Publications by authors named "Fábio Morotti"

15 Publications

  • Page 1 of 1

Ovarian follicular dynamics, progesterone concentrations, pregnancy rates and transcriptional patterns in Bos indicus females with a high or low antral follicle count.

Sci Rep 2020 11 11;10(1):19557. Epub 2020 Nov 11.

Animal Reproduction and Biotechnology Laboratory, State University of Londrina-UEL, Londrina, PR, Brazil.

We evaluated the effect of the antral follicle count (AFC) on ovarian follicular dynamics, pregnancy rates, progesterone concentrations, and transcriptional patterns of genes in Nelore cattle (Bos taurus indicus) after a timed artificial insemination (TAI) programme. Cows were separated based on the AFC, and those with a high AFC showed a larger (P < 0.0001) ovarian diameter and area than those with a very low AFC. Females with a very low AFC exhibited a larger (P < 0.01) diameter of the dominant follicle at TAI (13.6 ± 0.3 vs. 12.2 ± 0.4 mm) and a tendency (P = 0.06) to have different serum progesterone concentrations (2.9 ± 0.3 vs. 2.1 ± 0.3 ng/mL; on day 18, considering day 0 as the beginning of the synchronization protocol) than those with a high AFC. The pregnancy rate was higher (P ≤ 0.05) in animals with a very low (57.9%) and low (53.1%) AFC than in those with a high AFC (45.2%). The expression of genes related to intercellular communication, meiotic control, epigenetic modulation, cell division, follicular growth, cell maintenance, steroidogenesis and cellular stress response was assessed on day 5. In females with a low AFC, 8 and 21 genes in oocytes and cumulus cells, respectively, were upregulated (P < 0.05), while 3 and 6 genes in oocytes and cumulus cells, respectively, were downregulated. The results described here will help elucidate the differences in ovarian physiology and the reproductive success of Bos indicus females with a low or high AFC.
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http://dx.doi.org/10.1038/s41598-020-76601-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7658257PMC
November 2020

Synchronization of stage of follicle development before OPU improves embryo production in cows with large antral follicle counts.

Anim Reprod Sci 2020 Oct 14;221:106601. Epub 2020 Sep 14.

National Institute of Science and Technology for Dairy Production Chain (INCT-LEITE), Universidade Estadual de Londrina, Rodovia Celso Garcia Cid-Campus Universitário, PO Box 10011, Londrina, Paraná, 86057-970, Brazil; Laboratório de Reprodução Animal, DCV-CCA-UEL, Londrina, Paraná, Brazil. Electronic address:

In the present study, there was an evaluation of in vitro embryo production (IVEP) in Bos indicus donor cows with small or large antral follicle counts (AFCs) when there was synchronization of follicular dynamics among cows before ovum pick-up (OPU). Donor cows classified as having small or large AFC were submitted to OPU/IVEP program (Experiment-I) or had follicular-stage synchronization imposed before OPU/IVEP (Experiment-II). In Experiment-I, the cows with a large AFC had a greater (P < 0.01) mean of embryos developing to the blastocyst stage compared to those with a small AFC. In Experiment-II, percentage of viable oocytes/OPU were not affected (P = 0.33) by synchronization of follicular dynamics, but the AFC had an effect (P < 0.0001). There was an interaction (P = 0.01) indicating the larger AFC, with or without imposing of a synchronization treatment regimen, resulted in the most desirable outcome. The number of embryos was affected (P < 0.001) by follicular-stage synchronization and AFC, with there being an interaction (P = 0.002) with the most desirable results for the large AFC-synchronized group. Number of pregnancies was greater (P ≤ 0.02) for recipient females with embryos from synchronized donors and with a large AFC. There was an interaction (P = 0.03) with there being a greater pregnancy percentage for cows with synchronized follicular stages and the large AFC. Bos indicus donor with a large AFC when associated with the synchronization of stage of follicular dynamics pre-OPU results in improvement of the efficacy of IVEP.
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http://dx.doi.org/10.1016/j.anireprosci.2020.106601DOI Listing
October 2020

Follicular wave synchronization prior to ovum pick-up.

