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Morelli KG, Lourenço GG, Marangon VR, Feltrin IR, Imura Oshiro TS, Rodrigues da Silva IV, Pugliesi G. Use of Doppler ultrasonography for selection of recipients in embryo transfer programs in horses. Theriogenology 2023; 211:142-150. [PMID: 37634355 DOI: 10.1016/j.theriogenology.2023.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 08/29/2023]
Abstract
We aimed to evaluate the impact of corpus luteum (CL) and uterine characteristics accessed by B-mode and Color-Doppler ultrasonography in recipient mares at the time of embryo transfer (ET) on pregnancy outcomes. Recipient mares (n = 110), between days 3-9 after spontaneous ovulation, received a fresh embryo. Immediately before ET, the reproductive system was assessed by transrectal palpation for the following parameters: uterine tone (0-3), CL echogenicity (0-6), CL type (homogeneous, trabecular or anechoic center), luteal area (cm2), uterine echogenicity (0-3), uterine edema (0-3), luteal blood perfusion (0-100%) and uterine blood perfusion (1-4). Additionally, a blood sample was collected by puncture of the jugular vein for plasma P4 dosage. Retrospectively, recipients were classified according to the luteal area (small [≤ 6 cm2] or large [> 6 cm2]), luteal blood perfusion (low [≤ 55%] or high [> 55%]), and plasma concentration of P4 (low ≤ 9.98 ng/mL or high > 9.98 ng/mL). Pregnancy diagnosis was performed at 12 and 30 days of gestation. Luteal blood perfusion was significantly higher (P = 0.04) in pregnant recipients (n = 83) than in non-pregnant recipients (n = 27). Overall P/ET was higher (P ≤ 0.02) in mares with high luteal blood perfusion and high P4. Luteal blood perfusion was the most adequate significant (P = 0.01) predictor of pregnancy compared with the luteal area and plasma P4 concentration. Only luteal blood perfusion showed a linear (P = 0.03) and cubic (P = 0.004) effect on P/ET. In conclusion, CL blood perfusion determined by color-Doppler can be used in real-time to select recipients with the greatest chance of maintaining pregnancy in equine ET programs.
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Affiliation(s)
- Karine Galhego Morelli
- USP - Universidade de São Paulo, Avenida Duque de Caxias Norte 225, Jardim Elite, Pirassununga, SP, Brazil.
| | - Gilberto Guimarães Lourenço
- M.V. Haras Laglória - Médico Veterinário responsável pelo Haras Laglória, Fazenda Salgada, 00000 - RT-19, Itajara-Itaperuna, RJ, Brazil.
| | | | - Isabella Rio Feltrin
- UNESP - Botucatu - Universidade Estadual Paulista "Júlio de Mesquita Filho", Distrito de Rubião Júnior, s/n - Rubião Junior, SP, 18618-970, Brazil.
| | - Thaís Sayuri Imura Oshiro
- USP - Universidade de São Paulo, Avenida Duque de Caxias Norte 225, Jardim Elite, Pirassununga, SP, Brazil.
| | - Igor Vicente Rodrigues da Silva
- UNIPAC-JF, Faculdade Presidente Antonio Carlos, Juiz de Fora Av. Juiz de Fora, 1100, Granja Betânia, Juiz de Fora - MG, 36048-000, Brazil.
| | - Guilherme Pugliesi
- USP - Universidade de São Paulo, Avenida Duque de Caxias Norte 225, Jardim Elite, Pirassununga, SP, Brazil.
