8 SYNCHRONIZATION OF OVULATION IN DAIRY HEIFERS USING A SHORTENED ESTRADIOL-BASED PROTOCOL THAT PROVIDES FOR A LENGTHENED PROESTRUS

2014 ◽  
Vol 26 (1) ◽  
pp. 118 ◽  
Author(s):  
M. Re ◽  
J. J. de la Mata ◽  
G. A. Bo
Keyword(s):  
Body Condition Score ◽  
Prostaglandin F2α ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Treatment Protocols ◽  
Dairy Heifers ◽  
Buserelin Acetate ◽  
Condition Score ◽  
The Mean

Several studies, performed mainly in North America, have shown that the 5-day co-synch timed-AI (TAI) protocol results in similar or higher pregnancy rates than conventional 7-day co-synch protocols in beef cows and beef and dairy heifers. It is hypothesised that the 5-day co-synch protocol reduces the incidence of persistent follicles and provides for a longer proestrus, with increasing oestradiol concentrations due to continuous gonadotropin support for the dominant follicle (Bridges et al. 2008 Theriogenology 69, 843–851). Similar findings have been reported recently following the use of a shortened oestradiol-based protocol that also provides for a longer proestrus (named J-synch; de la Matta and Bo 2012 Taurus 55, 17–23). A study was designed to compare these 2 treatment protocols for synchronization of ovulation that allow for a prolonged proestrus with the conventional oestradiol-based protocol currently used for TAI in South America for heifers. Cycling Holstein heifers that were, on average, 17 months of age, weighting 350 to 380 kg, and with a body condition score of 2.5 to 3.5 (scale of 1 to 5), were randomly allocated to 1 of 3 treatment groups. Heifers in the 7-day estradiol benzoate (EB) group received a progesterone device (DIB 1 g of progesterone; Syntex SA, Buenos Aires, Argentina) and 2 mg EB (oestradiol benzoate, Syntex SA) on Day 0, 500 μg of cloprostenol (prostaglandin F2α; Sincronil, Proagro SA, Argentina) and DIB removal on Day 7, 1 mg of EB on Day 8, and TAI 30 h later (54 h after DIB removal). Heifers in the J-synch group received a DIB and 2 mg of EB on Day 0, PGF and DIB removal on Day 6, and 10 μg of buserelin acetate [gonadotropin-releasing hormone (GnRH); Receptal, Intervet, Millsboro, MD, USA] and TAI on Day 8 (72 h later). Heifers in the 5-day co-synch group received a DIB and GnRH on Day 0, DIB removal and prostaglandin F2α (twice, 12 h apart) on Day 5, and GnRH along with TAI on Day 8 (72 h later). Treatments were coordinated so that DIB were removed in all groups at the same time to decrease a possible time effect of follicle parameters and pregnancy rates. Two experiments were conducted; the first evaluated follicular dynamics and ovulation rates by twice daily ultrasonography (Honda 101 V, 5.0 MHz) in 20 heifers per group and the second determined pregnancy rates to TAI in 172 heifers. The mean (± standard error of the mean) interval from DIB removal to ovulation was shorter in the 7-day EB group (82.7 ± 3.1 h) than in the J-synch (103.8 ± 3.3 h) and 5-day co-synch (96.8 ± 3.3 h) groups (P = 0.01). However, the mean diameter of the dominant preovulatory follicle was smaller (P = 0.01) in the 7-day EB (12.8 ± 0.5 mm) and the J-synch (13.1 ± 0.6 mm) groups than in the 5-day co-synch group (14.9 ± 0.6 mm). Although pregnancy rates in the second experiment were numerically lower in the 7-day EB group (31/58; 53.4%) and 5-day co-synch group (30/55; 54.5%) than in the J-synch group (37/59; 62.7%), differences were not significant (P > 0.3). Preliminary results indicate that the 3 protocols evaluated result in comparable pregnancy rates to TAI in dairy heifers.

