156 Oestrus response, corpus luteum function, and pregnancy rates following aromatase inhibitor treatment in beef heifers

2020 ◽  
Vol 32 (2) ◽  
pp. 204
Author(s):  
E. M. Zwiefelhofer ◽  
M. L. Zwiefelhofer ◽  
J. Singh ◽  
M. G. Colazo ◽  
G. A. Franco ◽  
...  
Keyword(s):  
Aromatase Inhibitor ◽  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Repeated Measures ◽  
Plasma Concentrations ◽  
Prostaglandin F2α ◽  
Pregnancy Rates ◽  
Blood Sampling ◽  
Device Removal ◽  
Letrozole Treatment

In a previous study involving the use of the aromatase inhibitor letrozole to synchronise ovulation, incomplete luteolysis appeared to confound the synchronising effect in letrozole-treated heifers. Experiments were done to determine whether letrozole treatment interferes with luteolysis and affects the timing of oestrus (Experiment 1) and whether pregnancy rate is affected by the stage of the oestrous cycle during which letrozole treatment is initiated (Experiment 2). In Experiment 1, Hereford heifers were fitted with a HeatWatch sensor and given prostaglandin F2α (PGF2α). Ovulation (Day 0) was determined by daily ultrasonography, and on Day 3 heifers were given an intravaginal letrozole-releasing device or a sham device for 4 days (n=16 per group). Half of the heifers in each group were given PGF2α on Day 7 (PGF 1×) or on Day 7 and 7.5 (PGF 2×). Ultrasonography and blood sampling were done daily from device insertion to removal, every 12h for 72h following PGF2α and daily for 14 days following ovulation. In Experiment 2, heifers were randomly assigned to three groups (n=10-11 per group) in which a 4-day letrozole-releasing device treatment was initiated during metoestrus (Days 0-2), diestrus (Days 7-9), or pro-oestrus (Days 15-17). Prostaglandin F2α was given at device removal and again 12h later. Heifers were inseminated with frozen-thawed semen and given gonadotrophin-releasing hormone 66h after device removal. Ultrasonography and blood sampling were done twice daily from device removal until ovulation. End points examined included dominant follicle and corpus luteum (CL) diameters, onset of oestrus, and plasma concentrations of oestradiol determined by radioimmunoassay. Nominal data were compared using GENMOD, analysis of variance, or mixed model for repeated-measures and were expressed as means±s.e.m. Proportional data were analysed using chi-square. In Experiment 1, no main effects or interactions were detected between device or PGF treatment for onset of oestrus following PGF2α (overall 60.0±2.5h) or CL diameter profiles during luteolysis. Residual variation was reduced in the timing of the first PGF to ovulation in the PGF 2× group versus the PGF 1× group (5.6±2.2h vs. 15.2±3.2 h; P<0.01). The CL diameter following ovulation was greater in the PGF 2× group compared with the PGF 1× group (P=0.03). Circulating plasma oestradiol during treatment was greater (P=0.04) in both the PGF 1× and sham groups. In Experiment 2, a greater proportion of heifers in the pro-oestrus group ovulated ≤24h after device withdrawal compared with the metoestrus and diestrus groups combined (6/11 vs. 0/22, respectively; P<0.05). Pregnancy rate tended to be greater in the metoestrus group than in the diestrus group (10/11 vs. 6/10; P=0.08), and pregnancy rate in both groups was greater than that in the pro-oestrus group (0/11; P<0.05). In conclusion, letrozole treatment did not interfere with luteolysis, and PGF2α given 2× at a 12-h interval on Day 7 after ovulation decreased variance in the timing to ovulation. Treatment initiated during metoestrus and diestrus yielded greater pregnancy rates than that started during pro-oestrus and warrants efficacy testing in a large fixed-time AI field trial. This research was supported by Alberta Agriculture and Forestry and by Dechra.

