19 THE EFFECT OF PROGESTERONE ON FOLLICULAR DEVELOPMENT AND PREGNANCY RATE IN BEEF CATTLE

2008 ◽  
Vol 20 (1) ◽  
pp. 90 ◽  
Author(s):  
L. F. Pfeifer ◽  
R. Mapletoft ◽  
G. Adams ◽  
J. Kastelic ◽  
J. Small ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Follicular Development ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pulse Frequency ◽  
Dominant Follicle ◽  
Chi Square ◽  
Follicle Diameter ◽  
Student’S T

The objective was to determine the effect of the level of progesterone (P4) during the ovulatory wave on fertility. Low v. high progesterone concentrations which were expected to result in high v. low LH pulse-frequency were compared. Lactating, postpartum beef cows (n = 69) at random stages of the estrous cycle were given cloprostenol (PGF; Schering-Plough Animal Health, Pointe-Claire, QC, Canada) twice at an 11-day interval to synchronize ovulation (Day 0 = day of 2nd PGF). Cows were given 1.5 mg estradiol benzoate on Day 10 (7 days after expected ovulation). On Day 10, the Low-P4 group was given PGF and an intravaginal CueMate (Bioniche Animal Health, Belleville, ON, Canada) containing one P4 pod (expected to achieve a P4 plasma level of 1 ng mL–1). The High-P4 group also received a CueMate with one pod on Day 10, but no PGF was administered (i.e., cows were allowed to retain their CL for 4 days after expected emergence of the estradiol-induced wave). On Day 18, CueMates were removed and PGF was administered to both groups. Fifty-four to 56 h later, all animals received 12.5 mg of Lutropin-V (Bioniche) IM and were timed AI (TAI). Dominant follicle diameter was measured on Day 18 and at the time of AI. Pregnancy diagnosis was done by ultrasonography 27 days after AI to compare fertility between groups. Follicle diameter data were analyzed by Student's t-test and pregnancy rate data were compared by the chi-square test. The dominant follicle in the Low-P4 group was larger (P < 0.05) than in the high-P4 group on the day of the CueMate removal (Day 18) and on the day of the TAI (11.8 � 0.4 and 13.7 � 0.5 v. 13.3 � 0.6 and 15.3 � 0.6 in the High-P4 and Low-P4 groups, respectively). Pregnancy rate was similar (P = 0.16) between the groups (High-P4: 55.6% (20/36) and Low-P4: 44.4% (16/33)); however, a larger study is in progress to confirm these results. To conclude, Low-P4 resulted in a larger dominant follicle without any apparent effect on pregnancy rate. The project was funded by Saskatchewan ADF and NSERC. L. Pfeifer is funded through a CAPES scholarship. We acknowledge Schering-Plough and Bioniche for donation of pharmaceuticals.

scholarly journals 14OVARIAN FOLLICULAR DYNAMICS IN COWS TREATED WITH A CIDR, ESTRADIOL AND PROGESTERONE LATE IN THE ESTROUS CYCLE

2004 ◽  
Vol 16 (2) ◽  
pp. 129 ◽  
Author(s):  
J.P. Kastelic ◽  
M.G. Colazo ◽  
J.A. Small ◽  
D.R. Ward ◽  
R.J. Mapletoft
Keyword(s):  
Estrous Cycle ◽  
Ovarian Follicle ◽  
Animal Health ◽  
Beef Cows ◽  
Control Group ◽  
Dominant Follicle ◽  
Chi Square ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Follicular Dynamics

