233 Estrus Response and Pregnancy Rates of Beef Replacement Heifers Enrolled in Two Fixed-time Artificial Insemination Protocols, with or Without Pre-synchronization

Abstract Pre-synchronization strategies with prolonged exposure to exogenous progesterone have the potential to alter estrus expression and improve fertility in replacement beef heifers. The objective of this study was to evaluate the estrus response and pregnancy rate of beef heifers enrolled in two fixed-time artificial insemination (TAI) protocols. A total of 306 heifers (14 ± 2 months of age; 372 ± 24 kg body weight [BW]) at three locations were enrolled in the study. Within location, heifers were stratified by age and BW and randomly assigned to one of two treatments: 1) PG-CIDR54 (n = 152), heifers were administered prostaglandin F2α (PGF; 25 mg) and a controlled internal drug releasing (CIDR) insert (Day -14), an injection of GnRH [100 μg (Day -7)], PGF injection and CIDR removal (Day 0), and a second injection of GnRH concurrently with TAI 54 ± 2 h later (Day 2); 2) 7-day CO-Synch+CIDR (CTRL; n = 154), heifers were administered GnRH (100 μg) and a CIDR insert (Day -7), PGF (25 mg) injection and CIDR removal (Day 0), and a second injection of GnRH concurrently with TAI 54 ± 2 h later (Day 2). All heifers received an estrus alert patch on Day 0 and were evaluated for patch activation at TAI on Day 2. Pregnancy was diagnosed by transrectal ultrasonography between 35 and 55 days after TAI. The percentage of heifers exhibiting estrus between Day 0 and 2 was greater (P < 0.01) in PG-CIDR54 compared with CTRL (77.0 and 39.6%, respectively). In addition, pregnancy rate to TAI tended (P = 0.08) to be greater for PG-CIDR54 compared with CTRL (48.0 and 38.3%, respectively). We conclude that beef heifers enrolled in the PG-CIDR54 protocol had increased estrus expression and tended to have greater pregnancy rate when compared with heifers enrolled in the 7-day CO-Synch+CIDR protocol.

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130 Presynchronization with Prostaglandin F2αand prolonged exposure to exogenous progesterone impacts estrus expression and alters fertility in beef heifers

Journal of Animal Science ◽

10.1093/jas/skz397.043 ◽

2020 ◽

Vol 98 (Supplement_2) ◽

pp. 19-20

Author(s):

Nicola Oosthuizen ◽

Pedro Fontes ◽

Cliff Lamb

Keyword(s):

Prolonged Exposure ◽

Prostaglandin F2α ◽

Fixed Time ◽

Pregnancy Rates ◽

Beef Heifers ◽

Randomized Design ◽

Estrus Detection ◽

Completely Randomized Design ◽

Estrus Response ◽

Exogenous Progesterone

Abstract To determine the effects of 2 presynchronization strategies in conjunction with delayed fixed-time artificial insemination (TAI) on pregnancy rates to TAI (PR/AI), 1,700 Angus beef heifers at 3 locations were enrolled in a completely randomized design with a 2×2 factorial arrangement of treatments. Within location, all heifers were randomly assigned to 1 of 4 treatments: 1) PG54 (n = 434), heifers received a 25-mg injection of prostaglandin F2α (PGF) 7 d prior (d -14) to the initiation of the 7-d CO-Synch + CIDR protocol wherein they received a 100-µg injection of gonadotropin-releasing hormone (GnRH) and a CIDR insert on d -7, a 25-mg injection of PGF at CIDR removal on d 0, and a second injection of GnRH concurrently with TAI 54±2 h later; 2) PG72 (n = 426), heifers were exposed to the same treatment as PG54; however, TAI was performed 72 ± 2 h after CIDR removal; 3) PG-CIDR54 (n = 422), same as PG54 but heifers received a CIDR insert on d -14 in addition to PGF; 4) PG-CIDR72 (n = 418), same as PG-CIDR54; however, TAI was performed 72±2 h after CIDR removal. Estrus detection patches were applied to all heifers on d 0 and were evaluated for activation at TAI. Pregnancy was diagnosed between 30 and 47 d after TAI. The percentage of heifers exhibiting estrus between d 0 and TAI was greater (P < 0.001) in the PG72, PG-CIDR54, and PG-CIDR72 treatments compared to the PG54 treatment (78.11, 86.59, and 91.09 vs. 31.05%, respectively). Furthermore, estrus response was greater (P < 0.001) in PG-CIDR72 heifers when compared to PG72. Pregnancy rates to TAI differed among treatments and were greater (P < 0.05) in the PG72 and PG-CIDR54 treatments when compared to PG-CIDR72 (48.8 and 50.4 vs. 38.4%, respectively), and were greater (P = 0.034) in PG-CIDR54 vs. PG54 (43.1%). Moreover, a tendency (P = 0.097) was determined on PR/AI between PG54 and PG72. In conclusion, presynchronization strategies and prolonged exposure to exogenous progesterone have the potential to alter estrus expression and improve fertility in replacement beef heifers.

