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.

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.

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.

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.

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.

162 FERTILITY OF BEEF RECIPIENTS FOLLOWING A FIXED-TIME EMBRYO TRANSFER PROTOCOL WHICH INCLUDED FOLLICLE STIMULATING HORMONE DILUTED IN HYALURONAN

2013 ◽  
Vol 25 (1) ◽  
pp. 229
Author(s):  
J. W. Thorne ◽  
C. R. Looney ◽  
J. F. Hasler ◽  
D. K. Hockley ◽  
D. W. Forrest
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Transfer Rate ◽  
Animal Health ◽  
Fixed Time ◽  
Control Groups ◽  
Pfizer Animal Health ◽  
And Control ◽  
Estradiol 17Β

This study was performed to test the viability of administering Folltropin-V® (FSH, Bioniche Animal Health) diluted in hyaluronan (MAP-5 50 mg, sodium hyaluronate, Bioniche Animal Health) to beef cows enrolled in a recipient synchronization protocol to evaluate its effect on recipient fertility. All recipients were administered an estradiol 17β (2.5 mg, IM) and progesterone (50 mg, IM) combination injection on Day 0, a CIDR® (progesterone 1.34 g, Pfizer Animal Health, Groton, CT, USA) was inserted for 7 days. Lutalyse® (dinoprost tromethamine, Pfizer Animal Health, 25 mg, IM) was administered at the time of CIDR removal on Day 7, and estradiol 17β (1 mg, IM) was administered on Day 8. On Day 16, the presence of at least one corpus luteum, detected via ultrasound, resulted in the recipient receiving an embryo (both fresh and frozen–thawed embryos were used). Embryos were not transferred into cows that did not show ultrasonic evidence of a CL. Dependent variables for which data were collected included circulating progesterone levels at the time of transfer and CL diameter, area, and circumference; measured in millimeters. The total study (n = 274) consisted of both wet (n = 85) and dry (n = 189) cows and included both Bos indicus (Brahman-influenced) crossbred (n = 93) and Bos taurus (Angus-based) cows (n = 181). The experiment consisted of cows being placed in either the treated or control groups, with treated cows receiving a single 40 mg (1 mL) IM injection of Folltropin-V in hyaluronan on Day 5 and control cows receiving no additional injections. Results are shown in Table 1. Transfer rate, conception rate, and pregnancy rate were tested for significance with chi-square analysis and remaining statistics were analyzed with a t-test: two-sample assuming equal variances. There were no significant differences found between the treated and control groups for transfer rate, conception rate, or pregnancy rate. Corpus luteum diameter was shown to be larger in control cows (P < 0.05); however, CL area and circumference did not differ significantly. Folltropin-V given with hyaluronan at a 40-mg dose on Day 5 did not improve fertility, induce a larger CL, or increase circulating progesterone levels in synchronized beef recipients as hypothesized. Further work is needed with Folltropin-V in hyaluronan to determine if an alternative dose or timing of administration would be more appropriate for improving fertility in recipients. Table 1.Fertility data in beef recipients following synchronization for fixed-time embryo transfer with a protocol that included (Treated) or did not include (Control) FSH in hyaluronan

298 COMPARISON OF THREE DIFFERENT PROTOCOLS FOR SUPERSTIMULATION OF DAIRY CATTLE

2009 ◽  
Vol 21 (1) ◽  
pp. 246 ◽  
Author(s):  
R. G. Steel ◽  
J. F. Hasler
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
Estrous Cycle ◽  
Embryo Transfer ◽  
Animal Health ◽  
Bovine Embryo ◽  
Transfer Program ◽  
Frozen Semen ◽  
Pfizer Animal Health ◽  
Estradiol 17Β