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Santos GMGD, Junior LB, Silva-Santos KC, Ayres Dias JH, Dias IDS, Seneda MM, Morotti F. Conception rate and pregnancy loss in fixed-time cattle embryo transfer programs are related to the luteal blood perfusion but not to the corpus luteum size. Theriogenology 2023; 210:251-255. [PMID: 37549464 DOI: 10.1016/j.theriogenology.2023.07.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/10/2023] [Accepted: 07/31/2023] [Indexed: 08/09/2023]
Abstract
This study aimed to evaluate the effect of luteal blood perfusion and corpus luteum (CL) area on the conception rate and occurrence of pregnancy loss of recipients in a large-scale fixed-time embryo transfer (FTET) program. Multiparous Brangus cows (n = 1700) at 45 days postpartum and body condition scores (BCS) between 2.5 and 4.0 (3.0 ± 0.3) were used in this study. On a random day of the estrous cycle (day -10), the females received progesterone and estradiol based on the FTET protocol. On day 7, 1465 recipients had at least one CL and were evaluated using B-mode ultrasound for the CL area (cm2) and color Doppler for the luteal blood perfusion score (I/low-vascularization area <40% of the CL; II/medium-vascularization >45% to < 50%; and III/high-vascularization >50%). Immediately after CL evaluation, each recipient received a single fresh embryo (blastocyst stage) ipsilateral to the CL, in vitro produced from a commercial laboratory. Pregnancy diagnosis was performed at 30 days and repeated 60 days later to evaluate pregnancy loss (30-90 days). Ultrasound evaluation and embryo transfer were performed by a single technician. For data analysis, in addition to luteal blood perfusion groups, recipients were retrospectively ranked according to CL area into small (<3 cm2; 2.63 ± 0.01), medium (>3 to < 4 cm2; 3.44 ± 0.01), and large (>4 cm2; 4.77 ± 0.03). Data were analyzed using a logistic regression model (P < 0.05). The overall conception rate was 44.2% (648/1465), influenced by the luteal blood perfusion score [P = 0.03; high 48.4%a (134/277), medium 44.6%a (427/958), and low 37.8%b (87/230)] but not by CL area ranking [P = 0.37; large 41.8% (225/538), medium 45.2% (276/610), and small 46.4% (147/317)]. There was no interaction between the luteal blood perfusion score and CL area ranking (P = 0.81), and the BCS did not affect the results of this study (P = 0.51). In terms of pregnancy loss up to 90 days, there was no effect on the CL area ranking (P = 0.77), but the flow score showed an effect [P = 0.03; high 3.6%b (5/139), medium 9.3%a (44/471), and low 10.3%a (10/97)]. The conception rate and occurrence of pregnancy loss in the FTET program in beef cattle are related to luteal blood perfusion but not CL size.
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Affiliation(s)
| | | | | | | | | | | | - Fábio Morotti
- UEL - Universidade Estadual de Londrina, Londrina, PR, Brazil; UNOPAR - Universidade Pitágoras Unopar Anhanguera, Arapongas, PR, Brazil.
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Pugliesi G, Guimarães da Silva A, Viana JHM, Siqueira LGB. Review: Current status of corpus luteum assessment by Doppler ultrasonography to diagnose non-pregnancy and select embryo recipients in cattle. Animal 2023; 17 Suppl 1:100752. [PMID: 37567660 DOI: 10.1016/j.animal.2023.100752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 02/13/2023] [Accepted: 02/20/2023] [Indexed: 08/13/2023] Open
Abstract
A number of potentials uses of Doppler ultrasonography have been explored in the last decades, both as research tools in reproductive physiology investigations and for the reproductive management of farm animals. The objective of this review was to address some of the recent strategies developed in fixed-time reproductive programs and resynchronization of ovulation in cattle, based on the evaluation of corpus luteum function by color-Doppler ultrasound imaging. Recent studies in dairy and beef cattle pointed out to a high accuracy when Doppler ultrasonography is used to assess the functionality of the corpus luteum and identify non-pregnant females at 20-24 days after breeding. Therefore, super-early resynchronization programs starting in the second week after timed-artificial insemination or embryo transfer have been developed and are being implemented in commercial assisted reproduction programs; thus, anticipating conception with proven semen or genetically superior embryos. In addition, assessment of corpus luteum blood perfusion can be used for identifying high fertility embryo recipients in fixed-time embryo transfer programs.
