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1.
Objective of this study was to show plasma progesterone concentrations in ovariectomized beef cows after treatment with new, once-used and twice-used controlled internal drug-releasing devices (CIDRs). Four ovariectomized beef cows were used for the experiment. Plasma concentrations of progesterone were quantified using a validated ELISA. The CIDR was inserted into vagina of cows by using a standard CIDR applicator and then removed 7 days after insertion. One week later, once-used CIDR was inserted and removed on day 7. Twice-used CIDR was, then inserted at an interval of 7 days. Mean plasma concentrations of progesterone 24 h after new CIDR insertion was 4.0 ± 0.1 ng/ml, which thereafter decreased gradually to 1.4 ± 0.1 ng/ml at day 7. In cows treated with once-used CIDR or twice-used CIDR, mean plasma progesterone concentrations at day 1 were 2.4 ± 0.2 or 1.8 ± 0.2 ng/ml and 1.0 ± 0 or 0.9 ± 0.1 ng/ml at day 7 respectively. The results suggest that once-used CIDR may be still effective to produce luteal phase progesterone concentrations in plasma in non-suckling beef cows.  相似文献   

2.
The objectives of this study were first to show adrenocortical response to a long‐acting adrenocorticotropic hormone preparation (tetracosactide acetate zinc suspension) (ACTH‐Z) and its effect on adrenocortical function in beef cows ( Experiment 1 ) and second to apply the ACTH‐Z challenge in dairy cows based on cortisol concentrations in milk collected at routine milking ( Experiment 2 ). In Experiment 1 , four beef cows in luteal phase were challenged with ACTH‐Z, and plasma cortisol concentrations were determined for 48 h after the injection at 30‐min to 2‐h intervals. A rapid ACTH test was conducted 3 days before and 2 h after the completion of ACTH‐Z injection for 48 h to investigate the effect on adrenocortical function. Plasma cortisol concentrations increased significantly 30 min after ACTH‐Z injection (p < 0.001), and the high cortisol levels were maintained for approximately 10 h after the injection. In Experiment 2 , eight dairy cows were subjected to ACTH‐Z challenge 1–2 weeks and 4–5 weeks post‐partum. Blood and milk samples were taken at morning and afternoon milking. All the cows showed a significant increase in cortisol concentrations in plasma as well as in skim milk 8 h after ACTH‐Z injection 1–2 weeks and 4–5 weeks post‐partum (p < 0.001). There was a significant correlation between plasma and skim milk cortisol concentrations 8 h after ACTH‐Z challenge (r = 0.74, p < 0.001). The results obtained in this study suggest that elevated levels of plasma cortisol are maintained for approximately 10 h after ACTH‐Z treatment without adverse effect on adrenocortical function and a long‐acting ACTH‐Z challenge based on cortisol concentrations in milk, which were collected at the morning and the afternoon milking, can be a useful tool to monitor adrenocortical function in cows.  相似文献   

3.
The study was conducted to compare estrous rate, ovulatory response, plasma progesterone concentrations, and conception rate following cervical artificial insemination in goats given a new or once-used controlled internal drug release (CIDR) device with human chorionic gonadotropin (hCG). Fifty-six Thai-native goats with the average age and body weight of 11 months and 17.3 kg received a 14-day treatment with a new CIDR device (Eazi-BreedTMCIDR®, Pfizer, NY, USA) or a once-used CIDR device. All goats received a 300-IU injection of hCG (Chorulon®, Intervet International B.V., New Zealand) at the day of CIDR removal to induce ovulation. All goats displaying signs of Estrous behavior were artificially inseminated at 12 h after the onset of estrus with frozen semen. No differences in percentage of estrus and ovulation rates were observed; however, goats that received once-used CIDR devices exhibited shorter (P?P?>?0.05) between treatments during CIDR device insertion and at the time of CIDR removal except on day 4. No significant differences were found in overall conception rates between the treatments. This study indicates that the once-used CIDR device with hCG could be applied to synchronize the estrus and ovulation in small-size Thai-native goats without negative effects on Estrous behavior, ovulatory response, and plasma P4 concentration.  相似文献   

