169 THE RELATIONSHIP BETWEEN OOCYTE RECOVERY AND EMBRYO PRODUCTION IN BOS INDICUS

The ovarian follicular population has been used as a parameter to evaluate fertility and also the potential of donors undergoing assisted reproductive procedures in both human medicine and animal practice. There is a high correlation between follicular population and oocyte recovery by ovum pickup (OPU), but the relationship between oocyte recovery, embryo production and pregnancy rates may not be fully understood. The aim of the present study was to evaluate whether the conversion rate of oocytes to embryos and further pregnancies could be positively related to the number of cumulus–oocyte complexes (COC) recovered after OPU in cattle. For this purpose, records of 626 OPU sections from 251 nonlactating Gyr cows (dairy Zebu breed) were analysed. The animals had a good body condition score, were kept in a good feeding pasture (Brachiaria spp.) and were supplemented with corn silage and a mixture of corn, soybeans and vitamin and minerals, according to their nutritional requirements. For each ovarian aspiration, the ovarian follicular wave was previously synchronized with an auricular implant (Norgestomet-Crestar®), IM injections of 2 mg of oestradiol benzoate (Gonadiol®) and 0.25 mg of D-cloprostenol (Sincrocio®). The OPU procedures were performed using an ultrasound device (Aquila Vet, Esaote, São Paulo, Brazil) equipped with a vaginal sector 7.5-MHz probe, disposable 20 G needles and a vacuum pressure of 80 mmHg. The cows were ranked in quartiles regarding the total number of COC recovered. To reduce bias related to the eventual fluctuation of OPU results, for the present analysis the authors used only the recorded OPU session of each cow with the highest number of COC recovered. Viable COC were fertilized with sex-sorted (X) semen of Gyr bulls previously tested for in vitro embryo production. Conversion rates (%) of the total and viable oocytes to embryos, viable oocytes to pregnancy and embryo to pregnancy were evaluated for each quartile. Differences between the first and fourth quartiles were accessed by Fisher's exact test. In the 251 OPU, 4246 total and 3173 viable COC were recovered, resulting in the production of 1001 embryos (31.5%) and 453 pregnancies (45.3%). The cows ranked in the first, second, third and fourth quartiles produced >30 (41.6 ± 10.6), 21 to 30 (25.2 ± 3.0), 12 to 20 (15.9 ± 2.6) and <12 (6.7 ± 3.1) total oocytes. The average viable oocyte (29.1 ± 11.0, 18.1 ± 5.3, 11.1 ± 3.7 and 4.5 ± 2.7, respectively) and embryo production (8.6 ± 5.7, 5.2 ± 3.6, 3.8 ± 2.8 and 1.8 ± 1.8, respectively) were different (P < 0.0001) among all quartiles. Pregnancy rates, however, did not differ (46.0, 44.9, 43.9 and 45.6%, respectively; P > 0.05). Interestingly, the conversion rates (viable oocytes to embryos and viable oocytes to pregnancies) were higher (P < 0.0001 and 0.002) in cows from the last quartile (51.1 and 31.9%) compared with those from the first quartile (23.7 and 14.7%). In conclusion, the number of COC recovered by OPU (and consequently the ovarian follicular count) can further predict the total number of embryos and pregnancies produced, but it is not directly related to the oocyte development potential. Biotran and Fapemig Project CVZ APQ 01654/09 and BPD 0007/10.

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

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab207 ◽

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 >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: <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 > 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.

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100 COMPARISON OF PREGNANCY RATES OF FRESH IN VITRO-PRODUCED BOS INDICUS EMBRYOS PRODUCED IN THE SAME LABORATORY BUT COLLECTED AND TRANSFERRED IN PANAMA OR THE DOMINICAN REPUBLIC

Reproduction Fertility and Development ◽

10.1071/rdv26n1ab100 ◽

2014 ◽

Vol 26 (1) ◽

pp. 164

Author(s):

L. F. Nasser ◽

S. C. Feliú ◽

E. Rodríguez ◽

K. Mojica ◽

E. G. Oliveira ◽

...