Theriogenology 2020 Jul 14;150:180-185. Epub 2020 Jan 14.

Universidade Estadual de Londrina, Laboratório de Reprodução Animal, DCV-CCA-UEL, Londrina, Parana, Brazil.

Among the reproductive biotechnologies, in vitro embryo production (IVEP) is an important tool for multiplying genetic material of superior merit. Recently, the number of embryos produced and transferred in vitro became significantly higher than that produced in vivo worldwide. In this context, the enhancement was attributable to ovum pick-up (OPU). With the advent of genomic technology, shortened breeding intervals, and increased selection accuracy, IVEP has attracted increasing attention for commercial use. The IVEP technique is well-established, but the embryo production rate has reached a plateau at 30-40%. Despite constant advances, the OPU/IVEP programs face some challenges that hinder the efficient application of the technique. Previous studies have shown that the quantity and quality of aspirated oocytes are essential factors for successful IVEP. This paper presents a brief overview of alternatives that can be employed to improve the process-seeking methods that assist in the recovery of better-quality oocytes and higher competence in OPU to improve embryo production. These strategies include using follicular wave synchronization prior to OPU, employing the influence of antral follicle populations, using the pre-OPU gonadotrophic stimulus and applying non-hormonal methods for selecting female donors.
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http://dx.doi.org/10.1016/j.theriogenology.2020.01.024DOI Listing
July 2020

Influence of age and ovarian antral follicle count on the reproductive characteristics of embryo donor mares.

Vet Rec 2020 May 2;186(17):564. Epub 2020 Jan 2.

Department of Veterinary Clinics, State University of Londrina, Londrina, Parana, Brazil

Background: Age and antral follicle count (AFC) are related to fertility in cattle, but this information remains limited in mares.

Methods: To verify the influence of age and AFC on the reproductive characteristics of mares, 15 Quarter Horse donors, with 5-15 antral follicles, ranging from three to 17 years old, healthy and in good nutritional status, were divided into groups with low AFC (≤9 follicles) or high AFC (≥10 follicles) and mares considered young (≤9 years) or old (≥10 years). Mares were submitted to ultrasonography to determine the dominant follicle diameter, follicular growth rate, degree of uterine oedema and embryonic recovery for a minimum of three oestrous cycles.

Results: AFC was higher (P=0.001) in young mares compared with old mares. An interaction (P=0.001) between AFC and age was observed with regard to follicular growth rate, being that mares with low AFC and are old showed the lowest follicular growth compared with those of low AFC and young, high AFC and old, and high AFC and young. Younger mares and those with high AFC exhibited higher degree of uterine oedema (P<0.05) on the third day of oestrus compared with older mares and with low AFC (3 and 2, respectively). However, in both groups, the degree of oedema reduced by the time of ovulation.

Conclusion: Follicular growth rate, degree of uterine oedema and the number of antral follicles are higher in young mares with high AFC. However, the rate of embryonic recovery is not influenced by donors' age or AFC.
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http://dx.doi.org/10.1136/vr.105526DOI Listing
May 2020

Relationships between antral follicle count, body condition, and pregnancy rates after timed-AI in Bos indicus cattle.

Theriogenology 2019 Sep 17;136:10-14. Epub 2019 Jun 17.

University of Londrina (UEL), Laboratory of Animal Reproduction, Londrina, PR, Brazil. Electronic address:

An experiment was performed to evaluate the association between the antral follicle count (AFC) plus body condition score (BCS) and the pregnancy rate in Bos indicus undergoing timed artificial insemination (TAI). A total of 736 Nelore cows with BCSs ranging from 2 to 4 received a conventional protocol for TAI. On a random day of the estrous cycle (Day 0), all cows received an intravaginal P4 device and an intramuscular (i.m.) injection of 2.0 mg estradiol benzoate. On Day 8, the P4 device was removed, and 150 μg sodium D-cloprostenol, 300 IU equine chorionic gonadotrophin and 1.0 mg estradiol cypionate were administered by i.m. injection. TAI was performed 48 h after P4 device removal, and pregnancy diagnosis was performed by ultrasonography after 30 days. On Day 0, all cows were examined by ultrasonography to determine the AFC by counting the number of follicles >3 mm in diameter that were present in both ovaries and to evaluate the BCS (scale of 1-5). The cows were then classified based on their AFCs as those with low (≤10 follicles), intermediate (11-29 follicles) and high AFC (≥30 follicles). Furthermore, cows were classified as having low (≥2.0 to ≤ 2.9) and high (≥3.0 to ≤ 4.0) BCSs. The AFCs and BCSs were analyzed using the generalized linear model, and the pregnancy rate was assessed with the binary logistic regression model (P ≤ 0.05). The pregnancy rate was influenced (P < 0.05) by AFC and BCS classification and by interactions (P = 0.034) between these factors. Cows with a low AFC exhibited higher a pregnancy rate than did cows with a high or an intermediate AFC (57.7% , 47.9% and 49.7% , P = 0.008). Low BCS resulted in a higher pregnancy rate than did high BCS (55.2% vs. 50.4%, P = 0.008). Cows with a high BCS and a low AFC had a higher pregnancy rate (P < 0.05) than did those with a high BCS and an intermediate or a high AFC (59.8%, 48.0%, and 38.0%, respectively). An interaction (P < 0.05) was observed between the AFC and BCS, and the pregnancy rate decreased significantly in cows with an AFC > 30 and a BCS between 3 and 4. In conclusion, AFC and BCS classifications influence the pregnancy rate of Bos indicus beef cattle subjected to TAI. In addition, an important interaction between these factors was observed, namely, the lowest pregnancy rates were found in cows with high BCSs and high AFCs.
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http://dx.doi.org/10.1016/j.theriogenology.2019.06.024DOI Listing
September 2019

In vitro culture supplementation of EGF for improving the survival of equine preantral follicles.

In Vitro Cell Dev Biol Anim 2018 Dec 3;54(10):687-691. Epub 2018 Oct 3.

Department of Veterinary Clinical, Laboratory of Animal Reproduction, University of Londrina, Londrina, Parana, Brazil.

Folliculogenesis is a process of development and maturation of the ovarian follicles, being essential for the maintenance of fertility. In in vivo conditions, 99.9% of the follicles of an ovary do not ovulate and undergo atresia. In order to minimize this loss and to clarify the existing mechanisms, a technique was developed that allows for the in vitro follicular development. The objective of this study was to evaluate the effects of different epidermal growth factor (EGF) concentrations on the in vitro culturing of equine preantral follicles. Ovaries (n = 10) were collected from a local slaughterhouse of mares in seasonal anestrus, washed with 70% alcohol and PBS, and transported. The inner portion of the ovary was divided into 11 fragments of approximately 3 × 3 × 1 mm. A fragment of each ovary was immediately fixed in Bouin (control group). The remaining 10 fragments were individually cultured for 2 and 6 d. The medium was supplemented with different concentrations of EGF (0, 10, 50, 100, and 200 ng/mL). After cultivation, the fragments were processed and classified according to the developmental stage and morphology. In total, 1065 slides containing 6105 tissue sections were evaluated. Within 2 d of culture, there was a higher proportion of intact follicles at the EGF concentrations of 0 and 100 ng/mL (p > 0.05). After 6 d of culture, only the EGF concentration of 100 ng/mL demonstrated a difference when compared to the other treatments (0, 10, 50 and 200 ng/mL of EGF, p > 0.05). There was follicular development after 2 d at all EGF concentrations. Thus, we suggest that EGF promotes follicular survival in equines at a concentration of 100 ng/mL in in vitro cultures of ovarian fragments for 2 d. In addition, we suggest that EGF promotes follicular survival in equines at a concentration of 100 ng/mL in situ cultivation.
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http://dx.doi.org/10.1007/s11626-018-0296-9DOI Listing
December 2018

Intensified use of TAI and sexed semen on commercial farms.

Anim Reprod 2018 Sep 6;15(3):197-203. Epub 2018 Sep 6.

Laboratório de Reprodução Animal, DCV-CCA-UEL, Londrina, Parana, Brazil.

