Academic literature on the topic 'Recipient Synchronization'

This study aimed to test the effectiveness of the injection of a combination hormone GnRH, estrogen, progesterone and prostaglandin on response of estrus, onset estrus and duration estrus FriesianHolstain (FH) recipient dairy cattle. This study was used 15 recipient cows not pregnant, were divided into three treatment methods of synchronization of estrus and each treatment consisted of 5 cattle. Recipient cow estrus response after injection of the hormone combination estrus synchronization with all three treatments show symptoms of estrous. The percentage of estrous cows FH overall recipient reaches 100%, showed that the treatment effect is very good and effective way to bully the onset of estrous cows recipient FH. The results of data analysis using Chi-Square showed no significant difference among all treatments. It was concluded, that synchronization of estrous FHcow recipients using GnRH hormone, estrogen, progesterone and prostaglandin as good in all of the parameters.Keywords: estrous synchronization, GnRH, estrogen, progesterone, prostaglandin.

The timing of estrus synchrony between donor and recipient does is an important consideration in an embryo transfer program. Experiments were conducted to determine the optimal time of estrus synchrony between donor and recipient dairy goats used in a commercial nuclear transfer (NT) program. Donor and recipient synchronization was achieved by implanting either a 3-mg norgestomet ear implant (Crestar®, Intervet Int. B.V., Boxmeer, Holland) or a 300-mg progesterone vaginal implant (CIDR-G®, Pharmacia and Upjohn Ltd. Co., Auckland, NZ) on Day 0. A single 5mg intramuscular injection of prostaglandin (Lutalyse®, Pharmacia and Upjohn, Kalamazoo, MI, USA) was administered on Day 7. Recipients received a single 200–500IU intramuscular injection of PMSG (Calbiochem, LaJolla, CA, USA) on Day 13. Alternatively, starting on Day 12 donors received twice daily intramuscular injection (64mg/day) of FSH (Folltropin®, Vetrepharm, Ontario, Canada) over four consecutive days. On Day 15 the implants were removed from both donors and recipients and the animals were mated several times daily to vasectomized bucks over two consecutive days. In Experiment 1, estrus synchrony or asynchrony was achieved by removing the implant from recipients at the same time or 12h later than donors, respectively. In Experiment 2, only estrus asynchrony was utilized and was achieved by removing the implant from recipients either 12 or 18h later than donors. In vivo-ovulated MII oocytes surgically recovered from superovulated donors on Day 17 were enucleated and reconstructed with transfected caprine fetal or adult skin cells or transgenic adult skin cells. Couplets were simultaneously fused, activated, and then cultured in SOF/BSA for 48h at 38°C. Two-to-eight-cell NT embryos at 48h post-fusion and activation were surgically transferred to the oviducts of surrogate recipients with similar implant types and PMSG doses. Pregnancies were determined by ultrasonography starting at approximately Day 28 post-fusion and activation and then monitored weekly. In Experiment 1, there were significantly more pregnant asynchronous recipients compared with synchronous recipients (6 of 24 v. 12 of 124 does, respectively). While there were no significant differences, more offspring were produced per embryo transferred to asynchronous recipients compared with synchronous recipients (5 of 135 v. 11 of 690 offspring per embryo transferred, respectively). In Experiment 2, while not significant, there were more pregnant +12-h asynchronous recipients compared with +18-h asynchronous recipients (16 of 72 v. 5 of 36 does, respectively). Again, while there were no significant differences, more offspring were produced per embryo transferred to +12h compared with +18h asynchronous recipients (11 of 424 v. 3 of 224 offspring per embryo transferred, respectively). These results suggest that asynchrony of estrus between recipients and donors is more beneficial in a commercial caprine NT program, and that +12h may be a more optimal period of asynchrony for recipient does receiving NT embryos. Table 1 Summary of recipient estrus synchronization

Purchase and maintenance of recipient females account for a large proportion of the costs and determine the number of calves that can be produced in an embryo transfer program. However, the large variability of embryo production by the donors and the need to purchase and synchronize the recipients before knowing the number of embryos collected make it difficult for the decision maker to identify the ideal number of recipient females to allocate. An ex-ante evaluation to determine the optimal number of recipient females was carried out through a sensitivity analysis for the ratio between the number of recipients and donors in a simulation model. The variability for the number of embryos collected was accounted for by applying the Monte Carlo simulation technique, assuming normal distribution and known values for mean and variance. The simulation considered monthly intervals between collections, during a 24 months program. The effect of embryo freezing on the number of pregnancies was considered by introducing a stock of frozen embryos into the mathematical model. Optimal recipient/donor ratio and the cost per pregnancy were compared for three recipient synchronization protocols (prostaglandin, progesterone - P4 and Ovsynch), based on the expected performance for synchronization, conception and transfer/treated rates for each protocol. Stochastic simulation associated with sensitivity analysis was effective in identifying the optimal donor to recipient ratio. Freezing embryos is effective to reduce the operational costs per pregnancy. The estimated optimal recipient/donor ratio was 20 for prostaglandin and 16.7 for the other protocols. The P4 protocol, although the most expensive, resulted in the lowest pregnancy cost estimation followed by prostaglandin and Ovsynch.