Traditionally, successful superstimulation of cattle depended on initiating injections of gonadotrophin at mid-cycle, approximately at second follicular wave emergence. This approach limited the convenience of scheduling donors for superstimulation. With the use of intravaginal progesterone-releasing devices and estradiol 17β, superstimulation can be initiated successfully at any time of the estrous cycle. However, because estradiol cannot be legally injected into cattle in an increasing number of countries, the efficacy of GnRH as an estradiol substitute was investigated. A retrospective analysis was performed on data collected in a commercial bovine embryo transfer program over a period of several years. All donors were lactating dairy cows at least two years of age; approximately 75% were comprised of Holstein and the remainder of Jersey, Guernsey, or Brown Swiss breeds. The three treatments employed were (1) Controls injected twice daily for 4 days with a total of 240 to 400 mg of porcine FSH (Folltropin-V, Bioniche Animal Health, Inc.) in decreasing doses starting between day 7 and day 14 of diestrus, with PG (Lutalyse, Pfizer Animal Health) given at the time of FSH injections no. 5 (35 mg) and 6 (25 mg); (2) Estradiol females received a CIDR (Pfizer Animal Health), 5.0 mg estradiol 17β and 100 mg progesterone in oil on random days of the estrous cycle; FSH was initiated 4 days later as described for controls with CIDR removal at the time of FSH injection no. 6; (3) GnRH females received a CIDR on random days of the estrous cycle and 100 μg GnRH on day 1.5 following CIDR insertion; FSH was initiated 60 h after GnRH injection as described for controls with CIDR removal at the time of FSH injection no. 6. All donors were inseminated with one straw of frozen semen 12 and 24 h after the onset of estrus. Embryos were nonsurgically recovered 7 to 8 days after onset of estrus. Only embryos of grades 1 to 3 (IETS classification) were included in the data. Data were analyzed by ANOVA and Tukey’s hsd test was used to distinguish significance among means as shown in Table 1. Estradiol females produced approximately 2 more ova/embryos per procedure than Control and GnRH groups and an average of 0.8 more embryos per female than did the Control group, but there was no difference compared to the GnRH group. Similar to what has been shown in other commercial embryo transfer data sets, nearly 25% of the donors in each group failed to produce at least one good embryo. Clearly, all three treatments resulted in efficacious superstimulation. In light of the legality issues surrounding the use of estradiol, this study shows that GnRH can be used quite successfully to superstimulate dairy cattle at random times of the estrous cycle. Table 1.Average numbers of ova and embryos recovered from dairy cows superstimulated with three different protocols We thank G.E. Seidel, Jr. and S.C. Purcell for assistance with statistical analysis.

scholarly journals 166 EFFECT OF TREATMENT WITH hCG OR GnRH AT THE TIME OF EMBRYO TRANSFER ON PREGNANCY RATES IN COWS SYNCHRONIZED WITH PROGESTERONE VAGINAL DEVICES, ESTRADIOL BENZOATE, AND eCG

2005 ◽  
Vol 17 (2) ◽  
pp. 234 ◽  
Author(s):  
R. Tribulo ◽  
E. Balla ◽  
L. Cutaia ◽  
G.A. Bo ◽  
P.S. Baruselli ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Condition Score ◽  
Pregnancy Status ◽  
To Receive