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.

214 EFFECT OF TIMING OF PGF, eCG, AND ESTRADIOL BENZOATE IN RECIPIENTS SYNCHRONIZED WITH A PROGESTIN-BASED PROTOCOL FOR FIXED-TIME EMBRYO TRANSFER

2007 ◽  
Vol 19 (1) ◽  
pp. 224
Author(s):  
L. C. Peres ◽  
D. Pincinato ◽  
L. Cutaia ◽  
R. Tribulo ◽  
G. A. Bo
Keyword(s):  
Embryo Transfer ◽  
Body Condition Score ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Control Treatment ◽  
Treatment Groups ◽  
Condition Score ◽  
The Mean ◽  
Time Of Administration

An experiment was designed to evaluate alternative treatment protocols for fixed-time embryo transfer (FTET) in recipients in order to reduce cattle handling. Non-lactating, cycling Bos taurus � Bos indicus beef cows (n = 918), with a body condition score (BCS) of 2.5 to 3.5 out of 5, received a progesterone-releasing device (DIB; Syntex, Buenos Aires, Argentina) and 2 mg estradiol benzoate (EB; Syntex) IM on random days of the cycle (Day 0); DIB were removed on Day 8. Cows were placed randomly into 6 treatment groups in a 3 � 2 factorial design. The factors evaluated were time of administration of PGF and eCG [control treatment: PGF Day 5 and eCG Day 5 (Bo et al. 2002 Theriogenology 57, 53–72); PGF Days 0 and 8 and eCG Day 5; PGF Days 0 and 8 and eCG Day 8] and the time of administration of the second injection of EB (at DIB removal or 24 h later). Therefore, cows in the control treatment received 150 �g of d-Cloprostenol (PGF, Ciclase; Syntex) and 400 IU eCG (Novormon; Syntex) on Day 5, whereas cows in the other 2 treatments received 75 �g of PGF on Days 0 and 8 and 400 IU eCG on either Day 5 or Day 8. Each treatment group was further subdivided to receive 1 mg EB IM on either Day 8 (EB Day 8) or Day 9 (EB Day 9). All recipients, whether observed in estrus or not and with more than one CL with luteal area (total CL area minus cavity area) >76 mm2 on the day before embryo transfer, received frozen-thawed embryos (IETS Grade 1) on Day 16 (EB Day 8) or Day 17 (EB Day 9) by direct transfer. Pregnancy was determined by ultrasonography 30 days after FTET. Continuous data were analyzed by ANOVA and pregnancy rates were analyzed by logistic regression. No effects of body condition score or technician were detected (P > 0.1). Although there were no differences in conception rates between recipients treated with EB on Day 8 or Day 9 (168/321, 52.3% vs. 203/350, 58.0%, respectively; P > 0.1), treatment with EB on Day 8 resulted in fewer recipients selected/treated (321/460, 69.7% vs. 350/458, 76.4%; P < 0.05) and pregnant/treated (168/460, 36.5% vs. 203/458, 44.3%; P < 0.05) than 24 h later (EB Day 9), respectively. The mean interval from DIB removal to estrus was shorter (P < 0.05) for recipients in the EB Day 8 (28.1 � 7.2 h) than in the EB Day 9 (43.5 � 9.4 h) group, and the mean (� SEM) CL area was also less in the EB Day 8 group than in the EB Day 9 group (261.7 � 96.7 vs. 293.1 � 114. mm2; P < 0.05). The number of recipients selected/treated was higher in the group receiving PGF on Days 0 and 8 and eCG on Day 8 (243/305, 79.6%) than in the group receiving PGF on Days 0 and 8 and eCG on Day 5 (208/301, 69.1%) or the control group (220/312, 70.5%). Although the luteal area was greater (P < 0.05) in the PGF on Days 0 and 8 and eCG on Day 5 group (304.4 � 127.1 mm2) than in the groups receiving PGF and eCG on Day 5 (274.6 � 98.6 mm2) or PGF on Days 0 and 8 and eCG Day 8 (258.4 � 90.2 mm2), pregnancy rates did not differ between PGF and eCG treatment groups (P > 0.05). It was concluded that it may be possible to reduce animal handling by treating recipients with a half dose of PGF at the time of DIB insertion and removal, when eCG is also administered, without compromising pregnancy rates.