108 FACTORS AFFECTING PREGNANCY RATES IN RECIPIENTS RECEIVING IN VITRO-PRODUCED EMBRYOS BY FIXED TIME EMBRYO TRANSFER

2016 ◽  
Vol 28 (2) ◽  
pp. 184
Author(s):  
M. Pelizzari ◽  
A. Tribulo ◽  
J. Garzon ◽  
B. Bernal ◽  
R. Tribulo ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Embryo Transfer ◽  
Body Condition Score ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Uterine Horn ◽  
Device Removal ◽  
Embryo Transfer Technique

A retrospective analysis of factors that affect pregnancy rates from 4214 fresh in vitro-produced (IVP) embryos that were transferred at a fixed-time (FTET) in 20 different farms. Recipients were all cycling cows or heifers that were synchronized with 1 of 3 treatments: 1) treatments with progesterone (P4) devices and 2 mg of oestradiol benzoate (EB) on Day 0 (day of insertion) and 24 h after device removal (Day 8); 2) treatments with P4 devices and EB on Day 0, but with 0.5 mg of oestradiol cypionate (ECP) at device removal (Day 8); or 3) treatments with P4 devices and GnRH on Day 0 and a second GnRH 60 h after device removal (Day 5). Cows in all treatment groups also received 500 µg of cloprostenol (prostaglandin F2α) at the time of P4 device removal and 400 IU of eCG either at device removal or 3 days before device removal. All embryos were transferred 7 or 8 days after the expected time of oestrus (24 h after EB, 48 h after ECP or at the time of the second GNRH for each synchronization treatment, respectively). On the day of embryo transfer, recipients were examined by ultrasonography and those with corpus luteum >14 mm in diameter received a fresh, IVP embryo in the uterine horn ipsilateral to the corpus luteum. Pregnancy rates were determined by ultrasonography 35 days after FTET. Data were analysed by logistic regression. Independent variables were classified into the following three categories. 1) Factors related to the recipient and the environment; there were no significant differences in pregnancy rates for corpus luteum diameter (≥14 and <16 mm, ≥16 and <18 mm, or ≥18 mm; P = 0.46), number of corpus luteum (1 or ≥2; P = 0.26), and category of recipient (cow or heifer; P = 0.21). However, there were significant effects of farm (P = 0.01) and body condition score (BCS; P = 0.01). Cows with BCS ≥4.5 (1 to 5 scale) resulted in lower pregnancy rates (4/20, 20.0%) than those with BCS 2 (74/225, 32.9%), 2.5 (502/1434, 35.0%), 3 (570/1467, 38.9%), 3.5 (193/532, 36.3%), and 4 (44/118, 37.3%). 2) Factors related to the synchronization treatment; there were no significant differences between recipients receiving eCG at device removal (84/209, 40.2%) or 3 days before device removal (874/2291, 38.1%; P = 0.35). However, recipients synchronized with P4 devices and ECP had higher (P = 0.01) pregnancy rates (232/483, 48.0%) than those treated with EB (679/1888, 36.0%) or gonadotropin-releasing hormone (47/129, 36.4%). 3) Factors related to the embryo transfer technique; day of the recipient’s oestrous cycle (P = 0.36), stage of embryo transferred (IETS stages 6 or 7; P = 0.62), and operator (P = 0.57) did not affect pregnancy rates. However transfers made in the anterior third of the uterine horn resulted in higher (649/1545, 42.0%) pregnancy rates than those in the mid-third (845/2511, 33.6%) or in the distal third (6/35, 17.1%; P = 0.01). It was concluded that factors related to the recipient and the environment (farm and BCS), the synchronization treatment (ECP), and the embryo transfer technique (site of deposition) affect pregnancy rates in recipients of embryos produced in vitro and transferred at a fixed time.

4 EFFECT OF A PROLONGED AROMATASE INHIBITOR TREATMENT ON PRE-OVULATORY OVARIAN FOLLICLES IN CATTLE

2012 ◽  
Vol 24 (1) ◽  
pp. 113 ◽  
Author(s):  
J. Yapura ◽  
J. Singh ◽  
R. J. Mapletoft ◽  
R. Pierson ◽  
D. Rogan ◽  
...  
Keyword(s):  
Aromatase Inhibitor ◽  
Corpus Luteum ◽  
Repeated Measures ◽  
Slow Release ◽  
The Body ◽  
Maximum Diameter ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Letrozole Treatment ◽  
Intravaginal Device

