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SummaryThe goal of this study was to determine the distribution of preantral follicles in bovine ovaries. Follicular distribution in the ovaries (n = 12) was evaluated in the region of the greater curvature of the ovary (GCO) and the region close to the ovarian pedicle (OP) of Bos taurus indicus heifers of the Nelore breed. Two fragments were obtained from each region of the ovary (GCO and OP). The mean weight of the ovaries was 4.04 ± 0.32 g. The mean antral follicle count (AFC) was 54.58 ± 3.55 follicles (minimum and maximum variation of 30 and 71 follicles, respectively). In total, 1123 follicles were visualized in the region of the GCO; 949 (84.5%) of them were primordial follicles and 174 (15.5%) were developing follicles. The region close to the OP contained 1454 follicles, of which 1266 (87%) were primordial follicles and 44 (12.9%) were developing follicles. The OP region showed a higher proportion of intact follicles in the primordial (P < 0.0001) and primary (P = 0.042) stages compared with the GCO region. The proportion of secondary follicles was similar in the OP and GCO regions. The ovaries of two bovine females (16%; 2/12) contained multi-oocytes follicles, which were characterized as primary follicles. Therefore, the distribution of preantral follicles in the bovine ovary was heterogeneous, with the region close to the OP containing a greater number of preantral follicles compared with the GCO region (P < 0.05).

Context Antral follicle count (AFC) has been related to bovine fertility and response to reproductive biotechnologies, but its relationship to oestrus expression during timed artificial insemination (TAI) is not known. Aims This study evaluated the relationship between the AFC and oestrus expression in regard to the conception rate in beef cows that received an ovulation synchronisation protocol for TAI. Methods Multiparous Nelore cows up to 40 days postpartum were evaluated by an ultrasound to determine the AFC, and were classified into low (≤15 follicles; n = 150), intermediate (≥19 and ≤26 follicles; n = 150) and high count (≥30 follicles; n = 150). AFC evaluation was performed on a random day of the oestrous cycle (Day 0). The animals received a conventional TAI protocol based on progesterone and oestradiol benzoate. On Day 8, the animals received cloprostenol, equine chorionic gonadotrophin and oestradiol cypionate, in addition to a painting in the sacrococcygeal region. On Day 10, TAI was performed, and oestrus expression was evaluated and classified as high, low or absent, according to the removal of paint. Pregnancy diagnosis was performed by ultrasound 30 days after TAI. The data were analysed using a generalised linear model and a binary logistic regression model (P

SummaryThe aim of this study was to evaluate the follicular development, morphological integrity, and oxidative stress of preantral ovarian follicles from Bos taurus indicus females grown in vitro with ascorbic acid. Ovaries (n = 20) from Bos taurus indicus females were collected, fragmented, and were cultured in vitro for 6 or 12 days in minimum essential medium (MEM), or MEM supplemented with 50 or 100 ng/ml ascorbic acid, with an extracellular matrix of agarose gel, in an incubator at 38.5°C; every 2 days, 100% of the culture medium was replaced. The data were analyzed using the chi-squared test and/or Fisher’s exact test. In the event of a significant effect, the proportions were compared using a 2 × 2 proportion test. The oxidative stress analysis data were submitted to analysis of variance followed by the Bonferroni test. Values were considered significant when P ≤ 0.05. The addition of 100 ng/ml of ascorbic acid to the in vitro culture medium of preantral ovarian follicles from bovine females promoted follicular development, was efficient in maintaining morphological integrity, as well as the stability of reactive oxygen species, after 6 days of in vitro culture.

This study aimed to establish the relationship between antral follicle count (AFC), the time of puberty, and ovarian response in Nelore heifers subjected to timed-AI (TAI) protocols. Prepubescent Nelore heifers (Bos indicus; n = 30) were examined by transrectal ultrasound and videos of the ovaries were recorded for later CFA (? 3 mm). After AFC, heifers were divided into 2 groups, low and high AFC and then further ultrasonic ovarian assessments were performed to determine the onset of puberty. Once puberty was established in all heifers, they were submitted to an FTAI protocol. There were no differences (P > 0.1) between groups on the time of puberty, ovulation rate, the proportion of heifers that expressed estrus, and on preovulatory follicle diameter. However, heifers with low AFC had a smaller ovarian area in the prepubertal period (4.36 ± 0.3 vs. 5.65 ± 0.2 cm2) and, in the FTAI, they had the moment of estrus (48 ± 0.0 vs. 58.5 ± 3.1 h) and earlier ovulation (60 ± 1.8 vs. 72.6 ± 4.7 h) compared to heifers with high AFC (P < 0.05). In addition, heifers in the low AFC group had a higher (P = 0.05) pregnancy per AI (76.9%, 10/13) than the high AFC group (29.4%, 5/17). In this study, heifers with low AFC had the moment of ovulation anticipated and greater pregnancy per AI compared to heifers with high AFC. O objetivo deste estudo foi estabelecer a relação entre contagem de folículos antrais (CFA), idade à puberdade e resposta ovariana em novilhas Nelore submetidas a protocolos de Inseminação Artificial em Tempo Fixo (IATF). Novilhas Nelore pré-púberes (Bos indicus; n = 30) foram avaliadas por ultrassonografia transretal e vídeos dos ovários foram gravados para posterior CFA. Após a CFA, as novilhas foram divididas em 2 grupos, CFA baixa e alta e então avaliações ultrassonográficas dos ovários foram realizadas para determinar a puberdade. Uma vez estabelecida a puberdade em todas as novilhas, elas foram submetidas a protocolo de IATF. Não houve diferenças (P > 0,1) entre os grupos na idade à puberdade, na taxa de ovulação, na proporção de novilhas que expressaram estro e no diâmetro do folículo pré-ovulatório. No entanto, novilhas com baixa CFA apresentaram menor área ovariana no período prépúbere (4,36 ± 0,3 vs. 5,65 ± 0,2 cm2) e, na IATF, tiveram o momento do estro (48 ± 0,0 x 58,5 ± 3,1 h) e ovulação antecipados (60 ± 1,8 vs. 72,6 ± 4,7 h) em comparação com novilhas com alta CFA (P < 0,05). Além disso, as novilhas do grupo de baixa CFA apresentaram maior (P = 0,05) prenhez por IA (76,9%, 10/13) que o grupo de alta CFA (29,4%, 5/17). Nesse estudo, novilhas com baixa CFA tiveram o momento da ovulação antecipado e maior prenhez por IA em comparação com novilhas com alta CFA. El objetivo de este estudio fue establecer la relación entre el conteo de folículos antrales (AFC), el tiempo de pubertad y la respuesta ovárica en novillas Nelore sometidas a protocolos inseminación artificial a tiempo fijo (TAI). Novillas Nelore prepubescentes (Bos indicus; n = 30) fueron examinadas mediante ultrasonido transrectal y se grabaron videos de los ovarios para posterior CFA (? 3 mm). Después de AFC, las vaquillas se dividieron en 2 grupos, AFC bajo y entonces se realizaron evaluaciones de ovario para determinar el inicio de la pubertad. Una vez establecida la pubertad, las vaquillas fueron sometidas a un protocolo FTAI. No hubo diferencias (P > 0.1) entre los grupos en el momento de la pubertad, la tasa de ovulación, la proporción de vaquillas que expresaron celo y el diámetro del folículo preovulatorio. Sin embargo, las vaquillas con AFC bajo tuvieron menor área ovárica en el período prepuberal (4,36 ± 0,3 x 5,65 ± 0,2 cm2) y, en el IATF, tuvieron el momento del estro (48 ± 0,0 x 58,5 ± 3,1 h) y ovulación más temprana (60 ± 1,8 x 72,6 ± 4,7 h) en comparación con novillas con AFC alto (P < 0,05). Además, las vaquillas en el grupo de AFC bajo tuvieron una tasa de preñez más alta (P = 0.05) (76.9 %, 10/13) que el grupo de AFC alto (29.4 %, 5/17). Las vaquillas con AFC bajo tuvieron el momento de ovulación anticipado y mayor preñez por IA en comparación con las vaquillas con AFC alto. Made available in DSpace on 2022-06-02T17:19:41Z (GMT). No. of bitstreams: 1 cpafro-18763.pdf: 119509 bytes, checksum: 4a1721a3d036b32110f6ffd5843c632d (MD5) Previous issue date: 2022