scholarly journals 9THE USE OF ECG TO INCREASE PREGNANCY RATES IN POSTPARTUM BEEF COWS FOLLOWING TREATMENT WITH PROGESTERONE VAGINAL DEVICES AND ESTRADIOL BENZOATE AND FIXED-TIME AI

2004 ◽  
Vol 16 (2) ◽  
pp. 127 ◽  
Author(s):  
G.A Bo ◽  
L. Cutaia ◽  
P. Chesta ◽  
D. Moreno
Keyword(s):  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Control Group ◽  
Treatment Groups ◽  
Condition Score ◽  
N 93 ◽  
Rectal Palpation

Treatments with progesterone (P4) releasing devices and estradiol benzoate (EB) have been extensively used in fixed-time AI (FTAI) programs in beef cattle. However, pregnancy rates in postpartum cows kept on pasture often have been lower than expected because of poor body condition score (BCS) and a high incidence of anestrous. A recent study (Cutaia L et al., 2003 Theriogenology 59, 216) suggested that the addition of eCG to a P4/EB FTAI program may improve pregnancy rates in cows with fair to poor BCS, but results were not conclusive. Therefore, this experiment was designed to further investigate the effect of eCG treatment on pregnancy rates in postpartum beef cows in those conditions. The experiment was performed at 2 locations with lactating Angus cows (n=93), 60 to 90d postpartum with a BCS 1.9 (1 to 5 scale; Location 1), and crossbred Zebu cows (n=290), 60 to 90d postpartum with a BCS 2.0 (Location 2). In each Location, cows were randomly allocated to 1 of the following treatment groups: Control, eCG Day6, or eCG Day8. All cows received a P4 intravaginal device (DIB, Syntex, Argentina) and 2mg EB i.m. (Syntex) on Day0, 500mg cloprostenol (Estroplan, Syntex) at the time of DIB removal (Day8), 1mg EB i.m. on Day9 and FTAI 52 to 56h after DIB removal. Cows in the Control group received no further treatment, whereas cows in the eCG-treated groups received 400 IU eCG (Novormon 5000, Syntex) on Day6 or Day8. Cows were examined on Day0 by rectal palpation (Location 1) or by ultrasonography (US; Location 2) and were classified as those with a CL or without a CL, with either large (>8mm) or small (<8mm)small follicles. Pregnancy was determined by US 45d after FTAI. Data were analyzed by logistic regression and the effects of location, treatment, ovarian status, AI technician and semen were considered in the model. There was no effect of location (P=0.3), AI technician (P=0.2) or semen (P=0.8) on pregnancy rates. However, there was an effect of treatment (P=0.02), attributed to higher pregnancy rates in the eCG Groups than in the Control Group (Table). Furthermore, cows with a CL or without a CL but with large follicles on Day 0 had higher pregnancy rates than those with small follicles (P=0.04). It was concluded that the use of eCG in a P4/EB FTAI program improved pregnancy rates in postpartum beef cows that were in fair topoor BCS.