4.
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   

5.
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   

6.
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   

7.
Crossbred cows (n = 1073) from five locations had oestrous cycles synchronized with 100 μg of GnRH IM and insertion of controlled internal drug release device (CIDR) on Day 0 followed by 25 mg of PGF2α IM and CIDR removal on Day 7. Kamar® patches were placed on all cows at CIDR removal. Cows were observed three times daily for oestrus after PGF2α administration. In the Ovsynch‐CIDR group, cows detected in oestrus (n = 193) within 48 h after PGF2α were inseminated using the AM–PM rule. Among these cows, 80 received and 113 did not receive a second GnRH at 48 h after PGF2α. Cows (n = 345) not detected in oestrus received a second GnRH at 48 h after PGF2α on Day 9, and fixed‐time AI 16 h after the GnRH on Day 10. In the CO‐Synch‐CIDR group, cows detected in oestrus (n = 224) within 48 h after PGF2α were inseminated using the AM–PM rule. Among these cows, 79 received and 145 did not receive a second GnRH at 64 h after PGF2α. Cows (n = 311) not detected in oestrus received a second GnRH on Day 10 at the time of AI, 64 h after PGF2α. The AI pregnancy rates were not different between the Ovsynch‐CIDR and CO‐Synch‐CIDR groups (p = 0.48). There were no differences in the AI pregnancy rates for cows inseminated at a fixed time (p = 0.26) or at detected oestrus (p = 0.79) between the treatment groups. Among cows inseminated in oestrus, there were no differences in the AI pregnancy rates between cows that received or did not receive the second GnRH (p = 0.47). In conclusion, acceptable AI pregnancy rates can be achieved with or without inclusion of oestrus detection in the Ovsynch‐CIDR and CO‐Synch‐CIDR protocols. Among cows detected in oestrus, cows that received a second GnRH yielded similar pregnancy rates when compared with cows that did not receive the second GnRH.  相似文献   

8.
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   

9.
The pharmacokinetics of Dexamethasone (DXM) was studied in four cows all of which received DXM alcohol and DXM 21 isonicotinate (as a solution) by the intravenous and intramuscular routes. Concentrations of DXM and cortisol were determined using high performance liquid chromatography. An additional study was made in a second group of four cows which received intramuscular DXM 21 isonicotinate suspension for the assessment of DXM suppression of adrenal gland function. This was determined by measurements of base-line and ACTH-stimulated cortisol concentrations, before and following DXM administration. Following intravenous administration, the disposition kinetics of both formulations were described by a two-compartment open model. The half-times of elimination were similar; 335 and 291 min, respectively, for DXM alcohol and DXM 21 isonicotinate. All other pharmacokinetic parameters were not statistically different indicating that DXM was almost totally available (from DXM 21 isonicotinate). Following intramuscular administration, no significant difference in parameters was observed between the two formulations. Peak plasma concentrations were reached at 3 to 4 h post injection and bioavailability was approximately 70%. DXM was not detected in the plasma after the intramuscular administration of the suspension. The mean control plasma cortisol concentration was 8.8 ± 3.03 ng/ml. Following intravenous and intramuscular administrations of DXM alcohol and DXM 21 isonicotinate (solution), cortisol concentrations initially increased. However, at 120 min (intravenous) and 2–4 h (intramuscular), concentrations were negligible; 24–72 h and 48–96 h, respectively elapsed before concentrations returned control values. Following DXM 21 isonicotinate (suspension) there was no initial increase and concentrations had not returned to normal in all four cows until 52 days post administration. Similarly, ACTH-stimulated plasma cortisol concentrations decreased progressively and significantly post administration. At 52 days, response to ACTH was normal in all animals.  相似文献   