Its application improves the reproduction rate, creates experimental models for the study of physiology and pathology of reproduction, while it promotes genetic improvement of the species. The method includes the following stages: 1) Selection of the donor and recipient mares. 2) Induction of multiple ovulation in the donor-mare. A reliable method that could be applied commercially has not been developed yet. 3) Synchronization of donor and recipient mares' estrus. Recipients are usually used during the breeding season, but can be used during anestrus or after surgical removal of their ovaries as well. Non-synchronized recipients may also be used after proper treatment. 4) Artificial insemination of the donor mare. 5) Collection, evaluation and washing of the embryo. Embryo is usually collected by non-surgical and rarely surgical methods. Embryo evaluation involves the assessment of its developmental stage in relation with the day of selection and its quality evaluation. Embryo washing is accomplished by its successive passage through three different dilutions of culture medium. 6) Embryo transfer in the uterus of the recipient mare. Surgical (midventral laparotomy, flank laporotomy, laparoscopic and transvaginal method) or nonsurgical (unguarded and guarded methods) transcervical methods are used.

This study was carried out by selecting a total number of 17 Holstein Friesian cows divided into two main groups, the first group (4) cows as donors used to take the embryos from after artificial insemination and the second group (13) heifers cows as recipients for embryos. The same techniques were used on donor and recipient cows for the purpose of hormonal preparation in terms of instance synchronization, preparing recipient cows and superovulation for donor cows. Artificial insemination were done in field, and a nonsurgical flushing procedure embryos applied then graded. Donors reflected a good response to superovulation hormonal treatment. The total number of transferable embryos was 13 from four donors. Evaluation of all embryos was excellent quality. The pregnancy rate results for recipient cows was 61.5%. This result is an acceptable as compared to previous studies due to many factors, the study aim was taking into account all these factors, that can have an influence on these programs to obtain genetically improved animals in a shorter time and lower costs.