Keyword(s):

Dominican Republic ◽

Bos Indicus ◽

Disease Status ◽

Pregnancy Rates ◽

Bovine Embryo ◽

Department Of Agriculture ◽

Embryo Production ◽

Essential Variable ◽

Laboratory Facility

Because of Panama's stricter sanitary status, a specialised protocol was developed with the Department of Agriculture in the Dominican Republic to legalize the exchange of biological materials (oocytes/embryos). This protocol allows the team of specialised technicians, currently working in Born® Animal Biotechnology's Panamanian facility, to operate using the same in vitro bovine embryo production system (IVP, In vitro Brasil®) to service Dominican producers. Because the donors are not located at a specific centre with controlled sanitary management, a special protocol was developed in which blood tests were done to certify that the entirety of the herd at each client's farm was free of infectious bovine rhinotracheitis, DBVD, leptospirosis, leucosis, brucellosis, and tuberculosis. As timing during IVP is an essential variable that can have detrimental effects on the final results, precautions were taken to ensure that the oocytes arrived at the Panamanian laboratory facility within 24 h of aspiration. A portable incubator was used to transport oocytes and embryos during the import and export portions of the procedure. A comparison of pregnancy rates based on oocyte source and recipient transfers from September 2012 until May 2013 was analysed with ?2 (Table 1). The number of embryos produced in Panama was significantly higher than in the Dominican Republic, which was likely due to the larger number of donors and oocytes from the Panama herd. However, pregnancy rate was higher in the Dominican Republic likely because of the health status of the Dominican recipients, which were free of the diseases mentioned above. Recipients were the same type and breed and under similar management conditions in both countries. The disease status aspect will be examined with greater numbers of animals in the future. The data suggest that the present IVP and recipient management protocols could serve as a model for other Central American and Caribbean countries under similar management systems. Table 1.In vitro embryo production and pregnancy rates of Bos indicus embryos transferred in Panama or the Dominican Republic (September 2012 through May 2013)

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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

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab39 ◽

2010 ◽

Vol 22 (1) ◽

pp. 177 ◽

Cited By ~ 1

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.

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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

Reproduction Fertility and Development ◽

10.1071/rdv17n2ab166 ◽

2005 ◽

Vol 17 (2) ◽

pp. 234 ◽

Cited By ~ 3

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.

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241 EFFECT OF PRODUCTION EFFICIENCY IN THE LIKELIHOOD OF PREGNANCY OF IN VITRO-DERIVED BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv27n1ab241 ◽

2015 ◽

Vol 27 (1) ◽

pp. 210

Author(s):

L. F. Feres ◽

L. S. A. Camargo ◽

M. P. Palhao ◽

F. Z. Brandao ◽

J. H. M. Viana

Keyword(s):