12 THE EFFECT OF PROGESTERONE CONTENT IN A VAGINAL INSERT ON PREGNANCY RATES IN BEEF AND DAIRY CATTLE INSEMINATED AT FIXED TIME

2006 ◽  
Vol 18 (2) ◽  
pp. 114
Author(s):  
L. Cutaia ◽  
M. Aviles ◽  
F. Feresin ◽  
A. Franzoni ◽  
L. Peres ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Holstein Cows ◽  
Chi Square ◽  
Condition Score ◽  
Chi Square Test

Three experiments were conducted to compare pregnancy rates in cows and heifers treated with intravaginal progesterone (P4)-releasing devices impregnated with either 0.5 or 1.0 g of P4 and inseminated at a fixed time (FTAI). In Experiment 1, 102 postpartum beef cows (Hereford and Angus crossbred with Tuli, 60 to 90 d postpartum) with a body condition score (BCS) of 2.5 to 3.0 (1 to 5 scale) were used. On Day 0, all cows received 2 mg of estradiol benzoate (EB; Syntex, Argentina) i.m. and were randomly assigned to receive an intravaginal progesterone-releasing device with 0.5 g of P4 (DIB 0.5 g; Syntex) or 1.0 g of P4 (DIB 1.0 g; Syntex). On Day 7, DIB devices were removed and all cows received 150 µg D(+)cloprostenol (Ciclase; Syntex) i.m. On Day 8, all cows received 1 mg EB and were FTAI 52 to 56 h after DIB removal. In Experiment 2, 93 Holstein cows that were 90 to 110 days in milk (DIM), producing on average 5000 kg of milk per lactation and with a BCS of 2.5 to 3.0 received the same treatments as those in Experiment 1. In Experiment 3, 100 Holstein heifers, 20 to 22 months old, with a BCS of 2.5 to 3.0, also received the same treatments as those in Experiment 1. Pregnancy rates in all experiments were determined by ultrasonography 35 days after FTAI and compared by chi-square test. No differences in pregnancy rates were detected between lactating beef cows, dairy cows, or dairy heifers treated with DIB devices impregnated with 0.5 or 1.0 g of P4 (Table 1). It was concluded that vaginal P4 releasing devices impregnated with 0.5 g or 1.0 g of P4 results in comparable pregnancy rates in FTAI protocols in beef and dairy cattle. Table 1. Pregnancy rates in postpartum beef cows, Holstein cows, and Holstein heifers treated with DIB devices impregnated with 0.5 or 1.0 g of P4 and subjected to FTAI

scholarly journals 158 PREGNANCY RATES IN RECIPIENT COWS TREATED WITH PROGESTERONE VAGINAL DEVICES AND INDUCED TO OVULATE WITH ESTRADIOL BENZOATE GIVEN AT THE TIME OF DEVICE REMOVAL OR 24 h LATER

2005 ◽  
Vol 17 (2) ◽  
pp. 229 ◽  
Author(s):  
G.A. Bo ◽  
E. Balla ◽  
L. Cutaia ◽  
L. Peres ◽  
P.S. Baruselli ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Device Removal ◽  
The Mean ◽  
To Receive