The livestock sector has achieved many technological advances, which have resulted in continued improvements in animal production systems and in the reproductive efficiency of herds. The associated use of reproductive biotechnology and genetic improvements combined with adequate sanitary and nutritional management are essential conditions for sustainable intensified animal production and financial autonomy within farms. Timed artificial insemination (TAI) represents one of the strategies with the greatest impact of expansion in providing genetic improvements and increased reproductive efficiency at a decreased cost. Despite the high proportion of cows receiving TAI, this market still exhibits considerable potential for expansion. After a TAI procedure, approximately 40 to 60% of females become pregnant. This result can vary depending on such factors as the hormonal protocol employed, female category, body condition score, ovarian status, farm management and aspects related to bulls and semen. The fertility and genetic quality of the bull plays an important role in the herd because a single bull can influence the entire production system. Another important strategy is the use of sex-sorted semen associated with TAI, primarily when associated with management practices to improve the pregnancy rate. This paper presents a review of the intensification of TAI, supplying practical information regarding the implementation of TAI commercial programs.
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http://dx.doi.org/10.21451/1984-3143-AR2018-0070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8202457PMC
September 2018

Ovarian antral follicle populations and embryo production in cattle.

Anim Reprod 2018 Aug 17;15(3):310-315. Epub 2018 Aug 17.

Universidade Estadual de Londrina, Laboratório de Reprodução Animal (DCV-CCA-UEL), Londrina, PR, Brazil.

Reproductive biotechniques such as embryo production are important tools to increase the reproductive performance in cattle in a short time. In this context, the antral follicle count (AFC), which reflects the population of antral follicles present in an ovary, has been indicated as an important phenotypic characteristic related to female fertility and closely correlated to the performance of and embryo production (IVEP). A positive correlation was evidenced between AFC and oocyte retrieval by ovum pick up (OPU) sessions and and with the number of embryos produced. Several studies have reported that females with a high AFC had greater embryo yields compared to those with medium and low AFC. However, controversial results were obtained by studies conducted in different bovine breeds. Many conflicting data may be due to the differences in the experimental design, particularly regarding the classification of animals in AFC groups, subspecies particularities, herd aptitude or even issues related to animal management. Therefore, aspects such as the choice of donor, type of aspirated follicles and the stage of follicular wave need to be clarified. Thus, this text aims to discuss the use of AFC as a reproductive tool and its applications in the and production of embryos, besides describing consistent results and new challenges regarding AFC and embryo production.
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http://dx.doi.org/10.21451/1984-3143-AR2018-0072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8202465PMC
August 2018

Injectable progesterone in timed artificial insemination programs in beef cows.

Anim Reprod 2018 Aug 16;15(1):17-22. Epub 2018 Aug 16.

Laboratory of Animal Reproduction, University of Londrina, Parana, .

The aims of this study were I) to compare the follicular diameter, corpus luteum diameter and serum progesterone (P4) concentrations in cows treated with conventional protocol injectable P4 protocol; II) to determine the serum P4 profile in ovariectomized heifers; and III) to compare pregnancy rate between protocols. In experiment I, multiparous cows received a protocol for ovulation synchronization with an intravaginal P4 device (n = 38; device + EB day 0; device removal + PGF2α + eCG + EC day 8) or injectable P4 (n = 38; injection + EB day 0; PGF2α + eCG + EC day 8). In experiment II, ovariectomized heifers (n = 8) were treated with injectable P4 and blood samples were collected to determine the serum P4 profile. In experiment III, multiparous cows were timed AI with two different P4 approaches, intravaginal P4 device (n = 48) or injectable P4 (n = 47). In the first experiment, cows treated with P4 device had higher (P < 0.05) diameter of dominant follicle after ovulation induction (11.6 ± 1.8 10.3 ± 1.8 mm) and ovulation rate (97%, 37/38 . 47.3%, 18/38) than cows treated with injectable P4. But, the follicular growth daily was higher (P < 0.05) in cows treated with injectable P4 than intravaginal device (1.3 ± 0.4 1.0 ± 0.3 mm/day, respectively). In experiment II, the P4 concentration peak occurred within 48 hours (6.54 ng/mL) and decreased after 96 hours (P < 0.05) after P4 injection. In experiment III, cows with P4 device had higher (P < 0.05) pregnancy rate than the injectable P4 group (60.4 34.0%, respectively). These results demonstrate that although the intravaginal P4 devices showed a higher pregnancy rate, a protocol with injectable P4 represents an easier method and a promising alternative for TAI in cattle.
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http://dx.doi.org/10.21451/1984-3143-2017-AR928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7746219PMC
August 2018

Effect of breed on testicular blood flow dynamics in bulls.

