Relationships between antral follicle count and reproductive characteristics of embryo-recipient mares.

Mares (n = 77) were evaluated by antral follicle count (AFC) and selected as embryo recipients. Cyclic recipients received embryos between days 4-6 after ovulation. The acyclic recipients received an intramuscular (i.m.) protocol with 5mg of estradiol benzoate (EB) on the day of donor ovulation (D0; D-4 recipient), 3mg of EB on the following day (D1; D-3 recipient), and 3mg of EB (D2; D-2 recipient). Furthermore, 1500mg of progesterone (P4) i.m. given on D0 of the recipient (D4 donor) followed by 1500mg of P4 on the day of ET (D4-6 recipient). On the ET day, the AFC and animals' weight, body condition score (BCS), corpus luteum diameter, age and degree of uterine edema (UE) were measured. Pregnancy was confirmed on days 12 and 30. Low AFC was defined as ≤11 follicles (n = 43 mares) and high AFC as >11 follicles (n = 34 mares). Data were analyzed by a mixed effect model, including AFC group, reproductive seasonality, and season (P ≤ 0.05). UE was influenced (P = 0.05) by reproductive seasonality. The conception rate was higher (P = 0.016) in recipients with low (79.07 %) than high AFC (61.76 %) and higher (P = 0.005) in cyclic (81.40 %) than anestrus (58.82 %) mares. In addition, we observed a tendency (P = 0.06) for the interaction of AFC*reproductive seasonality, showing that high*anoestrus recipients had the lowest conception rate (37.50 %b) compared to high*cyclic (83.33 %a), low*anoestrus (77.78 %a) and low*cyclic (80 %a). The conception rate was higher in cyclic recipients with low AFC. Furthermore, UE was influenced by reproductive seasonality and mares in anestrus showed a higher degree of UE than cyclic mares.

Effects of maternal antral follicle count in Bos taurus indicus cattle on the genetic merit of male offspring and antral follicle count of female offspring.

This study evaluated the effects of antral follicle count (AFC) in female cattle on offspring characteristics. Recently calved multiparous Bos indicus cows (Nelore; n = 222) were evaluated using ultrasonography on random days of their estrous cycle to determine the AFC and were classified into "low" (≤15 follicles), "intermediate" (≥16 and ≤ 29 follicles), and "high" (≥30 follicles) AFC groups. Weight and scrotal circumference (SC) of male offspring from these cows (n = 127) were determined from 20 to 27 months, and the data were added to a genetic evaluation program (economic total genetic merit, MGTe and TOP value) that uses the kinship matrix to evaluate the genetic relationship between animals. The AFC of female offspring from these cows (n = 95) was evaluated to analyze the relationship between the AFC of mothers and daughters. The effects of maternal AFC on the genetic merit of male and female offspring were analyzed using GLIMMIX and GLM, respectively. Correlations were assessed using the Pearson's coefficient. Male offspring of cows with high AFC had superior MGTe (P = 0.005) and TOP values (P = 0.01) than those from cows with low AFC. Additionally, the AFC of mothers was positively correlated with MGTe (R = 0.33; P < 0.0001) and negatively correlated with TOP values (R = -0.32; P < 0.0001). The SC (P = 0.01), but not body weight of the offspring (P = 0.46) was affected by maternal AFC. The daughters' AFC were correlated (R = 0.29; P = 0.004) with mothers' AFC and were influenced by maternal (P = 0.05) but not paternal (P = 0.77) effect. In conclusion, cows with high AFC produced males with greater MGTe, superior TOP values and higher SC. Maternal AFC did not influence the weight of male offspring but was correlated with the AFC of daughters.

Progesterone Device Use Improves Ovum Pick-Up Efficiency in Acyclic Donors.

The aim of this study was to evaluate follicular dynamics and ovum pick-up (OPU) efficacy in untreated mares or mares treated with an intravaginal progesterone (P4) device during seasonal anestrus (acyclic) and during the breeding season (cyclic). Six mares (mean age = 5 years), were recruited into an ovum pick-up scheme that was performed every 14 days with and without the P4 device, during the acyclic and cyclic phases. Aspirations amounted to seven procedures with or without the P4 device during each phase. Five ultrasound assessments were performed at each interval between the OPUs. Data on follicular number and diameter as well as the numbers of recovered and the percentage of recovered oocytes were also collected. The number of follicles from mares in the acyclic phase was higher (P < .005) regardless of the treatment. However, the follicular diameter was smaller for the P4 group (P < .005) from the 2nd to the 5th evaluation post-OPU procedure. The percentage of oocytes recovered during the acyclic phase was higher for mares treated with the P4 device (P < .005). The P4 device resulted in follicles with smaller diameters and facilitated OPU efficacy.

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.

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.

Spatial distribution of preantral follicles in ovarian parenchyma of bovine species.

The 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).

Evaluation of hCG as gonadotropic support to timed embryo transfer protocol in beef cattle.

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.

Evaluation of three classification methods of antral follicle count and fertility to the timed artificial insemination in cattle.

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.

Follicular development, morphological integrity, and oxidative stress in bovine preantral follicles cultured in vitro with ascorbic acid.

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.

Culture of preantral ovarian follicles of Bos taurus indicus with alpha-lipoic acid.

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%; 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.

Impact of the antioxidant quercetin on morphological integrity and follicular development in the in vitro culture of Bos indicus female ovarian fragments.

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.