Although treatments with progesterone (P4) releasing devices, estradiol benzoate (EB) and eCG have been shown to result in acceptable pregnancy rates after embryo transfer, the treatment requires that the cows be run through the chute at least four times for treatments. An experiment was designed to compare pregnancy rates in cows treated with P4 releasing devices plus EB and eCG, and induced to ovulate with EB given at device removal or 24 h later. Non-lactating Bos taurus × Bos indicus crossbred beef cows (n = 165), with a body condition score between 2.5 to 3.5 (1 to 5 scale), were treated with a P4-device (DIB, Syntex, Argentina) and 2 mg EB i.m. (Syntex), on Day 0 and 400 IU of eCG i.m. (Novormon, Syntex) plus 150 μg D(+)cloprostenol i.m. (Ciclase, Syntex) on Day 5. On Day 8, DIB devices were removed and cows were randomly divided into two groups to receive either 1 mg EB i.m. at the time of DIB removal (EB0) or 24 h later (Day 9; EB24). Recipients were observed for signs of estrus for 48 h after DIB removal. On Day 16, all recipients observed in estrus and with >1 CL or a single CL with an area >256 mm2 were selected to receive fresh embryos on Day 16 (EB0) or Day 17 (EB24). Furthermore, 20 recipients not observed in estrus but with a CL >256 mm2 were randomly selected and transferred. The embryos used were 28 Grade 1, 40 Grade 2, and 24 Grade 3. 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 16 to measure CL area, and 60 days after embryo transfer to determine pregnancy status. Quantitative data were analyzed by Student's t-test and qualitative data were analyzed by logistic regression. There were no differences between groups in the mean (± SEM) CL area on Day 16 (EB0: 300.3 ± 12.0 mm2 and EB24: 324.9 ± 11.7 mm2; P = 0.14), the proportion of recipients in estrus (EB0: 38/82, 46.3%, and EB24: 34/83, 41.0%; P = 0.49), the number of recipients with >1 CL or a CL >256 mm2 (EB0: 68/82, 82.9%, and EB24: 72/83, 86.7%; P = 0.49) and the number of recipients pregnant/transferred (EB0: 31/49, 63.4%, and 20/43, 46.5%; P = 0.23). Furthermore, there were no significant effects of embryo quality (P = 0.31) or technician (P = 0.12) on pregnancy rates. The mean interval from DIB removal to estrus was shorter (P = 0.001) for recipients in the EB0 group (22.7 ± 1.0 h) than for those in the EB24 group (37.4 ± 1.2 h). Nevertheless, pregnancy rates did not differ (P = 0.14) between recipients seen in estrus (EB0: 21/38, 55.3%, and EB 24: 16/34, 47.1%) and those not seen in estrus but with a CL >256 mm2 on Day 16 (EB0: 10/11, 90.9%, and EB24 4/9, 44.4%). It was concluded that the two treatments evaluated are equally efficacious for synchronizing Bos taurus × Bos indicus recipients. Furthermore, the use of EB at device removal could reduce the number of trips through the chute without affecting pregnancy rates. Research was supported by Syntex S.A., Estancia El Mangrullo S.A., and Agencia Cordoba Ciencia S.E.

scholarly journals 14 EFFECT OF TEMPORARY WEANING AND ECG TREATMENT ON PREGNANCY RATES IN POSTPARTUM BOS INDICUS COWS FOLLOWING TREATMENT WITH PROGESTERONE VAGINAL DEVICES AND ESTRADIOL BENZOATE

2005 ◽  
Vol 17 (2) ◽  
pp. 157
Author(s):  
L. Cutaia ◽  
E. Balla ◽  
C. Rizzi ◽  
L. Peres ◽  
G.A. Bo
Keyword(s):  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Medium Size ◽  
Ovarian Activity ◽  
Condition Score ◽  
Rectal Palpation