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Affiliation(s)
- Guilherme Pugliesi
- Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, SP 13635-900, Brazil.
| | - Amanda Guimarães da Silva
- Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, SP 13635-900, Brazil
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Rossignolo EADA, Silva NCD, Stolf RL, Cavalieri FLB, Colombo AHB, Andreazzi MA, Seneda MM, Morotti F. Evaluation of hCG as gonadotropic support to timed embryo transfer protocol in beef cattle. Theriogenology 2023; 195:24-30. [DOI: 10.1016/j.theriogenology.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/11/2022] [Accepted: 10/03/2022] [Indexed: 11/17/2022]
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Couto SRB, Guerson YB, Caparelli NMPM, Andrade JPN, Jacob JCF, Barbero RP, Mello MRB. Mitigation of low pregnancy rate in excitable Nellore cows by administration of GnRH or P4. Theriogenology 2022; 192:14-21. [PMID: 36037572 DOI: 10.1016/j.theriogenology.2022.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/29/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022]
Abstract
This research aimed to determine the effect of temperament on reproductive parameters including cortisol and progesterone (P4) in Nellore cows. Additionally, two methods for increasing plasma progesterone (P4) levels in excitable animals to enhance pregnancy rate (P/AI) and reduce pregnancy loss were investigated. In total, 939 cows were subjected to timed artificial insemination (TAI) and divided into three groups: (P4LA; n = 305) 150 mg of injectable long-acting progestogen 7 days after TAI; (GnRH; n = 306), 10 μg of buserelin acetate on day 7 after TAI; control group (CG; n = 328) without hormonal treatment. In 213 cows, randomly chosen from each group, ultrasound evaluations of the preovulatory follicle (Mode B) were performed on the day of insemination and of the corpus luteum (Color Doppler) 7 and 16 days after TAI. Blood samples were obtained from 20% of the 939 animals, randomly chosen from each group, on the day of insemination and after 7 and 16 days to measure cortisol and progesterone, respectively. At the time of insemination, subjective temperament evaluations were performed with the animals being classified as excitable (EXC) or adequate (ADQ). The SAS GLIMMIX procedure was used to compare the pregnancy rate (P/AI) and gestational loss within each temperament for the three experimental groups. Continuous variables were analyzed utilizing SAS PROC MIXED procedure. Cortisol concentration was higher and POF (preovulatory follicle) and CL (corpus luteum) volumes at the time of insemination and 7 days after AI, respectively, were lower in EXC animals than in ADQ. No significant difference was observed between the number of pixels, CL intensity, and plasma concentration of P4, 7 days after TAI. However, 16 days post-insemination, among the animals classified as EXC, higher concentrations of P4 were observed in the GnRH and P4LA groups than in the control. Regarding P4 concentrations, there was a tendency to be lower in animals classified as EXC than in ADQ within the control group (P = 0.06), while rate of blood flow from the CL was lower in EXC animals than in ADQ animals (P = 0.04). Among the ADQ animals, the GnRH and P4LA groups showed a lower CL flow rate than that observed in the control (P = 0.04), 16 days after the TAI. Among EXC animals, a higher pregnancy rate was observed in the GnRH and P4LA groups than in the control group (P = 0.01). In the control group, the pregnancy rate (P/AI) of the ADQ animals was higher than that of the EXC animals (P = 0.05). No statistically significant differences were observed between gestational losses when the treatments or temperaments were compared. In conclusion, the use of GnRH or P4LA, 7 days after insemination, improves pregnancy rates in excitable animals and is a viable alternative to minimize the negative impact of stress and improve reproductive efficiency in beef cattle.