We evaluated the effects of nulliparous, primiparous, and multiparous conditions on the estrus and pregnancy rates in females that did not show estrus but were treated with gonadotropin-releasing hormone (GnRH) at the time of timed artificial insemination (TAI). Nelore females (n = 531) were allocated according to the following categories: nulliparous (n = 144), primiparous (n = 132), and multiparous (n = 255). The animals received a conventional TAI protocol, and estrus expression was identified by the absence of paint in the sacrococcygeal region on the day of TAI. Females that did not show estrus were treated with 10 µg of GnRH together with insemination. The rates of estrus and pregnancy were analyzed using a logistic regression model (P < 0.05). The estrus expression was lower (P = 0.006) in the primiparous (61.36%) group than in the nulliparous (76.39%) and multiparous (75.69%) groups. Similar pregnancy rates were observed in females that showed estrus (nulliparous 84.54%, primiparous 86.42%, and multiparous 80.31%; P = 0.39) and in females that did not show estrus and received GnRH (nulliparous 41.18%, primiparous 56.86%, and multiparous 58.06%; P = 0.24). The total pregnancy rates were also similar (P = 0.98) among the categories (nulliparous 74.3%, primiparous 75.0%, and multiparous 74.9%). The primiparous females had a lower rate of estrus, and the pregnancy rates were similar among the categories that received GnRH. O objetivo do trabalho foi avaliar o efeito das categorias nulíparas, primíparas e multíparas sobre a taxa de manifestação de estro e a taxa de prenhez de fêmeas que não manifestaram estro, mas foram tratadas com GnRH no momento da inseminação artificial em tempo-fixo (IATF). Foram utilizadas 531 matrizes, todas da raça Nelore, alocadas de acordo com a categoria: nulíparas (n = 144), primíparas (n = 132) e multíparas (n = 255). As matrizes foram submetidas a um protocolo reprodutivo para inseminação artificial em tempo-fixo (IATF) e tiveram a expressão do estro identificada pela ausência de tinta na região sacrococcígea no dia da inseminação. As fêmeas que não apresentaram estro receberam 10 µg de GnRH no momento que foram inseminadas. As taxas de estro e prenhez foram analisadas por meio de um modelo de regressão logística (P < 0,05). A expressão do estro foi menor (P = 0,006) no grupo de primíparas (61,36%) do que nos grupos de nulíparas (76,39%) e multíparas (75,69%). Taxas de prenhez semelhantes foram observadas em fêmeas que apresentaram estro (nulíparas 84,54%, primíparas 86,42% e multíparas 80,31%; P = 0,39) e em fêmeas que não apresentaram estro e receberam GnRH (nulíparas 41,18%, primíparas 56,86% e multíparas 58,06%; P = 0,24). As taxas de prenhez total também foram semelhantes (P = 0,98) entre as categorias (nulíparas 74,3%, primíparas 75,0% e multíparas 74,9%). As fêmeas primíparas apresentaram menor taxa de estro e as taxas de prenhez foram semelhantes entre as categorias que receberam GnRH.

We evaluated the effect of quercetin on the in vitro culture of bovine ovarian fragments in relation to morphology, development, and oxidative stress. Ovaries (n = 12) from Nelore heifers (n = 6) were used. Each pair of ovaries was divided into nine fragments, and one fragment from each animal was fixed in Bouin solution for 24 h (histology control) or frozen (− 80°C; control for oxidative stress). Other ovarian fragments (n = 8) were distributed into concentrations of 0, 10, 25, and 50 μg/mL of quercetin added to the culture medium for 5 or 10 d. Data were analyzed by chi-square test or ANOVA followed by Tukey’s test (P 0.1) was observed in the production of reactive oxygen species or in the oxidative degradation of lipids between treatments and non-cultivated controls. Treatment with 25 μg/mL quercetin preserved the morphological integrity of the developing follicles for 5 and 10 d of culture, in addition to promoting the best antioxidant potential after 10 d of culture in bovine ovarian fragments.