Although treatments with progesterone (P4)-releasing devices and estradiol benzoate (EB) have been extensively used in fixed-time AI (FTAI) programs in beef cattle, pregnancy rates in postpartum Bos indicus cows kept on pasture often have been lower than expected because of poor body condition score (BCS) and a high incidence of anestrus. Temporary weaning and eCG treatment have been shown to increase pregnancy rates in suckled beef cows. Therefore, this experiment was designed to compare the effect of eCG treatment and temporary weaning on pregnancy rates in postpartum cows in fair to poor BCS. Lactating multiparous crossbred Bos indicus cows (n = 393), 60 to 90 d postpartum with a BCS 2.0 (1 to 5 scale) were randomly allocated to 1 of 4 treatment groups, in a 2 × 2 factorial design. At the beginning of the experiment (Day 0), all cows received a P4 intravaginal device (DIB, Syntex, Argentina) and 2 mg EB i.m. (Syntex). On Day 8, DIB devices were removed and all cows received 150 μg D (+) cloprostenol i.m. (Ciclase, Syntex) and were randomly divided to receive 400 IU eCG (Novormon 5000, Syntex) or no treatment at the same time. Furthermore, half of the cows in each treatment group have their calves weaned temporarily, from the time of DIB removal until the end of the FTAI, whereas the other half remained with their calves all the time. Finally, all cows received 1 mg EB i.m. on Day 9 and were FTAI 52 to 56 h after DIB removal. Cows were examined by ultrasonography 42 d after FTAI to determine pregnancy status. Data were analyzed by logistic regression and the effects of treatment and semen used were considered in the model. Ovarian activity was estimated by rectal palpation on Day 0: there were 72/393 (18.2%) cows with a CL, 140/393 (35.6%) cows with palpable medium size follicles, and 181/393 (46.1%) cows with ovaries containing no detectable structures. There was no effect of ovarian status at the time of treatment (P = 0.91) or semen (P = 0.91) on pregnancy rates. Treatment with eCG tended (P = 0.08) to increase pregnancy rates (94/192, 48.9% and 79/201, 39.3% for cows treated or not treated with eCG, respectively). However, there was no effect of weaning or eCG by weaning interaction (P = 0.98) on pregnancy rates (86/191, 45.1% and 87/202, 43.1% for cows that have their calves weaned or not weaned for 56 h, respectively). Results confirm those of previous studies that demonstrated that the use of eCG in a P4/EB/FTAI program improved pregnancy rates in postpartum Bos indicus crossbred cows that were in fair-to-poor BCS. However, no improvement in pregnancy rates was observed after temporary weaning in the present study. Research was supported by Syntex S.A., Estancia El Mangrullo S.A., and Agencia Cordoba Ciencia S.E.

20 PREGNANCY RATES IN SUCKLED BEEF COWS SYNCHRONIZED WITH PROGESTERONE INTRAVAGINAL DEVICES AND RECEIVING eCG FOURTEEN DAYS AFTER BREEDING

2010 ◽  
Vol 22 (1) ◽  
pp. 168 ◽  
Author(s):  
L. Cutaia ◽  
M. Ramos ◽  
P. Chesta ◽  
G. A. Bó
Keyword(s):  
Body Condition ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Treatment Groups ◽  
Condition Score

An experiment was designed to test the following hypotheses: (1) the administration of 400IU of eCG (Novormón, Syntex SA, Buenos Aires, Argentina) 14 days after fixed-time artificial insemination (FTAI) increases pregnancy rates in cross-breed Zebu × Bonsmara suckled cows synchronized with progesterone releasing devices (DIB 0.5, 0.5 g of progesterone, Syntex SA); and (2) pregnancy rates in cows treated with estradiol or GnRH, combined with a DIB device, are not different. Primiparous suckled cows (n = 260), between 60 and 120 days postpartum (DPP) and with a body condition score between 2.0 and 2.5 (1 to 5 scale) were used. At the beginning of the experiment (Day 0), all cows were examined by rectal palpation (only 11% had a CL), received a DIB device, and were randomly allocated to 1 of 3 treatment groups. Cows in the E2 group received 2 mg of estradiol benzoate (EB) intramuscularly (i.m.) at DIB insertion and those in the two GnRH groups received 100 μg of gonadorelin (GDR Gonasyn, Syntex SA) at the same time. On Day 7, DIB devices were removed and all cows received 500 μg of cloprostenol (Ciclase DL, Syntex SA) plus 400 IU of eCG (i.m.). Cows in the E2 group received 0.5 mg of estradiol cypionate (ECP, Cipiosyn, Syntex SA) and underwent FTAI administered by one technician, using semen from 1 of 2 bulls between 52 and 56 h later. Cows in the GnRH groups received a dose of 100 μg of gonadorelin (full GnRH group) or 50 μg of gonadorelin (1/2 GnRH group) at the time of the FTAI (52 to 56 h after DIB removal). Fourteen days after FTAI cows in the 3 groups were further subdivided (3 × 2 factorial) to receive or not 400 IU of eCG i.m. Pregnancy was determined 30 days after FTAI using real-time ultrasonography. Data were analyzed by logistic regression, taking into account the effect of the synchronization treatment, eCG or noteCG, 14 days after FTAI and sire used. No differences in pregnancy rates were found (P = 0.16) among treatment groups (E2: 39/87, 43.7%, full GnRH: 38/92, 41.3%, and 1/2 GnRH: 25/81, 30.9%). However, there was a significant (P = 0.02) effect of eCG treatment 14 days after FTAI (eCG: 60/127, 47.2% v. no eCG: 41/133, 30.8%). Furthermore, bull A (77/155, 47.1%) resulted in higher pregnancy rate (P = 0.009) than bull B (28/107, 26.2%), but there were no significant interactions between bull and synchronization treatment or eCG administration 14 days after FTAI (P > 0.1). We conclude that the application of 400 IU of eCG 14 days after FTAI increases pregnancy rates in suckled Bos taurus × Bos indicus primiparous cows with fair to poor body condition score synchronized with progesterone releasing devices. Furthermore, the use of estradiol ester or GnRH at DIB insertion and removal did not affect pregnancy rates.