The objective was to characterize ovarian follicular dynamics in beef cows treated with a CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) and an injection of estradiol-17β (E2), with or without progesterone (P4), late in the estrous cycle. Previously synchronized, non-lactating, crossbred beef cows (n=36) received a CIDR (Day 0) 16 to 18 days after ovulation and were randomly allocated to one of three treatment groups: no further treatment (Control, n=12), an injection of 5mg E2 (E2, n=12), or 5mg E2 plus 100mg P4 (E2P4, n=12; both from Sigma Chemical Co., St.Louis, MO, USA) i.m. in 2mL canola oil. On Day 7, CIDR were removed and cows received 500μg i.m. of cloprostenol (Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada). Ovaries were examined once daily by transrectal ultrasonography to detect ovarian follicle growth profiles, and determine the time of ovulation. Blood samples were taken daily for progesterone determination. Data were analyzed by ANOVA (LSD and Bartlett’s tests), Student’s t-test and chi-square procedures. Diameter of the CL and the dominant follicle, and progesterone concentration on Day 0 did not differ among groups (P=0.6; overall mean (±SD), 16.8±2.7mm, 14.1±2.0mm, and 1.5±1.9ngmL, respectively). Thirteen cows ovulated within 3 days of treatment (50% of E2- and E2P4-treated cows and 8.3% of Control cows; P=0.05); cows that ovulated had smaller CL diameters (15.2±1.7 v. 17.7±2.7mm; P&lt;0.004) and lower progesterone concentrations (0.4±0.2 v.2.1±2.2ngmL; P&lt;0.001) at the time of treatment. Follicular wave emergence occurred within 7 days in 4/12 Control cows, 10/12 E2-treated cows, and 10/12 E2P4-treated cows (P&lt;0.01). Although the interval from treatment to wave emergence did not differ among treatments (P=0.8; overall, 3.4±1.5 days), follicular wave emergence was more synchronous (P&lt;0.004) in the E2 group than in the Control or E2P4 groups. At CIDR removal, dominant follicle diameter was larger (P&lt;0.02) in the Control group (15.9±5.5mm) than in the E2 (11.9±1.8mm) or E2P4 (11.5±3.4mm)groups, but dominant follicle diameter was less variable (P&lt;0.003) in the E2 group than in the other two groups. Three cows did not ovulate after CIDR removal; two in the Control group and one in the E2P4 group. Interval to ovulation was shorter (P&lt;0.05) in the Control group (70.8±10.5h)than in the E2 (87.0±9.0h) or E2P4 (86.2±7.2h) groups, and the intervals to ovulation in cows that ovulated following treatment (91.0±8.0h) was longer (P&lt;0.001) than in those that did not (76.6±9.6h). In summary, treatment of cows with an estradiol-progesterone protocol late in the estrous cycle resulted in ovulation (50.0%), atresia (33.3%) or persistence (16.6%) of the dominant follicle present at that time. As length of follicular dominance and timing of ovulation were affected, fertility may be impaired following AI.

scholarly journals Effect of injectable progesterone on follicular development in lactating beef cows treated with estradiol plus a low-concentration progesterone device

2018 ◽  
Vol 55 (2) ◽  
pp. e136924
Author(s):  
Luiz Francisco Machado Pfeifer ◽  
Reuben John Mapletoft ◽  
Dinesh Dardawal ◽  
Jaswant Singh
Keyword(s):  
Canola Oil ◽  
Animal Health ◽  
Follicular Development ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Crossover Design ◽  
Dominant Follicle ◽  
Device Removal ◽  
Progesterone Concentration ◽  
Ovulatory Follicle

The effect of injectable progesterone was evaluated along with estradiol benzoate (EB) on the fate of the dominant follicle (DF) present in the ovary at the beginning of low progesterone-based TAI protocol. All cattle were given 500 µg cloprostenol im (PGF; Schering-Plough Animal Health for Estrumate, Pointe-Claire, QC, Canada) twice, 11 d apart, and allocated into two groups: Estradiol group (E group, n = 11) and Estradiol-Progesterone group (EP group, n = 11). Ten days after the second PGF (Day 0), all cattle were given an intravaginal progesterone device with half progesterone concentration (Cue-Mate with a single pod containing 0.78 g progesterone). Concurrently, all cattle were given 1.5 mg im of estradiol benzoate in 3 mL of canola oil and PGF im on Day 0 of the protocol in a crossover design, in which each cow received both treatments. Cows in the EP group also received 100 mg im progesterone (Sigma) in 2 mL of canola oil. On Day 8, progesterone devices were removed and all cattle were given PGF im. All statistical analyses were performed with SAS 9.0. The DF present on Day 0 ovulated in 76% (16/21) of cows from E group and 28.6% (6/21) of cows from EP group (P = 0.002). After progesterone device removal, the size of ovulatory follicle did not differ between groups (E group, 15.5 ± 0.43 mm vs EP group, 15.8 ± 0.98 mm; P = 0.82). These follicles ovulated in 81.3 ± 3.1 h in E group and 71.0 ± 6.1 h in EP group (P = 0.13). In conclusion, injectable progesterone reduced the proportion of cows that ovulate the dominant follicle present in the ovary at the beginning of estradiol-progesterone-based protocols. However, no difference was detected on time of ovulation after progesterone device removal between groups.

scholarly journals 11THE EFFECT OF PRESYNCHRONIZATION ON PREGNANCY RATE TO FIXED-TIME AI IN BEEF HEIFERS SUBJECTED TO A COSYNCH PROTOCOL