SummaryThe aim of this study was to evaluate follicular development, morphological integrity, and antioxidant potential of preantral ovarian follicles from Bos taurus indicus females grown in vitro with alpha-lipoic acid. Ovaries (n = 24) of Bos taurus indicus (n = 12) females were collected during slaughter and fragmented. A randomly obtained fragment from each pair of ovaries was fixed in Bouin (non-cultivated control; D0). These fragments were intended for classical histology (morphology and evaluation of follicular growth), and a fragment from each pair of ovaries was frozen at −80°C (non-cultivated control; D0), and assigned for analysis of oxidative stress [thiobarbituric acid reactive substances (TBARS), nitroblue tetrazolium (NBT), and ferric reducing antioxidant power (FRAP)]. The remaining fragments were cultured in vitro for 6 (D6) or 12 (D12) days, containing only minimum essential medium (MEM) or MEM supplemented with alpha-lipoic acid (50, 100, or 250 ng/ml), on an extracellular matrix of agarose gel, in an oven at 38.5ºC. Every 2 days, 100% of the culture medium was replaced. Supplementation with 100 ng/ml was effective for maintaining follicular integrity after 6 days of culture (primordial: 51.28%; development: 36.88%; P < 0.0001). There was no difference (P > 0.05) between treatments compared with the non-cultivated control treatment (D0), using the NBT and TBARS assays. Therefore, supplementation of the in vitro culture medium of bovine preantral ovarian follicles with a concentration of 100 ng/ml of alpha-lipoic acid at 6 days of culture was effective for maintaining follicular integrity and, after 6 days, maintaining stable levels of reactive oxygen species.

This study used Holstein cattle to evaluate the following: I) the productive and reproductive characteristics of cows with low, intermediate and high antral follicle counts (AFCs) that were subjected to artificial insemination (AI) and comparison of AFC variability at the time of AI (nonpregnant) and at two time points during pregnancy (30 and 60 days), and II) whether the pregnancy status and different pregnancy periods in heifers improves the efficiency at in vitro embryo production (IVEP). In study I, 75 high-milk production cows with body condition scores (BCSs) of 2.75 to 4.75 and ages of 23 to 99 months were selected. On the day of estrus, AFCs (follicles ≥ 3 mm), BCS, body weight, and diameters of the dominant follicle, ovaries and the corpus luteum were evaluated. Posteriorly, AFC was monitored in pregnant cows at 30 days (n = 35) and at 60 days for comparison of AFC before pregnancy versus different periods. In study II, heifers (n = 9) with BCS of 2.5 to 3.5 and ages of 10 to 16 months were selected for ovum pick-up and an IVEP program before AI (nonpregnant) as well as at 0 to 30, 31 to 60, and > 60 days of pregnancy. Statistical analysis was performed using PROC GLM and binary logistic regression model (P ≤ 0.05). In study I, AFC was not associated with variations in productive and reproductive parameters. However, AFCs in the low group increased following pregnancy (AI: 14.82 ± 1.36, 30 days: 23.45 ± 2.31 and 60 days: 35.18 ± 3.17 follicles). AFCs increased from AI to 60 days in the intermediate group but did not vary among time points in the high group. AFCs varied among AFC groups in AI and at 30 days of pregnancy but not at 60 days. In study II, the mean of total oocytes (17.43 ± 4.52 vs. 41.67 ± 3.79) and viable oocytes (13.77 ± 3.63 vs. 30.56 ± 3.45) increased from AI (nonpregnant) to the first 30 days of pregnancy. The mean number of embryos produced increased during pregnancy and during the first 30 days of pregnancy (4.55 ± 0.75) compared to the nonpregnant period (1.39 ± 0.85). In conclusion, pregnancy positively influences AFC, and the greatest effect is noted in low count cows. In addition, the OPU at the time of pregnancy increased the efficiency of IVEP in heifers.

Melhorar o desempenho reprodutivo é importante para aumentar a lucratividade das propriedades. Assim, nós avaliamos a contagem de folículos antrais (CFA), o escore de condição corporal (ECC), o peso vivo e o comportamento animal sobre à taxa de concepção de vacas Brahman submetidas à inseminação artificial em tempo-fixo (IATF). Vacas (n=122) receberam um protocolo convencional de IATF de três manejos (D0, 8 e 10) a base de estrógeno e progesterona, além do monitoramento da expressão de estro antes da inseminação. O ECC e o comportamento animal foram avaliados em todos os dias do protocolo, o peso foi mensurado no D0 e no diagnóstico de gestação (D40) e a CFA no D0. Para análise, estabeleceu-se os grupos de CFA (baixa, intermediária e alta), do comportamento (calma, inquieta e agitada), do peso (ganhando, mantendo e perdendo) e do ECC (ganhando, mantendo e perdendo). A taxa de concepção geral foi de 50%, e não esteve associada (p>0,05) a classificação da CFA (baixa/52,6%, intermediária/50,9% e alta/45,4%), do peso (ganhando/43,0%, mantendo/54,7% e perdendo/47,1%), do ECC (ganhando/44,0%, mantendo/54,3% e perdendo/37,5%) e do comportamento (calma/43,0%, inquieta/54,7% e agitada/47,1%). No entanto, a baixa CFA apresentou maior (p=0,05) proporção de animais com alta intensidade de estro (94,7%) e foi observado maior escore de reatividade (p=0,001) no primeiro dia de manejo da IATF em relação aos outros dias. Vacas com baixa CFA resultaram em maior proporção de expressão de estro e o primeiro dia de manejo da IATF determinou uma maior reatividade animal em relação aos outros dias do protocolo. Palavras-chave: Condição Corporal. Inseminação Artificial. Performance Reprodutiva. Peso Vivo. Abstract Improving reproductive performance is important to increase farm profitability. The relationship of antral follicle count (AFC), body condition score (BCS), weight, and animal behavior on the conception rate in cows submitted to timed artificial insemination (TAI). Cows (n=122) received a conventional TAI protocol of three managements (D0, 8, and 10) based on estrogen and progesterone, in addition to monitoring estrus expression before insemination. The BCS and behavior score were assessed every day of the TAI protocol. Weight was measured at D0 and in the pregnancy diagnosis (D40), and AFC was determined at D0. For analysis, the groups were established according to AFC (low, intermediate, and high), behavior animal (calm, restless, and agitated), weight variation (gaining, maintaining, and losing), and BCS variation (gaining, maintaining, and losing). The overall conception rate was 50%, and it was not associated with (P>0.05) the AFC classification (low/52.6%, intermediate/50.9%, and high/45.4%), weight variations (gaining/43.0%, maintaining/54.7%, and losing/47.1%), BCS variations (gaining/44.0%, maintaining/54.3%, and losing/37.5%) and animal behavior (calm/43.0%, restless/54.7%, and agitated/47.1%). However, the low AFC showed a higher (P=0.05) proportion of animals with high intensity of estrus expression (94.7%). In addition, a higher score for animal reactivity (P=0.001) was noted on the first day of the management of TAI protocol than to the other days of the hormonal protocol. The low AFC resulted in a higher proportion of cows with high estrus expression and the management practices for TAI determined a greater animals reactivity at the beginning of the breeding program. Keywords: Body Condition. Artificial Insemination. Reproductive Performance. Live Weight.