Letrozole, a non-steroidal aromatase inhibitor, prevents the body from producing its own oestrogen. The potential use of this compound for herd synchronization is supported by previous studies in which letrozole treatment increased mean plasma LH concentrations, prolonged the period of dominance of the extant dominant follicle and delayed emergence of the next follicular wave. Heifers given a 3-day regimen of letrozole exhibited greater corpus luteum diameter indicative of a luteotrophic effect. The objective of the present study was to test the hypothesis that letrozole treatment during the development of the preovulatory follicular wave will delay ovulation. Post-pubertal beef heifers were given 2 luteolytic doses of PGF (12 h apart) and monitored by ultrasonography for ovulation. Ovarian follicular wave emergence was synchronized by ultrasound-guided transvaginal follicular ablation 5 to 8 days after PGF-induced ovulation (Day –1 = follicular ablation, Day 0 = wave emergence) and a luteolytic dose of PGF was given 60 and 72 h later. On Day 1, heifers were divided randomly into 2 groups (n = 15/group) and given an intravaginal device containing 1 g of letrozole or a blank device (control). The intravaginal devices were removed on Day 7, or at the time of ovulation, whichever occurred first. The ovaries were monitored by ultrasonography and a blood sample was collected daily from day of ablation to 12 days post-ovulation. Single point measurements were analysed by t-tests and serial data were analysed by analysis of variance for repeated measures. Multiple contrasts were made by Tukey's test. The interval from placement of the intravaginal device to ovulation was longer in letrozole-treated animals (6.1 ± 0.25 vs 5.1 ± 0.26 days, P < 0.01). Compared with controls, the day-to-day diameter profile of the dominant follicle of the ovulatory wave was larger (P < 0.05) and the maximum diameter greater (14.6 ± 0.51 vs 12.4 ± 0.53 mm; P < 0.01) in letrozole-treated heifers. The diameter profile of the corpus luteum formed post-letrozole treatment did not differ between groups; however, plasma P4 concentrations were higher (P < 0.01) in heifers treated with letrozole. In summary, a slow-release intravaginal letrozole device delayed ovulation by 24 h and induced the formation of a corpus luteum that secreted higher levels of progesterone. A slow-release intravaginal letrozole device may become useful for the development of an aromatase inhibitor-based protocol to control ovulation for herd synchronization and to enhance fertility by increasing circulating progesterone concentrations during the first 7 days post-AI or embryo transfer in cattle. Supported by the Natural Sciences and Engineering Research Council of Canada and Bioniche Life Sciences Inc.

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.

scholarly journals COMPARISON OF LONG-TERM PROGESTERONE-BASED PROTOCOL ON REPRODUCTIVE PERFORMANCE OF PREPUBERTAL AND PUBERTAL BEEF HEIFERS.

2014 ◽  
Vol 19 (1) ◽  
Author(s):  
Emanoel Faleiros Silveira ◽  
Luiz Ernandes Kozicki ◽  
Marcio Saporski Segui ◽  
Romildo Romualdo Weiss ◽  
Ivo Walter Santos ◽  
...  
Keyword(s):  
Ultrasound Examination ◽  
Prostaglandin F2α ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Estrus Synchronization ◽  
Device Removal ◽  
Timed Artificial Insemination ◽  
Red Angus ◽  
Natural Service

The aim of this study was to investigate estrus synchronization in prepubertal and pubertal heifers (crossbred ½ Nelore x Red Angus - commercial herd) submitted to a long-term progesterone-based protocol for timed artificial insemination (TAI), as well as overall pregnancy rates. Four hundred forty-seven heifers underwent ultrasound examination of the ovaries and were assigned to one of 3 groups: (1) prepubertal heifers (PPNS; n = 114) with ovarian follicles <8 mm in diameter and no corpus luteum (CL) that were submitted to natural service (NS) by bulls for 10 days; (2) prepubertal heifers (PPTAI; n = 124) with follicles <8 mm in diameter and no CL that underwent estrus synchronization with injection of 4.0 mg estradiol benzoate (EB) and insertion of a controlled-release intravaginal progesterone (P4) device containing 0.558 g P4 on d 0, followed by P4 device removal and injection of 150 mg prostaglandin F2α and 0.6 mg estradiol cypionate (ECP) on d 8, and TAI on d 10; and (3) pubertal heifers (PTAI; n = 209) with follicles >8 mm in diameter and/or a CL that underwent the same protocol as PPTAI heifers. Overall pregnancy rate was determined by transrectal ultrasonography on d 45 after NS or TAI. Data were analyzed using the FREQ procedure of SAS (SAS Inst. Inc., Cary, NC). Pregnancy rates were as follows: 20.1% in PPNS, 37.0% in PPTAI, and 48.5% in PTAI (P < 0.05). In conclusion, TAI after estrus synchronization with a hormonal protocol using EB and ECP in prepubertal and pubertal heifers resulted in higher pregnancy rates than prepubertal heifers exposed to natural service, and exposure of prepubertal heifers to a long-term progesterone-based protocol effectively synchronized estrus.