A retrospective analysis of factors that affect pregnancy rates from 4214 fresh in vitro-produced (IVP) embryos that were transferred at a fixed-time (FTET) in 20 different farms. Recipients were all cycling cows or heifers that were synchronized with 1 of 3 treatments: 1) treatments with progesterone (P4) devices and 2 mg of oestradiol benzoate (EB) on Day 0 (day of insertion) and 24 h after device removal (Day 8); 2) treatments with P4 devices and EB on Day 0, but with 0.5 mg of oestradiol cypionate (ECP) at device removal (Day 8); or 3) treatments with P4 devices and GnRH on Day 0 and a second GnRH 60 h after device removal (Day 5). Cows in all treatment groups also received 500 µg of cloprostenol (prostaglandin F2α) at the time of P4 device removal and 400 IU of eCG either at device removal or 3 days before device removal. All embryos were transferred 7 or 8 days after the expected time of oestrus (24 h after EB, 48 h after ECP or at the time of the second GNRH for each synchronization treatment, respectively). On the day of embryo transfer, recipients were examined by ultrasonography and those with corpus luteum >14 mm in diameter received a fresh, IVP embryo in the uterine horn ipsilateral to the corpus luteum. Pregnancy rates were determined by ultrasonography 35 days after FTET. Data were analysed by logistic regression. Independent variables were classified into the following three categories. 1) Factors related to the recipient and the environment; there were no significant differences in pregnancy rates for corpus luteum diameter (≥14 and <16 mm, ≥16 and <18 mm, or ≥18 mm; P = 0.46), number of corpus luteum (1 or ≥2; P = 0.26), and category of recipient (cow or heifer; P = 0.21). However, there were significant effects of farm (P = 0.01) and body condition score (BCS; P = 0.01). Cows with BCS ≥4.5 (1 to 5 scale) resulted in lower pregnancy rates (4/20, 20.0%) than those with BCS 2 (74/225, 32.9%), 2.5 (502/1434, 35.0%), 3 (570/1467, 38.9%), 3.5 (193/532, 36.3%), and 4 (44/118, 37.3%). 2) Factors related to the synchronization treatment; there were no significant differences between recipients receiving eCG at device removal (84/209, 40.2%) or 3 days before device removal (874/2291, 38.1%; P = 0.35). However, recipients synchronized with P4 devices and ECP had higher (P = 0.01) pregnancy rates (232/483, 48.0%) than those treated with EB (679/1888, 36.0%) or gonadotropin-releasing hormone (47/129, 36.4%). 3) Factors related to the embryo transfer technique; day of the recipient’s oestrous cycle (P = 0.36), stage of embryo transferred (IETS stages 6 or 7; P = 0.62), and operator (P = 0.57) did not affect pregnancy rates. However transfers made in the anterior third of the uterine horn resulted in higher (649/1545, 42.0%) pregnancy rates than those in the mid-third (845/2511, 33.6%) or in the distal third (6/35, 17.1%; P = 0.01). It was concluded that factors related to the recipient and the environment (farm and BCS), the synchronization treatment (ECP), and the embryo transfer technique (site of deposition) affect pregnancy rates in recipients of embryos produced in vitro and transferred at a fixed time.

Security is a major concern of the internet world because the development of the Internet requires the security of data transmission. The security method helps us to store valuable information and send it over an insecure network so that it can not be read by anyone except the intended recipient. Security algorithm uses data randomization method. This method of data information randomization has a low computation time with a large number of bits when compared to other encryption algorithms. In general, the encryption algorithm is used to encrypt data information, but in this research the encryption algorithm is used for synchronization between the sender and the intended recipient. Number of bits on asymmetric key algorithm for synchronization are the 64-bits, 512-bits and 1024-bits. We will prove that security methods can secure data sent with low computational time with large number of bits. In the result will be shown the value of computing time with variable number of bits sent. When data are sent by 50 bytes, encryption time required 2 ms using 1024 bits for synchronization technique asymmetric key algorithm.Â

Frozen-thawed Belgian Blue (BB) Embryo transfer (TE) is an effort of fulfilling meat demand in Indonesia. This research aimed at observing the correlation between estrus expressions of standing heat and the correlation of CL characteristics on the success rate of frozen-thawed BB embryo transfer. The study was conducted on 55 recipient cattle with 62 times of TE application, which were categorized into three groups, namely FTET estrus synchronization (n=14), 24-hour natural estrus detection (n=30) and twice-a-day natural estrus detection (n=18). The implemented synchronization was the combination of estradiol-progesterone and hCG with the modification of 24-hour estrus detection between day-9 and 10. The second method was a natural estrus detection, which was conducted four times for 30 minutes, and the third method was twice-aday estrus detection for 90 minutes. The CL characteristics were observed using ultrasonography (USG) in the TE application day. Pregnancy per ET (P/ET) was determined by ultrasonography on d-20, 30, and 50. This research revealed that expressions of standing heat increased P/ET (p<0.05). The pregnancy loss rate was lower of the recipient which showed the estrus expression of standing heat (18.18%) compared to recipients did not show standing heat (40%). Based on the estrus detection method, there was no significant difference between the FTET modification method and the percentage of pregnancy (p>0.05). The CL characteristics showed there was no correlation between CL diameter with the pregnancy success rate of TE (p>0.05).