2004 ◽  
Vol 16 (2) ◽  
pp. 128 ◽  
Author(s):  
M.G. Colazo ◽  
J.A. Small ◽  
D.R. Ward ◽  
N.E. Erickson ◽  
J.P. Kastelic ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Fixed Time ◽  
Control Group ◽  
Preovulatory Follicle ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Chi Square ◽  
Student’S T ◽  
Student’S T Test

The objective was to investigate the effect of presynchronization with PGF prior to a Cosynch protocol on estrus synchrony, CL and preovulatory follicle diameters and pregnancy rate following timed-AI (TAI) in beef heifers. Cycling beef heifers (n=148) were treated with 100μg GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada) on Day 0, 500μg cloprostenol i.m. (PGF; Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada) on Day 7, and GnRH concurrent with TAI on Day 9 (54h after PGF). Half of the heifers (Control) received the first GnRH treatment at random stages of the estrous cycle, while the other half (Presynch) received two injections of PGF 11 days apart, with the first injection of GnRH 11 days after the second injection of PGF. Estrus detection was done between the first GnRH and 12h after PGF, and heifers detected in estrus were inseminated (and considered nonpregnant to TAI), while all other heifers were TAI. Heifers were examined by transrectal ultrasonography for CL and follicle development, and confirmation of pregnancy. Data were compared between groups using Student’s t-test and chi-square procedures. The numbers of heifers in estrus early (after first GnRH and before TAI) was higher in the Control group than in the Presynch group (18/74 v. 2/74, respectively; P&lt;0.0001). Mean (±SD) diameters of the dominant follicle (12.1±3.1 v. 14.2±2.5mm) and CL (17.3±5.5v. 20.5±4.3mm) at first GnRH injection were smaller (P&lt;0.0001) and more variable (P&lt;0.03) in Control than Presynch heifers, but diameters of the preovulatory follicle (P=0.3) and CL (P=0.1) at TAI did not differ. Although the diameter of the preovulatory follicle was more variable (P&lt;0.004) in Control (5 to 19mm) than Presynch (8 to 17mm) heifers, pregnancy rate to TAI did not differ (P=0.4; 29.7 v. 36.5%, respectively). Overall pregnancy rates were 45.9 and 37.8% for Control and Presynch groups, respectively (P=0.3). Pregnancy rate tended (P&lt;0.08) to be affected by diameter of the preovulatory follicle at the time of TAI (0, 23.1, 45.7, 41.4, and 60.0% pregnant for diameters of &lt;9, 9–11, 12–14, 15–17, and &gt;17mm, respectively). Regardless of treatment, diameter of the preovulatory dominant follicle (P&lt;0.02) and CL (P&lt;0.03) 7 days after TAI was smaller, and CL diameter was more variable (P&lt;0.004), in open than in pregnant heifers (12.7±2.6v. 13.8±2.1mm, and 16.5±4.4v. 18.0±3.0mm, respectively). In summary, presynchronization with PGF prior to a Cosynch protocol reduced the proportion of heifers in estrus before TAI, suggesting that this approach may be useful in the successful application of Ovsynch or Cosynch programs in heifers. However, pregnancy rate to TAI did not differ between groups in this study. Diameter of the preovulatory follicle tended to positively affect pregnancy rate, regardless of treatment.

scholarly journals 183PREGNANCY RATE FOLLOWING TRANSFER OF IN VITRO- AND IN VIVO-PRODUCED BOVINE EMBRYOS TO LH-TREATED RECIPIENTS

2004 ◽  
Vol 16 (2) ◽  
pp. 213 ◽  
Author(s):  
J. Small ◽  
M. Colazo ◽  
D. Ambrose ◽  
R. Mapletoft ◽  
J. Reeb ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Animal Health ◽  
Beef Cows ◽  
Water Bath ◽  
Bovine Embryos ◽  
Chi Square ◽  
Embryo Survival ◽  
Frozen Embryos

