170 Embryonic loss and pregnancy rate in response to resynchronisation using oestradiol benzoate or injectable progesterone at 14 days after timed AI in Bos taurus×Bos indicus beef heifers

2020 ◽  
Vol 32 (2) ◽  
pp. 212
Author(s):  
C. C. Vieira ◽  
V. Buss ◽  
A. M. Oliveira ◽  
M. E. R. Costa ◽  
B. G. Freitas ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Pregnancy Rates ◽  
Beef Heifers ◽  
Graduate Studies ◽  
Oestradiol Benzoate ◽  
Embryonic Loss ◽  
Long Acting ◽  
Intravaginal Device

The effect of the exposure of pregnant cattle to oestradiol benzoate (EB) or injectable long-acting progesterone (iP4), as well as their use for early resynchronisation of non-pregnant (NP) females within the second week after timed AI (TAI), is yet to be assessed. This study aimed to assess the pregnancy rate and embryonic loss of cross-bred Bos taurus×Bos indicus beef heifers in response to an EB- or iP4-based resynchronisation strategy implemented 14 days after the first TAI. A total of 677 cyclic heifers (Braford and Brangus; 24 months old) were subjected to an EB/P4 synchronisation protocol for the first TAI (Day 0=TAI). On Day 14, all heifers received a new P4 intravaginal device (1g, Sincrogest, Ourofino Saúde Animal) and were randomly assigned to two groups: EB (1mg intramuscularly, Sincrodiol; n=339) or iP4 (75 mg intramuscularly, Sincrogest Injetável; n=338). On Day 22, P4 devices were removed and heifers underwent colour Doppler ultrasonography evaluation. Non-pregnant females were identified by the assessment of structural regression of the corpus luteum, as previously reported by our group. On Day 22, NP heifers received 1mg of oestradiol cipionate (SincroCP), 250µg of sodium cloprostenol (Sincrocio), and 200IU of equine chorionic gonadotrophin (SincroeCG), and they were inseminated on Day 24. On Day 22, the diameter of the preovulatory follicle (POF) was also recorded. Pregnancy was diagnosed via B-mode ultrasonography on Days 35-40 and 54. Statistical analyses were performed using SAS software (ver. 9.2, SAS Institute Inc.). The MIXED procedure was used to evaluate the POF diameter, and the GLIMMIX procedure was used to develop a multivariate model including treatment, breed, age, farm (1-7), and possible interactions of treatment with farm, breed, and age to evaluate the binomial data (pregnancy rates and embryonic loss). In NP heifers, the diameter of the POF on Day 22 did not differ (P>0.05) between the EB (9.77±0.25mm) and iP4 (9.92±0.22 mm) groups. Exposure to EB or iP4 on Day 14 post-TAI did not influence pregnancy rates as assessed on Day 22 (56.3% (191/339) vs. 60.1% (203/338)) and on Days 35-40 (49.6% (168/339) vs. 53.3% (180/338)). In addition, embryonic loss between Days 22 and 35-40 was not different between the EB (12%, 23/191) and iP4 (11.3%, 23/203) groups. On the other hand, pregnancy rates in heifers submitted to the second TAI were greater (P=0.01) in the EB group (45.95%, 68/148) than in the iP4 group (31.85%, 43/135). In conclusion, improved pregnancy rates can be achieved using 1mg of EB associated with a P4 intravaginal device on Day 14 of the resynchronisation protocol without affecting the first TAI pregnancy rates and embryonic loss. However, further investigation is warranted to assess the lower pregnancy rates obtained in response to the association of iP4 and P4 device. This research was supported by FAPESP (2015/10606-9; 2019/15514-6), Graduate Studies Support Program (PAPG-UNIPAMPA), and Ourofino Saúde Animal.

