19 BEEF CATTLE PREGNANCY RATES FOLLOWING INSEMINATION WITH AGED FROZEN ANGUS SEMEN

2010 ◽  
Vol 22 (1) ◽  
pp. 167 ◽  
Author(s):  
D. B. Carwell ◽  
J. A. Pitchford ◽  
G. T. Gentry Jr ◽  
H. Blackburn ◽  
K. R. Bondioli ◽  
...  
Keyword(s):  
New York ◽  
Animal Health ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Crossbred Cattle ◽  
Chi Square ◽  
Frozen Semen ◽  
Pfizer Animal Health ◽  
Time Periods ◽  
Chi Square Analysis

Artificial insemination has proven to be a valuable asset to the cattle industry. It is assumed that once good quality semen is frozen in liquid nitrogen it should remain viable indefinitely; however, semen viability has not been systematically evaluated after being stored for several decades. In this experiment, frozen semen from 25 purebred Angus bulls processed during 3 time periods (1960-1975 = 5 bulls; 1976-1991 = 11; 1992-2002 = 9 bulls) was used to randomly inseminate purebred lactating Angus cows and heifers and lactating crossbred beef cows. In experiment 1, Angus cows (n = 24) and Angus heifers (n = 16) and in experiment 2, crossbred cattle (n = 88) of 5 breeds (Beefmaster, Romosinuano, Bons Mara, Brangus, Brangus F1) were artificially inseminated with frozen-thawed Angus bulls semen from the 3 time periods. All females were in good body condition and at least 45 days postpartum and were synchronized using the SelectSynch protocol. Briefly, on treatment Day 0, females received an Eazi-Breed CIDR (Pfizer Animal Health, New York, NY, USA) implant and were administered GnRH (Factryl, 100 μg im), on Day 7, prostaglandin (Lutalyse, 25 mg im, Pfizer Animal Health) was administered and the CIDR removed. Cattle not responding to synchronization were subjected an additional prostaglandin treatment 8 to 10 days later. Estrus detection was conducted using the HeatWatch™ system for the Angus females and with Estrotect™ patches for the crossbred females. Females fitted with HeatWatch transponders that were successfully mounted 4 times within a 6-h period were considered to be in standing estrus and were inseminated 12 to 14 h later. Females fitted with Estrotect patches were observed twice daily (morning and evening) to identify females whose patch was scratched. Females were inseminated by an experienced technician 12 to 14h after the patch were observed as being scratched a minimum of 50%. Response to synchronization in Angus cows and heifers was 76% (n = 40), whereas in the crossbred cattle the response was 74% (n = 88). Cows and heifers were confirmed pregnant via transrectal ultrasonography 45 days postinsemination. Pregnancy rates confirmed by chi-square analysis were not different for Angus cows and heifers (58% and 43%, respectively). Also, pregnancy rates for the Angus females were not different across time periods 1, 2, and 3 (58, 43, and 53%, respectively). Pregnancy rates for crossbred females were not different across time periods 1, 2, and 3 (35, 60, and 44%, respectively). Overall pregnancy rates (experiments 1 and 2) were 47, 52, and 40% across time periods 1, 2, and 3 respectively. It is concluded from this study that semen units processed and frozen from Angus bulls from time periods 1, 2, and 3 (from the 1960s through to 2002) are still viable and produce similar pregnancy rates in artificially inseminated beef females. Thanks to Jared Pitchfordfor inseminating all of the cattle; Harvey Blackburn for providing the semen to make the project possible; and my advisors Dr. Gentry and Dr. Godkefor assisting throughout the entire project. I also thank all of the graduate students who have helped me throughout the project.