Theriogenology 2018 Sep 26;118:16-21. Epub 2018 May 26.

REPROA - Animal Reproduction Laboratory, Deparment of Animal Science, State University of Londrina, Rd. Celso Garcia Cid 445, Km 380 Campus Universitário, Londrina, Paraná, 86051-990, Brazil. Electronic address:

The evaluation of testicular hemodynamics can contribute significantly to the understanding of the thermoregulatory mechanisms and oxygen supply of the testis in domestic animals. The present study aimed to characterize circulatory dynamics using the mean velocity (MV), pulsatility index (PI) and resistive index (RI) of the supratesticular artery in bulls. We evaluated 334 bulls of five different breeds (Nelore, Hereford, Aberdeen Angus, Braford and Brangus) by performing a velocimetry analysis using Doppler ultrasonography. Data were compared by Welch's ANOVA, Games-Howell (post-hoc test) and Spearman correlation with a significance level of 5%. The overall MV of 12.14 ± 0.30 cm/s differed among breeds. In addition, we observed that Brangus bulls showed higher (P < 0.05) MV (16.28 ± 1.02 cm/s) compared to Nelore bulls (8.76 ± 0.40 cm/s). The RI had an overall mean of 0.41 ± 0.01 and differed among breeds. We observed higher (P < 0.05) RI values in Hereford (0.44 ± 0.01) compared to Brangus (0.36 ± 0.02) animals. Overall, the PI values (0.33 ± 0.01) did not differ (P > 0.05) among breeds. The correlation between the PI and RI (0.936; P < 0.001) was high and positive; however, the correlations were low and negative between MV and the PI (-0.228; P < 0.001) and between MV and the RI (-0.270; P < 0.001). We concluded that there are differences in the MV and RI of the bulls' supratesticular arteries among the different evaluated breeds. Moreover, the presented values attributed to blood flow dynamics can serve as parameters in future studies and can be used to identify alternative diagnostic tools for infertility or to understand issues of adaptability in bulls.
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http://dx.doi.org/10.1016/j.theriogenology.2018.05.022DOI Listing
September 2018

Histophilus somni-associated syndromes in sheep from Southern Brazil.

Braz J Microbiol 2018 Jul - Sep;49(3):591-600. Epub 2018 Mar 15.

Universidade Estadual de Londrina, Departamento de Medicina Veterinária Preventiva, Laboratório Multiusuário em Saúde Animal, Biologia Molecular, Londrina, PR, Brazil.

Histophilus somni is a Gram-negative bacterium that is associated with a disease complex (termed histophilosis) that can produce several clinical syndromes predominantly in cattle, but also in sheep. Histophilosis is well described in North America, Canada, and in some European countries. In Brazil, histophilosis has been described in cattle with respiratory, reproductive, and systemic disease, with only one case described in sheep. This report describes the occurrence of Histophilus somni-associated disease in sheep from Southern Brazil. Eight sheep with different clinical manifestations from five farms were investigated by a combination of pathological and molecular diagnostic methods to identify additional cases of histophilosis in sheep from Brazil. The principal pathological lesions were thrombotic meningoencephalitis, fibrinous bronchopneumonia, pulmonary abscesses, and necrotizing myocarditis. The main clinical syndromes associated with H. somni were thrombotic meningoencephalitis (n=4), septicemia (n=4), bronchopneumonia (n=4), and myocarditis (n=3). H. somni DNA was amplified from multiple tissues of all sheep with clinical syndromes of histophilosis; sequencing confirmed the PCR results. Further, PCR assays to detect Pasteurella multocida and Mannheimia haemolytica were negative. These findings confirmed the participation of H. somni in the clinical syndromes investigated during this study, and adds to the previous report of histophilosis in sheep from Brazil.
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http://dx.doi.org/10.1016/j.bjm.2017.12.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6066786PMC
October 2018

Ovarian follicular dynamics and conception rate in Bos indicus cows with different antral follicle counts subjected to timed artificial insemination.