Since the first success in producing cloned pigs, donor cells have been limited to fetal fibroblasts and a few other cell types. The aim of the present study was to determine if porcine preadipocytes can be efficient donor cells for somatic cell nuclear transfer (NT) in pigs. Preadipocytes established from subcutaneous adipose tissue of a male adult pig were used as nuclear donor cells. Cell cycle synchronization was carried out by serum starvation (5 days), confluency (5 days), roscovitine treatment (15 μM, 2 days), or differentiation induction by 0.5 mM 3-Isobutyl-1-methylxanthine, 0.25 μM dexamethasone, and 5 μg/mL insulin (5 days). Cell cycle synchronization and apoptosis of the donor cells were examined by flow cytometry and Annexin V staining and TUNEL. IVM oocytes were obtained from abattoir ovaries and matured in NCSU23. Donor cells were fused with the enucleated recipient oocytes by a single DC pulse of 200 V/mm for 10 μs in 0.28 M mannitol + 0.15 mM MgSO4. Reconstructed embryos were electrically activated at 1–1.5 h after the NT, followed by cytochalasin B treatment for 3 h. Development of the NT embryos was assessed by fixation/staining at 3 h after NT, culture for 7 days in NCSU23, and transfer to the oviducts of estrus-synchronized recipient gilts. The cells immediately entered the G0 phase by differentiation induction (92.5 ± 0.4%), with higher efficiency of synchronization than for the other methods (roscovitine: 80.3 ± 0.2%; confluency: 79.9 ± 0.3%, P < 0.05) except for serum starvation (89.8 ± 0.6%). The proportion of apoptotic cells in the differentiation group was significantly lower than the other groups (Annexin V: 7.7% vs. 15.7 to 19.3%, TUNEL: 8.3% vs. 12.8 to 14.0%, P < 0.05). Incidence of premature chromosome condensation following NT (88.0%) was as high as that observed after NT with fetal fibroblasts previously (data not shown). In vitro developmental rates of the NT embryos did not differ significantly among the cell cycle synchronization methods of the donor cells (7.2 to 10.8%). Cell number of the blastocysts was highest in the differentiation group (49.0 vs. 30.2 to 41.9, P < 0.05). Transfer of 1004 cloned embryos of the serum starvation group to 5 recipients resulted in the production of 4 live and 1 stillborn piglets from 1 recipient. Transfer of cloned embryos reconstructed of donor cells treated by differentiation induction is currently underway. These data demonstrate that preadipocytes collected from an adult pig are promising nuclear donor cells for pig cloning. This study was supported by PROBRAIN.

Dentre os inúmeros fatores para o sucesso dos programas de TE, as receptoras merecem grande destaque por serem fator determinante no sucesso desta biotecnologia. Atualmente, os produtos de liberação de progesterona disponíveis no mercado brasileiro são importados e confeccionados a base de nylon e silicone. O silicone é uma matriz biocompatível, mas não biodegradável, contrariamente aos novos dispositivos que utilizam biopolímeros obtidos a partir da fermentação bacteriana da cana-de-açúcar. O presente experimento tem como objetivo estudar a eficiência do novo dispositivo intravaginal de liberação sustentada de progesterona no programa de TETF, em novilhas e vacas cruzadas, pela avaliação das taxas de aproveitamento, concepção e de prenhez. O experimento foi realizado em parceria com a empresa de Embryo-sys®, a qual foi responsável por realizar a sincronização das receptoras, assim como das inovulações. As sincronizações e as inovulações foram realizadas em três propriedades nos municípios de Paranapanema-SP, Itapetininga-SP e Ouro Fino-MG. Todos os animais foram submetidos a rigoroso manejo sanitário e ginecológico, e mantidos a pasto (Brachiaria decumbens) com suplementação mineral e água ad libitum. As receptoras (n = 205) foram agrupadas equitativamente quanto ao escore de condição corporal, condição ovariana, categoria animal e período pós-parto, em dois grupos: Grupo Controle - dispositivo auricular (Crestar®, Intervet, Holanda) contendo 3mg de norgestomet (n=103) e Grupo Tratado - implante intravaginal (Progestar®, Innovare, Brasil) contendo 1,72g de progesterona (n=102). No início da sincronização ambos os