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Affiliation(s)
- Samuel R B Couto
- Departamento de Reprodução e Avaliação Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, 23897-000, Brazil
| | - Yuri B Guerson
- Departamento de Reprodução e Avaliação Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, 23897-000, Brazil
| | - Nicolas M P M Caparelli
- Departamento de Reprodução e Avaliação Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, 23897-000, Brazil
| | - João Paulo N Andrade
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, 53706, USA
| | - Júlio C F Jacob
- Departamento de Reprodução e Avaliação Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, 23897-000, Brazil
| | - Rondineli P Barbero
- Departamento de Produção Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, 23897-000, Brazil
| | - Marco R B Mello
- Departamento de Reprodução e Avaliação Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, 23897-000, Brazil.
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Fontes PLP, Oosthuizen N. Applied Use of Doppler Ultrasonography in Bovine Reproduction. FRONTIERS IN ANIMAL SCIENCE 2022. [DOI: 10.3389/fanim.2022.912854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The use of Doppler ultrasonography to quantify blood vascularization in reproductive organs has increased over the past decade. Doppler technology has predominantly been explored in research settings to evaluate uterine blood flow and to assess follicular and luteal blood perfusion. Recent research has also explored the use of Doppler technology in applied reproductive management for both the beef and dairy industries and has focused on the use of luteal color Doppler ultrasonography to evaluate embryo transfer recipients and perform early pregnancy diagnosis. Although significant progress has been made and current literature indicates a strong potential for the applied use of Doppler ultrasonography to increase reproductive efficiency in the cattle industry, uptake of this technology is still currently limited. This review summarizes the recent developments in the applied use of color Doppler ultrasonography for reproductive management in both beef and dairy cattle herds.
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Guedes PHE, Pinna AE, Morais RDCL, de Souza GN, Jacob JCF, Carvalho CFPDM, Nogueira LAG, Oliveira CS. Doppler evaluation of recipient cows treated with progesterone and estradiol. ANIMAL PRODUCTION SCIENCE 2022. [DOI: 10.1071/an21298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Guerson YB, Couto SR, Morais RDCL, Grillo GF, Jacob JC, Barbero RP, Mello MR. Vascular perfusion and the volume of the preovulatory follicle are affected by the temperament of Nellore cows. Livest Sci 2021. [DOI: 10.1016/j.livsci.2021.104744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Teixeira A, Riveros J, Diniz J, Fonseca A, Silva D, Leo A, Pereira I, Valle G, Monteiro G, Oliveira L. Intravaginal progesterone device (1.9g) and estradiol benzoate for follicular control in the mare during spring and summer. ARQ BRAS MED VET ZOO 2021. [DOI: 10.1590/1678-4162-12272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ABSTRACT The objective of this study was to evaluate follicular growth and ovulatory rates in mares treated with an intravaginal progesterone device (P4) during the 10-day period, associated with the use of estradiol benzoate (EB). The results were compared during the transition period (ET) in the spring and the breeding season in the summer (ER). The variables were submitted to ANOVA (Tukey's test), considering P<0.05. No ovulation occurred during the permanence of the P4 implant in both experimental periods. The ovulatory rate in the ER was 100% (n = 8) and in the ET 62.5% (n = 5; P = 0.0547). Significant differences were observed (<0.001), in both periods, comparing follicular growth rates during the permanence of P4 device (ER: 1.33 ± 0.89mm/d; ET: 1.00 ± 0.81mm/d) to the period without P4 (ER: 3.63 ± 1.33 mm/d; ET: 3.31 ± 1.66 mm/d). The present study demonstrated applicability and efficiency of a hormonal protocol using P4 intravaginal device and EB for follicular control in mares, both during ET and ER.
