Abstract The aim of this study was to evaluate the oxidative stress in ovaries and corpus luteum (CL) of Bos taurus indicus females and the oxidant effect of CL in ovarian tissues in regions near, intermediate, or distant from it. Ovaries (n=12) of Nelore heifers (n=6) were collected from a slaughterhouse and fragmented. Experiment 1, each ovary was obtained from three fragments, resulting in 18 fragments of ovaries with CL (OV+CL) and another 18 fragments of ovaries without CL (OV-CL). Three fragments were generated from CL, totaling 18 CL fragments. In experiment 2, the ovarian fragments were removed from specific regions near, intermediate, or distant from the CL. All the fragments were placed in Eppendorf-type microtubes (1 mL), kept in a thermal container at 4 ºC, and then stored in a -80 ºC freezer for analysis of oxidative stress (TBARS and NBT) and antioxidant potential (FRAP and ABTS). In the antioxidant activity analysis, luteal tissues showed more antioxidant activity than ovarian tissue (FRAP = P < 0.0001; ABTS = P < 0.02). In the oxidative stress analysis, CL had lower levels of reactive oxygen species (ROS; TBARS = P < 0.03; NBT = P < 0.0001) than ovarian tissues. There was no difference in antioxidant activity and oxidative stress between the fragments obtained from different regions (OV+CL versus OV-CL; P > 0.05). The presence of CL in the ovaries of Bos taurus indicus females did not influence the oxidative stress or antioxidant potential of the gonad. Thus, the removal of ovarian fragments with or without the presence of CL indicates that biotechnologies such as in vitro follicle cultivation is possible.

Resumo O objetivo deste trabalho foi avaliar se a puberdade e o parto alteram a contagem de folículos antrais (CFA) em fêmeas Nelore (Bos indicus) de corte. Foram realizados dois experimentos para comparar a CFA entre os períodos pré-púbere e púbere e entre os períodos pré-púbere e pós-parto. A CFA e a concentração folicular não diferiram entre os períodos pré-púbere e púbere. Entretanto, a área ovariana foi maior após a puberdade. Além disso, a CFA e a área do ovário foram maiores no período pós-parto quando comparado ao pré-púbere. Portanto, a CFA não é afetada pela puberdade de novilhas Nelore, mas aumenta significativamente quando as novilhas pré-púberes se tornam vacas. (CFA Bos indicus corte prépúbere pré pósparto. pósparto pós parto. Entretanto disso prépúbere. Portanto prépúberes púberes vacas

Abstract The objective of this work was to investigate whether puberty and parturition alter the antral follicle count (AFC) in female Nelore (Bos indicus) beef cattle. Two experiments were carried out to compare AFC between the prepubertal and pubertal periods and between the prepubertal and postpartum periods. AFC and follicle concentrations did not differ between the prepubertal and pubertal periods. However, the ovarian area increased after puberty. In addition, AFC and the ovarian area were greater in the postpartum than in the prepubertal period. Therefore, AFC is not affected by the puberty of Nelore heifers, but increases significantly when the prepubertal heifers become cows. (AFC Bos indicus cattle However addition period Therefore cows

Abstract 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.

Abstract The number of embryos produced by in vitro fertilization (IVF) has grown exponentially in recent years. Recently, for the first time, the number of embryos produced and transferred in vitro was significantly higher than the number developed in vivo worldwide. In this context, a particular boost occurred with ovum pick-up (OPU) and in vitro embryos produced in North America, and this technology is becoming more prominent for commercial dairy farms. However, despite many advances in recent decades, laboratories and companies are looking for methods and alternatives that can be used in collaboration with the existing process to improve it. Among the strategies used to improve the dairy industry are the use of genomic analysis for the selection of animals with desired traits or as an evaluation tool of oocyte and embryo quality, the optimization of the collection and use of gametes from prepubertal females and males, the effective use of sexed semen, and improvements in culture media and methods of embryo cryopreservation. Thus, this review aims to discuss the highlights of the commercial use of IVF and some strategies to increase the application of this technique in large-scale dairy programs.

Abstract This study aimed to evaluate different concentrations of growth and differentiation factor-9 (GDF-9) on the development and maintenance of equine preantral follicle morphology during short-term in vitro culture. Ovaries (n=5) from five mares were collected from a local slaughterhouse and transported to the laboratory, where nine fragments (5x5x1mm) were procured from each ovary. One fragment from each was immediately fixed and submitted for histological analysis (control group; D0). The other eight fragments were cultured in situ for two (D2) or six (D6) days in MEM+ or MEM+ supplemented with GDF-9 at different concentrations (i.e., 50, 100 and 200 ng/mL the GDF-9). After culturing with different concentrations of GDF-9 for 2 or 6 days, the fragments were processed for histological analysis. After two days of cultivation, we observed an increase in the percentage of developing follicles for 0 (MEM+), 50, 100 and 200 ng/mL GDF-9 compared to control (D0; P<0.05). When we evaluated all treatments that preserved follicular integrity, the GDF-9 concentration of 100 ng/mL presented results superior to those of the other cultures (P<0.05). While, at six days of culture, the concentration of 200 ng/mL of GDF-9 appeared to be more efficient in providing development compared to MEM+ (P<0.05). The percentage of morphologically intact follicles in the 6 days culture samples treated with 50 ng/mL of GDF-9 indicated that this concentration was effective in maintaining the integrity of the follicle (P<0.05). We conclude, therefore, that graduated GDF-9 addition to the medium ensure follicular development and is sufficient maintain the architecture.