Pregnancy Rate ◽

Production Efficiency ◽

Production Systems ◽

Bos Indicus ◽

Pregnancy Rates ◽

In Vitro Production ◽

Cleavage Rate ◽

Embryo Production ◽

Chi Square

Improving in vitro culture systems to optimize embryo yield has been a major research goal. The relationship between the efficiency of embryo production systems and the pregnancy outcomes, however, remain controversial. The aim of the present study was to evaluate the likelihood of pregnancy of in vitro-produced embryos derived from batches with different relative efficiency indexes. Data of 702 ovum pick-up (OPU) and in vitro embryo production (IVEP) sessions, and of 2456 embryo transfers, recorded from 2008 to 2012, were evaluated. All donors were from the same herd, and were of the same breed (Gir, Bos indicus), as well as the semen used for IVF. The cumulus-oocycte complex (COC) recovery and IVEP were performed by the same team, in a single IVF laboratory, and using standard medium and procedures. Only data from embryos transferred as fresh were used, and records from 97 OPU/IVEP sessions in which no embryo was produced, or embryos were frozen or discharged due to lack of recipients, were discharged. The remaining 605 sessions were stratified in quartiles (I to IV, each one corresponding to 25% of total data) according to COC production of the donors, or stratified in ranges (0–25%, 26–50%, 51–75%, and 76–100%) according to COC quality (percentage of viable COC or of grade I COC) and to embryo production efficiency endpoints (cleavage rate, blastocyst rate). Pregnancy rates were compared among quartiles or ranges by the chi-square method. On average, the Gir donors produced 24.8 ± 0.6 COC per OPU, from which 14.4 ± 0.4 were classified as viable (57.8%), and 3.2 ± 0.1 as grade I (12.9%). On average 6.1 ± 0.2 embryos (morulas and blastocysts) were produced per OPU per donor, and mean pregnancy rate was 30.9%. As expected, donors with greater total COC yield (quartile I) also produced more viable oocytes (25.5 ± 0.7 v. 15.7 ± 0.3, 10.5 ± 0.2 and 5.8 ± 0.2), more COC grade I (4.8 ± 0.4 v. 3.9 ± 0.3, 2.6 ± 0.2 and 1.6 ± 0.1), and more embryos (9.0 ± 0.4 v. 6.9 ± 0.3, 5.0 ± 0.2 and 3.3 ± 0.1) than donors from quartiles II, III, or IV, respectively (P < 0.0001). Nevertheless, there was no difference (P > 0.05) in pregnancy rates for embryos produced from donors ranked in the different quartiles (30.9 v. 29.3, 31.5, and 30.5% for quartiles I to IV, respectively). Similarly, there was no difference (P > 0.05) in the pregnancy rate of embryos derived from OPU sessions in which there was a high or low percentage of viable or grade I COC. In vitro production efficiency (cleavage and blastocyst rates) also had no effect (P > 0.05) on further pregnancy rates. In conclusion, these results suggest that there is no relationship among the average number or quality of the COC recovered by OPU, the efficiency of IVEP, and the likelihood of pregnancy of in vitro-derived embryos.Research was supported by Fazendas do Basa, CNPq, and Fapemig.

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172 Effect of period of insertion of a progesterone-releasing device and pro-oestrus length on follicular and luteal characteristics and pregnancy rates to fixed-time AI in Bos indicus heifers

Reproduction Fertility and Development ◽

10.1071/rdv32n2ab172 ◽

2020 ◽

Vol 32 (2) ◽

pp. 213

Author(s):

G. A. Bo ◽

A. Cedeño ◽

R. Maingón ◽

J. P. Cedeño ◽

H. Gamboa ◽

...

Keyword(s):

