α)–GnRH protocol to synchronize the ovulation in 40 Girolando heifers of a pasture-based dairy production system and its relationships with the temperature and humidity index (THI) during the dry (DS) and rainy season (RS) in the tropical savannah—Brazil's cerrado biome. Responses were characterized by follicular and corpus luteum number and diameter, ovulation (D9), and pregnancy rates after first AI. Total follicle number (8.1?±?0.3?×?8.8?±?0.3), D9 ovulatory follicle diameter (11.9?±?0.4?×?10.1?±?0.4 mm), corpus luteum diameter (8.6?±?1.3?×?3.9?±?1.5 mm), corpus luteum score (3.7?±?0.8?×?1.8?±?1.0), corpus luteum diameter after AI (9.6?±?1.6?×?3.9?±?1.5 mm), and corpus luteum score after AI (3.2?±?0.4?×?0.9?±?0.6) in DS and RS differed (P?<?0.01). D9 ovulation rate was 40 % (DS) and 20 % (RS), without differences (P?>?0.05). Pregnancy rate was 45 % (DS) and 11 % (RS), with differences (P?<?0.01). THI differed between DS and RS (P?<?0.01). THI may interfere in the follicular and luteal dynamics and in the response of Girolando heifers to the GnRH–PGF2α protocol in the tropical savannah, thus reducing the chances of pregnancy at the first artificial insemination.  相似文献   

8.
Application of AI in extensive beef cattle production would be facilitated by protocols that effectively synchronize ovarian follicular development and ovulation to enable fixed-time AI (TAI). The objectives were to determine whether use of a controlled internal drug release (CIDR) device to administer progesterone in a GnRH-based estrous synchronization protocol would optimize blood progesterone concentrations, improve synchronization of follicular development and estrus, and increase pregnancy rates to TAI in beef cows. Beef cows (n = 1,240) in 6 locations within the US Meat Animal Research Center received 1 of 2 treatments: 1)?an injection of GnRH [100 μg intramuscularly (i.m.)] followed by PGF(2α) (PGF; 25 mg i.m.) 7 d later (CO-Synch), or 2) CO-Synch plus a CIDR during the 7 d between GnRH and PGF injections (CO-Synch + CIDR). Cows received TAI and GnRH (100 μg i.m.) at 60 h after PGF. Progesterone was measured by RIA in blood samples collected 2 wk before and at initiation of treatment (d 0) and at PGF injection (d 7). Estrous behavior was monitored by Estrotect Heat Detectors. Pregnancy was diagnosed by ultrasonography 72 to 77 d after TAI. Plasma progesterone concentrations did not differ (P > 0.10) between synchronization protocols at first GnRH injection (d 0), but progesterone was greater (P < 0.01) at PGF injection (d 7) in cows receiving CO-Synch + CIDR vs. CO-Synch as a result of fewer CIDR-treated cows having progesterone ≤1 ng/mL at PGF (10.7 vs. 29.6%, respectively). A greater (P < 0.01) proportion of CO-Synch + CIDR vs. CO-Synch cows were detected in estrus within 60 h after PGF (66.7 vs. 57.8 ± 2.6%, respectively) and a greater (P < 0.01) proportion were pregnant to TAI (54.6 vs. 44.3 ± 2.6%, respectively). For both synchronization protocols, cows expressing estrus within 60 h before TAI had a greater pregnancy rate than cows without estrus. For cows with plasma progesterone ≤1 ng/mL at PGF injection, CO-Synch + CIDR increased pregnancy rate (65.2 ± 5.9 vs. 30.8 ± 3.4% with vs. without CIDR), whereas pregnancy rates did not differ (P > 0.10) between protocols (52.1 ± 2.1 vs. 50.0 ± 2.4%, respectively) when progesterone was >1 ng/mL (treatment × progesterone; P < 0.01). Inclusion of a CIDR in the synchronization protocol increased plasma progesterone concentration, proportion of cows detected in estrus, and pregnancy rate; however, the increase in pregnancy rate from inclusion of the CIDR was primarily in cows with decreasing or low endogenous progesterone secretion during treatment.  相似文献   