10.
We examined the relations between plasma insulin-like growth factor (IGF) -I concentrations during treatment with CIDR-based or Ovsynch protocol for timed AI and conception and plasma steroid concentrations in early postpartum Japanese Black beef cows. Cows in the control group (Ovsynch; n = 21) underwent Ovsynch protocol (GnRH analogue on Day 0, PGF(2alpha) analogue on Day 7, and GnRH analogue on Day 9), with AI on Day 10, approximately 20 h after the second GnRH treatment. Cows in the Ovsynch+CIDR group (n = 22) received Ovsynch protocol plus a CIDR for 7 days (starting on Day 0). Cows in the further treatment group (EB+CIDR+GnRH; n = 22) received 2 mg of estradiol benzoate (EB) on Day 0 in lieu of the first GnRH treatment, followed by the same treatment as in the Ovsynch+CIDR protocol. Plasma IGF-I concentrations were determined on Days -7, 0, 7, 9 and 17. Conception rates were improved in the CIDR-combined groups (both CIDR-treated groups were combined) relative to Ovsynch group (P < 0.05) for cows with low IGF-I concentrations (<1,000 ng/ml) on Days -7, 0, and 7, but improved conception rate produced by the CIDR-based protocols did not occur in cows with a high IGF-I concentration (> or =1,000 ng/ml). Plasma estradiol-17beta concentrations increased from Day 0 to 7 (P < 0.05) and were unchanged from Day 7 to 9 in the Ovsynch group with low IGF-I concentrations on Day 0, while they were unchanged from Day 0 to 7 and increased from Day 7 to 9 (P < 0.05) in the Ovsynch group with high IGF-I concentrations on Day 0 and in the CIDR-combined group. Plasma progesterone concentrations in the Ovsynch group with low IGF-I concentrations on Day 0 were higher on Day 14 than in the Ovsynch group with high IGF-I concentrations on Day 0 and in the CIDR-combined group (P < 0.05). In conclusion, CIDR-based protocols may improve conception relative to Ovsynch in early postpartum beef cows with lower plasma IGF-I concentrations at the start of the protocols. This improvement is probably due to prevention of premature increases of estradiol-17beta and progesterone concentrations, which occurred in cows with low IGF-I concentrations treated with Ovsynch, by the CIDR treatment.  相似文献   

11.
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   

12.
The objective was to test the efficacy of an intravaginal progesterone insert and injection of PGF2alpha for synchronizing estrus and shortening the interval to pregnancy in cattle. Cattle were assigned to one of three treatments before a 31-d breeding period that employed artificial insemination. Control cattle were not treated, and treated cattle were administered PGF2alpha or an intravaginal progesterone-releasing insert (CIDR) for 7 d and treated with PGF2alpha on d 6. The treatments were applied in one of three experiments that involved postpartum beef cows (Exp. 1; n = 851; 56+/-0.6 d postpartum), beef heifers (Exp. 2; n = 724; 442.5+/-2.8 d of age), and dairy heifers (Exp. 3; n = 260; 443.2+/-4.5 d of age). Luteal activity before treatment was determined for individual cattle based on blood progesterone concentrations. In Exp. 1, there was a greater incidence of estrus during the first 3 d of the breeding period in CIDR+PGF2alpha-treated cows compared with PGF2alpha-treated or control cows (15, 33, and 59% for control, PGF2alpha, and CIDR+PGF2alpha, respectively; P < 0.001). The improved estrous response led to an increase in pregnancy rate during the 3-d period (7, 22, and 36% for control, PGF2alpha, and CIDR+PGF2alpha, respectively; P < 0.001) and tended to improve pregnancy rate for the 31-d breeding period for cows treated with CIDR+PGF2alpha, (50, 55, and 58% for control, PGF2alpha, and CIDR+PGF2alpha, respectively, P = 0.10). Improvements in rates of estrus and pregnancy after CIDR+PGF2alpha, were also observed in beef heifers. Presence of luteal activity before the treatment period affected synchronization and pregnancy rates because anestrous cows (Exp. 1) or prepubertal heifers (Exp. 2) had lesser synchronization rates and pregnancy rates during the first 3 d of the breeding period as well as during the entire 31-d breeding period. The PGF2alpha, and CIDR+PGF2alpha but not the control treatments were evaluated in dairy heifers (Exp. 3). The CIDR+PGF2alpha-treated heifers had a greater incidence of estrus (84%) during the first 3 d of the breeding period compared with the PGF2alpha-treated heifers (57%), but pregnancy rates during the first 3 d or during the 31-d breeding period were not improved for CIDR+PGF2alpha compared with PGF2alpha-treated heifers. In summary, the concurrent treatment of CIDR and PGF2alpha improved synchronization rates relative to PGF2alpha alone or control. Improved estrus synchrony led to greater pregnancy rates for beef cows and beef heifers but failed to improve pregnancy rates for dairy heifers.  相似文献   