Avaliaram-se os efeitos da remoção temporária de bezerros (RTB) ou da aplicação de gonadotrofina coriônica eqüina (eCG) na taxa de prenhez (TP) de vacas Nelore lactantes tratadas com um dispositivo intravaginal liberador de progesterona (DILP). No experimento 1, 83 vacas Nelore e 102 mestiças (Nelore × Red Angus) foram distribuídas em três grupos. Em dia aleatório do ciclo estral (D0), os animais do grupo 1 foram tratados com benzoato de estradiol (BE; 2,5 mg, IM, Estrogin®) e um DILP (1 g de progesterona, DIB®), removido no D9, quando também se administrou d-cloprostenol (150 µg, IM, Prolise®) e aproximadamente 12 horas após identificação do estro realizou-se a inseminação artificial. No grupo 2 (IATF), o tratamento foi semelhante ao aplicado no grupo 1, porém, administrou-se uma segunda dose de benzoato de estradiol (1 mg) no D10 e 30-36 horas mais tarde realizou-se a inseminação artificial em tempo fixo (IATF). No grupo 3 (IATF/RTB), os bezerros foram removidos a partir do D9 até a inseminação artificial com tempo fixo (IATF). As taxas de prenhez para as vacas Nelore e mestiças foram, respectivamente, de 7,69 e 41% (Controle); 23,52 e 59,57% (IATF); 69,44 e 55,81% (IATF/RTB). No experimento 2, 255 vacas Nelore lactantes foram distribuídas em três grupos. Os animais do grupo 4 (IATF) foram tratados com benzoato de estradiol (2 mg) e um DILP (1,9 g de progesterona, CIDR-B®) no D0 e no D8 sofreram remoção do DILP no D8 e administração de 25 mg de dinoprost (IM, Lutalyse®). No D9, foi aplicado benzoato de estradiol (1 mg) realizando-se a IATF 30-36 horas mais tarde. No grupo 5 (IATF/RTB), os bezerros foram removidos no D9 até a IATF. O grupo 6 (eCG) foi semelhante ao IATF, exceto pela aplicação de eCG no D9 (400 UI, IM, Novormon®). As taxas de prenhez foram de 50,57 (IATF), 53,57 (IATF/RTB) e 54,76% (eCG). A associação de RTB ao tratamento hormonal com DILP aumenta as taxas de prenhez, enquanto a adição de eCG ao tratamento não melhora as taxa de prenhez de vacas Nelore lactantes ciclando e em boa condição corporal.

This study aimed to evaluate the effects of temporary calf removal (TCR) or eCG administration on pregnancy rates of milking Nelore cows treated with a intravaginal progesterone releasing device (IPRD). In the first experiment 83 Nelore and 102 Nelore vs. Red Angus crossbred cows were randomly allocated to 3 groups. Animals in Group 1 (CON) received estradiol benzoate (EB; 2.5 mg, i.m., Estrogin®) and an IPRD (1g progesterone, DIB®) in a random stage of the estrous cycle (D0). At D9 the IPRD was removed and the animals were treated with d-cloprostenol (150µg, i.m., Prolise®). The animals were artificially inseminated (AI) 12 h after estrus detection. Group 2 (FTAI) was similar to CON, except that another dose of EB (1mg) was administered at D10, and 30-36 hours later artificial insemination (FTAI) was performed at a fixed time. In Group 3 (FTAI/TCR) the calves were removed from D9 to the FTAI. Pregnancy rates for Nelore and crossbred cows were, respectively, 7.69 and 41% (CON); 23.52 and 59.57 (FTAI); 69.44 and 55.81 (FTAI/TCR). In the second experiment, 255 lactating Nelore cows were allocated to 3 groups. At D0, animals in Group 4 (FTAI) received EB (2 mg) and one IPRD (1.9g progesterone, CIDR-B®), which was removed at D8 when the cows received 25 mg of dinoprost (i.m., Lutalyse®). At D9 EB (1 mg) was administered and 30-36 hours later all animas were FTAI. In Group 5 (FTAI/TCR) the calves were removed from D9 to FTAI. The Group 6 (eCG) was similar to IATF except for the administration of eCC in D9 (400 IU, i.m., Novormon®). Pregnancy rates were: 50.57% (FTAI), 53.57% (FTAI/TCR) and 54.76% (eCG). These results indicated that TCR associated with IPRD increase pregnancy rates, whereas the addition of eCG to IPRD do not improve pregnancy rates in Nelore cows which are cycling and in lactation with good body condition.