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.

scholarly journals Evaluation of pregnancy rates of Bos indicus cows subjected to different synchronization ovulation protocols using injectable progesterone or an intravaginal device

2016 ◽  
Vol 37 (6) ◽  
pp. 4149
Author(s):  
Jefferson Tadeu Campos ◽  
Fábio Morotti ◽  
Camila Bortoliero Costa ◽  
Larissa Zamparone Bergamo ◽  
Marcelo Marcondes Seneda
Keyword(s):  
Pregnancy Rate ◽  
Bos Indicus ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Estrus Cycle ◽  
Device Removal ◽  
Alternative Source ◽  
Group Iii ◽  
Group I ◽  
Intravaginal Device

This study evaluated the pregnancy rate in Nelore cows (Bos indicus) that were subjected to fixed-time artificial insemination (FTAI) using different protocols consisting of injectable progesterone (P4) or an intravaginal device (impregnated with P4). Multiparous cows 72-84 months in age, 30-45 days postpartum, were selected on the basis of the absence of a corpus luteum (CL) and follicles < 8 mm after transrectal palpation and ultrasound examinations. On a random day of the estrus cycle (D0), the selected animals (n = 135) were randomly assigned to one of three experimental groups (n = 45 each). Group I (injectable P4/FTAI 36 hours) received 250 mg of injectable P4 and 2 mg EB on D0; on D7, they received 500 µg of cloprostenol; on D8, 300 IU of eCG and 1 mg of EB were administered; and finally, FTAI was performed 36 hours after the application of EB. Group II (injectable P4/FTAI 48 hours) received the same protocol as Group I, except that the FTAI was performed 48 hours after ovulation induction. The animals of Group III (Control/CIDR) received a conventional protocol for FTAI using an intravaginal device (D0: P4 and 2 mg EB; D8: device removal, 500 µg cloprostenol, 300 IU eCG, 1 mg EB; and FTAI performed 48 hours after removal of the device). The results showed that cows synchronized with the conventional protocol for FTAI (Control/CIDR) had a higher pregnancy rate (60 %, 27/45) than those synchronized with an injectable P4/FTAI 36 hours (33.33 %; 15/45, P = 0.010). However, the group receiving injectable P4 group/FTAI 48 hours had a similar pregnancy rate (48.9 %; 22/45; P = 0.290) when compared to both the group receiving the conventional protocol and that receiving injectable P4/FTAI 36 hours (P = 0.134). Although the injectable P4 may affect pregnancy rate with the FTAI performed in 36 hours, we found similar pregnancy rates from cows inseminated 48 hours after induction ovulation, considering injectable or intravaginal P4. Therefore, we suggest that injectable P4 represents an alternative source of progesterone for synchronization of cattle for FTAI.

scholarly journals Considerations for reproductive management of bos indicus-influenced beef heifers

2017 ◽  
Author(s):  
◽  
James William Cameron Locke
Keyword(s):  
United States ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Fixed Time ◽  
The United States ◽  
Pregnancy Rates ◽  
Breeding Period ◽  
Beef Heifers ◽  
Reproductive Management ◽  
Natural Service

