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.

Equine chorionic gonadotropin drives the transcriptional profile of immature cumulus-oocyte complexes and in vitro-produced blastocysts of superstimulated Nelore cows

Studies have shown that the use of equine chorionic gonadotropin (eCG), which binds both follicle stimulating hormone (FSH) and luteinizing hormone (LH) receptors, could modify the female reproductive tract. We, thus, aimed to quantify the messenger RNA (mRNA) abundance of genes related to cumulus-oocyte complexes (COCs) and embryo quality in Nelore cows (Bos taurus indicus) submitted to ovarian superstimulation using only FSH (FSH group; n = 10) or replacement of the last two doses of FSH by eCG (FSH/eCG group; n = 10). All animals were slaughtered and the ovarian antral follicles from both groups (10-14 mm in diameter) were aspirated for cumulus, oocyte and in vitro embryo production gene expression analysis. The relative mRNA abundance of 96 genes related to COCs development and embryo quality was measured by RT-qPCR. We found that oocytes are more affected by eCG use and that 35 genes involved in lipid metabolism, oxidative stress, transcriptional control, and cellular development were upregulated in the FSH/eCG group. In blastocysts, lipid metabolism seems to be the main pathway regulated by eCG use. We suggest that these multiple effects could be due to the ability of eCG to bind LHR and FSHR, which could activate multiple signal transduction pathways in the superstimulated ovary, further impacting the transcriptional profile of COCs and blastocysts.

Cumulus-oocyte interactions and programmed cell death in bovine embryos produced in vitro

This study investigated the interactions between cumulus cells (CCs) and oocytes and programmed cell death in bovine cumulus-oocyte complexes (COCs) with different morphological characteristics. DNA fragmentation was assessed in CCs at 0 and 24 h of maturation, as well as parthenogenetic developmental competence on the 9th day post-activation, blastocyst quality and BCL-2 and BAX transcript levels in matured CCs. Most immature oocytes in the COC-A group (full cumulus and several compact layers) were in the initial germinal vesicle (iGV) stage, exhibiting minimal or no DNA damage. In contrast, after follicle removal, the COCB (partial cumulus and one or two cell layers) and C (expanded cumulus) groups presented in more advanced GV stages and exhibited DNA fragmentation. After maturation, significant increases in fragmented nuclei were noted in COCC and COCB groups. Embryos resulting from the COC-A developed more rapidly and had increased competence compared to embryos resulting from groups COCB and COCC. The COCB group exhibited the highest BAX protein levels and a reduced BCL-2/BAX protein ratio. The results show a negative correlation between nuclear fragmentation and embryonic development potential in COCs with different morphologies. In addition, a low BCL-2/BAX protein ratio might be associated with an increase in nuclear fragmentation in CCs.

Improvement of bovine in vitro embryo production by ovarian follicular wave synchronization prior to ovum pick-up

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.

AVALIAÇÃO DA BIOQUÍMICA SANGUÍNEA EM ÉGUAS GESTANTES

Para que ocorra o desenvolvimento fisiológico da gestação é necessário que o animal receba uma alimentação equilibrada e que esteja em boas condições corporais, garantindo o sucesso da criação. Exames do perfil bioquímico sérico são realizados, rotineiramente, em éguas gestantes, pois constituem dados básicos importantes sobre as condições destes animais, contudo, existem, na literatura, variações nos parâmetros de referência, em função do manejo, da raça, idade, peso vivo e do período gestacional. O objetivo desta pesquisa foi avaliar os níveis de proteínas totais, albumina, ureia, creatinina e glicose no sangue de 8 éguas gestantes, no 6º mês de gestação, e 8 éguas vazias. Foram coletadas amostras de 10 mL de sangue, por punção venojugular e encaminhadas ao laboratório. As dosagens foram realizadas empregando-se kits comercias e o equipamento Bioplus 2000.  Não foram observadas diferenças significativas (P>0,05) nos níveis séricos de albumina, ureia e glicose entre as éguas vazias e gestantes. Entretanto, verificou-se efeito significativo (P<0,05) nos níveis de proteínas totais e creatinina, evidenciando níveis maiores destas moléculas no grupo das éguas gestantes, contudo, cabe ressaltar que os valores encontrados estão de acordo com alguns valores de referências citados na literatura. Sugere-se que mais pesquisas devam ser realizadas, visando a padronização dos valores de referência para éguas gestantes.