Anim Reprod Sci 2018 Jan 6;188:170-177. Epub 2017 Dec 6.

Laboratory of Animal Reproduction, University of Londrina, Parana, Brazil.

Two experiments in Nelore cows subjected to timed artificial insemination (TAI) were designed to compare the influence of the antral follicle count (AFC/AFCs) on (1) ovarian follicular dynamics and (2) conception rates. First, multiparous cows with high (≥45 follicles; n=43) or low (≤15 follicles; n=32) AFCs were selected to undergo a TAI protocol to monitor ovarian follicular dynamics. Second, the AFCs of 962 cows also subjected to TAI were determined and classified as groups of high (G-high; ≥45 follicles; n=194), intermediate (G-intermediate; ≥20≤40 follicles, n=397) or low (G-low; ≤15 follicles; n=243) AFCs. In study I, the ovarian measurements (diameter, perimeter and area) were greater (P≤0.05) and there was a greater consistency in number of antral follicles during the period of synchronization for TAI in the high than low group. Effects of the AFC and ultrasonic evaluation interval on the follicular diameter were observed (P≤0.05); however, there was no interaction (P>0.05). Dominant follicles had greater diameters (P≤0.05) in the G-low than in the G-high at D (7.3±2.2 vs. 6.2±1.4mm, respectively, P=0.06), D (11.2±1.8 vs. 9.5±1.8mm, respectively), D (12.3±1.7 vs. 10.6±1.7mm, respectively), and D (13.4±1.3 vs. 12.2±1.8mm, respectively), as well as greater estimated diameters of ovulatory follicles (14.4±1.5 vs. 13.4±2.1mm, respectively, P=0.08). In study II, the cows with fewer AFCs had greater (P≤0.05) conception rates (61.7%) than the cows with the intermediate (52.9%) and greater (49.5%) AFCs. Nelore cows with fewer AFCs subjected to synchronization of time of ovulation had a larger follicular diameter and a greater conception rate than the groups with intermediate and a greater AFCs.
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http://dx.doi.org/10.1016/j.anireprosci.2017.12.001DOI Listing
January 2018

High numbers of antral follicles are positively associated with in vitro embryo production but not the conception rate for FTAI in Nelore cattle.

Anim Reprod Sci 2016 Feb 3;165:17-21. Epub 2015 Dec 3.

Laboratório de Biotecnologia da Reprodução Animal (ReproA), DCV-CCA-Universidade Estadual de Londrina (UEL), Londrina 86051-990, PR, Brazil. Electronic address:

The objective was to compare the conception rates for FTAI and in vitro embryo production between Nelore cows with different antral follicle counts (AFC=number of follicles ≤3mm in diameter in the ovaries). Nelore cows (n=547) were subjected to ovulation synchronization. Randomly during the estrous cycle (D0), cows received an intravaginal device containing 1.9g P4 (CIDR(®)) and 2mg BE (Estrogin(®)), IM. When the device was removed (D8), the cows received 500μg PGF2α (Ciosin(®)), 300IU eCG (Novormon(®)) and 1mg EC (ECP(®)), IM. All cows were inseminated 48h after P4 device removal. Antral follicles ≥3mm were counted using an intravaginal microconvex transducer (D0), and the cows were assigned to high (G-High, ≥25 follicles, n=183), intermediate (G-Intermediate, 16-20 follicles, n=183) or low AFC groups (G-Low, ≤10 follicles, n=181). In another experiment, COCs were retrieved by OPU from Nelore cows (n=66), which were assigned to groups according to oocyte production: G-High (n=22, ≥40 oocytes), G-Intermediate (n=25, 18-25 oocytes) or G-Low (n=19, ≤7 oocytes). All COCs from the same cow were cultured individually (maximum of 25 COCs per drop) and then in vitro fertilized using thawed frozen sperm (2×10(8)/dose) from a Nelore sire of known fertility. The data were analyzed using a Kruskal-Wallis and a Chi-square test (P≤0.05). There was no difference in the conception rates after FTAI between Nelore cows with high, intermediate or low AFC (51.9 vs. 48.6 vs. 58.6%). The number of viable embryos was 18.4±6.7 (G-High), 6.1±3.6 (G-Intermediate) and 0.6±0.7 (G-Low; P<0.05). Therefore, AFC had no influence on the conception rates for FTAI; however, Nelore cows with high oocyte production exhibited better in vitro embryo production.
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http://dx.doi.org/10.1016/j.anireprosci.2015.11.024DOI Listing
February 2016