The objective was to evaluate the effect of pLH treatment on pregnancy rates in recipients receiving in vivo- or in vitro-produced bovine embryos. Heifers (n=37) and lactating (n=28) and non-lactating (n=150) beef cows were treated at random stages of the cycle with 100μg GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada) on Day −9, 500μg cloprostenol i.m. (PGF; Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada) on Day —2 and GnRH on Day 0 (66h post-PGF; without estrus detection). Cattle were placed at random, by class, into three groups: no further treatment (Control; n=71), or 12.5mg pLH (Lutropin-V, Bioniche Animal Health, Belleville, Ontario, Canada) on Day 5 (n=72) or on Day 7 (n=72) after the second GnRH. On Day 7, cattle with a CL &gt;10mm in diameter (determined ultrasonically) received in vivo-produced, fresh (Simmental) or frozen (Holstein), or in vitro-produced frozen (Holstein) embryos (embryo type balanced among groups). Embryos were cryopreserved in 10% ethylene glycol; in vivo-produced frozen embryos were thawed 5 to 10s in air, 15s in a water-bath at 30°C and then “direct-transferred” nonsurgically. In vitro-produced frozen embryos (donated by IND Lifetech Inc., Delta, British Columbia, Canada) were thawed in a water-bath at 27°C for 10s and placed in ViGro Holding Plus medium (AB Technology, Pullman, WA, USA) at room temperature, evaluated and then transferred nonsurgically. Pregnancy was determined by ultrasonography on Day 35. Data were analyzed with CATMOD, chi-square and GLM procedures (SAS Institute, Cary, NC, USA.). Twenty cattle (9.3%) did not receive embryos; five heifers had cervical problems, and five heifers and 10 cows did not have a CL &gt;10mm. Overall, 7.1% of the recipients had two CL on the day of embryo transfer. There was no effect (P&gt;0.05) of treatment, embryo type (or interaction) or class of recipient on pregnancy rate (overall, 44.1%, 86/195; Table 1). Similarly, mean (±SD) CL diameter and luteal area did not differ (P&gt;0.05) among groups or between pregnant and open recipients (overall, 22.0±3.4mm and 352.0±108.7mm, respectively). However, recipients with a CL diameter ≥18mm tended (P&lt;0.1) to have a higher pregnancy rate (45.8 vs 25.0%). In a subset of 40 recipients examined ultrasonically on Day 12, 50% of those treated on Day 5 and 70% of those treated with pLH on Day 7 had two CL. In summary, overall pregnancy rate in GnRH-synchronized recipients receiving in vitro- or in vivo-produced embryos by nonsurgical transfer was 44.1%. Embryo survival to Day 35 was not affected by type of embryo or treatment with pLH 5 or 7 days after ovulation. Table 1 Pregnancy rate in recipients on Day 35 based on pLH treatment and embryo-type

251 FOLLICLE DEVIATION AND OVULATORY CAPACITY IN BOS INDICUS HEIFERS

2007 ◽  
Vol 19 (1) ◽  
pp. 242 ◽  
Author(s):  
L. U. Gimenes ◽  
N. A. T. Carvalho ◽  
M. F. Sá Filho ◽  
H. Ayres ◽  
J. R. S. Torres-Júnior ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Animal Health ◽  
Bos Indicus ◽  
Estradiol Benzoate ◽  
Transrectal Ultrasonography ◽  
Holstein Cows ◽  
Second Phase ◽  
Chi Square ◽  
Follicle Diameter ◽  
Two Phases