AVALIAÇÃO DA BIOQUÍMICA SANGUÍNEA EM ÉGUAS GESTANTES

Para que ocorra o desenvolvimento fisiológico da gestação é necessário que o animal receba uma alimentação equilibrada e que esteja em boas condições corporais, garantindo o sucesso da criação. Exames do perfil bioquímico sérico são realizados, rotineiramente, em éguas gestantes, pois constituem dados básicos importantes sobre as condições destes animais, contudo, existem, na literatura, variações nos parâmetros de referência, em função do manejo, da raça, idade, peso vivo e do período gestacional. O objetivo desta pesquisa foi avaliar os níveis de proteínas totais, albumina, ureia, creatinina e glicose no sangue de 8 éguas gestantes, no 6º mês de gestação, e 8 éguas vazias. Foram coletadas amostras de 10 mL de sangue, por punção venojugular e encaminhadas ao laboratório. As dosagens foram realizadas empregando-se kits comercias e o equipamento Bioplus 2000.  Não foram observadas diferenças significativas (P>0,05) nos níveis séricos de albumina, ureia e glicose entre as éguas vazias e gestantes. Entretanto, verificou-se efeito significativo (P<0,05) nos níveis de proteínas totais e creatinina, evidenciando níveis maiores destas moléculas no grupo das éguas gestantes, contudo, cabe ressaltar que os valores encontrados estão de acordo com alguns valores de referências citados na literatura. Sugere-se que mais pesquisas devam ser realizadas, visando a padronização dos valores de referência para éguas gestantes.

Angiotensin II reverses the inhibitory action produced by theca cells on bovine oocyte nuclear maturation

The presence of prorenin, renin, angiotensinogen, angiotensin-converting enzyme, angiotensin II (Ang II) and Ang II receptors in the ovary is suggestive of a functional ovarian renin-angiotensin system (RAS). In cattle, the expression of Ang II is greatest in large follicles, suggesting that it is important during follicular growth and maturation. The present study was designed to investigate the role of Ang II in bovine oocyte nuclear maturation. Bovine cumulus-oocyte complexes (COCs) were cultured with or without follicular cells and Ang II or saralasin (Ang II antagonist). In the absence of follicular cells, Ang II at 0, 10(-11), 10(-9) and 10(-7) M did not affect the percentage of oocytes reaching the germinal vesicle breakdown (GVBD), metaphase I (MI) and metaphase II (MII) stage after 7-h (41.3 +/- 4.3, 35.3 +/- 4.0, 31.3 +/- 9.7, 38.7 +/- 8.6), 12-h (31.6 +/- 7.0, 34.7 +/- 6.1, 31.7 +/- 5.3, 28.9 +/- 9.1; mean +/- S.E.M.) and 18-h (44.9 +/- 7.3, 58.4 +/- 8.4, 53.1 +/- 7.4, 44.9 +/- 7.3) of culture, respectively. Similarly, saralasin at 0, 10(-11), 10(-9) and 10(-7) M did not affect the percentage of oocytes reaching MII stage after 18-h of culture (37.6 +/- 7.4, 34.4 +/- 7.7, 30.0 +/- 10.8 and 31.2 +/- 5.1, respectively). The theca cells (MII = 22.9%) or medium conditioned with follicular cells (GV = 65.5%, MI = 23.6%) inhibited oocyte maturation; however, theca cells (MII = 35.5 +/- 4.9; P < 0.05) or medium conditioned with follicular cells (GV = 34.6%, MI = 52.7%; P < 0.01) were not able to inhibit nuclear maturation when Ang II (10(-11) M) was present in the culture system. Theca cells remained viable during the culture period when Ang II was present. Therefore, results supported the idea of a role of Ang II in blocking the inhibitory effect of theca cells on nuclear maturation of bovine oocytes.