9.
Ovarian follicular dynamics and estrous synchronization after Gonadotropin-releasing hormone (GnRH) treatment at Controlled Internal Drug Releasing device (CIDR) insertion were investigated in Japanese Black cows. CIDR was inserted for eight cows at 7 days after estrus. Cows were allocated to either Group A: 8-day CIDR insertion with GnRH treatment on d 0 (n=4, d 0=CIDR insertion) or Group B: 8-day CIDR insertion (n=4). Both groups were injected with prostaglandin F2alpha (PGF2alpha) on d 7. Ultrasonography and blood sampling were performed twice daily. Intensive sampling was performed every 15 min for 8 hr to determine the pulsatile release of LH on d -1, d 5 and d 10. Three of four cows showed intermediate ovulation within 2 days after GnRH treatment during CIDR insertion in Group A, whereas no ovulation was found in Group B. Three of four cows in Group A and all four cows in Group B ovulated after CIDR removal. Plasma progesterone concentrations from d 3 to d 7 in three intermediate ovulatory cows in Group A (8.4 +/- 1.6 ng/ml) was significantly higher than those in Group B (4.1 +/- 1.2 ng/ml; 4 cows) during CIDR insertion (P<0.01). Interval to estrus and ovulation after CIDR removal was observed at 60.0 +/- 12.0 hr and 76.0 +/- 6.9 hr in three cows in Group A, and 75.0 +/- 15.1 hr and 93.0 +/- 20.5 hr in Group B, respectively. There was a significant increase in LH pulse frequency on d 10 compared on d -1 or d 5 in both groups (P<0.05), in addition those on d 10 in Group A tended to be higher than in Group B. As a result, GnRH treatment at CIDR insertion at 7 days after estrus induced intermediate ovulation with formation of corpus luteum (CL) and rather synchronized emergence of ovulatory follicle during CIDR insertion. These induced CL increased plasma progesterone concentrations and contributed to precise synchronization.  相似文献   