206 EFFECTS OF A COMBINATION OF A PRID, PGF2α AND eCG, ON ESTRUS SYNCHRONIZATION AND PREGNANCY RATE FOLLOWING EMBRYO TRANSFER IN HOLSTEIN HEIFERS

2007 ◽  
Vol 19 (1) ◽  
pp. 220 ◽  
Author(s):  
Y. Aoyagi ◽  
A. Ideta ◽  
M. Matsui ◽  
K. Hayama ◽  
M. Urakawa ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Plasma Concentrations ◽  
Pregnancy Rates ◽  
Bovine Embryo ◽  
Estrus Synchronization ◽  
Chi Square ◽  
End Of Treatment ◽  
Chi Square Analysis ◽  
Day Of Embryo Transfer

Successful bovine embryo transfer requires synchronization of luteolysis, estrus and ovulation. The objective of the present study was to evaluate the effect of a combination of a PRID, PGF2� and eCG, on estrus synchronization and pregnancy rate in recipient heifers. A PRID� (ASKA Pharmaceutical Co., Ltd., Tokyo, Japan) was inserted into the vagina at random days of the estrous cycle for 7 (n = 35) or 9 (n = 43) days. Two days before removal of the PRID, the heifers were injected with PGF2� IM (2 mL Resipron�-C containing 0.25 mg mL-1 cloprostenol; ASKA). About half of the heifers in each group received 250 IU eCG IM (Serotropin�; ASKA) at the time of PRID removal. Blood was collected several times from the start of treatment for 7 (n = 9) or 9 (n = 9) days and on the day of embryo transfer by jugular venipuncture; plasma was immediately separated and stored at -20�C until assayed for plasma concentrations of estradiol-17α (E2) and progesterone (P4). The E2 and P4 determinations were performed by enzyme immunoassay after extraction by diethyl ether. Pregnancy was determined by ultrasonography on Day 30 (Day 0 = estrus). The rates of successful standing estrus (no. in estrus/PRID inserted), embryo transfer (no. transferred/estrus), and pregnancy (no. pregnancy/transferred) were compared between groups. Data were analyzed by chi-square analysis or Fisher&apos;s PLSD test following ANOVA. Injection of eCG at the time of PRID removal had no significant effect on the rates of successful standing estrus, embryo transfer, or pregnancy (P &gt; 0.05). The proportion of heifers treated for 9 days that exhibited standing estrus (93&percnt;, 40/43) was significantly higher than the proportion of heifers treated for 7 days that exhibited standing estrus (66&percnt;, 23/35, P &lt; 0.01). Of the heifers that were treated for 9 days, the proportion of heifers exhibiting standing estrus within 2 days after the end of treatment was significantly higher (93&percnt;, 37/40) than for heifers that were treated for 7 days (65&percnt;, 15/23; P &lt; 0.01). Pregnancy rates of heifers treated for 9 days (84&percnt;, 32/38) and 7 days (81&percnt;, 17/21) were not significantly different. The E2 : P4 ratio normally increases during follicle growth and CL regression. The plasma E2 : P4 ratio between the time of injection of PGF2&alpha; and the time of PRID removal was significantly higher for heifers that were treated for 9 days than it was for heifers that were treated for 7 days (P &lt; 0.01). These results suggest that a combination of PRID treatment for 9 days and injection of PGF2&alpha; 2 days before PRID removal successfully synchronized estrus in recipient heifers and led to high pregnancy rates following embryo transfer.

10 INFLUENCE OF ADMINISTRATION OF HUMAN CHORIONIC GONADOTROPIN ON DAY 4 AFTER FIXED-TIME AI ON CORPUS LUTEUM SIZE, FUNCTION, AND PREGNANCY RATE IN BEEF COWS

2014 ◽  
Vol 26 (1) ◽  
pp. 119
Author(s):  
J. B. S. Borges ◽  
D. X. Thedy
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Control Group ◽  
Chi Square ◽  
Prostaglandin F2a ◽  
Successful Establishment ◽  
Early Rise