13.
The effects of estradiol-17beta (E-17beta) or estradiol benzoate (EB) on gonadotrophin release, estrus and ovulation in beef cattle were evaluated in two experiments. In experiment 1, 16 ovariectomized cows received a previously used CIDR insert from days 0 to 7 and 1mg of EB on day 8; they also received 5mg of E-17beta on days 0 or 1, or 5mg of E-17beta+100mg of progesterone on day 0. There was only an effect of time (P<0.0001) on plasma concentrations of progesterone, estradiol, FSH, and LH. Following treatment with E-17beta, plasma FSH concentrations were suppressed for approximately 36 h, whereas plasma LH concentrations were reduced (P<0.05) for 6 h, but surged within 24 h. Injecting 1mg of EB 24 h after CIDR removal decreased (P<0.02) plasma LH concentrations for 6h, followed by an LH surge at 18 h. In experiment 2, ovary-intact heifers (n=40) received a used CIDR and 5mg of E-17beta+100mg of progesterone on day 0. On day 7, CIDR were removed, PGF given, and heifers received nothing (control) or 1mg of EB 12, 24, or 36 h later. In these groups, plasma LH peaked (mean+/-SEM) 78.0+/-23.0, 37.8+/-8.5, 44.4+/-10.3, and 51.0+/-5.1 h after CIDR removal (means, P<0.001; variances, P<0.001) and intervals from CIDR removal to ovulation were 102.0+/-6.7, 63.6+/-3.6, 81.6+/-3.5, and 78.0+/-4.1h (P<0.05). The interval from CIDR removal to ovulation was shorter and less variable in EB-treated groups; the interval from EB to ovulation was shortest (P<0.05) in the 12-h group. In summary, E-17beta or EB decreased both FSH and LH, but LH increased after 6h (despite elevated progesterone concentrations). Following CIDR removal, 1mg of EB effectively synchronized LH release, and ovulation (in intact cattle), but the interval from CIDR removal to EB treatment affected the time of ovulation.  相似文献   

14.
We investigated whether CIDR-based ovulation-synchronization protocols inhibit secretion of prostaglandin (PG) F2alpha from the uterus in the following luteal phase in non-cycling beef cows. Ten early (a month) postpartum non-cycling Japanese Black beef cows were treated with (1) Ovsynch (GnRH analogue on Day 0, PGF2alpha analogue on Day 7, and GnRH analogue on Day 9; n=3), (2) Ovsynch+CIDR (Ovsynch protocol plus a CIDR for 7 days from Day 0; n=4), or (3) estradiol benzoate (EB) Ovsynch+CIDR (EB on Day 0 in lieu of the first GnRH treatment followed by the Ovsynch+CIDR protocol; n=3). An oxytocin challenge was administered on Day 24 to examine uterine PGF2alpha secretion. Plasma concentrations of 13,14-dihydro-15-keto- PGF2alpha were lower at 30-120 min after oxytocin administration in the Ovsynch+CIDR group and 75 min after administration in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). Plasma progesterone concentrations were higher from Days 1 to 7 in the Ovsynch+CIDR group and from Days 1 to 5 in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). The progesterone concentrations were higher on Days 27 and 29 in both CIDR-treated groups than in the Ovsynch group (P<0.05). In conclusion, in non-cycling beef cows, CIDR-based ovulation-synchronization protocols inhibit uterine PGF2alpha secretion in the following luteal phase and prevent premature luteolysis as is seen with the Ovsynch protocol.  相似文献   