The Bos indicus species of beef cattle presents a number of unique reproductive challenges, especially with regard to those that influence reproductive efficiency including timely attainment of puberty, response to certain pharmaceutical drugs used to control estrus and ovulation, and response to physiological stressors. Cattle of this biological type comprise a substantial percentage of the beef cattle population in southern regions of the United States because of their ability to withstand high ambient temperatures and relative humidity. Additionally, Bos indicus cattle are regarded to exhibit increased parasite and disease resistance, resulting in improved production in subtropical climates as compared to Bos taurus cattle in those same regions. Research utilizing composite breeds of Bos taurus and Bos indicus beef heifers has been limited in the United States, and adoption of reproductive technologies such as artificial insemination and estrus synchronization has been sluggish compared to Bos taurus cattle in other regions of the country. To help answer a number of questions about this biological type, an experiment was designed to evaluate reproductive performance of Bos indicus-influenced heifers (n = 1,456). Weights and reproductive tract scores (RTS; Scale 1-5) were obtained for heifers prior to assignment of one of five treatments: Non-synchronized + natural service (NS); melengestrol acetate + natural service (MGA + NS; 0.5 mg x animal-1 x d-1); 14-d controlled internal drug release + natural service (CIDR + NS; 1.38g progesterone); 14-d MGA-PG + fixed-time AI (FTAI); and 14-d CIDR-PG + FTAI. Heifers in the three NS treatments were exposed to fertile bulls for 65 d, beginning 10 d after progestin removal for CIDR + NS and MGA + NS groups. Heifers in FTAI treatments were administered PGF2[alpha] (PG; 25 mg, IM) 16 or 19 d following CIDR or MGA removal. Fixed-time AI was performed 66 and 72h after PG for CIDR-PG and MGA-PG treatments, respectively. Gonadotropin-releasing hormone (GnRH; 100[mu]g, i.m.) was administered at FTAI. Estrus detection aids were applied at PG for heifers in FTAI treatments and evaluated at AI. Heifers in FTAI treatments were exposed to fertile bulls 12 d following FTAI. Blood samples were collected and ovarian ultrasounds performed at PG administration and FTAI to compare serum concentrations of estradiol and progesterone and to evaluate follicular dynamics among a subset of heifers assigned to FTAI treatments. Pregnancy status was determined at the end of a 65-d breeding period. Data were analyzed using PROC FREQ and GLIMMIX procedures of SAS. Mean concentrations of estradiol at AI differed between MGA- versus CIDR-treated heifers (P = 0.04; 8.2 versus 6.6 pg/ml), however estrous response after PG (52% versus 53%) and pregnancy rates after FTAI (40%) did not differ between MGA- and CIDR-PG treatments, respectively. Across all treatments, pregnancy rates were compared on 21, 30 and 60 d of the breeding period based on pubertal status (prepubertal RTS = 1 and 2; peripubertal RTS = 3; pubertal RTS = 4 and 5). Pregnancy rates differed at each time point based on pretreatment pubertal status (P [less than or equal to] 0.02) and weight (P [less than or equal to] 0.05). No differences were apparent with regard to progestin type at any time point, although higher pregnancy rates (P [less than or equal to] 0.004) were observed among NS treatments than FTAI followed by NS exposure at Days 30 and 60. This experiment is the largest comprehensive field trial conducted in the United States and reported in the literature involving Bos indicus-influenced beef heifers utilizing estrus synchronization prior to natural service or FTAI. This study reinforced results from previous studies, however raises a number of questions yet to be answered for heifers of this biological type. These data should be used as a basis for improvements in reproductive management of Bos indicus-influenced beef heifers prior to their first breeding season, and creates a number of possibilities for future research trials that build upon results reported in this thesis. Selection, management, and post-weaning to pre-breeding development of Bos indicus-influenced replacement beef heifers should involve the cooperative efforts of beef producers, veterinarians, and research scientists to further investigate methods to improve reproductive efficiency and genetic merit of these herds.

Resynchronization of follicular wave using long-acting injectable progesterone or estradiol benzoate at 14 days post-TAI in Bos taurus x Bos indicus beef heifers

2021 ◽  
Author(s):  
Camila Cupper Vieira ◽  
Hirya Fernandes Pinto ◽  
Vanessa Buss ◽  
Bruno Gonzalez de Freitas ◽  
Bruna Martins Guerreiro ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Bos Indicus ◽  
Estradiol Benzoate ◽  
Beef Heifers ◽  
Follicular Wave ◽  
Long Acting

25 ADDITION OF FSH, IN CONTRAST TO eCG, DOES NOT INCREASE PREGNANCY RATES IN ANESTROUS NELLORE (BOS INDICUS) COWS TREATED WITH FIXED-TIME AI PROTOCOL

