scholarly journals 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

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.

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

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.

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

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.

7 KISSPEPTIN SLOWLY ADMINISTERED DURING PROESTRUS IMPROVES FOLLICLE GROWTH AND OVULATION IN ANESTROUS COWS

2016 ◽  
Vol 28 (2) ◽  
pp. 133 ◽  
Author(s):  
G. G. Macedo ◽  
R. V. Sala ◽  
L. F. Martins ◽  
P. S. Baruselli
Keyword(s):  
Growth Rate ◽  
Body Condition Score ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Ovulation Rate ◽  
Growth Promoter ◽  
Dominant Follicle ◽  
Follicle Growth ◽  
Growth Promoters ◽  
Follicle Diameter

This study evaluated whether kisspeptin (Kp) administered slowly from the moment of prostaglandin F2α (PGF) treatment for fixed-time AI protocol of anestrous cows provides suitable dominant follicle (DF) growth similarly to eCG. Postpartum, anestrous, primiparous Nelore cows (n = 50; <8-mm follicles with no corpus luteum) and lean (body condition score 2.7 ± 0.1; 0–5 score scale) were enrolled. On Day 0, females received an intravaginal device with 1.0 g of progesterone (Sincrogest®, Ourofino, Brazil) and 2 mg of oestradiol benzoate IM (Sincrodiol®, Ourofino, Brazil). On Day 8, the device was removed, and cows were administered 500 μg of sodic cloprostenol IM (Sincrocio®, Ourofino, Brazil) and 1 mg of oestradiol cypionate IM (E.C.P.®, Zoetis, Brazil). Females were blocked by dominant follicle diameter and allotted in following groups: (1) control (CTRL), 1.5 mL of saline IM; (2) eCG, 300 IU IM of eCG (Novormon®, Intervet, Brazil); and (3) Kp SC with an osmotic minipump (9.65 μg kg–1 of Kp diluted in saline) over 48 h. Dominant follicle growth and ovulation evaluation were performed by ultrasound at 0, 24, 48, 60, 72, 84, and 96 h after PGF treatment. Dominant follicle growth rate was calculated by difference on DF from 0 to 48 h. Ovulation dispersion was analysed by proc GLIMMIX of SAS (SAS Institute Inc., Cary, NC, USA). Follicle variables, ovulation rate, and interval from PGF to ovulation were analysed by orthogonal contrast. Differences were considered when P < 0.05, and tendencies were considered when P < 0.1. There were no difference between CTRL and growth promoters (eCG and Kp) or between growth promoters on DF diameter at 0 h, larger follicle registered from 0 h to ovulation, ovulatory DF diameter, ovulation rate, and interval between PGF treatment and ovulation (Table 1). Dominant follicle diameter at 48 h was larger for growth promoters than for CTRL. Treatment with Kp proved as efficient as eCG in the DF growth rate, with tendency (P = 0.1) to be greater than CTRL. Data from our laboratory (Sales et al. 2011 Anim. Rep. Sci. 124, 12–18.) with same model and animal profile (n = 150 per group) presented positive effect of eCG treatment for growth and size of DF. Cows treated with Kp ovulated in only 3 specific times (60, 72, and 84 h), unlike eCG (48, 60, 72, and 84 h) and CTRL (24, 48, 60, 72, 84, and 96 h; P > 0.05). Also, it is noted that Kp treatment dose and releasing does not cause negative effect on follicle growth and ovulation (down-regulation on LH releasing) or alteration on interval of PGF treatment to ovulation. Thus, synchronized anestrous cows treated with Kp delivered slowly during proestrus have similar results to eCG on follicle growth and ovulation. Table 1.Ovarian variables of anestrous Nelore cows treated with saline, eCG (300 IU), or kisspeptin (Kp; 9.65 μg kg–1). Data were analysed by orthogonal contrast, where C1 = growth promoter (eCG and Kp) v. control; C2 = eCG v. Kp

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

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 125-126
Author(s):  
Vitor R G Rodrigues Gomes Mercadante ◽  
G Cliff C Lamb ◽  
Nicky Oosthuizen ◽  
Nicholas W Wege Dias ◽  
Stefania Pancini ◽  
...  
Keyword(s):  
Body Weight ◽  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Prolonged Exposure ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Transrectal Ultrasonography ◽  
Beef Heifers ◽  
Estrus Response ◽  
Exogenous Progesterone

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 &lt; 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.

scholarly journals 147 Presynchronization and delayed fixed-time artificial insemination increases pregnancy rates with sex-sorted semen in replacement beef heifers

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 115-116
Author(s):  
Nicky Oosthuizen ◽  
Pedro Fontes ◽  
Ramiro Filho ◽  
Carl R Dahlen ◽  
David M Grieger ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Bos Taurus ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Beef Heifers ◽  
Randomized Design ◽  
Initial Injection ◽  
Estrus Detection ◽  
Completely Randomized Design