20 ADMINISTRATION OF FOLLICLE-STIMULATING HORMONE AT CIDR REMOVAL DOES NOT AFFECT THE PREGNANCY RATE IN A CIDR-BASED, COSYNCH PROTOCOL IN LACTATING BEEF COWS

2008 ◽  
Vol 20 (1) ◽  
pp. 90 ◽  
Author(s):  
J. Small ◽  
F. Dias ◽  
L. Pfeifer ◽  
K. Lightfoot ◽  
M. Colazo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Pregnancy Rate ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Animal Health ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Condition Score ◽  
Secondary Objective ◽  
Pfizer Animal Health

In previous studies, giving eCG at CIDR removal significantly increased the pregnancy rate after timed-AI in beef cows. However, eCG is not universally available. Therefore, we tested the hypothesis that giving pFSH at CIDR removal might improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows; a secondary objective was to compare pregnancy rates when GnRH v. pLH was used to synchronize wave emergence and ovulation. This work was conducted as two experiments (separate locations). All cows were given a CIDR (containing 1.9 g progesterone; Pfizer Animal Health, Montreal, QC, Canada) on Day 0 (without regard to stage of estrous cycle or cyclicity). On Day 7, CIDRs were removed, all cows were concurrently given 25 mg PGF (Lutalyse; Pfizer Animal Health, Groton, CT, USA), half were given 20 mg pFSH (Folltropin-V; Bioniche Animal Health, Belleville, ON, Canada), and all cows were timed-AI 54 h later (Day 9). In Experiment 1, 240 cows [94 � 10.8 days postpartum; body condition score (BCS: 1 = emaciated, 9 = obese; mean � SD): 5.8 � 0.4] were used; at CIDR insertion and AI, cows were allocated to receive either 100 µg GnRH (n = 160; Cystorelin, Merial Canada Inc., Victoriaville, QC, Canada) or 12.5 mg pLH (n = 80; Lutropin-V, Bioniche Animal Health). In Experiment 2, 109 cows (59.2 � 19.5 days postpartum; BCS: 5.6 � 1.1) were used; all received 100 µg GnRH (Cystorelin) at CIDR insertion and AI. In Experiment 1, three cows that lost their CIDR were excluded; pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, synchronizing treatment, and their interactions) were not different between cows given pFSH v. control cows (64.7 v. 65.2%; P > 0.80), nor between cows given GnRH v. pLH (62.7 v. 69.6%; P = 0.91). However, there was an interaction (P < 0.04) between parity and the synchronizing treatment; in primiparous cows, pregnancy rates were significantly lower in those given GnRH v. pLH (59.3 v. 83.3%). In Experiment 2, pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, and their interaction) were not different between cows given pFSH v. control cows (38.2 v. 42.6%; P > 0.6). In conclusion, our hypothesis was not supported; giving pFSH at CIDR removal did not significantly improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows.

PSI-7 Comparison of 6-day versus 7-day CIDR protocol with GnRH and PGFα to synchronize crossbred beef cows for fixed-timed ai with sexed semen at two different times

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 281-282
Author(s):  
Nicole N Noga ◽  
Jeremy G Powell ◽  
Brittni P Littlejohn ◽  
Whitney L Rook ◽  
Martin Mussard ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Chi Square ◽  
Treatment Groups ◽  
Conception Rates ◽  
Sexed Semen ◽  
Chi Square Analysis