grupos foram tratados com 2mg de benzoato de estradiol (BE, Innovare, Brasil) intramuscular (IM). Os dispositivos permaneceram nos animais por oito dias, e no momento da retirada foram administradas 400UI de eCG (Novormon®, Syntex, Argentina) IM e 530&mu;g cloprostenol sódico (Sincrocio®,Ouro Fino, Brasil) IM. Após 24 horas da retirada, foi aplicado 1mg de BE IM, como indutor de ovulação. Analisando as novilhas (n=77), vacas solteiras (n=69) e paridas (n=59), obtiveram-se os seguintes resultados, respectivamente para os grupos controle e tratamento: taxa de aproveitamento (TA) 72,8% (n=103) vs 83,3% (n=102), de concepção (TC) 47,9% (n=73) vs 42,7% (n=82) e de prenhez (TP) 34,7% (n=101) vs 35,0% (n=100). Em analise posterior, as vacas paridas foram divididas em duas classes de período pós-parto: PP1 de 2 a 4 meses (n=35) e PP2 de 4 a 8 meses (n=24). Houve efeito da interação entre PP e condição ovariana (CO) para a variável TA, obtendo no PP2, os valores, significativamente diferentes (P<0,05), foram de 83,3% para as que estavam ciclando e 50% para as que não estavam ciclando. Também houve efeito de período pós-parto para TC e os valores de PP1 foi de 48,5% e no PP2 foi de 35,3% (P<0,05). Assim como para TC, houve efeito de PP para TP: vacas no PP1 tiveram 45,7% de prenhez, enquanto as que estavam no PP2, 26,4% (P<0,05). Concluiu-se que o novo dispositivo à base de biopolímeros Progestar® foi capaz de proporcionar taxas de ovulação, de concepção e de prenhez nas inovulações em programas TETF, em novilhas e vacas cruzadas, tanto quanto dispositivos confeccionados com silicone que liberam progestágenos (Crestar®).<br>There are many factors for the successful of ET programs, and the recipients are the major factor on this biotechnique. Nowadays, the products available in the brazilian market for releasing progesterone are imported and made of silicone, a biocompatible polymer, but not biodegradable. Recently, intravaginal progesterone devices made of PHB, a biodegradable polymer made from bacteria fermentation of sugar cane, have been studied. The objective of this present study was to compare the efficiency in ET programs of a new intravaginal device on ovulation, conception and pregnancy rate, in croosbreed heifers and cows, with a device made of silicone Crestar®, currently available in the brazilian market. The experiment was done with help of Embryo-sys® Company, which was responsible for the recipient\'s synchronizations and inovulations. The synchronizations and inovulations were done in three different places: Paranapanema-SP, Itapetininga-SP and Ouro Fino-MG. All the animals were kept in pasture of Brachiaria decumbens with mineral supplementation and ad libitum water. The body and ovary condition score, postpartum period and animal category were utilized for equal division of recipients (n=205), in two groups: control - auricular device (Crestar®) with 3mg of norgestomet (n=103) and treatment - intravaginal device (Progestar®) with 1.72g of progesterone (n=102). On day 0, all the animals received 2mg of estradiol benzoate (IM). On day 8, the devices were removed, 400UI of eCG and 500&mu;g of PGF2&alpha; were injected (IM). After 24 hours, was injected 1mg of estradiol benzoate (IM), as ovulation inductor. The animals had the following results, respectively for control and treatment group: ovulation rate (OR) - 72.8% (n=103) vs 83.3% (n=102), conception rate (CR) - 47.9% (n=73) vs 42.7% (n=82) and pregnancy rate (PR) - 34.7% (n=101) vs 35.0% (n=100). In further analysis, postpartum cows were divided in two classes: PP1 (2 - 4 months, n=35) and PP2 (4 - 8 months, n=24). There was an interaction between PP and ovary condition (OC) on OR, in which animals in PP2 and cyclic showed better results (83.3%) than the animals not cyclic (50%). There was effect of PP on CR, and the values for PP1 and PP2 were 48.5% and 35.5%, respectively. There was also effect of PP on PR: cows in PP1 showed 45.7% of PR, while cows in PP2, 26.4%. This experiment showed that the new intravaginal device (Progestar®) had the same efficiency on ovulation, conception and pregnancy rate, in ET programs, in crossbreed heifers and cows, as the commercially available device Crestar®.