In Holstein cows, the diameter of the dominant follicle (DF) at the time of follicle deviation is 8.5 mm and the subordinate follicle (SF) is 7.2 mm (Ginther et al. 1996 Biol. Reprod. 55, 1187–1194). However, follicular responsiveness to an ovulatory treatment occurs only with 10.0-mm-diameter follicles (Sartori et al. 2001 Biol. Reprod. 65, 1403–1409). The current study tested the hypothesis that, in Bos indicus (Nelore and crossbred Nelore � Gir) females, the follicular diameters at the time of deviation and ovulation responsiveness are smaller than those in Holstein cows. The experiment was performed in two phases. In the first phase, 12 Nelore heifers were previously synchronized with a protocol using progestagen and estradiol benzoate. After implant removal, all heifers were evaluated by transrectal ultrasonography (Aloka SSD-500, Tokyo, Japan) every 12 h until Day 5 of the estrous cycle (Day 0 = Day of the ovulation) to assess the time of ovulation, the time of follicle deviation, and the follicular diameter at the deviation. In the second phase, 29 Bos indicus heifers (Nelore and crossbred Nelore � Gir) were previously synchronized with the same protocol as cited above. After the ovulations (Day 0), the follicles were evaluated by transrectal ultrasonography every 24 h, until they reached the diameter of 7.0–8.4 mm (n = 9); 8.5–10.0 mm (n = 10); and &gt;10.0 mm (n = 10). In order to assess the ovulatory capacity, all animals were treated with 25 mg of LH (Lutropin-V�; Bioniche Animal Health, Inc., Belleville, Ontario, Canada) at these follicle diameter ranges. After the LH treatment, all animals were monitored by ultrasonography every 12 h for 48 h. ANOVA, Bartlett, and chi-square tests were used in the statistical analyses. In the first phase, the diameters of the DF and SF at the time of follicular deviation (61.9 � 4.9 h after ovulation) were 6.2 � 0.2 and 5.8 � 0.2 mm, respectively. In the second phase, the the average follicular diameters at the time of LH administration in the groups 7.0–8.4 mm, 8.5–10.0 mm, and &gt;10.0 mm were 7.6a � 0.1 mm, 9.6b � 0.1 mm, and 10.9c � 0.2 mm; and their ovulation rates were 33.3%a (3/9), 80.0%b (8/10), and 90.0%b (9/10), respectively (P &lt; 0.05). The interval from LH treatment to ovulation was 38.0 � 4.0 h, 31.5 � 2.7 h, and 30.0 � 2.0 h, respectively (P &gt; 0.05). In conclusion, in Bos indicus heifers, follicle deviation occurred with smaller diameters than previously reported in Bos taurus breeds. In addition, Bos indicus heifers are able to ovulate in response to 25 mg of LH with smaller diameters compared to those of Bos taurus breeds. Moreover, in Bos indicus heifers, ovulatory capacity is acquired by follicles as small as 7.0–8.4 mm, but this responsiveness significantly increases after follicles reach 8.5–10.0 mm. This work was supported by FAPESP (Proc:03/10203-4); Bioniche Animal Health, Inc., Belleville, Ontario, Canada; and Tecnopec, S�o Paulo, Brazil.

scholarly journals 13 EFFECTS OF PRESYNCHRONIZATION WITH A USED CIDR, AND TREATMENT WITH eCG ON FERTILITY IN LACTATING COWS SUBJECTED TO A COSYNCH PROTOCOL

2005 ◽  
Vol 17 (2) ◽  
pp. 156 ◽  
Author(s):  
M. Colazo ◽  
M. Rutledge ◽  
J. Small ◽  
J. Kastelic ◽  
L. Siqueira ◽  
...  
Keyword(s):  
Factorial Design ◽  
Pregnancy Rate ◽  
Animal Health ◽  
Beef Cows ◽  
Preovulatory Follicle ◽  
Dominant Follicle ◽  
Treatment Control ◽  
Lactating Cows ◽  
Follicle Size ◽  
To Receive

The objectives were to investigate the effects of pretreatment with a used CIDR on follicle size and ovulation rate in cows after an injection of GnRH, and treatment with eCG at the time of PGF on preovulatory follicle size and fertility in cows subjected to a Cosynch protocol. Lactating crossbred beef cows (n = 292), 2 to 12 years of age were allocated to two groups to receive either a used CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) for 15 days or no treatment (Control). At CIDR removal (Day 0), all cows received 100 μg of GnRH i.m. (Cystorelin, Merial Canada Inc., Victoriaville, Quebec, Canada). On Day 7, all cows received 500 μg of cloprostenol i.m. (PGF; Estrumate, Schering-Plough Animal Health, Pointe-Claire, Quebec, Canada) and were further allocated to receive either 400 IU of eCG i.m. (Pregnacol; Bioniche Animal Health) or no treatment (2 × 2 factorial design; n = 73 per group). On Day 9 (54 h after PGF), cows were given 100 μg of GnRH i.m., concurrent with timed AI (TAI). Transrectal ultrasonographic examinations were done on a subset of approximately 40 cows in each group on Days −15, 0, 7, and 9 to assess ovarian structures, and on all cows on Day 37 to confirm pregnancy. Data were analyzed by SAS CATMOD and ANOVA. Overall, 53% of cows had a CL present on Day −15 (P = 0.23). At first GnRH (Day 0), fewer CIDR-treated cows than Control cows had a CL (15.2 vs. 85.0%, respectively; P < 0.001), while mean (± SEM) diameters of the dominant follicle were larger in CIDR-treated cows (18.2 ± 0.4 vs. 13.8 ± 0.4 mm, respectively; P < 0.001). Moreover, the proportion of cows that ovulated following the first GnRH was higher (P < 0.001) in CIDR-treated (75.0%) than Control (48.7%) cows. Eight (10.0%) cows presynchronized with a CIDR did not ovulate and had a luteinized follicle (31.7 ± 1.9 mm) at the time of PGF. Although CIDR-treated cows had larger (P < 0.002) dominant follicles than Control cows on Day 9 (16.6 ± 0.3 vs. 15.2 ± 0.3 mm), presynchronization did not affect fertility (53.4 vs. 54.1%, respectively). However, diameter of the dominant follicle at TAI in cows that became pregnant was smaller in CIDR-treated vs. Control cows (15.3 ± 0.3 vs. 16.6 ± 0.3; P < 0.005). Treatment with eCG on Day 7 did not affect (P = 0.17) the diameter of the dominant follicle at TAI, but tended (P = 0.06) to increase pregnancy rate (58.9 vs. 48.6%). Furthermore, pregnancy rate tended to be higher (P = 0.08) in Control cows given eCG (47/73, 64.4%) than in the Control- (32/73, 43.8%), CIDR- (39/73, 53.4%) or CIDR/eCG- (39/73, 53.4%) treated cows. In addition, pregnancy rate was affected by parity; 2-yr-old cows had a lower (P < 0.04) pregnancy rate than older cows (42.9, 58.7, and 58.2% for 2, 3–4, and >5 years, respectively). Treatment with eCG increased pregnancy rate by 33% (P < 0.03) in 2-yr-old Control cows. In summary, presynchronization with a used CIDR prior to a Cosynch protocol increased the proportion of cows responding to the first GnRH. Although CIDR-treated cows had a smaller dominant follicle at TAI, pregnancy rate was not affected. Treatment with eCG increased fertility in Control cows; eCG may be useful in GnRH-based protocols in lactating beef cows.