Abstract Preliminary data indicate that shortening the progesterone exposure with CIDR can improve conception rates compared to the established 7-day CO-Synch protocols. The objective was to determine the effects of shortening progesterone exposure from 7 days to 6 days among crossbred beef cows and fixed-time artificial insemination (FTAI) with sex-sorted semen. A total of 147 fall calving (September-November) crossbred beef cows from one location were randomized to one of four treatments: 1 and 4) 7-d CO-Synch + CIDR protocol with administration of gonadotropin-releasing hormone (GnRH) and a CIDR insert on day 0, prostaglandin F2α (PGF) at CIDR removal on day 7, and FTAI occurring 66 h (Treatment 1) or 74 h (Treatment 4) later; 2 and 3) 6-d CO-Synch + CIDR protocol with administration of GnRH and CIDR insert on day 0, prostaglandin F2α (PGF) at CIDR removal on day 6, and FTAI occurring 72 h (Treatment 2) or 80 h (Treatment 3) later. Sex-sorted semen from Angus sires was used for AI. Pregnancy was determined by ultrasound 40 days after AI. Pregnancy rate was analyzed using the MIXED procedure of SAS with CIDR and AI service time as fixed effects. Chi-square analysis was used to assess the number of pregnant and open cows in each treatment using the FREQ procedure of SAS. There was no difference (P = 0.78) in pregnancy rates between 6-d CIDR (0.59 ± 0.05%) and 7 d CIDR (0.57 ± 0.05%) protocols. Cattle bred a shorter period after CIDR removal (0.64 ± 0.05%) had numerically (P = 0.11) greater pregnancy rates compared to those with a longer period after CIDR removal (0.51 ± 0.05%). There was no difference in the number of pregnant and open cows between treatment groups. These data suggest that using a 6-day or 7-day protocol, regardless of breeding time, results in similar conception rates.

scholarly journals 98CONCEPTION RATES USING BRAHMAN BULL SEMEN FROZEN IN MILK BASED EXTENDER CONTAINING EGG YOLK OR SOYBEAN LIPIDS; A FIELD STUDY IN A TROPICAL ENVIRONMENT

2004 ◽  
Vol 16 (2) ◽  
pp. 170 ◽  
Author(s):  
R. Gonzales ◽  
M. Rosales ◽  
F. Perea ◽  
J. Velarde ◽  
E. Soto ◽  
...  
Keyword(s):  
Egg Yolk ◽  
Pregnancy Rates ◽  
Glycerol Concentration ◽  
Forest Environment ◽  
Chi Square ◽  
Bull Semen ◽  
Frozen Semen ◽  
The Mean ◽  
Semen Extender ◽  
Chi Square Analysis

The objective of this study was to examine the substitution of soybean-origin phospholipids for egg yolk in Brahman bull semen extender. Semen was frozen in 3 different low-fat milk (1%) based extenders containing 10mgmL−1 of fructose and supplemented with: 8% of whole egg yolk (Extender 1, control), 8% rectified egg yolk (egg yolk granules were removed by double centrifugation at 3000g for 1h at 5°C; Extender 2), and 7.3mgmL−1 of phospholipids of soybean-origin containing 10% of phosphatidyl choline (Extender 3). All 3 extenders were supplemented with 1000IU of penicillin, 1mgmL−1 streptomycin and 150μgmL−1 lincomycin. The semen was collected by means of artificial vagina from 3 Brahman bulls, and AI was performed during the dry season between December and April in a tropical forest environment. The mean temperature for the region was 26–30°C, with mean rainfall of 900–1500mm/year and the relative humidity of 60–70%. Ejaculates with at least 60% motility were diluted in 2 steps as follows: in step 1, each ejaculate was split into 3 even parts and diluted at 26°C with each of the extenders containing no glycerol, and in step 2, 14% of glycerol was added in 15-minute intervals to a final glycerol concentration of 7%. Semen was aspirated into 0.5mL plastic straws (20×106 sperm/per straw), frozen 7cm above liquid nitrogen (LN2) for 8min, and then plunged into LN2. Straws were thawed in a water bath at 37°C for 30s. Each experiment was replicated 3 times (different collection days). Sperm viability was tested within artificial insemination trials. Results are based on the pregnancy rates of crossbreed Brahman cows determined by palpation 45 Days after AI and by calving rates. Data were compared by chi-square analysis. In Experiment I, a total of 157 cows were inseminated with semen collected from 3 different bulls (A, B and C) and frozen in 3 different extenders (1, 2 and 3; 3×3 factorial design). Bull A, Extender 1, 2 and 3 (n=19, 20 and 22); Bull B, Extender 1, 2 and 3 (n=20, 20 and 20) and Bull C, Extender 1, 2 and 3 (n=22, 15 and 24), respectively. Although semen from all 3 bulls frozen in Extenders 2 and 3 fostered numerically higher pregnancy rates (from 30% for Bull B and Extender 2 to 50% for Bull C and Extender 3) than in Extender 1 (from 23.5% for Bull C to 40% for Bull B), there were no differences (P&lt;0.05) between bulls with any of 3 extenders on the pregnancy rates. In Experiment II, a total of 117 cows were inseminated with semen collected from Bull B and frozen in Extender: 1 (n=37), 2 (n=48) and 3 (n=39). There were significantly higher (P&lt;0.05) calving rates for cows inseminated with semen frozen in Extender 2 and 3 (41.6% and 46.1%, respectively) than in Extender 1 (24.3%). It can be concluded that rectified egg yolk may improve viability of frozen semen, and that phospholipids of soybean origin can be successfully substituted for egg yolk in Brahman bull milk based semen extender. Supported by Bioniche Inc, Belleville, Ontario, Canada.