Although several studies have investigated the relationship between circulating progesterone and pregnancy rates in cattle, the beneficial effect of treatments that increase progesterone concentrations, by insertion of a progesterone (P4) releasing device or induction of an accessory CL with hCG, GnRH, or LH treatment, has resulted in inconsistent effects on pregnancy rates in embryo recipients. An experiment was designed to evaluate the effect of hCG or GnRH treatment, given at the time of embryo transfer without estrus detection, on pregnancy rates in recipients treated with intrauterine P4-releasing devices, estradiol benzoate (EB), and eCG. The experiment was performed in two replicates; non-lactating Bos taurus × Bos indicus crossbred beef cows with a body condition score between 2.5 to 3.5 (1-to-5 scale) were used (replicate 1, n = 180; replicate 2, n = 140). All cows received 1 g of P4 via a P4-releasing device (DIB, Syntex, Argentina) and 2 mg EB i.m. (Syntex) on Day 0, and 400 IU of eCG i.m. (Novormon 5000, Syntex) plus 150 μg d(+)cloprostenol i.m. (Ciclase, Syntex) on Day 5. DIBs were removed on Day 8 and all cows received 1 mg EB i.m. on Day 9. Recipients were not observed for signs of estrus, and those >1 CL, or a single CL with an area >256 mm2, received 195 Grade 1 and 46 Grade 2 frozen/thawed “direct transfer” embryos on Day 17. At the time of embryo transfer, recipients were randomly allocated to 1 of 3 treatment groups to receive 1500 IU hCG (Ovusyn, Syntex), 50 μg Lecirelina (GnRH, Gonasyn, Syntex), or no treatment (control) at that time. Ovarian ultrasonography was performed on Day 0 to determine ovarian status (only cows with a CL or a follicle >10 mm and uterine tone were used), on Day 17 to measure CL area, and 40 days after embryo transfer to determine pregnancy status. Data were analyzed by logistic regression and the effects of replication, technician, treatment, and embryo quality were considered in the model. From the 320 recipients treated with a DIB plus EB and eCG, 241 (75.3%) were selected to receive an embryo. Nine (3.7%) and 1 (0.4%) of the selected recipients had 2 and 3 CL, respectively. Pregnancy rates did not differ between replicates (replicate 1: 80/140, 57.1%; and replicate 2: 57/101, 56.4%; P = 0.84), technicians (technician 1: 65/118, 55.1%; and technician 2: 72/123, 58.5%; P = 0.64), or treatments (hCG: 43/80, 53.8%; GnRH: 45/83, 54.2%; and control: 49/78, 62.8% P = 0.99). However, pregnancy rates were higher (P = 0.001) in recipients receiving Grade 1 embryos (121/195, 62.1%) than in those receiving Grade 2 embryos (16/46, 34.8%). GnRH or hCG treatment at the time of embryo transfer did not increase pregnancy rates in recipients synchronized with P4 releasing devices, EB, and eCG. Research was supported by Syntex S.A., Estancia El Mangrullo S.A., and Agencia Cordoba Ciencia S.E.

scholarly journals The incompletely fulfilled promise of embryo transfer in cattle—why aren’t pregnancy rates greater and what can we do about it?

2020 ◽  
Vol 98 (11) ◽  
Author(s):  
Peter J Hansen
Keyword(s):  
Embryo Transfer ◽  
Artificial Insemination ◽  
Blastocyst Stage ◽  
Pregnancy Rates ◽  
Bovine Embryos ◽  
Uterine Receptivity ◽  
Stage Of Development ◽  
Stage Embryo ◽  
Repeat Breeder ◽  
In Pregnancy

Abstract Typically, bovine embryos are transferred into recipient females about day 7 after estrus or anticipated ovulation, when the embryo has reached the blastocyst stage of development. All the biological and technical causes for failure of a female to produce a blastocyst 7 d after natural or artificial insemination (AI) are avoided when a blastocyst-stage embryo is transferred into the female. It is reasonable to expect, therefore, that pregnancy success would be higher for embryo transfer (ET) recipients than for inseminated females. This expectation is not usually met unless the recipient is exposed to heat stress or is classified as a repeat-breeder female. Rather, pregnancy success is generally similar for ET and AI. The implication is that either one or more of the technical aspects of ET have not yet been optimized or that underlying female fertility that causes an embryo to die before day 7 also causes it to die later in pregnancy. Improvements in pregnancy success after ET will depend upon making a better embryo, improving uterine receptivity, and forging new tools for production and transfer of embryos. Key to accelerating progress in improving pregnancy rates will be the identification of phenotypes or phenomes that allow the prediction of embryo competence for survival and maternal capacity to support embryonic development.

Effects of equine chorionic gonadotropin on follicle development and pregnancy rates in suckled beef cows with or without calf removal1

2013 ◽  
Vol 91 (3) ◽  
pp. 1216-1224 ◽  
Author(s):  
G. H. L. Marquezini ◽  
V. R. G. Mercadante ◽  
K. C. Olson ◽  
J. R. Jaeger ◽  
G. A. Perry ◽  
...  
Keyword(s):  
Chorionic Gonadotropin ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Follicle Development ◽  
Equine Chorionic Gonadotropin