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129 Presynchronization with Prostaglandin F2αand prolonged exposure to exogenous progesterone impacts estrus expression and alters fertility in beef heifers

Journal of Animal Science ◽

10.1093/jas/skz397.094 ◽

2020 ◽

Vol 98 (Supplement_2) ◽

pp. 41-41

Author(s):

Nicola Oosthuizen ◽

Pedro Fontes ◽

Cliff Lamb

Keyword(s):

Prolonged Exposure ◽

Prostaglandin F2α ◽

Fixed Time ◽

Pregnancy Rates ◽

Beef Heifers ◽

Randomized Design ◽

Estrus Detection ◽

Completely Randomized Design ◽

Estrus Response ◽

Exogenous Progesterone

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13 USE OF EQUINE CHORIONIC GONADOTROPIN OR FOLLICLE-STIMULATING HORMONE-LUTEINIZING HORMONE AT IMPLANT REMOVAL OR AT FIXED-TIME ARTIFICIAL INSEMINATION TIME IN PREGNANCY RATE OF SUCKLED NELLORE COWS

Reproduction Fertility and Development ◽

10.1071/rdv27n1ab13 ◽

2015 ◽

Vol 27 (1) ◽

pp. 99

Keyword(s):

Pregnancy Rate ◽

Artificial Insemination ◽

Bos Indicus ◽

Prostaglandin F2α ◽

Fixed Time ◽

Pregnancy Rates ◽

Implant Removal ◽

Transrectal Ultrasonography ◽

Follicular Growth ◽

The Difference

Use of eCG as an inducer of follicular growth has improved the efficacy of fixed-time artificial insemination (FTAI) protocols and increased the ovulatory responses and pregnancy rates in beef cattle with low body condition scores (BCS) or are recently postpartum and anestrous. However, there are other gonadotropins such as FSH in different commercial applications (Pluset® – FSH : LH proportion ~50.0%) that could be potentially used to increase follicular growth but with controversial results. The goal of this trial was to evaluate the effects of replacing eCG with FSH/LH in two moments on the pregnancy rates (PR) of lactating Bos indicus cows raised in native grassland at Pantanal. The cows were subjected to a synchronization-of-ovulation protocol and FTAI based on progesterone, oestradiol benzoate (EB), and prostaglandin F2α. On Day 0, Nellore multiparous cows (n = 352) at 42 days postpartum with BCS = 4.9 (1–9) were evaluated by transrectal ultrasonography and received progesterone implant (DIB 1.0 g of progesterone) plus 2 mg of EB IM. Devices were removed and prostaglandin F2α was injected on Day 8 with 1 mg of EB. At the time of implant removal, the animals received T1 – 1 mL of saline solution IM (control; n = 80); T2 – 300 IU IM of eCG (Novormon®; ECG; n = 92); T3 – 40 IU IM of FSH/LH (Pluset®; Pluset; n = 98). The T4-group cows received 40 IU IM of FSH/LH (Pluset®) at FTAI time (Pluset-FTAI; n = 82); cows were timed-AI on Day 10 (44–48 h after implant removal) and evaluated by transrectal ultrasonography to measure the preovulatory follicle (POF) at FTAI and to estimate the pregnancy rate on Day 45. The effects of the treatment, sire, and BCS on pregnancy rate were evaluated using PROC GLIMMIX (SAS Institute Inc., Cary, NC). Because there was no difference between BCS, sire, and PR, they were removed from model. Pregnancy rate was not different between the treatment groups (control: 38.70%; ECG: 51.08%; Pluset: 45.91%, and Pluset-FTAI: 39.02%; P > 0.05), but the difference was found in POF, higher in ECG group – 13.53 mm compared with others (Pluset: 12.79 mm; control: 11.73 mm, and Pluset-FTAI: 12.01 mm; P < 0.05). Although PR was not different between treatments, the data are in agreement with the size of POF, where the largest POF are associated with tendency of higher pregnancy rates in ECG group. In conclusion, commercial FSH solution does not provide increases in PR, and eCG increases the preovulatory follicles in Nellore cows with a low-moderate BCS submitted to a progesterone-based FTAI protocol with EB at implant removal.