18 THE EFFECTS OF CIDR AND eCG TREATMENTS IN A GnRH-BASED PROTOCOL FOR TIMED AI OR EMBRYO TRANSFER ON PREGNANCY RATES IN LACTATING BEEF COWS

2007 ◽  
Vol 19 (1) ◽  
pp. 127 ◽  
Author(s):  
J. A. Small ◽  
M. G. Colazo ◽  
J. P. Kastelic ◽  
D. R. Ward ◽  
O. Dochi ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Animal Health ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Ultrasonographic Examination ◽  
Pfizer Animal Health ◽  
Equine Chorionic Gonadotropin ◽  
Recipient Selection ◽  
In Pregnancy ◽  
Synchronization Protocol

Two experiments were conducted to determine the effects of the addition of a progestin, equine chorionic gonadotropin (eCG), or both, in a GnRH-based protocol for timed AI (TAI) or timed embryo transfer (TET). In both experiments, Angus, Gelbvieh, and Simmental cross-bred cows were randomized by breed and postpartum interval [50 � 10 days (mean � SD); range, 27 to 89] into 4 groups in a 2 � 2 factorial design. All injections were given IM. In Experiment 1, 288 cows (89.6% cycling) were given 25 mg dinoprost (PGF; Lutalyse�; Pfizer Animal Health, Montreal, Quebec, Canada) on Day –11; on Day 0, they were given 100 �g GnRH (Cystorelin�; Merial Canada, Pointe-Claire, Quebec, Canada), with or without concomitant insertion of a CIDR (1.9 g progesterone; Pfizer Animal Health, Montreal, Quebec, Canada). On Day 7, CIDR inserts were removed and cows were given PGF, with or without concomitant injection of 400 IU of eCG (Pregnecol�; Bioniche Animal Health, Belleville, Ontario, Canada). On Day 9 (54-56 h after PGF), TAI was done, with concomitant injection of 100 �g GnRH. Ultrasonographic examination of 147 cows on Day 7 revealed that 62.4% had ovulated in response to the first GnRH. Pregnancy rates (ultrasonographic examination) on Day 38 did not differ between cows with or without a CIDR (52.9 and 51.4%, rspectively; P ≥ 0.64), with or without eCG treatment (53.5 and 50.7%, respectively; P ≥ 0.28), in cycling vs. anestrous cows (51.6 vs 56.7%, respectively; P ≥ 0.76), and in cows that had ovulated (58.1%) or did not ovulate (50.0%) after the first GnRH treatment (P ≥ 0.58). In Experiment 2, 151 cows were given 500 �g cloprostenol (PGF; Estrumate�; Schering–Plough Animal Health, Pointe-Claire, Quebec, Canada) on Day –12, 100 �g GnRH on Day 0, with or without concomitant insertion of a CIDR. On Day 3, half of the cows were given 400 IU eCG. On Day 7, CIDRs were removed and cows were given PGF; on Day 9 (54–56 h after PGF), all cows were given 100 �g GnRH. On Day 15, ultrasonography was done to select suitable recipients for transfer of frozen–thawed embryos on Day 16 (part of another experiment, balanced across synchronization groups). Recipient selection rates did not differ whether cows received or did not receive a CIDR (93.4% vs 85.5%, respectively; P ≥ 0.27) or eCG (91.0 vs 87.8%, respectively; P ≥ 0.67). In addition, pregnancy rates on Day 43 did not differ whether cows received or did not receive a CIDR (32.3 vs 32.4%, respectively; P ≥ 0.52) or eCG (35.2 and 29.2%, respectively; P ≥ 0.21). In summary, the addition of a CIDR or eCG to a GnRH-based synchronization protocol initiated after PGF presynchronization in lactating beef cattle yielded no improvement in pregnancy rates following TAI, or recipient selection and pregnancy rates following TET.