Successful establishment of pregnancy in the cow depends on early rise of progesterone (P4) to improve embryo development. The present study was carried out to determine the corpus luteum (CL) function and pregnancy rate following the administration of 1.500 IU of hCG in suckled beef cows on Day 4 after fixed-time AI (FTAI). Crossbred Angus cows (n = 429), 40 to 70 days postpartum, were synchronized using 2 mg of oestradiol benzoate (EB) i.m. and an intravaginal progesterone-releasing device containing 1 g of P4 for 7 days. At device removal, prostaglandin F2a (150 mg of D-cloprostenol) was injected i.m.; 24 h later, 1 mg of EB was given and the FTAI were done 30 to 36 h after EB using semen of just 1 bull. Cows were assigned alternatively to receive 1.500 IU of hCG i.m. (n = 200) or 1 mL of saline i.m. (n = 229) on Day 4 after FTAI. Ovaries were examined by transrectal ultrasonography (n = 71) on Days 4 and 7 to detect the presence and to measure the area of CL. Blood samples were collected on Days 4, 7, 10, 14, and 30 post-oestrus to determine P4 concentration by RIA. Pregnancy diagnoses were done 30 days after FTAI. The effects of treatments on CL area and serum P4 levels were analysed by ANOVA (Proc GLM, SAS Institute Inc., Cary, NC, USA) and pregnancy rates compared by chi-square (Proc CATMOT, SAS). The induction of accessory CL determined on Day 7 was 44% in cows treated with hCG and not observed in the control group. The area of the CL on Day 7 was significantly higher (P < 0.01; 3.37 ± 2.56 v. 2.56 ± 0.22 cm2) in the hCG group. Despite the increase in CL size, the mean levels of P4 on Days 4, 7, 10, 14, and 30 post-AI indicated no difference (P > 0.05) in CL function between control and hCG-treated cows. On Day 30, pregnancy rates were not different (P = 0.08), at 46.7 and 55% for control and hCG-treated cows, respectively. In conclusion, administration of 1.500 IU of hCG on Day 4 post-FTAI did not improve pregnancy rate in suckled beef cows.

109 RELATIONSHIP BETWEEN ULTRASONIC MORPHOLOGY OF CORPUS LUTEUM IN HOLSTEIN HEIFERS AND PREGNANCY RATE AFTER EMBRYO TRANSFER

2012 ◽  
Vol 24 (1) ◽  
pp. 167
Author(s):  
A. Shirasawa ◽  
Y. Nakamura ◽  
A. Ideta ◽  
Y. Oono ◽  
M. Urakawa ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Blood Clot ◽  
Pregnancy Rates ◽  
Bovine Embryo ◽  
Tissue Area ◽  
The Mean ◽  
Rectal Palpation ◽  
Experimental Group

Recipient animals for bovine embryo transfer (ET) are routinely selected according to the morphology of the corpus luteum (CL) estimated by rectal palpation. However, rectal palpation is not a precise method of diagnosing the functional status of a CL. Ovarian ultrasonography (US) may be used to improve such diagnoses. The aim of this study was to evaluate the relationship between ultrasonographic images of CL and pregnancy rates after ET in Holstein heifers to determine whether US can be used to select recipients for ET. Recipient heifers (n = 285) were selected by detection of natural oestrus or following oestrus synchronization using a progesterone-releasing intravaginal device (PRID; ASKA Pharmaceutical, Tokyo, Japan). Transrectal US was performed immediately before ET, on Days 6 to 8 of the oestrous cycle (oestrus = Day 0), using a B-mode scanner (HS1500V; Honda Electronics Co. LTD, Aichi, Japan) equipped with a 7.5-MHz linear-array transducer designed for intrarectal placement. A cross-sectional image of the maximal area of the CL and luteal cavity was obtained. The areas of the CL and luteal cavity were each calculated using the formula for the area of an ellipse (height/2 × width/2 × π). (1) Ultrasonic morphology of CL was classified into 3 types: without cavity (n = 128), with cavity (n = 145) and with blood clot (n = 12). (2) The luteal cavity was categorized into 3 groups: small (<100 mm2, n = 93), medium (100 ≤ x < 200 mm2, n = 32) and large (≥200 mm2, n = 20). (3) Luteinized tissue area (total area of CL minus the area of the luteal cavity) was categorized into 3 groups: small (<250 mm2, n = 61), medium (250 ≤ x < 350 mm2, n = 128) and large (≥350 mm2, n = 84). In vivo–produced embryos were transferred nonsurgically into the uterine horn ipsilateral to the CL. Pregnancy was determined by transrectal US on Days 30 to 40 of gestation. The pregnancy rates of each experimental group were analysed by logistic regression. In this study, the pregnancy rate did not differ significantly in each experimental group: (1) without cavity: 77.3% (99/128), with cavity: 75.2% (109/145) and blood clot: 75.0% (9/12); (2) small cavity: 73.1% (68/93), medium: 75.0% (24/32) and large: 85.0% (17/20). The mean area of the cavity was 100.8 ± 110.3 mm2 (mean ± standard deviation) and recipients with 0 to 539.7 mm2 sized cavities had successful pregnancies (observational range was 0 to 539.7 mm2). (3) The pregnancy rates of recipients that had small, medium and large luteinized tissue were 77.0% (47/61), 75.0% (96/128) and 77.4% (65/84), respectively. The mean area of luteinized tissue was 318.9 ± 90.3 mm2 and 155.0 to 620.0 mm2 sized luteinized tissue had pregnancy success (observational range was 132.8 to 620.0 mm2). In conclusion, the results from this study indicate that the presence of a luteal cavity or blood clot has no detrimental effect on pregnancy success after ET in Holstein heifers. Furthermore, no relationship was found between luteinized tissue area at the time of ET and pregnancy rate.