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Affiliation(s)
| | | | | | | | - D.F. Silva
- Universidade Federal de Minas Gerais, Brazil
| | - A.M.P. Leo
- Universidade Federal de Minas Gerais, Brazil
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Gallelli MF, Bianchi C, Zampini E, Trasorras V, Gambarotta M, Miragaya M. Corpus luteum vascularization during the maternal recognition of pregnancy in llamas (Lama glama). Reprod Domest Anim 2019; 55:74-80. [PMID: 31737943 DOI: 10.1111/rda.13588] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 11/13/2019] [Indexed: 10/25/2022]
Abstract
The aim of this study was to characterize corpus luteum vascularization and its association with plasma progesterone concentration in early stages of pregnancy, when maternal recognition of pregnancy is expected to occur. In all animals, both plasma progesterone concentration and corpus luteum vascularization increased from Day 6 to Day 8 post-mating and afterwards in non-pregnant llamas they started to decrease to reach basal levels around Days 12 to 14 post-mating, while in pregnant animals, both variables remained elevated until the end of the study. A lineal positive relationship between corpus luteum vascularization and plasma progesterone concentration was observed in pregnant (r2 = .46, p < .0001) and non-pregnant llamas (r2 = .66, p < .0001). Pregnant animals showed higher plasma progesterone concentration and corpus luteum vascularization than the non-pregnant ones from Day 12 post-mating until the end of the study (p ˂ .05 and p ˂ .01, respectively). These results suggest that maternal recognition of pregnancy should occur before Day 12 post-mating in order to expand luteal lifespan, maintaining corpus luteum vascularization and progesterone production. Also, the assessment of CL vascularization area could be a useful and non-invasive method for early pregnancy diagnosis due to its association with plasma progesterone concentration.
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Affiliation(s)
- Maria Florencia Gallelli
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.,Facultad de Ciencias Veterinarias, Instituto de Investigación y Tecnología en Reproducción Animal (INITRA), UBA, Buenos Aires, Argentina
| | - Carolina Bianchi
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.,Laboratorio de Endocrinología, Fac. de Cs. Veterinarias, CIVETAN, UNCPBA, Tandil, Argentina
| | - Enzo Zampini
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.,Facultad de Ciencias Veterinarias, Instituto de Investigación y Tecnología en Reproducción Animal (INITRA), UBA, Buenos Aires, Argentina
| | - Virginia Trasorras
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.,Facultad de Ciencias Veterinarias, Instituto de Investigación y Tecnología en Reproducción Animal (INITRA), UBA, Buenos Aires, Argentina
| | - Mariana Gambarotta
- Cátedra de Bioestadística, Facultad de Ciencias Veterinarias, UBA, Buenos Aires, Argentina
| | - Marcelo Miragaya
- Facultad de Ciencias Veterinarias, Instituto de Investigación y Tecnología en Reproducción Animal (INITRA), UBA, Buenos Aires, Argentina
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Caunce SL, Dadarwal D, Adams GP, Brar P, Singh J. An objective volumetric method for assessment of ovarian follicular and luteal vascular flow using colour Doppler ultrasonography. Theriogenology 2019; 138:66-76. [PMID: 31302433 DOI: 10.1016/j.theriogenology.2019.06.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 06/20/2019] [Accepted: 06/24/2019] [Indexed: 12/15/2022]
Abstract
Our goal was to develop an objective computer-assisted volumetric method of assessing vascular flow from colour Doppler ultrasound data of ovarian structures recorded by free-hand movement. We hypothesized that a vascularity index (ratio of the region of blood flood to the region of ovarian structure) obtained from the three-dimensional volumetric analysis would be more precise (less variable) than conventional two-dimensional analysis of single images in estimating the functional status of the preovulatory follicles and corpus luteum. Doppler ultrasound cineloops of water buffaloes (Bubalus bubalis; n = 22) ovaries were recorded daily from 12 h before GnRH treatment to four days after ovulation. Cineloops were processed using Fiji and Imaris software packages for segmenting the area (two-dimensional analysis) and the volume (three-dimensional analysis) occupied by the blood-flow and associated tissue to calculate the vascularity index. For volumetric measurement, all images in a