17 MANIPULATION OF PROESTRUS PERIOD BY EXOGENOUS GONADOTROPIN AND ESTRADIOL DURING TIMED ARTIFICIAL INSEMINATION PROTOCOL IN SUCKLED BEEF COWS

2013 ◽  
Vol 25 (1) ◽  
pp. 155
Author(s):  
P. C. S. F. Pitaluga ◽  
M. F. Sá Filho ◽  
J. N. S. Sales ◽  
P. S. Baruselli ◽  
L. Vincenti
Keyword(s):  
New York ◽  
Animal Health ◽  
Bos Indicus ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Additional Treatment ◽  
Control Group ◽  
Device Removal ◽  
Pfizer Animal Health ◽  
Synchronization Protocol

The objective of this study was to evaluate the effect of eCG or estradiol cypionate (ECP) during the proestrus period on estrus occurrence, ovarian responses, and pregnancy per AI (P/AI) in suckled Bos indicus beef cows subjected to timed AI (TAI) protocols. A total of 393 cows in random stages of estrus (Day 0), received an intravaginal progesterone (P4) device (1.9 g of P4; CIDR®, Pfizer Animal Health, New York, NY, USA) and 2.0 mg of estradiol benzoate IM (EB; Gonadiol®, MDS Animal Health). Eight days later, the P4 devices were removed, and cows were given 0.15 mg of d-cloprostenol (Prostaglandina Tortuga®, Tortuga Companhia Zootécnica Agrária, São Paulo, Brazil). At this time, cows were randomly assigned to 1 of 3 treatments: 300 IU of eCG (Group eCG; n = 138), 300 IU of eCG plus 1 mg of ECP IM (Group eCG+ECP; n = 124), or no additional treatment (control; n = 131). Cows were timed inseminated 48 h after P4 device removal and were administrated simultaneously 100 µg of gonadorelin IM (Profertil®, Tortuga Companhia Zootécnica Agrária). A subset of cows (n = 98) were evaluated according to the occurrence of estrus between the P4 device removal and TAI and their ovarian follicles were evaluated by ultrasound at P4 device removal and corpus luteum (5 days after TAI). The data were analyzed using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC, USA) and differences with P < 0.05 were considered statistically significant. A greater pregnancy rate (P/AI; P = 0.04) was observed in cows receiving the eCG treatment at P4 device removal [eCG = 42% (58/138) and eCG+ECP = 50.8% (63/124)] than cows from the control group [29.8% (39/131)]. There was no additive effect of ECP supplementation on P/AI. Cows that received ECP [eCG+ECP = 56.3% (18/32)] displayed more estrus (P = 0.002) compared with those receiving eCG [eCG = 23.5% (8/34)] or only GnRH at TAI [control = 15.6% (5/32)]. In addition, regardless of the ECP supplementation, cows receiving the eCG treatment at P4 device removal [eCG = 85.3% (29/34) and eCG+ECP = 90.1% (29/32)] presented a greater ovulation rate than cows from the control group [65.6% (21/32)]. In conclusion, exogenous estradiol administrated at device removal increased the proportion of suckled Bos indicus cows that displayed estrus. Cows receiving eCG treatment (with or without estradiol supplementation) had greater ovulatory and pregnancy responses after the estradiol/P4-based synchronization protocol.