15.
We determined whether a fixed-time AI (TAI) protocol could yield pregnancy rates similar to a protocol requiring detection of estrus, or estrous detection plus TAI, and whether adding a controlled internal device release (CIDR) to GnRH-based protocols would enhance fertility. Estrus was synchronized in 2,598 suckled beef cows at 14 locations, and AI was preceded by 1 of 5 treatments: 1) a CIDR for 7 d with 25 mg of PG F(2alpha) (PGF) at CIDR removal, followed by detection of estrus and AI during the 84 h after PGF; cows not detected in estrus by 84 h received 100 mug of GnRH and TAI at 84 h (control; n = 506); 2) GnRH administration, followed in 7 d with PGF, followed in 60 h by a second injection of GnRH and TAI (CO-Synch; n = 548); 3) CO-Synch plus a CIDR during the 7 d between the first injection of GnRH and PGF (CO-Synch + CIDR; n = 539); 4) GnRH administration, followed in 7 d with PGF, followed by detection of estrus and AI during the 84 h after PGF; cows not detected in estrus by 84 h received GnRH and TAI at 84 h (Select Synch & TAI; n = 507); and 5) Select Synch & TAI plus a CIDR during the 7 d between the first injection of GnRH and PGF (Select Synch + CIDR & TAI; n = 498). Blood samples were collected (d -17 and -7, relative to PGF) to determine estrous cycle status. For the control, Select Synch & TAI, and Select Synch + CIDR & TAI treatments, a minimum of twice daily observations for estrus began on d 0 and continued for at least 72 h. Inseminations were performed using the AM/PM rule. Pregnancy was diagnosed by transrectal ultrasonography. Percentage of cows cycling at the initiation of treatments was 66%. Pregnancy rates (proportion of cows pregnant to AI of all cows synchronized during the synchronization period) among locations across treatments ranged from 37% to 67%. Pregnancy rates were greater (P < 0.05) for the Select Synch + CIDR & TAI (58%), CO-Synch + CIDR (54%), Select Synch & TAI (53%), or control (53%) treatments than the CO-Synch (44%) treatment. Among the 3 protocols in which estrus was detected, conception rates (proportion of cows that became pregnant to AI of those exhibiting estrus during the synchronization period) were greater (P < 0.05) for Select Synch & TAI (70%; 217 of 309) and Select Synch + CIDR & TAI (67%; 230 of 345) cows than for control cows (61%; 197 of 325). We conclude that the CO-Synch + CIDR protocol yielded similar pregnancy rates to estrous detection protocols and is a reliable TAI protocol that eliminates detection of estrus when inseminating beef cows.  相似文献   

16.
The aim of this study was to evaluate whether an additional intramuscular (im) injection of pFSH would increase the embryo production in zebu cows superovulated with a single subcutaneous (sc) pFSH injection. Twenty‐one Nelore cows were treated with a progesterone vaginal implant (Controlled Internal Drug Relased – CIDR B®) and injected im with 2.5 mg estradiol benzoate. Four days later, cows were assigned randomly into three groups and superovulated with pFSH. Groups A and B received single sc injections of 400 and 320 IU, respectively; Group C received multiple im injections of 400 IU in decreasing doses at 12‐h intervals over 4 days. In the morning (07:00 am) of day 3 after starting superovulation, cows received im 150 mcg cloprostenol and Group B was additionally injected im with 80 IU of pFSH. CIDR‐B was withdrawn in the afternoon (07:00 pm). Cows were inseminated 48 and 62 h after the cloprostenol injection. Embryo collection and corpora lutea (CL) estimation were done 7 days after insemination. Alternation of treatments (crossover design) occurred at a 60‐day interval. There was no significant difference (p > 0.05) of CL counts among treatments. The total (transferable and no transferable) number of recovered embryos from Group A (6.9 ± 1.5) was not different from Group C (9.8 ± 1.2), whereas Group B (5.7 ± 1.5) was lower than Group C (p < 0.05). The number of transferable embryos from Groups A (2.4 ± 0.7) and B (1.7 ± 0.6) was lower (p < 0.05) than Group C (4.6 ± 1.2). Lesser (p < 0.05) embryo production from Group B was related to lower recovery rate (46.4%), compared with Groups A (65.1%) and C (81.7%). It was concluded that an additional im subdose of pFSH, injected 48 h after a single subcutaneous (sc) dose of pFSH, does not improve the embryo production in zebu cows.  相似文献   