cineloop were used (i.e., no a-priori selection of images) while for two-dimensional analysis, three images from the region with apparent maximum vascularity were selected. The volumetric method was verified with theoretical ellipsoidal volume of the follicle (r = 0.96 P < 0.01) or corpus luteum (r = 0.58 P = 0.02). The variability in the follicular vascularity index among animals was lower using the volumetric method than two-dimensional analysis (0.018 ± 0.002 vs 0.030 ± 0.005, P < 0.01), while the variability for CL vascularity was similar between methods (P = 0.23). An increase in the follicular vascularity index was detected at 12 h after GnRH treatment using both methods (two-dimensional: 0.030 ± 0.008, P < 0.01; three-dimensional: 0.016 ± 0.006, P < 0.02). Buffaloes that ovulated tended to have a greater increase in 3D vascularity index than non-responding buffaloes (P = 0.06); the two-dimensional method was not able to detect these changes. Using the three-dimensional method, a moderate positive correlation (r = 0.59; P = 0.02) was evident between the follicular vascularity index at 14-16 h after GnRH treatment and follicular diameter. In conclusion, an objective volumetric method for assessing relative ovarian blood flow changes was developed using Doppler ultrasound cineloops recorded by free-hand movement. The 3-dimensional method eliminates the need for a-priori selection of images and is more precise as a result of decreased technical variability.
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Affiliation(s)
- Serena L Caunce
- Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada
| | - Dinesh Dadarwal
- Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, Canada
| | - Gregg P Adams
- Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada
| | - Parkash Brar
- Department of Obstetrics and Gynecology, Guru Angad Dev Veterinary and Animal Science University, Ludhiana, Punjab, India
| | - Jaswant Singh
- Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada.
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Use of color-Doppler ultrasonography for selection of recipients in timed-embryo transfer programs in beef cattle. Theriogenology 2019; 135:73-79. [PMID: 31203090 DOI: 10.1016/j.theriogenology.2019.06.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/31/2019] [Accepted: 06/05/2019] [Indexed: 11/21/2022]
Abstract
We aimed to study the association between CL characteristics assessed by color-Doppler ultrasonography (Doppler-US) at the time of embryo transfer (ET) and pregnancy rate (P/ET) in beef recipients. Estrous cycles of crossbred beef recipients were synchronized for timed-ET. On the day of ET (Day 7), CL area, proportion of luteal blood perfusion (BP), and the relationship between the largest dominant follicle (DF) and CL (ipsilateral or contralateral) were determined. Animals (n = 444) received an in vitro produced embryo from Nelore donors, placed in the uterine horn ipsilateral to the CL. Recipients were split retrospectively in three subgroups according to CL area [small (<3 cm2), medium (3-4 cm2), or large (>4 cm2)] and three subgroups according to luteal signals of BP [low (≤40%), medium (45-50%) or high (≥55%)]. Pregnancy was detected on Days 30-45 by transrectal ultrasonography and P/ET was analyzed considering the effects of cow's category (suckling or non-suckling), CL area, luteal BP and side of DF. P/ET increased along with BP category [low, 45.9%B, (62/135); medium, 54.1%AB (93/172); and high, 58.4%A (80/137)]. When luteal BP was evaluated as a continuous variable, a significant (P < 0.05) linear and positive effect was observed on P/ET. A greater (P < 0.05) CL area and serum progesterone concentrations were observed in the medium and high BP than in the low BP category. Although an effect of luteal size category was not significant on P/ET [small, 49% (76/155); medium, 59.7% (83/139); and large, 50.7% (75/148); P > 0.1], when CL area was evaluated as a continuous variable, a quadratic effect (P < 0.05) indicated a positive relationship between P/ET and CL area until luteal tissue reached 4.07 cm2, followed by a negative relationship. The location of the first-wave DF in relation to the CL did not affect P/ET (P > 0.1). In conclusion, Doppler-US is an innovative tool that has the potential to be used for selection of suitable embryo recipients based on luteal BP. Selection of recipients that have a greater chance of maintaining pregnancy will increase the success of timed-ET programs.
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