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Presynchronization with prostaglandin F2α and prolonged exposure to exogenous progesterone impacts estrus expression and fertility in beef heifers

Theriogenology ◽

10.1016/j.theriogenology.2020.02.010 ◽

2020 ◽

Vol 146 ◽

pp. 88-93

Author(s):

N. Oosthuizen ◽

P.L.P. Fontes ◽

K. Porter ◽

G.C. Lamb

Keyword(s):

Prolonged Exposure ◽

Prostaglandin F2α ◽

Beef Heifers ◽

Exogenous Progesterone

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Effects of prolonging the interval from progestin removal to prostaglandin F2α injection from 16 to 17 days in a long-term estrus synchronization protocol in beef heifers

Translational Animal Science ◽

10.1093/tas/txab062 ◽

2021 ◽

Author(s):

N Oosthuizen ◽

G D Melo ◽

G E Seidel ◽

R L Stewart ◽

L Rowden ◽

...

Keyword(s):

Prostaglandin F2α ◽

Fixed Time ◽

Transrectal Ultrasonography ◽

Dominant Follicle ◽

Beef Heifers ◽

Treatment Groups ◽

Follicle Diameter ◽

Randomized Design ◽

Angus Heifers

Abstract To determine effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG protocol, 1,049 Angus heifers at six locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to one of two treatment groups: 1) PG16 (n = 518), heifers received a controlled internal drug release (CIDR) insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal (Day 30), and a 100-µg injection of gonadotropin-releasing hormone concurrent with TAI 66 ± 2 h later; or 2) PG17 (n = 531), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal (Day 31), and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to a subset (n = 482) of heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 116). Transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI differed by treatment where PG17 heifers had greater (P < 0.01) expression of estrus than PG16 heifers (57.8 ± 6.1 vs. 43.4 ± 6.1%, respectively). Nevertheless, dominant follicle diameters at PGF and at TAI were similar (P ≥ 0.59) between PG16 and PG17 heifers. In addition, PR/AI did not differ (P = 0.29) between PG16 and PG17 treatments (50.5 ± 3.2 vs. 45.7 ± 3.1%, respectively). Results of this experiment indicate that delaying the injection of PGF and TAI in the 14-day CIDR-PG protocol increased estrus expression prior to TAI yet did not improve fertility in beef heifers.

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PSII-29 Effects of delayed injection of prostaglandin F2α and TAI in the 14-d CIDR-PG & TAI protocol in replacement beef heifers

Journal of Animal Science ◽

10.1093/jas/skaa278.660 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 375-376

Author(s):

Nicky Oosthuizen ◽

Gabriela Melo ◽

Lawton Stewart ◽

George Seidel ◽

Graham Cliff Lamb ◽

...

Keyword(s):

Prostaglandin F2α ◽

Fixed Time ◽

Pregnancy Rates ◽

Transrectal Ultrasonography ◽

Dominant Follicle ◽

Beef Heifers ◽

Treatment Groups ◽

Follicle Diameter ◽

Randomized Design ◽

Angus Heifers

Abstract To determine the effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG & TAI protocol, 911 Angus heifers at 5 locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to 1 of 2 treatment groups: 1) PG16 (n = 452), heifers received a CIDR insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal [d 30], and a 100-µg injection of gonadotropin-releasing hormone concurrently with TAI 66 ± 2 h later; or 2) PG17 (n = 459), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal [d 31], and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 171). Furthermore, transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI was similar (P = 0.50) between treatments (48.9 vs. 52.0%, respectively). Moreover, dominant follicle diameter at PGF and TAI was similar (P ≥ 0.43) between PG16 and PG17 heifers. Pregnancy rates to TAI did not differ (P = 0.48) between treatment groups (46.4 vs. 48.9%, respectively). The results of this experiment indicate that delaying the injection of PGF from d 30 to d 31 along with TAI in the 14-day CIDR-PG & TAI protocol had no effects on fertility parameters in beef heifers. In conclusion, the PGF injection and TAI in the 14-d CIDR-PG & TAI protocol may be delayed, providing more flexibility in scheduling without negatively affecting fertility.

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Effect of two prostaglandin F2α injections administered 24 hours apart on the pregnancy rate of Simmental cows subjected to the Ovsynch or Ovsynch + Controlled internal drug release (CIDR) protocols

Medycyna Weterynaryjna ◽

10.21521/mw.6451 ◽

2020 ◽

Vol 76 (10) ◽

pp. 6451-2020

Author(s):

MUSHAP KURU ◽

CIHAN KACAR ◽

HASAN ORAL ◽

SEMRA KAYA ◽

NEBI CETIN ◽

...