2010 ◽  
Vol 22 (1) ◽  
pp. 170 ◽  
Author(s):  
L. A. Lima ◽  
V. G. Pinheiro ◽  
J. R. Cury ◽  
C. M. Barros
Keyword(s):  
Pregnancy Rate ◽  
Buenos Aires ◽  
Animal Health ◽  
Bos Indicus ◽  
Fixed Time ◽  
Sao Paulo ◽  
Pregnancy Rates ◽  
Control Group ◽  
São Paulo ◽  
Intravaginal Device

There are reports in the literature indicating that use of eCG improves pregnancy rates in Bos indicus anestrous cows treated with a progesterone-based fixed-time AI (FTAI) protocol. More recently, replacement of eCG by FSH in FTAI protocols was reported to have beneficial effects (Bos indicus) or no effect (Bos taurus) on pregnancy rates. In the present experiment the effects of eCG and FSH on pregnancy rates were compared in an FTAI protocol. Primiparous lactating Nellore cows (40 to 80 days postpartum, n = 421) with a body condition score of 2.5 to 3.0 (on a 1 to 5 scale) were randomly allocated in 3 groups: Control (CTR), eCG, and FSH. In the control group, all animals received a progesterone (P4)-releasing intravaginal device (1.55 g, PRID®, Ceva Sante Animale S.A., Libourne, France) and 2.5 mg of estradiol benzoate (EB, i.m. Estrogin®, Farmavet, São Paulo, Brazil), on Day 0 (D0). Eight days later (D8), at the time of the intravaginal device withdrawal, PGF2α (150 μg, D-cloprostenol, i.m. Prolise®, ARSA S.L.R., Buenos Aires, Argentina) was administered. Twenty-four hours after PRID removal, cows were treated with EB (1.0 mg, i.m.), and FTAI was done 30 to 36 h later. In the eCG and FSH groups, the cows were treated with 20 mg of FSH (Folltropin-V®, i.m. Bioniche, Belleville, Canada) or400IU of eCG (Novormon®, i.m. Syntex, Buenos Aires, Argentina), respectively, at the time of PGF2α administration. Ovarian ultrasonography (Aloka SSD 500, 7.5-MHz probe, Aloka, Tokyo, Japan) was performed 10 days prior to and at the beginning of FTAI protocol to select the animals in postpartum anestrous (absence of CL in both examinations). The pregnancy diagnosis was performed by ultrasonography 30 days after FTAI. Data were analyzed by logistic regression (SAS Institute, Cary, NC, USA). Cows treated with eCG had a higher pregnancy rate (41.5%, 95/229; P < 0.05) than those treated with FSH (22.7%, 22/97) or in the control group (26.3%, 25/95). Pregnancy rates of animals treated with FSH did not differ (P > 0.05) from those in the control group. These results indicated that, in lactating primiparous anestrous Nellore cows, the use of eCG in a FTAI protocol improves the pregnancy rate, whereas FSH has no beneficial effect. V. G. Pinheiro received a fellowship from FAPESP (São Paulo, Brazil). The authors are grateful to Ceva Animal Health for providing the intravaginal devices (PRID®) used in this experiment.

10 Effect of 1 or 2 doses of prostaglandin in a resynchronization protocol for timed artificial insemination in beef cows

2019 ◽  
Vol 31 (1) ◽  
pp. 131
Author(s):  
G. A. Pessoa ◽  
A. P. Martini ◽  
A. P. Baioco ◽  
E. F. Machado Filho ◽  
H. F. Pinto ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Device Removal ◽  
Pregnancy Diagnosis ◽  
Oestradiol Benzoate ◽  
Device Use