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.

39 EFFECT OF TIME OF FIXED-TIME AI ON PREGNANCY RATES IN ZEBU CROSS-BRED BEEF HEIFERS TREATED WITH PROGESTERONE RELEASING DEVICES AND ESTRADIOL CYPIONATE

2010 ◽  
Vol 22 (1) ◽  
pp. 177 ◽  
Author(s):  
M. Ramos ◽  
L. Cutaia ◽  
P. Chesta ◽  
G. A. Bó
Keyword(s):  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Beef Heifers ◽  
Treatment Groups ◽  
Condition Score ◽  
To Receive

Two experiments were designed to evaluate the effect of the timing of fixed-time AI (FTAI) in relation to the removal of an intravaginal progesterone-releasing device (1 g of progesterone, DIB, Syntex SA, Buenos Aires, Argentina) on pregnancy rates in Bos indicus × Bos taurus cross-bred heifers. In experiment 1, 285 Bonsmara × zebu cross-bred heifers, between 18 and 24 months of age and with a body condition score (BCS) between 3.0 and 3.5 (1-5 scale) were used. On the day of initiation of treatment (Day 0), the heifers’ ovaries were palpated (92% of them had a CL) and they received a new DIB plus 2 mg of estradiol benzoate (EB; Syntex SA) and 250 μg of cloprostenol (Ciclase DL, Syntex SA). On Day 8, DIB devices were removed and all heifers received 250 μg of Ciclase plus 0.5 mg of estradiol cypionate (ECP; Cipiosyn, Syntex SA). At that time the heifers were randomly divided to receive FTAI between 48 to 49 h, 53 to 54 h, or 58 to 59 h after DIB removal. The heifers underwent FTAI with semen from 4 bulls by 2 inseminators. In experiment 2, 260 heifers from the same group as those used in experiment 1 (87% with a CL) were treated exactly as those in experiment 1, except that previously used DIB was inserted on Day 0. Pregnancy diagnosis was performed 30 days post-fixed-time AI by ultrasonography. The data were analyzed by logistic regression, taking into account the effect of time of FTAI, semen, and inseminator on pregnancy rates. In experiment 1, pregnancy rates were lower (P = 0.04) in the heifers undergoing FTAI between 48 and 49 h after DIB removal (46/95, 48.4%) than those undergoing FTAI 53 to 54 h (61/99, 61.6%) or 58 to 60 h (57/91, 62.6%) after DIB removal. However, no differences in pregnancy rates were found (P = 0.72) in experiment 2 between the 3 treatment groups, with 39/91 (42.9%) for the 48 to 49 h group, 45/89 (50.6%) for the 53 to 54 h group, and 35/89 (43.8%) for the 58 to 59 h group. There was no effect of the semen or inseminator (P > 0.2) in either experiment. We conclude that when Bos indicus × Bos taurus beef heifers are synchronized with new DIB devices and ECP, higher pregnancy rates are obtained in heifers undergoing FTAI late (between 53 to 60 h after DIB removal) than in those undergoing FTAI early (48 to 49 h after DIB removal). However, time of insemination does not apparently affect pregnancy rates when Bos indicus × Bos taurus beef heifers are synchronized with previously used DIB devices and ECP.