Retirada de corpo estranho (dispositivo impregnado com progesterona) da cavidade abdominal de novilha da raça Jersey ­ relato de caso / Removal of a foreign body (progesterone impregnated device) from the abdominal cavity of a Jersey heifer ­ a case report / Extracción de cuerpo extraño (dispositivo impregnado con progesterona) de la cavidad abdominal de novilla raza Jersey - reporte de caso

A inseminação artificial em tempo fixo (IATF) é uma biotécnica com inúmeras vantagens para a produção de bovinos. Para a realização da IATF, as fêmeas bovinas devem receber um protocolo farmacológico que induz a ovulação de forma sincronizada. Esse protocolo inicia com a inserção de um dispositivo impregnado com progesterona que deve permanecer no fundo vaginal da fêmea por tempo determinado. O presente relato tem por objetivo descrever a remoção de um implante impregnado com progesterona que foi encontrado na cavidade abdominal de uma novilha. Durante um atendimento reprodutivo de rotina em uma propriedade rural, uma novilha da raça Jersey, recém-adquirida, com histórico de ter sido submetida à IATF, foi avaliada para diagnóstico de gestação. No exame a novilha não estava gestante e apresentava um cisto folicular ovariano. A novilha foi submetida novamente à IATF em que foi inserido e removido um implante, com isso o cisto regrediu e ao inseminar a novilha não foi possível passar a cérvix com o aplicador. Vinte dias após a inseminação a novilha manifestou estro e ao ser avaliada para nova inseminação, foi identificado um implante solto na cavidade abdominal da novilha. Foi realizada uma laparotomia pelo flanco esquerdo e o implante foi removido. Após a recuperação da cirurgia a novilha foi inseminada e novamente e ficou gestante. Os protocolos de IATF devem ser realizados por profissionais capacitados para evitar problemas como a presente situação em que um implante foi encontrado na cavidade abdominal de uma novilha.(AU)

The fixed-time artificial insemination (FTAI) is a biotechnique with numerous advantages for cattle production. In order to perform the FTAI, the cows must receive a pharmacological protocol to induce ovulation in a synchronized way. This protocol begins with the insertion of a device impregnated with progesterone that must remain in the vaginal fundus of the cow for a specific period of time. This report aims at describing the removal of a progesterone impregnated implant that was found in the abdominal cavity of a heifer. During a routine reproductive service in a rural property, a recently acquired Jersey heifer, with history of having been submitted to FTAI, was evaluated for pregnancy diagnosis. At the exam, it was observed that the heifer was not pregnant and presented an ovarian follicular cyst. The heifer was then submitted to FTAI again, where an implant was inserted and removed. This made the cyst to recede, and upon subsequent insemination, the applicator was not able to pass the cervix. Twenty days after insemination, the heifer was in estrus and when it was evaluated for insemination, a loose implant was identified in the abdominal cavity of the heifer. A laparotomy was performed through the left flank and the implant was removed. After recovery from the surgery, the heifer was inseminated again and became pregnant. The FTAI protocols should only be carried out by trained professionals to avoid problems such as the one presented herein, where an implant was found in the abdominal cavity of a heifer.(AU)

La inseminación artificial a tiempo fijo (FTAI) es una biotécnica con numerosas ventajas para la producción de ganado. Para realizar FTAI, las hembras bovinas deben recibir un protocolo farmacológico que induzca la ovulación de forma sincronizada. Este protocolo comienza con la inserción de un dispositivo impregnado con progesterona que debe permanecer en el fondo vaginal de la hembra durante un tiempo específico. Este informe tiene como objetivo describir la extracción de un implante impregnado de progesterona que se encontró en la cavidad abdominal de una novilla. Durante la atención reproductiva de rutina en una propiedad rural, se evaluó el diagnóstico de preñez de una novilla de Jersey recién adquirida con antecedentes de someterse a FTAI. En el examen, la novilla no estaba embarazada y tenía un quiste folicular ovárico. La novilla fue nuevamente sometida a FTAI, en la cual se insertó y removió un implante, con esto el quiste retrocedió y al inseminar a la novilla no fue posible pasar el cérvix con el aplicador. Veinte días después de la inseminación, la vaquilla manifestó estro y cuando se evaluó para una nueva inseminación, se identificó un implante suelto en la cavidad abdominal de la vaquilla. Se realizó una laparotomía a través del flanco izquierdo y se extrajo el implante. Después de recuperarse de la cirugía, la novilla fue inseminada y nuevamente quedó embarazada. Los protocolos FTAI deben ser realizados por profesionales capacitados para evitar problemas como la situación actual donde se encontró un implante en la cavidad abdominal de una novilla.(AU)

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

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.

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

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.

Follicular wave synchronization prior to ovum pick-up.

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.

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

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.

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

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% a, 47.9% b and 49.7% b, 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%a, 48.0%b, and 38.0%b, 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.

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

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.

Histophilus somni-associated syndromes in sheep from Southern Brazil

Abstract 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.

Effect of breed on testicular blood flow dynamics in bulls.

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 ±â€¯0.30 cm/s differed among breeds. In addition, we observed that Brangus bulls showed higher (P < 0.05) MV (16.28 ±â€¯1.02 cm/s) compared to Nelore bulls (8.76 ±â€¯0.40 cm/s). The RI had an overall mean of 0.41 ±â€¯0.01 and differed among breeds. We observed higher (P < 0.05) RI values in Hereford (0.44 ±â€¯0.01) compared to Brangus (0.36 ±â€¯0.02) animals. Overall, the PI values (0.33 ±â€¯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.

Histophilus somni-associated syndromes in sheep from Southern 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.