17.
Direct enzyme immunoassay of progesterone in bovine plasma   总被引：2，自引：0，他引：2  
The present study was undertaken to develop a novel, practical and simple procedure for enzyme immunoassay (EIA) of plasma progesterone in cows. Diluted plasma was heated for 70°C for 30 min and applied directly to wells of a microtitre plate without extraction. Then plasma was incubated with antiprogesterone antibody and horseradish peroxidase‐labeled progesterone. The sensitivity of the assay was estimated as 4.4 pg/mL (0.11 pg/well). The intra‐assay and interassay coefficients of variation were 5.7–19.1% and 6.6–19.3%, respectively. When 0.3, 1 and 3 ng of progesterone were added to plasma, the recovery rates ranged between 79.9 and 108.4%. Only 4 h were needed to complete an assay to measure progesterone concentration. To apply the present direct EIA, progesterone concentration in plasma was assayed in crossbred cows used for the embryo transfer program. During insertion of controlled‐internal drug release (CIDR), progesterone concentrations were kept at a high level, although the removal of CIDR with treatment of dinoprost trometamine reduced progesterone concentration drastically. These results suggest that the present direct EIA is a practical and suitable method for measuring the plasma concentration of progesterone.  相似文献   

18.
The objective of this study was to determine the effect of exogenous progesterone administration at ovulation and during the early development of the CL, on its future sensitivity to a single administration of PGF2a in mares and cows. Horse Retrospective reproductive data from an equine clinic in the UK during three breeding seasons were used. Mares were divided into: control group, cycles with single ovulations; double ovulation group cycles with asynchronous double ovulations; and PRID group: cycles with single ovulations and treatment with intravaginal progesterone device (CIDR) immediately after the ovulation. All mares were treated with d‐cloprostenol (PGF) at either: (i) 88 hr; (ii) 96 hr; (iii) 104 hr; or (iv) 112 hr after the last ovulation. Cattle A total of nine non‐lactating Holstein cows were used. All cows were administered PGF14 d apart and allocated to one of two groups control group GnRH was administered 56 hr after the second PGF administration. CIDR group CIDR was inserted at the same time of GnRH administration. All cows were administered PGF at 120 hr post‐ovulation. The complete luteolysis rate of mares with double ovulation (66.7%) and those treated with exogenous progesterone (68.4%) was significantly higher than the rate of mares with single ovulation (35.6%) at 104 hr. In the cow, however, the treatment with CIDR did not increase the luteolytic response in cows treated at 120 hr post‐ovulation. In conclusion, the degree of complete luteolysis can be influenced by increasing the concentration of progesterone during the early luteal development in mares.  相似文献   