7 INFLUENCE OF ESTRUS EXPRESSION AND TREATMENT WITH GnRH ON PREGNANCY RATES IN BEEF CATTLE SYNCHRONIZED WITH PROGESTERONE DEVICES AND ESTRADIOL AND INSEMINATED AT A FIXED-TIME

2017 ◽  
Vol 29 (1) ◽  
pp. 111 ◽  
Author(s):  
G. A. Bó ◽  
A. Cedeño ◽  
A. Tribulo ◽  
S. Andrada ◽  
R. Tribulo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Beef Cattle ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Device Removal ◽  
Oestradiol Benzoate ◽  
Condition Score ◽  
To Receive

We have previously shown that expression of oestrus significantly influences the time of ovulation and pregnancy rates to timed-AI (P/TAI) in beef cattle synchronized with progesterone devices and oestradiol (Bó et al. 2016 Theriogenology 86, 388–396). Furthermore, delaying TAI from 48 h to 54–58 h after device removal improved P/TAI of those animals not showing oestrus by 48 h. The objective of the present study was to determine whether the administration of GnRH to those animals not showing oestrus by 48 h after device removal had an impact on P/TAI. Non-lactating and suckled beef cows and heifers (Bonsmara, Brangus, and Braford; n = 868), with a corpus luteum (CL) or a follicle ≥8 mm in diameter detected by ultrasonography (Mindray DP 30 Vet, 7.5 MHz, China) and body condition score 2 to 4 (1 to 5 scale) were synchronized in 3 replicates. On Day 0, animals received a progesterone device (DIB 0.5 g, Zoetis, Argentina) and 2 mg of oestradiol benzoate (Von Franken, Argentina). On Day 8, DIB were removed and cows received 0.150 mg of D+cloprostenol (Río de Janeiro, Argentina) plus 0.5 mg oestradiol cypionate (Cipiosyn, Zoetis). In addition, all cows were tail-painted on the sacrococcygeal area (CeloTest, Biotay, Argentina) at DIB removal and were observed to determine the expression of oestrus, according to the percentage of paint loss (PL) 48 h later. The animals that showed oestrus (PL > 30%) were recorded and TAI at that time while those with PL ≤ 30% (not in oestrus) were randomly allocated to receive 100 μg of gonadorelin (GnRH; Gonasyn, Zoetis) or no treatment and TAI between 54 to 58 h after DIB removal. Pregnancy was diagnosed by ultrasonography at 45 days after TAI, and data were analysed by logistic regression. There were no significant differences among replicates, inseminators, semen source or animal class (dry cows, suckled cows or heifers; P > 0.11). However, animals showing oestrus by 48 h after DIB removal had higher P/TAI (371/666; 55.7; P < 0.04) than those that did not show oestrus (96/202; 47.5%). Within animals not showing oestrus at 48 h, those that were in oestrus by the TAI at 54 to 58 h had higher P/TAI (71/124, 57.3%; P < 0.01) than those that did not show oestrus within that period (27/78; 34.6%). In addition, P/TAI was higher (P < 0.01) in animals that received GnRH (66/113; 58.4%) than in those that did not receive GnRH (30/89; 33.7%). In conclusion, the expression of oestrus significantly affected P/TAI in beef cattle synchronized with progesterone devices and oestradiol. Furthermore, treatment of animals not showing oestrus by 48 h after DIB removal with GnRH resulted in improved P/TAI performed 6 to 10 h later.

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