The objective of this study was to compare the effects of 1 and 2 prostaglandin doses in a timed AI (TAI) resynchronization protocol on the pregnancy rate. This study was performed during the 2017-2018 breeding season on 10 commercial farms located in the central and southwest region of Rio Grande do Sul, Brazil. A total of 2347Bos taurus beef cows (Angus, Hereford) with a body condition score 2.90±0.15 (1=thin, 5=obese) and 40±5.1 days postpartum were used. In the beginning of first synchronization TAI protocol, on Day −11, the animals received 2mg of oestradiol benzoate IM (Gonadiol®, Zoetis Saúde Animal, São Paulo, SP, Brazil) and a progesterone (P4) intravaginal device (CIDR®, Zoetis). On Day −4, the cows received 12.5mg of dinoprost tromethamine IM (PGF, Lutalyse®, Zoetis). On Day −2, the animals received 1.0mg of oestradiol cypionate IM (ECP®, Zoetis) associated with the treatment with 300IU of eCG IM (Novormon®, Zoetis) and the P4 device was removed. The TAI was done on Day 0 (48 h after P4 device removal). The resynchronization protocol was started on Day 23 without pregnancy or oestrus detection; all cows were randomly assigned to receive a new, once-used, or twice-used P4 device (CIDR®) and given 2mg of oestradiol benzoate. On Day 30, pregnancy diagnosis was performed with transrectal ultrasonography. Pregnant cows (n=1021) had the P4 device withdrawn and received no further treatment. Nonpregnant cows (n=1326) were randomly assigned into 2 groups. The 1PGF group (n=674) received a single dose of PGF on Day 30, and the 2PGF group (n=652) received PGF on Days 30 and 32. On Day 32, all cows received eCG and ECP, and the P4 device was removed. In both groups the TAI was performed 48h after the P4 device removal (Day 34). Pregnancy diagnosis was performed by ultrasound 30 days after TAI (Day 64 of the breeding season). Data were analysed using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC, USA). The pregnancy rate obtained in the first synchronization protocol was 43.5% (1021/2347). The pregnancy rate in the resynchronization protocol was similar (P=0.49) between PGF doses [1PGF=39.5% (266/674); 2PGF=40.6% (265/652). No interactions were observed between P4 device use and PGF dose (P=0.38). The pregnancy rates were similar when comparing 1PGF and 2PGF using a new P4 device [1PGF=43.2% (35/81); 2PGF=56% (93/166); P=0.67], once-used P4 device [1PGF=39% (163/418); 2PGF=40.6% (140/345); P=0.64], or twice-used P4 device [1PGF=38.9% (68/175); 2PGF=22.7% (32/141); P=0.14]. In conclusion, a second dose of prostaglandin in the resynchronization protocol was not necessary to achieve high resynchronization pregnancy rates with TAI in Bos taurus beef cows.

scholarly journals 243 PREGNANCY RATES IN THE FIELD AFTER THE TRANSFER OF BOVINE IVP EMBRYOS VITRIFIED BY THE CRYOLOGIC VITRIFICATION METHOD

2005 ◽  
Vol 17 (2) ◽  
pp. 272 ◽  
Author(s):  
R. Fry ◽  
C. Earl ◽  
K. Fry ◽  
W. Lindemans
Keyword(s):  
Large Scale ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Pregnancy Rates ◽  
Chi Square ◽  
Full Field ◽  
Transfer Programs ◽  
Short Period ◽  
Rectal Palpation ◽  
User Friendly

Although large numbers of IVP embryos can be produced from donor cattle in a short period of time, commercial acceptance of the technology depends on the ability to cryopreserve these embryos and achieve a 50% pregnancy rate in large-scale embryo transfer programs. Many studies have reported low pregnancy rates of about 20% after the transfer of cryopreserved IVP embryos. We have developed the user friendly CryoLogic Vitrification Method (CVM) that vitrifies embryos on a solid surface at −196°C and warms them rapidly in a one-step procedure prior to transfer (Lindemans et al. 2004 Reprod. Fertil. Dev. 16, 174). We present an overview of the pregnancy rates in the field after vitrification of bovine IVP embryos by the CVM. The bos taurus IVP embryos in southern Australia (bT) and the bos indicus-based IVP embryos in northern Australia (bI) were produced by our standard TVR and IVP methodology (Fry et al., 2003 Theriogenology 59, 446). Pregnancy was determined by rectal palpation between Day 40 and Day 90 and differences between treatments were analyzed by chi-square. The development of the CVM has enabled the successful cryopreservation of bovine IVP embryos. In the laboratory the typical survival (90% re-expansion) and development (80% hatching) of IVP embryos post-vitrification is high and, as demonstrated here, the pregnancy rates after transfer are approaching commercially acceptable levels. However, further research is required to identify factors that may influence success under full field conditions, for both the IVP and the vitrification technologies. Table 1. Pregnancy rates for fresh IVP, CVM-vitrified IVP, and traditionally flushed embryos cryopreserved in glycerol