scholarly journals 15EFFECT OF DOSE OF ESTRADIOL VALERATE ON OVARIAN FOLLICULAR DYNAMICS IN CIDR-TREATED BEEF COWS

2004 ◽  
Vol 16 (2) ◽  
pp. 130 ◽  
Author(s):  
R.J. Mapletoft ◽  
M.G. Colazo ◽  
J.A. Small ◽  
D.R. Ward ◽  
J.P. Kastelic
Keyword(s):  
Ovarian Follicle ◽  
Animal Health ◽  
Beef Cows ◽  
Estradiol Valerate ◽  
Control Group ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Follicle Diameter ◽  
Growth Profiles ◽  
Follicular Dynamics

The objective was to investigate the effect of dose of estradiol valerate (EV) on ovarian follicular growth profiles, intervals to follicular wave emergence and, following CIDR removal, estrus and ovulation in beef cows. On Day 0, 43 non-lactating, crossbred beef cows, 3 to 9 yr of age and at random stages of the estrous cycle, received a CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) and were randomly allocated to one of four groups to receive no further treatment (Control; n=10), or an injection of 1mg (n=11), 2mg (n=10), or 5mg (n=12) i.m. of EV (Sigma Chemical Co, St. Louis, MO, USA) in 2mL canola oil. On Day 7, CIDR were removed and cows received 500μg i.m. of cloprostenol (Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada). Ovaries were examined by transrectal ultrasonography once daily until 48h after CIDR removal to detect ovarian follicle growth profiles, and twice daily thereafter to detect ovulation. Data were analyzed by ANOVA (LSD and Bartlett’s tests) and chi-square procedures. One cow (5mg EV group) lost the CIDR and was removed from all analyses. There was an effect of day (P&lt;0.0001) on CL diameter, but the effects of treatment (P=0.3), and the treatment-by-day interaction (P=0.1), were not significant. Follicular wave emergence occurred within 7d in 7/10 (70%) Control cows and 31/32 (97%; P&lt;0.04) EV-treated cows (one cow in late diestrus at the time of treatment did not respond to 1mg EV). Mean (±SD) interval from treatment to wave emergence was longer (P&lt;0.03) in cows treated with 5mg EV (4.8±1.2d) than in those treated with 1mg (3.2±0.9 days) or 2mg EV (3.4±0.8 days), while Control cows were intermediate (3.8±2.0 days). Although follicular wave emergence tended (P&lt;0.09) to be more synchronous in cows receiving EV, intervals from CIDR removal to estrus (P=0.7) and ovulation (P=0.8) did not differ among groups. Diameter of the dominant follicle was smaller (P&lt;0.04) at CIDR removal and tended to be smaller (P&lt;0.08) just prior to ovulation in the 5mg EV group (8.5±2.2 and 13.2±0.6mm, respectively) than in the Control (11.8±4.6 and 15.5±2.9mm, respectively) or 1mg EV (11.7±2.5 and 15.1±2.2mm, respectively) groups, with the 2mg EV group (10.7±1.5 and 14.3±1.7mm, respectively) intermediate. Diameter of the dominant follicle at CIDR removal was less variable (P&lt;0.01) in the 2 and 5mg EV groups than in the Control group and intermediate in the 1mg EV group. In summary, dose of EV affected follicular dynamics, interval to and synchrony of follicular wave emergence, and dominant follicle diameter at CIDR removal and just prior to ovulation in CIDR-treated cows. However, interval from CIDR removal to estrus and ovulation was not affected by treatment. Results suggest that a dose of 2mg EV may be most efficacious in synchronizing follicular wave emergence in CIDR-treated cows.