Corpus Luteum ◽

Binary Data ◽

Body Condition Score ◽

Bos Indicus ◽

Fixed Time ◽

Pregnancy Rates ◽

Conventional Group ◽

Preovulatory Follicle ◽

Device Removal ◽

Condition Score

An experiment was designed to evaluate the effect of the length of insertion of a progesterone (P4)-releasing device and the length of pro-oestrus on follicular and luteal characteristics and pregnancy rates to AI (P/AI) in Bos indicus heifers treated with oestradiol/P4-based treatments. Bos indicus beef heifers (n=374), 22-26 months of age, with a corpus luteum (CL) or at least one follicle ≥8mm in diameter and with a body condition score between 2.5 and 3.5 (1-to-5 scale) were synchronised using three treatments for fixed-time AI (FTAI). On Day 0, all heifers received 2mg of oestradiol benzoate (Sincrodiol, Ourofino) and an intravaginal device with 1g of P4 (Sincrogest, Ourofino). The P4 device was removed on Day 6 in heifers in the J-Synch 6 group (n=120) and on Day 7 in heifers in the J-Synch 7 group (n=105) and conventional group (n=165). All heifers received 500μg of cloprostenol (Sincrocio, Ourofino) and 300IU of equine chorionic gonadotrophin (SincroeCG 6000UI, Ourofino) at the time of P4 device removal. Furthermore, heifers in the conventional treatment group received 0.5mg of oestradiol cypionate (SincroCP, Ourofino) at the same time. In addition, all heifers were tail-painted for oestrus detection (CeloTest, Biotay). Heifers that had lost ≥50% of the tail paint by 70-74h (J-Synch groups) or 48-52h (conventional group) after device removal were FTAI at that time. Heifers not showing oestrus by 70-74h (J-Synch groups) or 48-52h (conventional group) received 10μg of gonadotrophin-releasing hormone (Sincroforte, Ourofino) at the same time and were FTAI 8h later. All heifers were also examined using ultrasonography (Mindray DP50 Vet) every 12h from the time of device removal to determine the time of ovulation, 6 days after ovulation to determine the diameter of the CL, and 28 days after FTAI for P/AI determination. Data were analysed using the MLGM procedure (InfoStat) for normal data families (follicular dynamics) and binary data family (P/AI). The results are shown in Table 1. The diameter of the dominant preovulatory follicle and the CL did not differ among groups (P>0.12). However, the interval from device removal to ovulation was longer in heifers in the J-Synch groups than in heifers in the conventional group (P<0.05). Furthermore, P/AI was not different among groups. In conclusion, although the J-Synch protocols delayed the interval from P4 device removal to ovulation, the three protocols evaluated in the present study were equally effective in Bos indicus heifers. Table 1.Mean (±s.e.m.) diameter of the preovulatory follicle (P/Foll) and corpus luteum (CL), interval from progesterone (P4) device removal to ovulation, and pregnancy rates to AI (P/AI) in Bos indicus heifers Treatment P/Foll, mm Interval to ovulation, h CL diameter, mm P/AI,% (n) J-Synch 6 10.5±0.7 101.4±2.3a 18.6±1.0 52.0 (62/120) J-Synch 7 10.6±0.7 96.0±2.2a 16.5±0.9 39.0 (41/105) Conventional 9.4±0.7 73.0±1.9b 16.8±0.9 45.0 (74/165) a,bDifferent superscripts denote differences between groups in the interval from P4 device removal to ovulation.

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126 A Comparison of Two Different Follicular Coasting Periods for In Vitro Embryo Production in Indian Nelore Cattle

Reproduction Fertility and Development ◽

10.1071/rdv30n1ab126 ◽

2018 ◽

Vol 30 (1) ◽

pp. 203

Author(s):

P. Tiwari ◽

S. Zawar ◽

J. H. Pryor ◽

C. R. Looney ◽

R. Kaushik ◽

...

Keyword(s):