Made available in DSpace on 2015-03-26T13:47:29Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1590039 bytes, checksum: 13d7ea7a1ad688110149bf5448ece2d8 (MD5) Previous issue date: 2003-05-08<br>This work had as objective the administration of an luteolytic agent (Cloprostenol Sodic-Ciosin) in different doses and routes, to evaluate the synchronization rates, interval of the application to the estrus, hormonal plasma concentrations of progesterone (P4) and pregnant rates of fresh embryos transferred. Still, genital organs of bovine females were collected at slaughterhouses for the study of the angioarchitecture, through veined infusions of radiographic contrasts. There were used 199 Holstein-Zebu embryo recipients with corporal score &#8805; 3,0 in a scale from 1 to 5 and live weight among 320-450 kg. A total of 103 animals presented historic of estrus previous to the treatments (between days 7-16 of the estrous cycle; estrous = day 0) and 96 animals didn't present historic of estrous, these were examined by rectal palpation for the presence of ripe CL in one of the ovaries. The animals were randomly assigned to three experimental groups. Treatment 1: 68 animals (38 with report of previous estrus) received 1 mL of Cloprostenol via intra-vulvo-submucosal (IVSM). Treatment 2: 66 animals (33 with report of previous estrus) received 1 mL of Cloprostenol via intramuscular (IM) and in Treatment 3, 65 animals (32 with report of previous estrus) received 2 mL of Cloprostenol via IM. It was considered immobility reflex as an indicative of estrous and only the animals that showed estrus up to 96 hours after the application of the Cloprostenol were used. The averages of plasma progesterone concentrations (P4) were analyzed by RIA in the moment previous to the application of the drug and 48 hours after. There was no difference in synchronization rates (P>0,05) between the three treatments (72,1%, 53,0% , 64,6%, respectively), when just the animals with report of previous estrus were appraised (76,3%, 60,6% , 68,8%, respectively) and when the animals without report of previous estrus were appraised (66,7%, 45,5% , 60,6%, respectively). The answer interval to the estrus was similar (p >0,05) among the three treatments (69,3± 15,2; 67,9± 16,7; 68,3± 16,9 hours, respectively), but they showed differences (p<0,05) when the animals with report of estrus were divided in luteal classes, in witch animals belonging to days 11-13 of estrous cycle showed larger intervals (75,3 ± 13,3 hours), in relation to days 7-10 of the estrous cycle (63,6 ± 18,3 hours) and to days 14-16 (61,1 ± 11,3 hours). Synchronization rates were similar among the three luteal classes (P>0,05). Regarding pregnant rates there were not differences (P>0,05) in the animals fertility among the three treatments, (45,5%, 50,0%, 55,0% respectively). As for the plasma P4 concentrations, the percentile fall of the progesterone values after 48 hours of the application was similar (p>0,05) in the three treatments (79%; 68% and 83%, respectively). Regarding the angioarchitecture of the genital organs it was observed through radiographic sheets that the caudal vaginal vein drains the vagina mucosal and it presents anastomoses with the vases from the cervix, body and uterine horns. The present study demonstrated that embryo recipients with and/or without report of previous estrus, when synchronized with Sodic Cloprostenol in reduced doses (50% of the conventional), as by IM or IVSM roads showed similar synchronization rates, answer intervals to the estrus, fall of the progesterone concentrations and pregnat rates. The variations in the answer intervals to the estrous are influenced by the diestrous phase in the moment of treatment and not for the route or dose of administration of an luteolytic agent. A portion of luteolytic agents administered through IVSM can be transported directly to the uterus and consequently to the ovary for a local route without passing for the systemic circulation is suggested.