Abstract To determine effects of presynchronization and delayed fixed-time artificial insemination (TAI) on pregnancy rates to TAI (PR/AI) with sex-sorted semen, 2,855 Bos taurus beef heifers were enrolled in a completely randomized design. Within location, heifers were randomly assigned to one of eight treatments: 1 and 2), heifers were exposed to the 7-d CO-Synch+CIDR protocol wherein they received gonadotropin-releasing hormone (GnRH) and a CIDR insert on d 0, prostaglandin F2α (PGF) upon CIDR removal on d 7, and were TAI 54 ± 2 h later with conventional (CTRL54-CNV; n = 359) or sex-sorted semen (CTRL54-SEX; n = 356); 3 and 4), same as CTRL54 but were TAI at 72 ± 2 h with conventional (CTRL72-CNV; n = 366) or sex-sorted semen (CTRL72-SEX; n = 360); 5 and 6), same as CTRL54 but also received PGF 7 d prior to initial injection of GnRH (d -7) and were TAI with conventional (PRE54-CNV; n = 355) or sex-sorted semen (PRE54-SEX; n = 353); 7 and 8), same as PRE54 but had TAI delayed to 72 ± 2 h and were inseminated with conventional (PRE72-CNV; n = 351) or sex-sorted semen (PRE72-SEX; n = 355). All heifers received estrus detection patches on d 7, which were evaluated for activation at TAI. Ultrasonography was performed 30–45 d after TAI to determine PR/AI. Estrus expression was greater (P &lt; 0.01) in the CTRL72 heifers compared to CTRL54, PRE54, and PRE72 heifers (73.0 vs 55.4, 43.4, and 65.7%, respectively). Moreover, estrus expression was greater (P &lt; 0.01) in PRE72 heifers compared to CTRL54 and PRE54 heifers. Within treatment pairs, PR/AI were greater (P ≤0.04) when conventional semen was utilized compared to sex-sorted semen. Furthermore, PR/AI were greater (P = 0.02) in PRE72-SEX heifers than CTRL54-SEX heifers (45.8 vs. 37.5%). No difference (P = 0.20) was determined in PR/AI between CTRL54-CNV and PRE72-SEX heifers (50.5 vs. 45.8%). In conclusion, presynchronization in combination with delayed TAI increased estrus expression and PR/AI with sex-sorted semen in replacement beef heifers.

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

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

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 &lt; 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 &lt; 0.001) in PG-CIDR72 heifers when compared to PG72. Pregnancy rates to TAI differed among treatments and were greater (P &lt; 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.

Estrous synchronization and fertility of cross-bred dairy cows using prostaglandin F2α and gonadotropin releasing hormone

2021 ◽  
pp. 171-175
Author(s):  
Abubakr O. Ismail ◽  
◽  
Erneo B. Ochi ◽  
Ambrose S. Jubara ◽  
Bakri Ahmed A/Rahim ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Artificial Insemination ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Gonadotropin Releasing Hormone ◽  
Pregnancy Rates ◽  
Releasing Hormone ◽  
Treatment Groups ◽  
Estrous Synchronization ◽  
Descriptive Statistical Analysis

A comparative hormonal study of prostaglandin, gonadotropin releasing hormone and their combination was conducted on 30 randomly selected cross-bred dairy cows of SEMEX project for artificial insemination in Hillat Kuku, Khartoum North, Sudan. The study attempts to determine the response of the animals to hormonal induction and synchronization of estrous as well as fertility following fixed time artificial insemination. Three treatment groups of 10 cows each were undertaken. Groups 1, 2 and 3 involved administration of prostaglandin F2α (PGF2α), gonadotropin releasing hormone (GnRH) and a combination of PGF2α + GnRH, respectively. Descriptive statistical analysis was performed. The results revealed that all the three protocols induced and synchronized estrous were almost synchronous in all the treated groups. However, protocol 3 revealed a significantly (p<0.05) better result of 70% pregnancy rate compared to other two protocols that equally provided 50% pregnancy rates. The study resolves that protocol 3 be highly recommended to change the mindset of farmers about the spread of reproductive technology in Sudan. Protocols 1 and 2 provided acceptable pregnancy rates that can be enhanced with the improvement of management.

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.

Effects of extending the length of pro-oestrus in an oestradiol- and progesterone-based oestrus synchronisation program on ovarian function, uterine environment and pregnancy establishment in beef heifers

2018 ◽  
Vol 30 (11) ◽  
pp. 1541 ◽  
Author(s):  
J. J. de la Mata ◽  
R. Núñez-Olivera ◽  
F. Cuadro ◽  
D. Bosolasco ◽  
V. de Brun ◽  
...  
Keyword(s):  
Ovarian Function ◽  
Progesterone Receptors ◽  
Fixed Time ◽  
Conventional Group ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Serum Progesterone ◽  
Ovulatory Follicle ◽  
Sexual Steroid ◽  
Uterine Environment