This study compared the reproductive performance of embryo recipients treated with a timed embryo transfer (TET) protocol using human chorionic gonadotropin (hCG) or equine chorionic gonadotropin (eCG). On a random day of the estrous cycle (Day -10) indicus-taurus recipients (n = 341; 194 nulliparous and 147 multiparous cows) with a body condition score between 3.0 and 4.0, were submitted to the TET protocol consisting of an intramuscular (i.m.) injection of 2.0 mg estradiol benzoate (EB) and the insertion of intravaginal progesterone (P4) device that remained until Day -2.5. On the same day (-2.5), the recipients received i.m. 150 mg D-cloprostenol and 1 mg estradiol cypionate and were randomly divided into two groups: the eCG group (n = 179), in which females received i.m. 300 IU eCG and the hCG group (n = 162), in which females received 150 IU hCG. Then, estrus intensity and the diameter of the dominant follicle (DF) were monitored on D0 and the quality of the corpus luteum (CL) (B mode and color Doppler) was assessed on D7 to select recipients eligible for receiving the transfer of an embryo produced in vitro. Pregnancy diagnosis was assessed 23 days after the transfer. Continuous data were analyzed by ANOVA using a mixed-effects model and Tukey's test. The rates were analyzed using a logistic regression model. The diameter of the DF on day 0 of the TET protocol was influenced by the interaction between gonadotropic treatment and category (P = 0.01), and nulliparous recipients treated with hCG had the smallest diameter. Treatment with hCG and eCG resulted in a high rate of estrus expression; however, the proportion of females with a high-intensity of estrus was higher in the hCG group (79.84 vs. 68.61%, respectively; P = 0.03). The utilization rate (recipients with CL) showed a tendency (P = 0.06) to be influenced by the interaction between gonadotropic treatment and category, wherein nulliparous recipients treated with hCG exhibited a lower utilization rate than the other groups. The diameter, perimeter, and area of the CL were similar (P 0.1) in all groups. However, the hCG group resulted in CL with a better Doppler evaluation score (P = 0.04), central blood flow (P = 0.03), and tendency towards greater peripheral blood flow (P = 0.08). The rates of conception (32.00% hCG vs. 35.10% eCG; P = 0.46) and pregnancy (24.69% hCG vs. 29.61% eCG; P = 0.20) were similar between the hCG and eCG groups. However, an interaction between the gonadotropic treatment and category revealed lower conception (P = 0.01) and pregnancy rates (P = 0.001) in nulliparous recipients treated with hCG. Treatment with hCG resulted in a greater intensity of estrus expression and CL with a higher Doppler score, which determined rates of utilization, conception, and pregnancy similar to conventional protocols using eCG. However, nulliparous recipients treated with hCG exhibited a lower overall reproductive rate.

The aim of this study was to evaluate the follicular development, morphological integrity, and oxidative stress of preantral ovarian follicles from Bos taurus indicus females grown in vitro with ascorbic acid. Ovaries (n = 20) from Bos taurus indicus females were collected, fragmented, and were cultured in vitro for 6 or 12 days in minimum essential medium (MEM), or MEM supplemented with 50 or 100 ng/ml ascorbic acid, with an extracellular matrix of agarose gel, in an incubator at 38.5°C; every 2 days, 100% of the culture medium was replaced. The data were analyzed using the chi-squared test and/or Fisher's exact test. In the event of a significant effect, the proportions were compared using a 2 × 2 proportion test. The oxidative stress analysis data were submitted to analysis of variance followed by the Bonferroni test. Values were considered significant when P ≤ 0.05. The addition of 100 ng/ml of ascorbic acid to the in vitro culture medium of preantral ovarian follicles from bovine females promoted follicular development, was efficient in maintaining morphological integrity, as well as the stability of reactive oxygen species, after 6 days of in vitro culture.