<br>Este trabalho teve como objetivo a administração de um agente luteolítico (Cloprostenol Sódico-Ciosin®) em diferentes doses e vias, para avaliar as taxas de sincronização, intervalo da aplicação ao estro, concentrações de progesterona sérica (P4) e taxas de gestação de embriões transferidos à fresco em receptoras de embrião bovino. Ainda, órgãos genitais de fêmeas bovinas foram coletados em matadouros para o estudo da angioarquitetura, por meio de infusões venosas de contrastes radiográficos. Foram utilizadas 199 receptoras mestiças Holandês-Zebu com escore corporal &#8805; 3,0 numa escala de 1 a 5 e peso vivo entre 320-450 kg. Um total de 103 animais apresentavam histórico de estro anterior aos tratamentos (entre os dias 7-16 do ciclo estral; estro= dia zero) e 96 não apresentavam histórico, apenas selecionados pela palpação transretal para a presença de CL característico em um dos ovários. Os animais foram divididos ao acaso em três grupos experimentais. No Tratamento 1: 68 animais (38 com histórico de estro anterior) receberam 1 mL de Cloprostenol na parede interna da vulva (IVSM). Tratamento 2: 66 animais (33 com histórico) receberam 1 mL de Cloprostenol via intramuscular (IM) e no Tratamento 3: 65 animais (32 com histórico) receberam 2 mL de Cloprostenol via IM. Considerou-se o reflexo de imobilidade como indicativo do estro e somente foram considerados para os estudos os animais que manifestaram estro até 96 horas após a aplicação. As médias das concentrações de Progesterona Séricas (P4) foram analisadas por RIA no momento anterior à aplicação da droga e 48 horas após. Não houve diferença na taxa de sincronização (P>0,05) entre os três tratamentos (72,1%, 53,0% e 64,6% respectivamente), quando apenas os animais com histórico foram avaliados (76,3%, 60,6% e 68,8%, respectivamente) e quando os animais sem histórico foram avaliados (66,7%, 45,5% e 60,6%, respectivamente). O intervalo de resposta ao estro foi semelhante (p>0,05) entre os três tratamentos (69,3± 15,2; 67,9± 16,7; 68,3± 16,9 horas, respectivamente), mas apresentaram diferenças (p<0,05) quando os animais com histórico foram divididos em classes luteais, nas quais os animais pertencentes aos dias 11-13 do ciclo estral apresentaram intervalos maiores (75,3 ± 13,3 horas) de resposta ao estro, em relação aos animais dos dias 7-10 do ciclo (63,6 ± 18,3 horas) e os animais dos dias 14-16 (61,1 ± 11,3 horas). Mas a taxa de sincronização foi semelhante entre as três classes luteais (P>0,05). Em relação à taxa de gestação não houve diferenças (P>0,05) nos três tratamentos (45,5%, 50,0% e 55,0% respectivamente). Quanto a P4, a queda percentual dos valores de progesterona após 48 horas da aplicação foram semelhantes (p>0,05) nos três tratamentos (79%; 68% e 83%, respectivamente). Em relação à angioarquitetura dos órgãos genitais, foi observado por meio de lâminas radiográficas, que a veia vaginal caudal drena a parede da vagina e apresenta anastomoses com os vasos provenientes da cérvix, corpo e cornos uterinos. Este presente estudo demonstrou que receptoras bovinas com e/ou sem histórico de estro anterior, quando sincronizadas com Cloprostenol Sódico em doses reduzidas (50% da convencional), tanto pelas vias IM ou IVSM apresentam taxas de sincronização, intervalos de resposta ao estro, queda das concentrações de progesterona e taxas de gestação semelhantes. As variações nos intervalos de resposta ao estro são influenciadas pela fase de diestro em que o animal se encontra no momento do tratamento e não pela rota ou dose de administração de um agente luteolítico. Sugere-se ainda que parte da dosagem de agentes luteolíticos administrados via IVSM pode ser transportada diretamente ao útero e, por conseguinte ao ovário por uma rota local sem passar pela circulação sistêmica.