Asynchronous embryo transfer as a tool to understand embryo-uterine interaction in cattle: is a large conceptus a good thing?

Reprod Fertil Dev 2016 Oct;28(12):1999-2006

School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.

The aim was to examine the effect of embryo-uterine synchrony on conceptus elongation and pregnancy rate in cattle. In Study 1, crossbred beef heifers each received 10 Day-7 in vitro-produced blastocysts on either Day 5, 7 or 9 after oestrus. A proportion of Day 5 recipients were supplemented with progesterone, via a progesterone-releasing intravaginal device from Days 3-5 plus either 750IU equine chorionic gonadotrophin or 3000IU human chorionic gonadotrophin on Day 3. At embryo age Day 14, all heifers were slaughtered and the uterus was flushed. Fewer recipients yielded conceptuses (P<0.05) and fewer conceptuses were recovered (P<0.05) following transfer on Day 5 compared with Day 7 or 9. Supplementation with progesterone resulted in short cycles in approximately 50% of recipients. Mean conceptus length was greater (P<0.05) following transfer to an advanced uterus. In Study 2, overall pregnancy rate following the fresh transfer of a single in vitro-produced blastocyst was 43.5% (2065/4749). Transfer of a Day 7 embryo to a synchronous Day-7 uterus resulted in a pregnancy rate of 47.3%. Transfer to a Day-5 (40.8%) or a Day-8 (41.3%) uterus moderately impacted pregnancy rate (P<0.01) while transfer to a uterus 2 days in advance (Day-9, 24.4%) or 3 days behind (Day-4, 27.0%) reduced (P<0.001) pregnancy rate compared with synchronous transfers. In conclusion, transfer of an embryo into an advanced uterus results in an acceleration of conceptus development, but does not result in greater pregnancy rates.
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http://dx.doi.org/10.1071/RD15195DOI Listing
October 2016

Influence of category--heifers, primiparous and multiparous lactating cows--in a large-scale resynchronization fixed-time artificial insemination program.

J Vet Sci 2015 20;16(3):367-71. Epub 2015 Mar 20.

Geraembryo, Cornélio Procópio 86300-000, Brazil.

This study was conducted to evaluate the influence of category (heifers, primiparous or multiparous cows) on pregnancy rates in a large scale resynchronization ovulation program. Nelore heifers (n = 903), primiparous lactating cows (n = 338) and multiparous lactating cows (n = 1,223) were synchronized using a conventional protocol of estradiol/P4-based fixed-time artificial insemination (FTAI). Thirty days after ultrasonography, females who failed the first FTAI were resynchronized with the same hormonal protocol prior to a second FTAI. The pregnancy status of each cohort was evaluated by ultrasonography 30 days after each FTAI. The average conception rate after the first FTAI and resynchronization was 80.5%. Heifers had a higher conception rate (85%) than primiparous (76%) or multiparous cows (78%; p = 0.0001). The conception rate after the first FTAI was similar among heifers (57%), primiparous cows (51%) and multiparous cows (56%; p = 0.193). After the second FTAI, heifers exhibited a higher conception rate (66%) than primiparous or multiparous cows (51%; p = 0.0001). These results demonstrate the feasibility of resynchronization in large beef herds for providing consistent pregnancy rates in a short period of time. We also demonstrated that ovulation resynchronization 30 days after FTAI is particularly effective for heifers, providing a conception rate of up to 66%.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4588023PMC
http://dx.doi.org/10.4142/jvs.2015.16.3.367DOI Listing
July 2016