The controversial data about antral follicle count (AFC) may be partially explained by the different criteria used to determine what is high, intermediate and low AFC. This study evaluated different classification methods for AFC groups, relating them to the conception rate, dominant follicle size and body condition score (BCS) in cows submitted to timed artificial insemination (TAI). Nelore cows (Bos indicus; n = 935), received a reproductive program consisting of TAI and natural breeding. Conception rate, BCS and dominant follicle size during TAI were evaluated by three AFC methodologies: i) mean and standard deviation: low (≤ 15 follicles); intermediate (≥ 16 to ≤ 44 follicles) or high (≥ 45 follicles); ii) quartiles: low (≤ 15 follicles); intermediate (≥ 16 to ≤ 39 follicles), or high (≥ 40 follicles); and iii) AFC score: I (low; ≤ 15 follicles); II (intermediate; ≥ 16 to ≤ 30 follicles); III (high; ≥ 31 to ≤ 44 follicles) or IV (very high; ≥ 45 follicles). Data were analyzed by a GLIMMIX and Tukey test or binary logistic regression model (P ≤ 0.05). The conception rate to TAI was influenced (P < 0.05) by AFC in the three methods classification, being the highest conception rate observed in the low AFC group regardless of method utilized: Mean (low 61.73%a, intermediate 54.02%ab and high 49.48%b), Quartiles (low 61.73%a, intermediate 53.59%ab and 51.46%b) and Score (I 61.73%a, II 54.80%ab, III 53.23%ab and IV 49.48%b). There were variations (P < 0.05) in the conception rate within the 2.50 to 2.75 BCS range for all AFC classification methods, with the low AFC females presenting the best results, regardless of the method used. Also, females with low AFC showed larger (P < 0.05) diameters of dominant follicles at the TAI regardless of method. The different methodologies used (Mean, Quartile and Score) to AFC classification showed a consistency between the main findings, and we believe that this standardization will facilitate the interpretation of data involving AFC.

The aim of this study was to evaluate follicular development, morphological integrity, and antioxidant potential of preantral ovarian follicles from Bos taurus indicus females grown in vitro with alpha-lipoic acid. Ovaries (n = 24) of Bos taurus indicus (n = 12) females were collected during slaughter and fragmented. A randomly obtained fragment from each pair of ovaries was fixed in Bouin (non-cultivated control; D0). These fragments were intended for classical histology (morphology and evaluation of follicular growth), and a fragment from each pair of ovaries was frozen at -80°C (non-cultivated control; D0), and assigned for analysis of oxidative stress [thiobarbituric acid reactive substances (TBARS), nitroblue tetrazolium (NBT), and ferric reducing antioxidant power (FRAP)]. The remaining fragments were cultured in vitro for 6 (D6) or 12 (D12) days, containing only minimum essential medium (MEM) or MEM supplemented with alpha-lipoic acid (50, 100, or 250 ng/ml), on an extracellular matrix of agarose gel, in an oven at 38.5ºC. Every 2 days, 100% of the culture medium was replaced. Supplementation with 100 ng/ml was effective for maintaining follicular integrity after 6 days of culture (primordial: 51.28%; development: 36.88%; P0.0001). There was no difference (P0.05) between treatments compared with the non-cultivated control treatment (D0), using the NBT and TBARS assays. Therefore, supplementation of the in vitro culture medium of bovine preantral ovarian follicles with a concentration of 100 ng/ml of alpha-lipoic acid at 6 days of culture was effective for maintaining follicular integrity and, after 6 days, maintaining stable levels of reactive oxygen species.

Atualmente existe uma preocupação mundial com a redução dos impactos ambientais gerados pelas diferentes áreas produtivas, inclusive com relação aos resíduos provenientes das atividades rurais, como é o caso da pecuária. Contudo, estudos que relacionem o manejo reprodutivo, o emprego de biotécnicas da reprodução e os cuidados com o meio ambiente são escassos na literatura. Desta forma, tornar as cadeias produtivas mais sustentáveis é necessário, por isso, o objetivo deste trabalho foi elaborar uma revisão de literatura sobre o emprego e o papel fisiológico da progesterona nas biotécnicas da reprodução animal, sobretudo em bovinos, e apontar os benefícios reprodutivos e ambientais do uso dos implantes de progesterona reutilizáveis. Foi adotada como estratégia metodológica a revisão bibliográfica e foram consultados livros e bases de dados da área, empregando os descritores: biotécnicas reprodutivas em bovinos, protocolo hormonal em bovinos, pecuária sustentável, implantes de progesterona e reprodução animal. A população do estudo foi composta por toda a literatura relacionada ao tema de estudo, publicada no período de 1992 a 2018 e, após a coleta dos dados, foi feita a leitura do material e as principais informações foram compiladas e analisadas. Com base no estudo, conclui-se que a suplementação com P4 pode trazer vários benefícios, dentre eles, a melhoria na taxa de gestação e nos processos de sincronização de estro em vacas. Além dessas vantagens, quando a opção pela suplementação for pelo emprego de protocolos baseados no uso de implantes reutilizáveis, soma-se a redução no tempo, no custo da técnica e na geração de resíduos no meio rural. Estes resultados melhoram a eficiência do processo, tornando-o mais operacional, lucrativo e ambientalmente sustentável, contribuindo positivamente com a cadeia produtiva bovina.

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 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.

This study evaluated the efficiency of a post-thaw diluent on the conception rate of timed artificial insemination (TAI), on the in vitro embryo production (IVEP), the fertilization rate and the computerized semen analysis. In the execution of all the techniques, semen straws of a single bull with previously known fertility were evaluated both as control and extender groups. The conception rate was similar (P = 0.517) between the extender (52.11%) and the control group (55.48%), but the extender group showed a reduction (P 0.05) between the extender and control group, respectively. The total (58.1 vs. 58.3%) and progressive (42.4 vs. 40.0%) motility post-thawing did not differ (P > 0.05) between the extender vs. the control group, respectively. However, when comparing different moments post-thawing (0 h, 10 min, 3 h, 6 h, 8 h e 12 h), initially (3 h) the extender group had a higher (P

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.