Keyword(s):

Drug Release ◽

Pregnancy Rate ◽

Artificial Insemination ◽

Pregnancy Loss ◽

Prostaglandin F2α ◽

Fixed Time ◽

Group 4 ◽

Group 3 ◽

Group 2 ◽

Group 1

The aim of the present study was to determine the effects of one or two doses of prostaglandin F2α (PGF) on the pregnancy rate (PR) in Simmental cows subjected to the Ovsynch or Ovsynch + Controlled internal drug release (CIDR) protocols. On d 0, 100 µg gonadorelin diacetate tetrahydrate (GnRH) was injected into cows in group 1 (n = 50) and group 2 (n = 40) and CIDR was intravaginally inserted. On d 7, 25 mg dinoprost tromethamine (PGF2α, PGF) was administered, and GnRH was injected 56 h later. Fixed-time artificial insemination (TAI) was performed 16 h after GnRH injection. In group 3 (n = 62) and group 4 (n = 63), PGF was administered 7 d following GnRH treatment, and GnRH was injected 56 h later. TAI was performed 16 h after GnRH injection. In groups 2 and 4, a second dose of PGF was injected 24 h after the first dose. Pregnancy was determined by transrectal ultrasonography on d 30 and 60 post-TAI. The pregnancy rate (PR) on d 30 post-TAI was significantly different among the groups: 46%, 55%, 29%, and 36.5%, in groups 1, 2, 3, and 4, respectively (P = 0.048). In addition, the PR was 36.3% and 43.7% in the single PGF and double PGF injection groups, respectively. There was no statistical difference in the PR on d 60 post-TAI (P > 0.05). Pregnancy loss was between 4.34% and 11.11% (P > 0.05). The highest PR in the primiparous cows was observed in group 3 (57.7%). The PR was not significantly different among multiparous cows (P > 0.05). In conclusion, two injections of PGF administered 24 h apart in Simmental cows may increase the PR in the Ovsynch or Ovsynch + CIDR protocols.

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Pregnancy rates in hair sheep after Ovsynch synchronization and a combined intracervical fixed-time artificial insemination and 10-day mating period

Veterinary World ◽

10.14202/vetworld.2019.1779-1783 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1779-1783

Author(s):

D. A. Vallejo ◽

J. D. Londoño ◽

Y. A. Yepes ◽

V. Tamayo ◽

A. F. Mejia ◽

...

Keyword(s):

Pregnancy Rate ◽

Artificial Insemination ◽

Prostaglandin F2α ◽

Fixed Time ◽

Pregnancy Rates ◽

Control Group ◽

Mating Period ◽

Mating Group ◽

Alternative Materials ◽

And Control

Aim: This study aimed to evaluate the pregnancy rates in hair ewes using an Ovsynch synchronization protocol under a breeding system that combines fixed-time insemination plus a 10-day mating period as an alternative. Materials and Methods: Through an experimental study (n=27), ewes were randomly located into one of three treatments: (1) Pre-synch (n=9): Prostaglandin F2α (PGF2α)+Gonadotropin-releasing hormone (GnRH)+PGF2α+GnRH; (2) Ovsynch (n=9): GnRH+PGF2α+GnRH; and (3) control: Ewes bred by natural mating (NM) (n=9). Ewes were fixed-time inseminated (fixed-time artificial insemination [FTAI]) with fresh semen, collected just before the insemination time through vaginoscopy at 16 h after the second GnRH (gonadorelin) injection. Each experimental group was placed separately during 15 days and, after this time, fertile rams were allowed back with ewes for a 10-day mating period. Control group ewes remained with the rest of the herd suitable for breeding and were bred under NM. Pregnancy diagnosis was performed by ultrasound at 28-, 56-, and 84-day post-breeding to differentiate between FTAI and NM pregnancies. Total (FTAI±NM) pregnancy rates at 56-day post-breeding were used to compared Pre-synch, Ovsynch, and control. For this purpose, two-tailed proportions comparison z-test was used with a 95% confidence level, for testing as the null hypothesis whether two proportions were equal. Results: Pregnancy rates were higher in control ewes (66.4%) than FTAI (46.6%). When pregnancy rates after a 10-day mating period (40%) were added, the final rate (86.6%) was significantly (p<0.05) higher in Ovsynch-based protocols. The pregnancy rate was significantly lower in FTAI ewes compared to FTAI +10-day mating group (p<0.05). The overall pregnancy rate was 88.0, 85.7, and 67.0 (p>0.05) for Pre-synch, Ovsynch, and control ewes, respectively. Conclusion: These results provide evidence on the benefits of combined FTAI protocols for improving the reproductive efficiency of sheep.

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