10.
The objectives of the experiment were to determine the effect of two doses of equine chorionic gonadotropin (eCG) in a standard synchronization protocol based on a short-term progesterone (P4) priming on ovarian structures and haemodynamics, concentrations of steroid hormones and prolificacy rate when oestrus was induced during low-breeding season (LBS) in Beetal dairy goats. We hypothesized that inclusion of eCG in a short-term P4 priming-based synchronization protocol would increase the blood perfusion to ovarian structures leading to enhance oestrous and ovulatory responses and prolificacy rate in goats. Forty-two multiparous acyclic goats were blocked by body condition and, within block, assigned randomly to receive saline as control (CON), low eCG (L-eCG; 300 IU) or high eCG (H-eCG; 600 IU) dose. Initially, a controlled internal drug release (CIDR) device was placed in the anterior vagina on d −8, followed by removal of CIDR on d −3, concurrent with the administration of PGF2α and eCG according to their respective treatments. Goats were monitored for oestrous response. B-mode and Doppler ultrasonography was performed with 12-h interval, starting from day −3 until natural breeding (day 0), and then on days 5, 10, 15 and 20 post-breeding to monitor follicular and luteal dynamics and blood flow, respectively. Blood was sampled at 0, 12, 24, 36 and 60 h after CIDR removal to quantify plasma concentrations of estradiol-17β (E2), whereas plasma concentrations of P4 were assayed at days 5, 10, 15 and 20 after breeding. Pregnancy and prolificacy rates were determined at day 30 and 150 after breeding, respectively. Data were analysed with mixed-effects models, and orthogonal contrasts were used to evaluate the effect of treatment [Con vs. (½ L-eCG + ½ H-eCG)] and dose of eCG (L-eCG vs. H-eCG). Data are presented in sequence as CON, L-eCG, H-eCG (LSM ± SEM). The oestrous intensity score (152.9 vs. 182.7 vs. 186.5 ± 15.1; p = .02) was greater in eCG-treated goats as compared to CON. Administration of eCG reduced the intervals to standing oestrus (66.2 vs. 41.8 vs. 48.9 h ± 5.5; p = .05), breeding (70.2 vs. 44.4 vs. 45.4 h ± 4.5; p = .03) and ovulation (84.5 vs. 61.2 vs. 63.4 h ± 6.2; p = .05) compared with CON goats. The mean growth rate of pre-ovulatory follicle was greater (1.11 vs. 1.49 vs. 1.45 mm ± 0.08; p = .01) in eCG-treated goats resulting in an increased diameter of pre-ovulatory follicle (6.27 vs. 7.20 vs. 7.31 mm ± 0.07; p < .01) and corpora lutea (6.75 vs. 8.26 vs. 8.07 mm ± 0.42; p = .04) than CON. The mean follicular blood flow did not differ among treatments; however, the mean luteal blood flow was greater in L-eCG-treated goats (0.81 vs. 1.61 vs. 1.07 cm2 ± 0.12; p = .001). The mean concentrations of E2 (4.03 vs. 5.21 vs. 4.78 pg/ml ± 0.42; p = .04) and P4 (4.85 vs. 6.39 vs. 6.22 ng/ml ± 0.34; p = .04) were greater in eCG-treated goats. The twinning rate did not differ between treatments; nevertheless, prolificacy rate was greater (p = .04) in L-eCG-treated goats. Collectively, our data suggest that the administration of eCG improves the induction of oestrous and ovarian dynamics. Administration of L-eCG enhances prolificacy rate, therefore, a low dose of eCG might be practically beneficial to improve reproduction during LBS in acyclic Beetal dairy goats.  相似文献   

11.
An experiment was designed to evaluate the effects of estradiol‐17β (E17β) on follicular wave dynamics and ovulatory response in Holstein heifers receiving either a progestogen ear‐implant (Crestar®; Intervet International b.v. Boxmeer, The Netherlands) or an intravaginal progesterone‐releasing device [controlled internal drug release‐bovine device (Eazibreed, CIDR‐B®; Bodinco BV, Alkmaar, The Netherlands)]. For comparison, another group of heifers was also synchronized using Crestar plus an injection of estradiol valerate (EV) and norgestomet as recommended by the pharmaceutical company. Twenty 20–22‐month‐old cycling Holstein heifers were allocated to one of the following treatment groups at random stages of the oestrous cycle: (I) simultaneous insertion of Crestar and intramuscular injection of 3 mg norgestomet and 5 mg EV (Crestar 9 + EV 9); (II) simultaneous insertion of Crestar and intramuscular injection of 5 mg E17β (Crestar 9 + E17β 9); (III) insertion of Crestar followed 2 days later by intramuscular injection of 5 mg E17β (Crestar 9 + E17β 7); or (IV) insertion of CIDR‐B device followed 2 days later by intramuscular injection of 5 mg E17β (CIDR 9 + E17β 7). The CIDR‐B or Crestar implants were removed after 9 days and all heifers received 500 μg Cloprostenol (Estrumate®, Pitman‐Moore Nederland BV, Houten, The Netherlands). Ovarian ultrasonographic examinations were performed once daily during the synchronization period using a B‐mode scanner equipped with a 7.5 MHz linear‐array transrectal transducer. In addition, heifers were scanned every 12 h after implant/device withdrawal until 3 days after ovulation in order to monitor follicular activity, detect ovulation and subsequent early luteal formation. Detection of oestrus was performed every 6 h for 4 days after device/implant removal. Oestrus was observed 24–32 h before ovulation in all heifers. The mean hours interval from treatment withdrawal to ovulation was not significantly different (84.0 ± 16.5, 77.6 ± 4.1, 73.6 ± 4.1 and 64.0 ± 4.4 h for treatments I, II, III and IV, respectively; p > 0.1). However, the variance for heifers treated with EV + norgestomet was significantly larger (Levene’s Test; p < 0.01) than those treated with E17β. All E17β treatments resulted in dominant follicle suppression and a new wave emerged 4.1 days after treatment compared with 6.6 days for the EV + norgestomet treatment (p < 0.05). The time from emergence of the new ovulatory wave to ovulation was longer for the new wave that emerged after E17β treatment (9.2 ± 0.3 days) than after EV + norgestomet treatment (6.9 ± 0.4 days; p < 0.05). The results of this study suggest that the four treatments used were effective in inducing synchronous behavioural oestrus and ovulation. However, a higher degree of oestrus and ovulation synchrony was observed in heifers treated with E17β than in heifers treated with EV + norgestomet. Synchronization treatments with exogenous E17β or EV + norgestomet at the time of progestin device insertion (Crestar or CIDR‐B) or 2 days later in heifers can regulate a different emergence pattern of ovarian follicular development in randomly cyclic heifers. The E17β was effective in inducing follicular suppression and resulted in the consistent emergence of a new follicular wave.  相似文献   