116 PREGNANCY RATES AFTER ADMINISTRATION OF EQUINE CHORIONIC GONADOTROPIN (eCG) AT PROGESTERONE INTRAVAGINAL DEVICE REMOVAL AND 14 DAYS AFTER FIXED-TIME AI IN BEEF CATTLE

2011 ◽  
Vol 23 (1) ◽  
pp. 163 ◽  
Author(s):  
R. Núñez ◽  
T. de Castro ◽  
L. Cutaia ◽  
G. Bó ◽  
A. Menchaca
Keyword(s):  
Beef Cattle ◽  
Pregnancy Rate ◽  
Body Condition Score ◽  
Fetal Loss ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Control Group ◽  
Device Removal ◽  
Embryo Survival ◽  
Intravaginal Device

An important proportion of embryonic deaths in cattle occur during the critical period of embryo development and maternal recognition of pregnancy. High serum progesterone concentrations during this period are associated to higher embryo survival, and the use of eCG could enhance luteal activity. Two experiments were carried out to evaluate the effect of administering eCG at the time of removal of a progesterone-releasing device and 14 days after fixed-time artificial insemination (FTAI) in beef cattle. Multiparous suckled cows between 60 and 90 days postpartum (n = 297; Exp. 1), and two-year old prepuberal heifers (n = 689; Exp. 2) with a body condition score (BCS) between 3.5 and 5 (1 to 8 scale) were used. At the beginning of the experiments, none of females used had a corpus luteum detected by ultrasonography. Females received an intravaginal device containing 0.5 g progesterone (DIB 0.5, Syntex, Buenos Aires, Argentina) and 2 mg oestradiol benzoate i.m. (Benzoato de Oestradiol, Syntex). Eight days later, 500 μg of cloprostenol (Ciclase DL, Syntex) and 0.5 mg oestradiol cypionate (Cipiosyn, Syntex) were given i.m. and devices were removed; FTAI was performed 52 to 56 h after DIB removal. At the time of device removal, the animals were randomly allocated to 4 groups, to receive 400 IU of eCG i.m. (Novormon, Syntex) or placebo at device removal and/or 14 days after FTAI, in a 2 × 2 factorial design. Control group did not receive eCG. In Exp. 1, nose plates were placed on calves on the day of DIB insertion and left for 10 days in order to prevent suckling. Pregnancy diagnosis was performed by ultrasonography at 30 and 60 days after FTAI. Data were analysed by logistic regression. Pregnancy rate at 30 days after FTAI was affected by treatment (P < 0.05; Table 1). Late embryonic/fetal loss rates (non-pregnant females at 60 days after FTAI over those pregnant at 30 days) were 1.6% (3/182) for cows in Exp. 1 and 4.8% (14/292) for heifers in Exp. 2; no differences were detected among groups. In conclusion, administration of 400 IU of eCG at device removal increases pregnancy rate, both in anestrus cows and heifers. However, the administration of a second dose of eCG 14 days after FTAI suggests a possible effect on embryo survival within the first 30 days of pregnancy in cows but not in heifers. Further studies are required to confirm these results. Table 1.Pregnancy rates after administration of eCG at time of progesterone device removal and/or 14 days after insemination in beef cattle Supported by Syntex.

scholarly journals Effect of different dosages of PG-600 on ovulation and pregnancy rates in ewes during the breeding season