18 PREGNANCY RATES IN LACTATING DAIRY COWS TREATED WITH GONADOTROPIN-RELEASING HORMONE-BASED SYNCHRONIZATION PROGRAMS AND INSEMINATED AT A FIXED TIME

2013 ◽  
Vol 25 (1) ◽  
pp. 156
Author(s):  
D. Romero ◽  
G. Romero ◽  
G. Veneranda ◽  
L. Filippi ◽  
D. Racca ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Pregnancy Rate ◽  
Milk Production ◽  
Animal Health ◽  
Fixed Time ◽  
Gonadotropin Releasing Hormone ◽  
Pregnancy Rates ◽  
Lactating Dairy Cows ◽  
Pfizer Animal Health ◽  
Group 3

An experiment was designed to compare pregnancy rates in lactating dairy cows synchronized with a 7-day CIDR-Synch or a 5-day CIDR-Synch program and to determine if the addition of a second prostaglandin F2α (PGF) injection to the 7-day CIDR-Synch program would improve pregnancy rates following fixed-time AI (FTAI). The experiments were performed on 2 dairy farms in Argentina, with year-round calving and a mixed feeding system (35% grazing plus 65% corn silage and grain). Cows (n = 621) were 39.3 ± 6.5 days in milk (DIM, mean ± SD) when they were enrolled in the program, had 2.4 ± 1.5 lactations and a body condition score (BCS) of 3.1 ± 0.2 (range: 2.7 to 4.0). All cows received a pre-synchronization treatment with 2 doses of prostaglandin (PGF, 25 mg of dinoprost, Lutalyse, Pfizer Animal Health, Argentina) 14 days apart, and 11 days after the second PGF (Day 0) received 10 µg of Buserelin (GnRH, Receptal, MSD-Intervet, Argentina) and a CIDR device (1.9 g of progesterone, Pfizer Animal Health). Cows were randomly allocated to 1 of 3 groups. The CIDR devices were removed and PGF was administered to cows in Groups 1 and 2 on Day 7. A second GnRH was given 56 h later and cows experienced FTAI 16 h after gonadotropin-releasing hormone (GnRH) injection (i.e. 72 h after CIDR removal). Cows in Group 2 also received a second PGF injection on the afternoon of Day 7. Cows in Group 3 had the CIDR removed and received 2 PGF injections 12 h apart on Day 5. A second dose of GnRH was given and FTAI was performed at the same time, on Day 8 (i.e. 72 h after CIDR removal). All cows were examined by ultrasonography (Aloka 500V, Aloka, Tokyo, Japan) on the day of the first PGF injection and at CIDR removal to determine the presence and number of corpora lutea (CL), and 30 days after FTAI to determine pregnancy status. Data were analyzed by logistic regression to determine the effects of treatment, parity, days postpartum, milk production, BCS, presence of a CL at enrollment, and number of CL at the time of CIDR removal on pregnancy rates. Overall pregnancy rates did not differ among groups: 32.9% (68/207), 38.2% (78/204), and 38.3% (80/209) for Groups 1, 2, and 3, respectively (P = 0.2). Although the number of CL present at CIDR removal did not significantly affect pregnancy rates (P = 0.4), pregnancy rates in cows with 1 CL in Groups 1 and 2 tended to differ [29.0% (11/38) v. 48.9% (21/43); P < 0.07], but neither differed from that in Group 3 [37.2% (16/43)]. No differences were detected among groups in cows without a CL at CIDR removal [overall pregnancy rate: 29.4% (5/17)] and those with ≥2 CL [overall pregnancy rate: 36.1% (173/479)]. Among the other variables evaluated, first-parity cows had 1.96 (1.38–2.78) times more chance of getting pregnant than second-or-more-parity cows (P = 0.002) and cows with BCS >3 had 1.63 (1.16–2.28) times more chance of getting pregnant than those with BCS <3 (P = 0.003). Finally, herd, days postpartum, milk production, and presence of a CL at enrollment did not significantly affect pregnancy rates. We concluded that the 3 treatments resulted in similar pregnancy rates for lactating dairy cows and that the benefit of adding a second PGF injection to the 7-day protocol was only marginal in cows with 1 CL at CIDR removal.

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