We evaluated the effect of quercetin on the in vitro culture of bovine ovarian fragments in relation to morphology, development, and oxidative stress. Ovaries (n = 12) from Nelore heifers (n = 6) were used. Each pair of ovaries was divided into nine fragments, and one fragment from each animal was fixed in Bouin solution for 24 h (histology control) or frozen (- 80°C; control for oxidative stress). Other ovarian fragments (n = 8) were distributed into concentrations of 0, 10, 25, and 50 μg/mL of quercetin added to the culture medium for 5 or 10 d. Data were analyzed by chi-square test or ANOVA followed by Tukey's test (P 0.05). Treatment with 25 μg/mL quercetin resulted in the highest proportion of total intact follicles for 5 (67.3%) and 10 d (57.1%); the concentration of 25 μg/mL also presented the best proportion of developing follicles for 5 d (68.7%) and 10 d (62.8%). Treatment with 25 μg/mL quercetin resulted in significant ferric reduction for 10 d of culture, but not for 5 d. No difference (P 0.1) was observed in the production of reactive oxygen species or in the oxidative degradation of lipids between treatments and non-cultivated controls. Treatment with 25 μg/mL quercetin preserved the morphological integrity of the developing follicles for 5 and 10 d of culture, in addition to promoting the best antioxidant potential after 10 d of culture in bovine ovarian fragments.

Reproductive biotechnologies emerge as an important element for livestock, however, some strategies must be modified to adapt the different breeding systems, such as the use of follicular synchronization protocols. This study aimed to evaluate follicular synchronization using estradiol benzoate, with the presence of the corpus luteum, on the in vitro embryo production (IVEP) from Wagyu oocytes donors. Routines of IVEP were performed in heifers and cows (n=19), classified into three groups: G1/CL- animals with corpus luteum; G2/SCL- animals without corpus luteum, these groups being the control, and had the natural process of follicular dynamics and G3/CL + EB - animals with the presence of corpus luteum, submitted to follicular synchronization at D0, with estradiol benzoate. The results obtained showed that the synchronization of the follicular wave with the application of EB, in the presence of the corpus luteum (CL), reduced the number of small (6.05 ± 0.55) and large follicles (0.45 ± 0.15), but increased (P0.05). It was concluded that follicular synchronization using estradiol benzoate in Wagyu oocyte donors, presenting a corpus luteum, increased the number of medium follicles, however, there was no improvement in the efficiency of ovum pick-up, in vitro embryo production and pregnancy rate. As biotecnologias reprodutivas estão emergindo como um elemento importante para a pecuária, entretanto, algumas estratégias devem ser modificadas para se adaptar a diferentes sistemas de criação, como o uso de protocolos de sincronização folicular. Este estudo teve como objetivo avaliar a sincronização folicular utilizando benzoato de estradiol (BE), na presença do corpo lúteo (CL) de doadoras de oócitos Wagyu na produção in vitro de embriões (PIVE). Sessões de PIVE foram realizadas em novilhas e vacas (n=19) que foram classificadas em três grupos: G1/CL - animais com CL, G2/SCL - animais sem CL e G3/CL+BE - animais com CL que foram submetidos para sincronização folicular com BE em D0. Os grupos G1/CL e G2/SCL foram considerados o controle e realizaram o processo natural da dinâmica folicular. Os resultados mostraram que a sincronização da onda folicular com a aplicação de BE na presença de CL, apresentou um menor número de folículos pequenos (6,05 ± 0,55) e grandes (0,45 ± 0,15), mas aumentou (P < 0,05) o número de folículos de tamanho médio (16,20 ± 0,90). No entanto, os resultados da ovum pick up mostraram que independente da aplicação ou não de BE, e independente da presença ou ausência de CL na doadora Wagyu, não houve diferença entre os grupos (P > 0,05) quanto ao número de oócitos viáveis e a taxa de viabilidade. Concluiu-se que a sincronização folicular por meio de BE em doadoras de oócitos Wagyu que apresentaram CL, aumentou o número de folículos de tamanho médio. No entanto, não houve melhora na eficiência da ovum pick up, na produção in vitro de embriões e na taxa de prenhez.

This research aimed to evaluate the relationship of membrane integrity analysis, mitochondrial cytochemical analysis, and sperm kinetics of bovine semen after thawing and the pregnancy rate in Nelore females submitted to fixed-time artificial insemination (FTAI). Thirty-seven conventional semen straws, from 16 Nelore bulls and 3 Aberdeen Angus bulls were used. The semen samples were evaluated in conventional microscopy for sperm motility, vigor, and morphology, through flow cytometry for membrane integrity and mitochondrial function, and the CASA system for evaluation of sperm kinetics. All females were subjected to the same FTAI protocol and were inseminated by the same technical team. The correlation between all variables was performed by Pearson's correlation. Cluster analysis was used to analyze the relationship between pregnancy rate and combinations of laboratory tests (P ≤ 0.05). Semen samples from Angus bulls (89.2 ± 5.5) presented superior VSL (P=0.004) to Nelore semen (78.6 ± 8.6), but this did not affect the pregnancy rate (Nelore: 51.0% versus Angus: 50.5%, P > 0.05). By flow cytometry, 44.3% membrane integrity and 47.3% mitochondrial integrity were identified. Five clusters were selected, one of which presented the best pregnancy rate, containing the most balanced rates between progressive velocity and mitochondrial activity (VSL 71.16 μm/s, MITO 49.69%, TxP 62.4%). Samples of thawed bovine semen with progressive velocity and balanced mitochondrial activity demonstrated better fertility to TAI program. El objetivo fue evaluar la relación entre el análisis de la integridad de la membrana, la actividad mitocondrial y la cinética de los espermatozoides bovinos, con taxones de preñez en hembras Nellore sometidas a inseminación artificial por tiempo fijo (IATF). Muestras de semen fueron validadas por microscopía óptica para la motilidad, vigor y morfología de los espermatozoides; la citometría de flujo evaluó la integridad de la membrana y la función mitocondrial; y el sistema CASA analizó la cinética de los espermatozoides. Las vacas fueron sometidas al mismo protocolo IATF e inseminadas con el mismo equipo técnico. Una relación entre los diversos se encuentra a través de la correlación de Pearson. Un análisis de conglomerados evaluó la relación entre las tasas de preñez y combinaciones de pruebas in vitro (P ≤ 0,05). Las señales de semen de toros Angus (89,2 ± 5,5) presentarán un VSL más alto (P = 0,004) que el semen de Nelore (78,6 ± 8,6), pero esto no afectó la tasa de preñez (Nelore: 51, 0% frente a Angus: 50,5%, P> 0,05). La citometría de flujo identificó 44,3% de integridad de membrana y 47,3% de integridad mitocondrial. Se seleccionaron cinco grupos, y el grupo que contiene valores más equilibrados entre la velocidad progresiva y la actividad mitocondrial (VSL 71,16 μm / s, MITO 49,69%, TxP 62,4%) demostrarán tasas de preñez más altas. Muestras de semen bovino con taxones progresivos y actividad mitocondrial equilibrada muestran una mejora de la fertilidad para el programa IATF. Objetivou-se avaliar a relação entre a análise de integridade de membrana, atividade mitocondrial e cinética de espermatozoides bovinos pós-descongelação, com a taxa de prenhez em fêmeas Nelore submetidas à inseminação artificial em tempo fixo (IATF). Foram utilizadas 37 doses de sêmen convencional, de 16 touros Nelore e 3 touros Aberdeen Angus. As amostras de sêmen foram avaliadas sob microscopia óptica para motilidade, vigor e morfologia espermática; a citometria de fluxo avaliou integridade de membrana e função mitocondrial; e o sistema CASA analisou a cinética espermática. As vacas foram submetidas ao mesmo protocolo da IATF e inseminadas pela mesma equipe técnica. A relação entre todas as variáveis ​​foi feita por meio da correlação de Pearson. A análise de agrupamento foi usada para avaliar a relação entre a taxa de prenhez e as combinações de teste in vitro (P ≤ 0,05). Amostras de sêmen de touros Angus (89,2 ± 5,5) apresentaram maior VSL (P = 0,004) do que sêmen de Nelore (78,6 ± 8,6), mas isso não afetou a taxa de prenhez (Nelore: 51,0% vs Angus: 50,5%, P > 0,05). Na citometria de fluxo identificou-se 44,3% de integridade de membrana e 47,3% de integridade mitocondrial. Cinco grupos foram selecionados, sendo que o cluster contendo valores mais equilibradas entre velocidade progressiva e atividade mitocondrial (VSL 71,16 μm / s, MITO 49,69%, TxP 62,4%) demonstraram maior taxa de prenhez. Amostras de sêmen bovino descongelado com taxa progressiva e atividade mitocondrial balanceada demonstraram fertilidade melhorada para o programa IATF.