12.
To investigate the efficiency of hCG/CIDR after breeding to increase the reproductive performance, 35 synchronized ewes were mated with fertile rams and were assigned to three treatment groups. Ewes in hCG group (n?=?12) received 400 IU hCG on day 11 post-mating, and ewes in CIDR group (n?=?11) received CIDR from day 7 until day 19 post-mating. Ewes in the control group (n?=?12) did not receive any treatment. Blood samples were collected on days 7, 12, 17, and 22 post-mating. Plasma P4 concentrations were higher on days 12 and 17 post-mating in hCG- and CIDR-treated groups (P?<?0.05). However, the concentrations of P4 on day 22 post-mating in hCG and control groups were higher than that in CIDR group (P?<?0.05). Ewes in hCG group produced more quadruplets (P?<?0.05) and triplets, and as a result, they had a larger litter size (P?<?0.05). The lamb mortality rate by weaning in hCG group (3.6%) was less than that in control (11.8%; P?<?0.05) and CIDR (9.1%; P?>?0.05) groups. Post-mating administration of hCG or CIDR did not affect the lamb birth weight in single and quadruplet births (P?>?0.05), but the birth weight of twin lambs was higher in the hCG and CIDR groups (P?<?0.05). Weaning weights of twin lambs were higher in the hCG and CIDR groups (P?<?0.05). In conclusion, hCG/CIDR administration post-mating increased the maternal P4 concentrations and enhanced reproductive performance.  相似文献   

13.
The objective of the experiment was to compare the use of a PGF2α analogue (Cloprostenol) IM, with an intravaginal progestagen sponge, flurogestone acetate (FGA), and equine chorionic gonadotropin (eCG) IM application protocol. A total of 30 cyclical hair ewes (54.07?±?0.5 kg live weight, body condition score 3.5?±?0.5, and age 3?±?1 years) were used. For the control group ewes (n?=?15), intravaginal sponges (IS) impregnated with 20 mg of FGA were inserted for 12 days with 500 IU of eCG IM at sponges withdrawal. For the PG group ewes (Treatment group n?=?15), two injections of Cloprostenol (75 mcg) were given 12 days apart. The presence of estrus was detected using two rams with 8 h interval beginning at the end of the treatment. Progesterone concentrations in blood were measured by solid phase radioimmunoassay. A student’s t test was performed to analyze the duration of estrus and the interval between the ends of the treatment and the onset of estrus (ET-OE) presentation. Progesterone levels were compared with two-way ANOVA, with treatment, and day of menstrual cycle as fixed factors. Treatment costs ratio was calculated by dividing the total costs of FGA IS application between total costs of Cloprostenol application. Significant differences (P?P?相似文献   