Animal Health ◽

Bos Indicus ◽

Embryo Production ◽

Treatment Groups ◽

Lactating Cows ◽

Oocyte Recovery ◽

Minimum Interval ◽

Nelore Cattle ◽

Donor Cows

Ongole, also known as Nelore (Bos indicus) cattle, are indigenous to the Andhra region in the Prakasam District in the State of Andhra Pradesh in India. A better understanding and utilisation of follicular wave dynamics within this breed would ultimately enhance oocyte and potential embryo production. Therefore, the aim of this study was to evaluate the differences between coasting periods of 24 h (S1) and 36 h (S2) on oocyte recovery, the rate of viable oocytes, cleavage, and Day 7 blastocyst rates of Nelore cattle in India. A total of 58 ovum pick-up (OPU) sessions (29 per treatment) were performed on 32 healthy donor cows that were randomly assigned to 1 of 2 coasting treatments (S1 or S2). Donors were stimulated as follows: 2.5 mL of gonadotropin-releasing hormone (GnRH; Receptal, MSD Animal Health, New Zealand) given IM on Day 1 followed by once-daily descending dose of Folltropin® (FSH, Vetoquinol, Canada) on Days 3 to 5 for a total of 180 mg. Cumulus-oocyte complexes were collected following OPU on Day 6 either at 24 (S1) or 36 h (S2) following the last FSH injection (coasting period). Donors were subject to OPU 1 to 3 times with a minimum interval of 15 days between procedures from March to April 2017. All 32 donor cows were non-lactating at the time of aspiration and divided equally between treatment groups. A total of 1492 follicles produced 850 total oocytes with oocyte recovery numbers for treatments S1 and S2 (785, 707; 441, 409; respectively). All data were analysed by ANOVA (P < 0.05). The mean number of follicles aspirated from S1 (27 ± 20.2) was not significantly different from that of S2 (24.4 ± 14.4). For S1, 393/441 (89%) quality oocytes were utilised for culture compared with 323/409 (78.9%) for S2, with no differences between rates. Additionally, there were no differences between mean number of oocytes, cleaved embryos, and blastocysts for S1 (15.2 ± 12.7; 9.9 ± 9.2; 4.3 ± 5.4) and S2 (14.1 ± 10; 7.4 ± 6.0; 3.6 ± 3.3; respectively). In conclusion, there were no differences found between 24- or 36-h coasting periods of Nelore cattle undergoing OPU for follicle counts, oocyte recovery, viable oocyte rates, cleavage, and blastocyst rates. Further research is needed to determine whether different stimulation protocols, the use of lactating cows, or coasting periods could alter outcomes.

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104 FACTORS AFFECTING PREGNANCY RATES AND EMBRYO/FETAL LOSSES IN RECIPIENTS RECEIVING IN VITRO-PRODUCED EMBRYOS BY FIXED-TIME EMBRYO TRANSFER

Reproduction Fertility and Development ◽

10.1071/rdv29n1ab104 ◽

2017 ◽

Vol 29 (1) ◽

pp. 160

Author(s):

A. Tribulo ◽

A. Cedeño ◽

B. Bernal ◽

S. Andrada ◽

J. L. Barajas ◽

...

Keyword(s):