207 INFLUENCE OF THE INTERVAL BETWEEN THAWING TO TRANSFER ON PREGNANCY RATES OF FROZEN - THAWED DIRECT-TRANSFER EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 220
Author(s):  
G. A. Bo ◽  
L. C. Peres ◽  
D. Pincinato ◽  
M. de la Rey ◽  
R. Tribulo
Keyword(s):  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Direct Transfer ◽  
Condition Score ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

An experiment was designed to evaluate the effect of the interval between thawing to deposition of the embryo into the uterine horn on pregnancy rates of in vivo-produced frozen–thawed embryos in 1.5 M ethylene glycol (direct transfer). Data were collected from 1122 embryo transfers performed in the same farm (Estancia El Mangrullo, Lavalle, Santiago del Estero, Argentina) during the spring and summer of 2004/05 and 2005/06 (6 replicates, ambient temperature between 20 and 40�C). Recipients used in all replicates were non-lactating, cycling, multiparous Bos taurus � Bos indicus crossbred cows with body condition score between 3 and 4 (1 to 5 scale) that were synchronized using fixed-time embryo transfer protocols. Briefly, the synchronization treatments consisted of the insertion of a Crestar ear implant (Intervet, Sao Paulo, Brazil) or a progesterone-releasing device (DIB; Syntex SA, Buenos Aires, Argentina), plus 2 mg of estradiol benzoate (EB; Syntex) intramuscularly (IM) on Day 0, and 400 IU of eCG (Folligon 5000; Intervet, or Novormon 5000; Syntex) IM plus 150 �g d-cloprostenol IM (Preloban; Intervet, or Ciclase; Syntex) on Day 5. Progestin devices were removed on Day 8 and all cows received 1 mg of EB IM on Day 9. All cows were examined by ultrasonography on Day 16 and those with a luteal area &gt;76 mm2 (by calculating the area of the CL minus the area of the cavity) received, on Day 17, frozen–thawed embryos by nonsurgical transfer. All embryos were Grade 1, and all were frozen in 1.5 M ethylene glycol at the Embryo Plus Laboratory (Brits, South Africa). After being stored in liquid nitrogen, the embryos were plunged directly (no air thawing) in a 30�C water bath for 30 s, and then transferred to the recipient cows by either one of two technicians. Based on the interval between thawing and transfer, the transfers were classified as being in one of 3 groups: Group 1: &lt;3 min; Group 2: 3 to 6 min; and Group 3: 6 to 16 min. The main reason for delayed transfers beyond 6 min was the replacement of one recipient for another because of difficulty in threading the cervix (1% of the total transfers) or a recipient falling down into the chute or with very bad disposition and behavior. Pregnancy was determined by ultrasonography 28 to 35 days after fixed-time embryo transfer, and data were analyzed by logistic regression. There were no effects of replicate, technician, CL area, recipient body condition score, embryo stage, and time from thawing to transfer on pregnancy rates. Pregnancy rates in the 3 thawing to transfer intervals were: Group 1: 215/385, 55.8%; Group 2: 372/655, 56.8%; Group 3: 42/82, 51.2%; P &gt; 0.6. These results may be interpreted to suggest that there is no significant effect of time from thawing to transfer (up to 16 min) in direct transfer embryos using Bos taurus � Bos indicus recipients transferred at a fixed time.

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

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

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

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.

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