14.
The effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given 100 microg of GnRH im were determined in three experiments. In Experiment 1, heifers were given GnRH 3, 6 or 9 days after ovulation; 8/9, 5/9 and 2/9 ovulated (P<0.02). Mean plasma concentrations of progesterone were lowest (P<0.01) and of LH were highest (P<0.03) in heifers treated 3 days after ovulation. In Experiment 2, heifers received no treatment (Control) or one or two previously used CIDR inserts (Low-P4 and High-P4 groups, respectively) on Day 4 (estrus=Day 0). On Day 5, the Low-P4 group received prostaglandin F(2alpha) (PGF) twice, 12 h apart and on Day 6, all heifers received GnRH. Compared to heifers in the Control and Low-P4 groups, heifers in the High-P4 group had higher (P<0.01) plasma progesterone concentrations on Day 6 (3.0+/-0.3, 3.0+/-0.3 and 5.7+/-0.4 ng/ml, respectively; mean+/-S.E.M.) and a lower (P<0.01) incidence of GnRH-induced ovulation (10/10, 9/10 and 3/10). In Experiment 3, 4-6 days after ovulation, 20 beef heifers and 20 suckled beef cows were given a once-used CIDR, the two largest follicles were ablated, and the cattle were allocated to receive either PGF (repeated 12h later) or no additional treatment (Low-P4 and High-P4, respectively). All cattle received GnRH 6-8 days after follicular ablation. There was no difference between heifers and cows for ovulatory response (77.7 and 78.9%, P<0.9) or the GnRH-induced LH surge (P<0.3). However, the Low-P4 group had a higher (P<0.01) ovulatory response (94.7% versus 61.1%) and a greater LH surge of longer duration (P<0.001). In conclusion, although high plasma progesterone concentrations reduced both GnRH-induced increases in plasma LH concentrations and ovulatory responses in beef cattle, the hypothesis that heifers were more sensitive than cows to the suppressive effects of progesterone was not supported.  相似文献   

15.
The objectives of this study were to determine the effects of incorporating a progesterone intravaginal insert (CIDR) between the day of GnRH and PGF2alpha treatments of a timed AI protocol using estradiol cypionate (ECP) to synchronize ovulation on display of estrus, ovulation rate, pregnancy rate, and late embryonic loss in lactating cows. Holstein cows, 227 from Site 1 and 458 from Site 2, were presynchronized with two injections of PGF2alpha on study d 0 and 14, and subjected to a timed AI protocol (100 mixrog of GnRH on study d 28, 25 mg of PGF2alpha on study d 35, 1 mg of ECP on study d 36, and timed AI on study d 38) with or without a CIDR insert. Blood was collected on study d 14 and 28 for progesterone measurements to determine cyclicity. Ovaries were scanned on d 35, 37, and 42, and pregnancy diagnosed on d 65 and 79, which corresponded to 27 and 41 d after AI. Cows receiving a CIDR had similar rates of detected estrus (77.2 vs. 73.8%), ovulation (85.6 vs. 86.6%), and pregnancy at 27 (35.8 vs. 38.8%) and 41 d (29.3 vs. 32.3%) after AI, and late embryonic loss between 27 and 41 d after AI (18.3 vs. 16.8%) compared with control cows. The CIDR eliminated cows in estrus before the last PGF2alpha injection and decreased (P < 0.001) the proportion of cows bearing a corpus luteum (CL) at the last PGF2alpha injection because of less ovulation in response to the GnRH and greater spontaneous CL regression. Cyclic cows had greater (P = 0.03) pregnancy rates than anovulatory cows at 41 d after AI (33.8 vs. 20.4%) because of decreased (P = 0.06) late embryonic loss (16.0 vs. 30.3%). The ovulatory follicle was larger (P < 0.001) in cows in estrus, and a greater proportion of cows with follicles > or = 15 mm displayed estrus (P < 0.001) and ovulated (P = 0.05) compared with cows with follicles <15 mm. Pregnancy rates were greater (P < 0.001) for cows displaying estrus, which were related to the greater (P < 0.001) ovulation rate and decreased (P = 0.08) late embryonic loss for cows in estrus at AI. Cows that were cyclic and responded to the presynchronization protocol (high progesterone at GnRH and CL at PGF2alpha) had the highest pregnancy rates. Incorporation of a CIDR insert into a presynchronized timed AI protocol using ECP to induce estrus and ovulation did not improve pregnancy rates in lactating dairy cows. Improvements in pregnancy rates in cows treated with ECP to induce ovulation in a timed AI protocol are expected when more cows display estrus, thereby increasing ovulation rate.  相似文献   