Embryo Transfer ◽

Body Condition Score ◽

Prostaglandin F2α ◽

Fixed Time ◽

Gonadotropin Releasing Hormone ◽

Pregnancy Rates ◽

Device Removal ◽

Releasing Hormone ◽

Condition Score

A retrospective analysis evaluated pregnancy rates and embryo losses with in vitro-produced embryos in a commercial embryo transfer program on 15 different beef farms. Recipients were beef cows and heifers (n = 1841) that were synchronized with 5 different protocols and transferred at a fixed-time (FTET). Recipients were examined by ultrasonography on Day 0, and those with a corpus luteum (CL) or a follicle ≥8 mm in diameter and with body condition score 2 to 4 (1 to 5 scale) were synchronized. The synchronization treatments were as follows. (T1) Recipients received an intravaginal device with 0.5 g of progesterone plus 2 mg of oestradiol benzoate on Day 0; device removal, plus 500 μg of cloprostenol (prostaglandin F2α), 400 IU of eCG, and 0.5 mg of oestradiol cypionate on Day 8; and FTET on Day 17. (T2) This treatment was similar to T1 but 1 mg of oestradiol cypionate was injected at device removal instead of 0.5 mg of oestradiol cypionate. (T3) This treatment was similar to T1 except that animals were tail-painted on Day 8 and observed on Day 10. Those with the tail-paint intact on Day 10 received 100 μg of gonadorelin (gonadotropin-releasing hormone) and all recipients were FTET on Day 17. (T4) Recipients received a progesterone device on Day 0; device removal, prostaglandin F2α, and eCG on Day 5; gonadotropin-releasing hormone on Day 8; and FTET on Day 15. (T5) Recipients received a progesterone device and 2 mg of oestradiol benzoate on Day 0; device removal, prostaglandin F2α, and eCG on Day 6; gonadotropin-releasing hormone on Day 9; and FTET on Day 16. On the day of FTET all recipients with CL ≥18 mm in diameter (G1), ≥16 and <18 mm in diameter (G2), and ≥14 mm and <16 mm in diameter (G3) received in vitro-produced fresh embryos. Pregnancy was diagnosed by ultrasonography at 30 and 60 days of gestation, and data were analysed by logistic regression. The overall proportion of recipients synchronized that were FTET was 80.8% (1487/1841), with a 30-day pregnancy rate to FTET (P/FTET) of 45.6% (678/1487) and the rate of 30- to 60-day embryo/fetal loses on the 528 recipients that were re-checked at 60 days was 12.8% (68/528). There were no significant differences in P/FTET among operators, animal category, time of the year, embryo stage, or body condition score; however, there was a significant effect of farm (P < 0.001) and CL diameter (P < 0.05), but no interaction between CL diameter and farm or treatment (P > 0.1). Recipients with G1 (443/953, 46%) and G2 (221/462, 47%) CL had higher pregnancy rates than those with G3 CL (23/71, 32%). There was a significant effect of synchronization treatment on the proportion of recipients transferred and on P/FTET (P < 0.01) that was highly influenced by farm (farm by treatment interaction P < 0.01). The proportions of recipients selected for embryo transfer were as follows: T1: 386/486, 79.4%; T2: 233/331, 70.3%; T3: 342/377, 90.7%; T4: 126/160, 78.7%; and T5: 400/487, 82.1%. The P/FTET were as follows: T1: 190/386, 49.2%; T2: 96/233, 41.2%; T3: 175/342, 51.1%; T4: 49/126, 38.8%; and T5: 168/400, 42.0%. Although 30- to 60-day embryo/fetal losses were not influenced by synchronization treatments, they were highly influenced by farm (P < 0.001) and ranged from 0 to 34.5%. In conclusion, P/FTET in a commercial program with beef in vitro-produced embryos was influenced by factors related to the recipient (CL diameter) and the environment (farm), whereas embryo/fetal losses were influenced by farm but not treatment or recipient factors.

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34 Reproductive management of beef females in tropical and sub-tropical environments

Journal of Animal Science ◽

10.1093/jas/skz258.074 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 37-37

Author(s):

Nicola Oosthuizen ◽

Pedro Levy Piza Fontes ◽

G Cliff Lamb

Keyword(s):

Assisted Reproductive Technologies ◽

Bos Taurus ◽

Management Strategies ◽

Bos Indicus ◽

The United States ◽

Reproductive Technologies ◽

Pregnancy Rates ◽

Embryo Production ◽

Reproductive Management

Abstract Bos indicus and Bos taurus cattle diverged from an evolutionary standpoint more than 110,000 years ago. Since then, Bos indicus cattle have undergone genetic adaptations beyond the commonly discussed increased thermo-tolerance and parasite resistance. Several physiological differences exist between Bos indicus and Bos taurus cattle, and it is important to consider these differences when establishing reproductive management strategies. It has been well described that Bos indicus cattle have a delayed onset of puberty and longer periods of postpartum anestrus, yet through the utilization of estrus synchronization protocols these challenges can be attenuated. However, when Bos indicus females are exposed to these protocols, they are known to have smaller dominant follicles, lower expression of estrus, and decreased pregnancy rates to artificial insemination (AI) when compared to Bos taurus females. These factors can be overcome through the utilization of estradiol and progesterone based synchronization protocols, which improve follicular dynamics and yield acceptable pregnancy rates to assisted reproductive technologies in cattle adapted to tropical or subtropical conditions. However, the use of estrogens for synchronization purposes is not permitted in the United States, and cattle producers need to rely on GnRH-based protocols. Another key difference between subspecies, is that Bos indicus females have greater antral follicle counts than Bos taurus females, which proves beneficial for in vitro embryo production. Therefore, an opportunity exists to explore the greater productivity of donors in embryo production in order to improve genetics in herds that utilize these breeds.

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