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 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

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.

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.

191 INFLUENCE OF THE DIFFERENT TIME COMPONENTS BETWEEN FLUSHING AND TRANSFER ON PREGNANCY RATES OF FROZEN CATTLE EMBRYOS

2006 ◽  
Vol 18 (2) ◽  
pp. 203
Author(s):  
C. Ponsart ◽  
H. Quinton ◽  
A. Rohou ◽  
J. Kelhembo ◽  
G. Bourgoin ◽  
...  
Keyword(s):  
Pregnancy Rates ◽  
Chi Square ◽  
Frozen Embryos ◽  
Multivariate Logistic Model ◽  
Parity Number ◽  
Embryo Stage ◽  
Chi Square Analysis ◽  
Fresh Embryos ◽  
Donor Cows

Previous studies have shown that the time between flushing and freezing of bovine embryos can influence pregnancy rates (PRs) following embryo transfer (ET). The aim of this study was to determine which time components can influence ET results. Time components between flushing of a superovulated donor and freezing of the collected embryos were investigated under field conditions. Embryos were frozen in 1.5 M ethylene glycol (EG) for direct transfer. During January 2003, ET technicians (EmbryoTop, Rennes cedex, France) recorded systematically times corresponding to each step comprising the time spent in vitro (TIV) from 153 recovery sessions (RS) with freezing: end of flushing, beginning and end of search of embryos, start of equilibration in EG, beginning and end of straw loading, introduction to −7°C in the freezer, and seeding. Numbers of donor cows and ET technicians doing the freezing (n = 5) were noted for each RS. Embryo (stage, quality) and recipient (breed, parity) characteristics were also noted. A total of 548 frozen embryos were transferred and PRs were assessed. Variability of time components was investigated (Bourgoin et al. 2004 Reprod. Fertil. Dev. 16, 207). The influence of time components and other variation factors was tested on PRs (t-tests and chi-square analysis). The TIV averaged 210 ± 80 min and did not influence PR (≤4 h = 51.9% (n = 393) vs. >4 h = 55.5% (n = 155); P > 0.05), as well as duration of flushing (32 ± 8 min), interval between end of flushing and search (31 ± 27 min), duration of search (45 ± 25 min) and interval between end of search and beginning of freezing (101 ± 63 min). Only significant factors were kept for further analysis. The effects of recipient parity, number of donor cows per RS, and interval between introduction of straw to −7°C, and seeding were tested in a multivariate logistic model. PR varied strongly with parity of recipient (+25% in heifers vs. cows; P = 0.001). PRs were higher when the interval between straw introduction in the freezer and seeding lasted at least 5 min (2–4 min = 48.0% (n = 254) vs. 5–8 min = 57.1% (n = 294); P = 0.009). Time and operator effects were confounded. Overall PR results for the two technicians who used mostly 2–4 min intervals averaged 47% (operator values = 35.6, 48.9, and 54.5) whereas PRs were 54.9 and 60.5% for those waiting 5 min or more before inducing seeding (n = 2). PRs were higher when at least two donor cows were collected per RS (1 donor cow = 49% (n = 259) vs. ≥2 donor cows = 56.4% (n = 289); P = 0.003). This was not in agreement with previous observations in fresh embryos (Bourgoin et al. 2004). However, the number of donor cows strongly influenced the number of viable embryos per RS (1 donor cow = 11 ± 5 vs. ≥2 donor cows = 18 ± 8.5; P < 0.05) and could permit the choice of more embryos to be frozen. These results show that good PR may be achieved with a delay of several hours between flushing and freezing, when heifers are used as recipients. Moreover, confirmed from higher numbers of operators, these data show that it is better to wait at least 5 min to achieve equilibration of the embryo before seeding.

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