The aim of the present study was to investigate the effects of a strategy for extending pro-oestrus (the interval between luteolysis and ovulation) in an oestrus synchronisation protocol (named J-Synch) in beef heifers on follicular growth, sexual steroid concentrations, the oestrogen receptor ERα and progesterone receptors (PR) in the uterus, insulin-like growth factor (IGF) 1 and pregnancy rates. In Experiment 1, heifers treated with the new J-Synch protocol had a longer pro-oestrus period than those treated with the conventional protocol (mean (± s.e.m.) 93.7 ± 12.9 vs 65.0 ± 13.7 h respectively; P < 0.05). The rate of dominant follicle growth from the time of progesterone device removal to ovulation was greater in heifers in the J-Synch than conventional group (P < 0.05). Luteal area and serum progesterone concentrations were greater in the J-Synch Group (P < 0.05) for the 12 days after ovulation. Progesterone receptor (PGR) staining on Day 6 after ovulation in the uterine stroma was lower in the J-Synch than conventional group (P < 0.05), and the expression of PR gene (PGR) and IGF1 gene tended to be lower in J-Synch-treated heifers (P < 0.1). In Experiment 2 (n = 2349), the pregnancy rate 30–35 days after fixed-time AI (FTAI) was greater for heifers in the J-Synch than conventional group (56.1% vs 50.7% respectively). In conclusion, our strategy for extending pro-oestrus (i.e. the J-Synch protocol) significantly improves pregnancy establishment in beef heifers. This improvement was related to an increased rate of growth of the dominant ovulatory follicle, greater progesterone concentrations during the ensuing luteal phase and different uterine patterns of PGR and IGF1, which may have favoured embryo development and pregnancy establishment.

29 SHORT-TERM v. LONG-TERM PROGESTERONE PROTOCOL USING CERVICAL OR INTRAUTERINE FIXED-TIME INSEMINATION IN SHEEP

2010 ◽  
Vol 22 (1) ◽  
pp. 172
Author(s):  
A. Menchaca ◽  
M. Vilariño ◽  
E. Rubianes
Keyword(s):  
New York ◽  
Pregnancy Rate ◽  
Body Condition Score ◽  
Skim Milk ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Short Term ◽  
Condition Score ◽  
N 93

The short-term protocol with progesterone, prostaglandin F2α (PGF2α), and eCG is used to control follicular dynamics and luteal activity synchronizing the ovulation for fixed-time AI in sheep. The objective of this experiment was to compare the pregnancy rate obtained with short-term protocol (6 d) and long-term protocol (14 d) using cervical or intrauterine fixed-time AI in sheep. Three hundred fifty-two Merino ewes with a body condition score of 2.9 ± 0.3 (mean ± SD; scale 0 to 5) were used during the breeding season (April, 33S, Uruguay). All the females received a CIDR-G (0.3 g of progesterone, InterAg, Hamilton, New Zealand) for 6 d (short-term protocol; n = 178) or 14 d (long-term protocol, n = 174). One imdose of eCG (300 IU, Novormon, Syntex, BA, Argentina) was given at the moment of device withdrawal for the both protocols, and one imdose of PGF2α (10 mg of dinoprost, Lutalyse, Pfizer, New York, NY, USA) was given at the end of the short-term protocol to ensure luteolysis. Cervical AI (short-term protocol, n = 85; long-term protocol, n = 104) or intrauterine AI (short-term protocol, n = 93; long-term protocol, n = 70) was performed 48 or 54 h after device withdrawal, using 200 × 106 or 100 × 106 spermatozoa per ewe, respectively. Fresh semen was extended in UHT skim milk (1000 × 106 spermatozoa mL-1) and used within 1 h of collection. Estrus was recorded twice a day for 4 days after device withdrawal using vasectomized males. Pregnancy diagnosis was performed by transrectal ultrasonography 40 d after AI (5.0 MHz, Aloka, Tokyo, Japan). Logistic regression was used to analyze the effect of the treatment (P < 0.05), the AI technique (P < 0.05), and their interaction (P = NS). Pregnancy rate was higher for the short-term than for the long-term protocol, and for intrauterine than for cervical AI (Table 1). The highest pregnancy rate was achieved with short-term protocol using intrauterine AI (54.8%, 51/93), and the lowest response was obtained with long-term protocol using cervical AI (33.7%, 35/104; P < 0.05). These data were not different from data of short-term protocol using cervical AI or long-term protocol using intrauterine AI (42.4%, 36/85; and 44.3% 31/70, respectively). Ewes in estrus/treated ewes was not different among short-term and long-term protocols (83.7%, 149/178; and 82.8%, 144/174, respectively; P = NS). In summary, regardless of insemination technique, short-term protocol of 6 d enhances pregnancy rate in fixed-time AI programs in sheep. Table 1.Main effects of short-term (6 d) v. long-term (14 d) protocol using cervical or intrauterine fixed-time AI on pregnancy rate in sheep Financially supported by Pfizer, SP, Brazil.

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