16.
Two experiments were designed to investigate the administration of intravaginal progesterone in protocols for oestrus and ovulation synchronization in beef heifers. In Experiment 1, cyclic Black Angus heifers (n = 20) received an Ovsynch protocol and were randomly assigned to receive (CIDR‐Ovsynch) or not (Ovsynch) a progesterone device between Days 0 and 7. Treatment with a controlled internal drug release (CIDR) device significantly increased the size of the dominant follicle prior to ovulation (12.8 ± 0.4 CIDR‐Ovsynch vs 11.4 ± 0.4 Ovsynch) (p < 0.02). Plasma progesterone concentrations throughout the experiment were affected by the interaction between group and day effects (p < 0.004). In Experiment 2, cyclic Polled Hereford heifers (n = 382) were randomly assigned to one of the six treatment groups (3 × 2 factorial design) to receive a CIDR, a used bovine intravaginal device (DIB), or a medroxiprogesterone acetate (MAP) sponge and GnRH analogues (lecirelin or buserelin). All heifers received oestradiol benzoate plus one of the devices on Day 0 and PGF on Day 7 pm (device withdrawal). Heifers were detected in oestrus 36 h after PGF and inseminated 8–12 h later, while the remainder received GnRH 48 h after PGF and were inseminated on Day 10 (60 h). The number of heifers detected in oestrus on Day 8 and conception rate to AI on Day 9 were higher (p < 0.01) in the used‐DIB than in the CIDR or MAP groups, while the opposite occurred with the pregnancy rate to FTAI on Day 10 (p < 0.01). There was no effect of progesterone source, GnRH analogue or their interaction on overall pregnancy rates (64.9%). Progesterone treatment of heifers during an Ovsynch protocol resulted in a larger pre‐ovulatory follicle in beef heifers. Progesterone content of intravaginal devices in synchronization protocols is important for the timing of AI, as the use of low‐progesterone devices can shorten the interval to oestrus.  相似文献   

17.
不同季节绒山羊同期发情效果研究   总被引：1，自引：0，他引：1       下载免费PDF全文
 试验旨在研究不同季节绒山羊同期发情处理效果,为绒山羊胚胎移植和绒山羊养殖采用新繁殖技术实现集约化、工厂化生产管理提供配套技术。在2007~2008两年期间的四个季节,利用孕激素阴道栓（CIDR）+孕马血清（PMSG）方法,对766只绒山羊进行同期发情处理,48 h内有730只羊发情,发情羊第7 d在进行绒山羊胚胎移植时观察卵巢卵泡发育及排卵情况。结果表明：春、夏、秋、冬季绒山羊的同期发情率分别为94.08%、90.59%、97.54%、92.68%,平均为95.30%。经X2检验,秋季与夏季绒山羊的同期发情率（P＜0.01）存在显著差异,其它季节绒山羊的同期发情率（P＞0.05）差异不大。春、夏、秋、冬季发情绒山羊的排卵率分别为92.31%、90.91%、95.20%、91.23%,平均为93.56%。经X2检验,四个季节发情绒山羊的排卵率（P＞0.05）没多大差异。试验结果表明在四个季节对绒山羊采用的CIDR+ PMSG同期发情处理方法可行,发情率和排卵率均在90%以上,效果好且稳定。季节虽然对绒山羊同期发情率有一定影响,但对发情绒山羊排卵率影响不大。  相似文献   