19.
In Exp. 1, 187 lactating beef cows were treated with injections of GnRH 7 d before and 48 h after prostaglandin F2alpha (PGF2alpha; Cosynch) or with Cosynch plus a 7-d treatment with an intravaginal progesterone (P4)-releasing insert (CIDR-B; Cosynch + CIDR). In Exp. 2, 183 lactating beef cows were treated with the Cosynch protocol or with Cosynch plus a 7-d treatment with norgestomet (Cosynch + NORG). In Exp. 1 and 2, blood samples for later P4 analyses were collected on d -17, -7 (first GnRH injection), 0 (PGF2alpha injection), and at timed artificial insemination (TAI; 48 h after PGF2alpha). In Exp. 3, 609 lactating beef cows were treated with the Cosynch + CIDR protocol or were fed 0.5 mg of melengestrol acetate (MGA) per day for 14 d before initiating the Cosynch protocol 12 d after the 14th d of MGA feeding (MGA + Cosynch). Blood samples were collected as in Exp. 1 and 2, plus additional samples on d -33 and -19 before PGF2alpha. In Exp. 4, 360 lactating beef cows were treated with a Cosynch + CIDR protocol, with TAI occurring at either 48 or 60 h after PGF2alpha, while receiving either GnRH or saline to form four treatments. Blood samples were collected as in Exp. 1 and 2. In Exp. 1, addition of P4 reduced the ability of the first GnRH injection to induce ovulation in anestrous cows with low P4 before PGF2alpha but improved (P = 0.06) pregnancy rates (61 vs 66%). In Exp. 2, the addition of NORG mimicked P4 by likewise increasing (P < 0.01) pregnancy rates (31 vs 51%) beyond those after Cosynch. In Exp. 3, the Cosynch + CIDR protocol increased (P < 0.001) pregnancy rates from 46 to 55% compared to the MGA + Cosynch protocol. In Exp. 4, administration of GnRH at TAI improved (P < 0.05) pregnancy outcomes (50 vs 42%), whereas timing of TAI had limited effects. We conclude that a progestin treatment concurrent with the Cosynch protocol improved pregnancy outcomes in all experiments, but pretreatment of cows with MGA was not as effective as the CIDR insert or NORG implants in this Cosynch-TAI model. Most of the improvement in pregnancy rates was associated with the increase in pregnancy rates of anestrous cows, regardless of whether ovulation was successfully induced in response to GnRH 7 d before PGF2alpha. Injection of GnRH at TAI following the Cosynch + CIDR protocol increased pregnancy rates in cycling cows with high P4 before the PGF2alpha injection and in anestrous cows with low P4 before PGF2alpha injection.  相似文献   

20.
Twenty dairy cows with left abomasal displacement were used to investigate the effects of vitamin E and selenium treatment on thiobarbituric acid reactive substances (TBARS) and blood cortisol in dairy cows stressed by omentopexy. The cows were randomly divided into two groups. Ten hours before surgery 6 g of DL‐α‐tocopheryl acetate (6 mg/kg) and 67 mg of natrium selenite (0.1 mg/kg) in volume of 40 ml (Vitaselen®) were administered subcutaneously to 10 cows; the control animals (n = 10) received an equivalent volume of injectable water (40 ml). The injection of vitamin E and selenium produced a rapid rise (p < .05) in blood α‐tocopherol and selenium concentrations. The serum vitamin E increased several times 10 hr after vitamin E and Se injection and raised continuously to the highest average concentration 21.6 mg/L at hr 24 after the surgery. The highest selenium concentration was seen 10 hr after selenium administration with holding the increased concentrations in comparison with initial ones during the whole study. Two‐way ANOVA did not show significant treatment effect on plasma concentrations TBARS in the study. The plasma concentrations of thiobarbituric acid reactive substances reached the maximum value of 0.18 μmol/L in the control group 5 hr after the surgery. Twenty‐four hours after the surgery, the TBARS values returned to the initial ones. Serum cortisol increased in both groups after surgery. The highest cortisol concentrations were reached at 1 hr after surgery in the experimental and control group (56.7 ± 28.8 and 65.3 ± 26.1 μg/L respectively). A return to the levels similar to the initial ones was recognized 24 hr after the surgery. The ANOVA revealed a significant effect of vitamin E and selenium injection on plasma cortisol (p < .05). In conclusion, we have demonstrated that abdominal surgery resulted in typical stress changes with no significant effects of a single vitamin E/Se injection on blood lipid peroxidation. In addition, a weaker cortisol response to the abdominal surgery was recognized in animals treated with vitamin E and selenium.  相似文献   

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