2018 ◽  
Vol 3 (1) ◽  
pp. 429-432 ◽  
Author(s):  
Hayder Mohammed Hassan Habeeb ◽  
Timothy M Hazzard ◽  
Fred Stormshak ◽  
Michelle A Kutzler
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Chorionic Gonadotropin ◽  
Repeated Measures ◽  
Animal Health ◽  
Pregnancy Rates ◽  
Analysis Of Covariance ◽  
Future Research ◽  
Nonbreeding Season ◽  
Estradiol 17Β

Abstract This study compared the reproductive effects of different dosages of PG-600 (Intervet/Merck Animal Health, Madison, NJ) during the breeding season of ewes. PG-600 is a single-dose injectable product labeled for estrous induction in swine, containing equine chorionic gonadotropin (80 IU/mL) and human chorionic gonadotropin (40 IU/mL). PG-600 is routinely used off-label for out-of-season estrous induction in sheep. However, at the most common dose administered to ewes (5 mL), PG-600 is likely to overstimulate the ovaries, resulting in reduced pregnancy rates. Following estrous synchronization with intravaginal progesterone and cloprostenol, Polypay ewes were treated with 5 mL PG-600 (T1; n = 8), 1.5 mL PG-600 (T2; n = 8), or 5 mL saline (C; n = 8) and then mated to rams. Jugular vein samples were collected prior to the PG-600 injection (0 hr) and at 2, 4, 8, 12, and 24 hr after injection. Serum estradiol-17β was determined by chemiluminescence and among groups using repeated measures analysis of covariance. Ovulation and pregnancy rates were determined by transrectal ultrasonography and compared by one-way ANOVA and chi-square, respectively. Estradiol-17β concentrations were greater in T1 compared to T2 and C (P &lt; 0.001). Ovulation rate was greater (P &lt; 0.001) but pregnancy rate was lower (P &lt; 0.001) in the T1 compared to C and T2. These data confirm that a 5 mL dose of PG-600 administered to ewes during the breeding season overstimulates the ovaries, which may then reduce fertilization or embryo survival. Future research will focus on the effects of different dosages of PG-600 on pregnancy rate of ewes during the nonbreeding season.

161 EFFECT OF MELOXICAM TREATMENT ON PREGNANCY RATES IN HOLSTEIN HEIFERS

2007 ◽  
Vol 19 (1) ◽  
pp. 197
Author(s):  
A. Guzeloglu ◽  
H. Erdem
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Treated Group ◽  
Early Embryo ◽  
Pregnancy Rates ◽  
Control Group ◽  
Critical Stage ◽  
Embryo Survival ◽  
Flunixin Meglumine ◽  
Pregnancy Recognition

We previously reported that administration of flunixin meglumine two times at a critical stage approaching pregnancy recognition associated with corpus luteum maintenance increased early embryo survival and pregnancy rate via an additive antiluteolytic effect with the conceptus (Guzeloglu et al. 2006 Reprod. Fertil. Dev. 18, 183). In this study, the objective was to determine if a single administration of meloxicam, a non-steroid anti-inflammatory drug (NSAID) with a longer half-life, could be used instead of flunixin meglumine to avoid repeated injections in heifers at a critical stage following insemination to increase pregnancy rate due to its inhibitory effect on PGF2� synthesis. Eighty-five 15-18-month-old Holstein heifers were synchronized; following insemination (Day 0), the heifers were randomly assigned to receive a subcutaneous meloxicam injection (0.5 mg kg-1; n = 37) in the afternoon of Day 15 or left untreated as controls (n = 48). Pregnancy rates were defined as the percentage of heifers diagnosed pregnant by ultrasound between Days 31 and 38 after AI. The effect of treatment on pregnancy rates was analyzed by chi-square test. Meloxicam treatment on Day 15 after insemination dramatically decreased the pregnancy rates in the heifers (25 of 48 (52%) in the control group vs. 9 of 37 (24.3%) in the meloxicam-treated group; P &lt; 0.01). This result indicates that administration of meloxicam around a time associated with pregnancy recognition and corpus luteum maintenance was harmful to the pregnancy even though the drug is considered to be safe during pregnancy in cattle. It is concluded that direct or indirect effects of meloxicam on the uterine environment and/or embryo are not favorable at least during early pregnancy in cattle. How meloxicam exerted its detrimental effect on pregnancy warrants further investigation.

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