18.
The Controlled Internal Drug Releasing (CIDR) device is an intravaginal pessary containing progesterone (P4) designed for synchronizing estrus in ruminants. To date, there has been little information available on the timing, duration, and quality of the follicular phase after CIDR removal and how those characteristics compare with natural periovulatory endocrine events. The present communication relates the results of methods we used to characterize the endocrine events that followed CIDR synchronization. Breeding-season ewes were given an injection (10 mg) of Lutalyse (PGF2α), and then studied during three consecutive estrous cycles, beginning in the luteal phase after the estrus induced by PGF2α. Cycle 1 estrus was synchronized with 1 CIDR (Type G) inserted for 8 d beginning 10 d after PGF2α. Cycles 2 and 3 were synchronized with two CIDRs for 8 d beginning 10 d after previous CIDR removal. Cycle 1 estrous behavior and serum gonadotropins showed a follicular phase (the interval from CIDR withdrawal to gonadotropin surge [surge] peak) of 38.2 ± 1.5 hr. Two CIDRs lengthened the interval to 46.2 ± 1.5 hr (P < 0.0001). At CIDR removal, circulating P4 concentrations were higher in ewes treated with two CIDRs (5.1 ± 0.3 and 6.4 ± 0.4 ng/mL in Cycles 2 and 3 vs. 2.7 ± 0.3 ng/mL in Cycle 1), whereas estradiol concentrations were higher in the 1 CIDR cycle (3.3 ± 0.5 pg/mL in Cycle 1 vs. 0.5 ± 0.1, and 0.7 ± 0.2 pg/mL in Cycles 2 and 3), suggesting that the lower levels of P4 achieved with one CIDR was not sufficient to arrest follicular development. There were no differences in any other endocrine variable. Both one and two CIDR synchronization concentrated surges within a 24-hr period in 92% of the ewes in Cycles 1 and 2. Cycle 3 ewes were euthanized at estimated luteal, early follicular, late follicular, LH surge, and secondary FSH rise timepoints. Endocrine data and ovaries showed that 88% of the ewes synchronized with two CIDRs were in the predicted stage of the estrous cycle. These data demonstrate that the CIDR device applied during the luteal phase effectively synchronizes estrus and results in a CIDR removal-to-surge interval of similar length to a natural follicular phase.  相似文献   

19.
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.  相似文献   

20.
The aim of the present study was to evaluate the control of ovulation by the administration of human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) at the onset of estrus. Thirty-three multiparous sows housed under tropical conditions and showing standing estrus within 5 days after weaning were included. The sows were allocated to three groups, spontaneous ovulation (control group, n = 10), induced ovulation using 750 IU hCG (hCG group, n = 10), and induced ovulation using 50 μg GnRH (GnRH group, n = 13). The hormones were given at the onset of estrus and the occurrence of ovulation was monitored every 6 h by transrectal ultrasonography. Data for weaning-to-estrus interval, onset of estrus-to-ovulation interval (EOI), and the length of estrus were recorded. All sows in the control and hCG groups ovulated, while 3 out of 13 sows treated with GnRH developed cystic ovaries (did not ovulate). Of those sows ovulating, the EOI of the hCG (40.2 ± 1.7 h) and GnRH (37.5 ± 3.3 h) groups were shorter than that of the control group (63.6 ± 9.6 h; P < 0.05). In conclusion, the administration of either hCG or GnRH at the onset of estrus can control time of ovulation but, at the dose employed, sows receiving GnRH may develop ovarian cysts.  相似文献   

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