Artificial insemination is a key technique to increase reproductive efficiency and the genetic improvement in cattle. The first report of artificial insemination has been dated to more than 220 years ago; after that, many studies have been published, and this biotechnology is widely used in domestic animals. Despite the advances of embryo transfer programs in vivo and in vitro in cattle, artificial insemination still represents the main form of assisted reproduction in many herds, being one of the lowest cost strategies to improve genetic merit in the farms. Artificial insemination has many advantages compared to natural breeding, such as health benefits, e.g. control of infectious diseases; genetic improvement, e.g. use of genetically improved bulls; reproductive management improvements; and more stringent control of the zootechnical and economic features of the herd, e.g. standardized management and animals.

Made available in DSpace on 2021-06-25T11:02:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) 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. Universidade do Oeste Paulista (UNOESTE) Presidente Prudente 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 Laboratório de Reprodução Animal DCV-CCA-UEL Laboratório de Reprodução Animal Unicesumar ICETI Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Dracena PROGEST Biotecnologia em Reprodução Animal, Botucatu Qualis In Vitro Presidente Prudente Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Dracena CNPq: 403862/2016-7

The antral follicle count (AFC) is an important tool in the selection of bovine females destined for biotechnology. However, little is known about AFC in prepubertal and pubertal heifers. Some challenges inherent to the physiology of young females must be considered to achieve efficient rates with different procedures, such as ovum pick-up and IVF. This paper covers some important topics about ovarian physiology related to the population of antral follicles and reproductive efficiency in young female cattle.

This study evaluated the effects of the synchronization of ovarian follicular wave emergence on the efficiency of in vitro embryo production. Bos indicus cows (n = 20) were divided into two groups (control vs. synchronization) and subjected to repeated ovum pick-up (OPU) sessions (8 replicates each, with an interval of 21 days in a 2 × 2 crossover design) and subsequent in vitro embryo production. Cows in the control group (n = 10) were submitted to OPU procedures without any stimulation every 21 days. Animals in the synchronization group received a protocol-based progesterone implant, estradiol benzoate and prostaglandin on a random day of the estrus cycle (Day 0) and the OPU was performed on Day 5. After in vitro production, embryos were transferred to recipients synchronized at a fixed time and the diagnosis was performed 60 days later. An evaluation of the parameters for each OPU session revealed that donors that received the synchronization protocol pre-OPU showed a greater number of embryos (5.9 ± 0.5 vs. 4.5 ± 0.4; P = 0.037), higher rate of embryo production (45.8% vs. 38.5%; P = 0.001) and higher mean number of conceptions per group (2.2 ± 0.2 vs. 1.6 ± 0.2; P = 0.07) in relation to the group that did not receive hormonal treatment. We concluded that synchronization of the follicular wave prior to OPU showed positive effects on in vitro embryo production as well as on pregnancy rates.

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.

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 in vivo and in vitro 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 in vivo and in vitro production of embryos, besides describing consistent results and new challenges regarding AFC and embryo production.