scholarly journals Calving sub-season and reproductive efficiency of beef cows

2010 ◽  
Vol 39 (10) ◽  
pp. 2182-2186
Author(s):  
Cristiane Reinher ◽  
Júlio Otávio Jardim Barcellos ◽  
Vanessa Peripolli ◽  
Ênio Rosa Prates ◽  
Maria Eugênia Andrighetto Canozzi
Keyword(s):  
Pregnancy Rate ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Reproductive Efficiency ◽  
Climate Variations ◽  
Southern Brazil ◽  
Chi Square ◽  
Chi Square Test

It was evaluated in this work the effect of calving sub-season on the pregnancy rate of 7,726 multiparous Hereford beef cows grazing on natural pastures in southern Brazil, from 1994 to 2007. Calving sub-season periods were divided in 20-day intervals from August 12th to 31st; from September 1st to 20th; from September 21st to October 10th; from October 11th to 31st; from November 1st to 20th. Calving in each sub-season and pregnancy rate (PR) were analyzed by the Chi-square test. Overall means of each sub-season were 92.7% (from August 12th to 31st), 90.6% (from September 1st to 20th), 82.1% (from September 21st to October 10th), 77.7% (from October 11th to 31st), and 70.6% (from November 1st to 20th). Calving sub-season significantly influenced pregnancy rate. Cows which calved in the initial sub-season showed higher pregnancy rates than cows which calved from the fourth calving sub-season. However this difference did not occur in 1999 and in 2007 since calving rates did not statistically differ among the five sub-seasons. In 1998 and 2004, calving rates were lower and the effects of calving sub-season on pregnancy rates were higher, possibly due to climate variations. In general, pregnancy rate decreases as calving occurs later in the year, particularly in years when the weather adversely affects pasture growth.

scholarly journals The Effect of A PRID®Delta-Based Estrus Synchronization Protocol On Pregnancy Rates In Cows With No Estrus Symptoms

2022 ◽  
Author(s):  
Murat Can Demir ◽  
Cihan Kaçar ◽  
Umut Çağın Arı ◽  
Semra Kaya ◽  
Oğuz Merhan ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Prostaglandin F2α ◽  
Pregnancy Rates ◽  
Dominant Follicle ◽  
Serum Progesterone ◽  
Blood Samples ◽  
Follicle Diameter ◽  
Follicle Size ◽  
Equine Chorionic Gonadotropin

Abstract The present study aimed to determine the effects of progesterone-based gonadotropin-releasing hormone (GnRH), prostaglandin F2α (PGF2α), and equine chorionic gonadotropin (eCG) injections on progesterone profiles and pregnancy rates in cows with no estrus symptoms within 60 days after parturition. A total of 80 cows were included in the study. All animals had the progesterone-releasing device PRID®Delta placed intravaginally for nine days with an injection of GnRH. On the eighth day, PGF2α was injected, and PRID®Delta was removed from the vagina on day nine. Artificial insemination was carried out 60 hours after PRID®Delta removal. In half of the animals (n = 40), 600 IU of eCG was injected when PRID®Delta was removed on the ninth day before artificial insemination 60 hours later. Blood samples were taken from the tail vein on days 0 and 8 to determine progesterone levels. The pregnancy rate in the group that received eCG was 37.5%, while it was 27.5% in those that did not (P = 0.4). While the dominant follicle diameter was 15.5 mm in cows injected with eCG during timed artificial insemination, the follicle diameter was 12.4 mm in cows with no eCG injection (P <0.001). There were no differences in serum progesterone values in blood samples taken until the time of artificial insemination. However, progesterone values in the blood taken during artificial insemination were 0.94 ng/ml in the eCG- group and 0.72 ng/ml in the eCG+ group (P <0.05). As a result, it was determined that eCG injections, in addition to progesterone-based GnRH and PGF2α applications, increased the pregnancy rates in cows without symptoms of estrus. The dominant follicle diameter was larger in cows treated with eCG during artificial insemination; however, follicle size did not increase the pregnancy rate.

13 EFFECTS OF PLASMA PROGESTERONE CONCENTRATIONS ON LH RELEASE AND OVULATION IN BEEF CATTLE GIVEN GnRH

2006 ◽  
Vol 18 (2) ◽  
pp. 115
Author(s):  
H. Davis ◽  
M. Colazo ◽  
M. Rutledge ◽  
J. Small ◽  
J. Kastelic ◽  
...  
Keyword(s):  
Animal Health ◽  
Beef Cows ◽  
Dominant Follicle ◽  
Plasma Progesterone ◽  
Lactating Cows ◽  
Significant Difference ◽  
Prostaglandin F ◽  
Pfizer Animal Health ◽  
Lh Release ◽  
To Receive

Two experiments were conducted to determine the effects of plasma progesterone (P4) concentrations on LH release and ovulation in beef heifers and lactating beef cows given gonadotropin-releasing hormone (GnRH). Previously autoclaved, once-used CIDR inserts (Colazo et al. 2004 Anim. Reprod. Sci. 81, 25-34) were used for experimental purposes to induce differential plasma progesterone concentrations. In Experiment 1, postpubertal heifers received 25 mg of dinoprost i.m. (prostaglandin F (PGF); Lutalyse; Pfizer Animal Health, Montreal, Quebec, Canada). On Day 4 (estrus = Day 0), heifers were randomly assigned (10/group) to receive no treatment (control) or 1 or 2 autoclaved once-used CIDR (Pfizer Animal Health) inserts (1CIDR and 2CIDR, respectively). On Day 5, heifers in the 1CIDR group were given PGF twice 12 h apart. On Day 6, all heifers received 100 �g of GnRH i.m. (Cystorelin; Merial Canada, Inc., Victoriaville, Quebec, Canada). Once daily on Days 4 to 9, a blood sample was collected and ultrasonography was performed. On Day 6, heifers in the control (3.0 � 0.4 ng/mL; mean � SD) and 1CIDR groups (3.0 � 0.3 ng/mL) had lower (P < 0.01) plasma progesterone concentrations than those in the 2CIDR group (5.7 � 0.4 ng/mL). However, the diameter of the dominant follicle was larger (P < 0.001) in heifers in the control and 1CIDR groups than in the 2CIDR group (12.1 � 1.0, 11.5 � 0.7, and 10.1 � 0.7 mm, respectively). More (P < 0.01) heifers ovulated in response to GnRH in the control and 1CIDR groups than in the 2CIDR group (10/10, 9/10, and 3/10, respectively). In Experiment 2, ultrasound-guided follicular ablation (FA) was performed (to synchronize ovarian follicular wave emergence) 4 to 6 days after estrus in 20 postpubertal heifers and 20 mature lactating cows. Cattle were randomly and equally assigned to receive an autoclaved, once-used CIDR, either with no further treatment (High-P4) or with two PGF treatments 12 h apart (Low-P4) given after FA. All cattle received 100 �g of GnRH either 6 days after FA or the day after the dominant follicle reached 9 mm in diameter. Ultrasonography was performed daily (from 4 days after FA to ovulation or to 3 days after GnRH treatment). In three cows and three heifers per group, blood samples were collected every 30 min for 12 h after GnRH. The dominant follicle at GnRH treatment was larger in cows than heifers (11.0 � 1.1 vs. 10.3 � 0.9 mm, respectively; P = 0.05) and tended to be smaller in the High-P4 group vs. the Low-P4 group (10.3 � 1.0 vs. 11.0 � 1.0 mm; P = 0.06). Ovulatory response was not different (P = 0.9) between heifers (77.7%) and cows (78.9%), but combined for heifers and cows, was lower in High-P4 vs. Low-P4 cattle (61.1 vs. 94.7; P < 0.01). The GnRH-induced LH surge did not differ (P = 0.23) between cows and heifers, but it was lower and of shorter duration (P < 0.001) in the High-P4 group than in the Low-P4 group. In summary, higher plasma P4 concentrations resulted in decreased LH release and the proportion of cattle ovulating in response to GnRH treatment. There was no significant difference between heifers and cows in LH release or ovulatory response.

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