The increase of the world population generates the need to raise the production of food of vegetal and animal origin. In Brazil, livestock farming has evolved, demonstrating the important role of the country in the production of food. In this way, researchers of this productive chain have been looking for technologies related to production and reproduction, above all, to the use of reproduction biotechnologies, seeking to increase the production of different bovine breeds. Thus, the objective of this research was to investigate the efficacy of ovarian FSH super stimulation in bovine Wagyu oocyte donor females on follicular dynamics and in vitro embryo production. Twelve Wagyu animals, aged 12 to 24 months, randomly distributed in a crossover design were used in two groups: Group 1= animals not stimulated with FSH and Group 2= animals stimulated with FSH. The follicular, oocyte and embryonic variables were evaluated. It was observed that ovarian overstimulation in Wagyu oocyte donor cows with FSH improved the mean and large follicles but reduced the rate of oocyte recovery and, despite the best percentage of viable oocytes, there was no improvement in the amount of embryos produced in vitro. El aumento de la población mundial crea la necesidad de incrementar la producción de alimentos de origen vegetal y animal. En Brasil, la ganadería ha evolucionado, lo que demuestra el importante papel del país en la producción de alimentos. Así, los investigadores de esta cadena productiva han estado buscando tecnologías relacionadas con la producción y la reproducción, sobre todo, el uso de biotecnologías de reproducción, buscando incrementar la producción de diferentes razas bovinas. Por lo tanto, el objetivo de esta investigación fue investigar la eficacia de la superestimulación de la FSH en hembras bovinas donantes de ovocitos Wagyu sobre la dinámica folicular y la producción de embriones in vitro. Se utilizaron doce animales Wagyu, de edades comprendidas entre 12 y 24 meses, distribuidos aleatoriamente en un diseño cruzado en dos grupos: Grupo 1 = animales no estimulados con FSH y Grupo 2 = animales estimulados con FSH. Se evaluaron variables foliculares, ovocitarias y embrionarias. Se observó que la superestimulación ovárica con FSH en vacas Wagyu donantes de ovocitos aumentó el número de folículos medianos y grandes, pero redujo la tasa de recuperación de ovocitos y, a pesar del mejor porcentaje de ovocitos viables, no hubo mejoría en el número de embriones producidos in vitro. O aumento da população mundial gera a necessidade de elevar a produção de alimentos de origem vegetal e animal. No Brasil, a pecuária tem evoluído, demonstrando o importante papel do país na produção de alimentos. Dessa forma, pesquisadores dessa cadeia produtiva têm buscado tecnologias relacionadas à produção e reprodução, sobretudo, ao uso de biotecnologias de reprodução, buscando aumentar a produção de diferentes raças bovinas. Assim, o objetivo desta pesquisa foi investigar a eficácia da superestimulação com FSH em fêmeas bovinas doadoras de ovócitos da raça Wagyu sobre a dinâmica folicular e a produção de embriões in vitro. Doze animais Wagyu, com idades entre 12 e 24 meses, distribuídos aleatoriamente em delineamento crossover foram utilizados em dois grupos: Grupo 1= animais não estimulados com FSH e Grupo 2= animais estimulados com FSH. Foram avaliadas as variáveis foliculares, oocitárias e embrionárias. Observou-se que a superestimulação ovariana com FSH em vacas Wagyu doadoras de oócitos aumentou o número de folículos médios e grandes, mas reduziu a taxa de recuperação de oócitos e, apesar da melhor porcentagem de oócitos viáveis, não houve melhora na quantidade de embriões produzidos in vitro.

The goal of this study was to determine the distribution of pre-antral follicles in the ovarian parenchyma of mares. For Experiment 1, each ovary was cut longitudinally at the greater curvature, performing two hemiovaries. After that, six fragments from each hemiovary were obtained, resulting in 12 fragments, which were divided into the innermost region of the parenchyma, the middle region and the outermost region. All the three obtained sections were cut transversally to obtain two fragments from each one. For Experiment 2, each ovary also submitted to a longitudinal cut on the greater curvature, forming two hemiovaries. Each hemiovary was sectioned into four symmetrical fragments, resulting in eight fragments per ovary. The fragments were related as being near to or far from the ovulatory fossa. The fragments of both experiments were immediately fixed in Carnoy for 12 hr and kept in 70% ethanol for 24 hr. Follicles were classified according to the stages of development and for morphological integrity according to oocyte morphology and granulosa cells. After the histological assessment, a total of 1,130 follicles were visualized from Experiment 1, being 1,054 (93.3%) primordial follicles and 76 (4.7%) follicles in development. The innermost region had the highest percentage of pre-antral follicles compared to the other regions (p < .05). The middle and outermost regions showed higher percentages of intact primordial and developing follicles than the innermost region (p < .05). Considering Experiment 2, 938 follicles were found, being 894 (95.3%) primordial and 44 (4.7%) follicles in development. The region near the ovulatory fossa presented higher (58.7%; 551 of 938) follicular concentration compared to the region far from the ovulatory fossa (41.3%; 387 of 938; p < .05). As a conclusion, distribution of pre-antral follicles in the equine ovary has a specific pattern through the parenchyma. Also, the follicular integrity differed in the studied ovarian areas.

The present study was performed in indicus-taurus heifers 1) to determine if the antral follicle count (AFC) exhibits repeatability from puberty to yearling age and 2) to evaluate whether the phenotypic and genotypic parameters used in genetic improvement programs are correlated with AFC. In study I, Braford heifers (3/8 Nelore x 5/8 Hereford, n = 137) were serially examined by ultrasonography (with 60-day intervals) from weaning (9 ± 1 mo of age) to yearling ages (20 ± 1 mo of age) to monitor the numbers of antral follicles. In study II, the AFC of animals from experiment I and contemporary (same farm, considered at same age and kept under same conditions heifers n = 270 18-24 months) was correlated with the records of a genetic selection program using four statistical models with different covariates: i) model 1 considered effects of contemporary group and covariates age, weight gain from birth to weaning and visual scores for carcass traits at weaning, ii) model 2 covered contemporary group, age, weight gain from weaning to yearling and visual scores for carcass traits at yearling. The effects, variables and covariates of models 1 and 2 were combined to form model 3. Model 4 included the model 3 with addition of paternal effect. In study I, AFC varied from 3 to 64 follicles among females but was highly repeatable (0.89-0.92) within individuals in the same group. In study II, the four models tested showed low correlations with AFC: 0.072, 0.056, 0.082 and 0.172 for models 1, 2, 3 and 4, respectively. However, the model with paternal effect provided 17% of correlation of AFC and genotypic and phenotypic characteristics. Models 1, 3 and 4 also showed that AFC in indicus-taurus heifers can be influenced by finishing precocity at weaning (P

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.

Age and antral follicle count (AFC) are related to fertility in cattle, but this information remains limited in mares.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.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 (P0.05) 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.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.