Fabiana de Andrade Melo-Sterza

The effect of postpartum interval at the beginning of the timed artificial insemination (DPP-D0) and conception rate (P/AI) and pregnancy loss (PL) in conventional and early primiparous, as well as, the impact of uterine inflammation on P/AI in early primiparous (EP) cows were studied. In Experiment 1, early primiparous (first calving at 24 months of age; n= 1.495) and conventional primiparous (CP: first calving at 36 months of age; n= 2.342) cows were evaluated. P/AI was similar between EP and CP cows (54.45% vs. 53.71%; P= 0.65), as was PL (EP 9.48 vs. CP: 8.87%; P= 0.63). P/AI was greater above the DPP-D0 thresholds identified for EP (>46.5 days: 60.14% vs. 51.20%) and CP cows (>42.5 days: 56.35% vs. 48.54%; P< 0.05). PL was negatively associated with DPP-D0 (P=0.03). In experiment 2, 661 EP cows were randomly assigned to PGF2α (N = 335) or saline solution (SS; N = 326) on D0. The treatment did not affect P/AI (55.52% vs. 55.83%; P= 0.93) or PL (P=0.27). In the cytology subset (n= 100), D0 PMN proportions ranged from 1% to 19%, and P/AI tended to be lower with PMN>4% (42.8% vs. 63.8%; P=0.059). A time × treatment × purulent vaginal discharge (PVD) interaction was detected for PMN proportion (P = 0.03) PMN decreased from D0 to D8 in PVD-positive cows treated with PGF2α but not in PVD-positive SS cows. Thus, PGF2α modified PMN dynamics according to uterine clinical status without altering fertility.

Summary: This study aimed to evaluate the effects of linseed supplementation on the in vitro production of embryos subjected to vitrification. Pantaneira cows supplemented with linseed or not (control) were evaluated. The best-quality embryos produced in vitro from both groups were vitrified. Oocyte quality and blastocyst rate did not differ between the groups. However, the rates of vitrifiable embryos and re-expansion at 3 h were higher in the linseed-supplemented group. In conclusion, linseed supplementation in Pantaneira cows improved the quality of embryos produced in vitro .

Sirtuins are of central importance in many cellular functions and promote cell survival under stress. However, little information is available regarding the relationship between sirtuins and female reproductive biology, especially in response to thermal stress. This study investigated the influence of moderately high (40°C) and low (37°C) thermal stress during in vitro maturation on the development competence of bovine oocytes and embryos. The expression and abundance of sirtuins and other proteins involved in stress response were also studied. The cumulus-oocyte complexes (COCs) of Simmental (Bos taurus) cows underwent in vitro maturation (IVM) at different temperatures (37°C, 38.5°C and 40°C). Before maturation, the oocytes were stained with Brilliant Cresyl Blue (BCB) and categorized as labeled (BCB+) or unlabeled (BCB-). Embryo production was analyzed at the different IVM temperatures. Polar body extrusion was evaluated following IVM, and the mRNA and protein abundance of sirtuins and P53 in oocytes and cumulus cells were analyzed. The differing temperatures during IVM did not significantly alter polar body extrusion and cleavage rates; however, significant differences in blastocyst production were observed. COCs matured at 38.5°C (control, 37.3%) had the highest blastocyst rate, in contrast to those matured at 37°C (33.2%) and 40°C (21.5%). In all groups, the blastocyst rates were higher for BCB+ oocytes than for BCB- oocytes. In BCB+ oocytes, the expression of SIRT1, SIRT2, SIRT3, and SIRT5 genes was higher after maturation than that before maturation and in most of the cases, the expression was higher when IVM was performed at 38.5°C. In the cumulus cells of BCB+ COCs, only SIRT2 remained unaffected by the maturation temperature. In summary, the temperature change of ±1.5°C for 24 h during bovine oocyte maturation impaired in vitro embryo development. This lead to several cellular biochemical alterations in oocytes and granulosa cells from COCs with higher developmental competence (BCB+). Thus, SIRT1 is important for in vitro embryonic development and may protect against cold and heat stress.

The objective of this study was to identify parameters, before the start of the breeding season, that affect the conception rate of precocious Nelore heifers through ultrasonographic ovarian evaluation and evaluation of weight and body condition score (BCS). A total of 407 heifers aged 404±69 days (≈14 months old), weighing 267.1±31.2 kg, and with mean BCS of 3.1±0.5, were used. Heifers were subjected to hormone treatment to induce cyclicity and, 30 days later, to a fixed-time artificial insemination (FTAI) [...] ABSTRACT The objective of this study was to identify parameters, before the start of the breeding season, that affect the conception rate of precocious Nelore heifers through ultrasonographic ovarian evaluation and evaluation of weight and body condition score (BCS). A total of 407 heifers aged 404±69 days (≈14 months old), weighing 267.1±31.2 kg, and with mean BCS of 3.1±0.5, were used. Heifers were subjected to hormone treatment to induce cyclicity and, 30 days later, to a fixed-time artificial insemination (FTAI)

This study aimed to evaluate the physiological and reproductive parameters of Nelore cows under various microclimatic conditions. The experiment was performed in Central Brazil, which has a tropical climate with dry winters and rainy summers. The experimental groups were divided into an area with shading (5.8 trees/ha; n = 42) and an area with little shading (0.4 trees/ha; n = 42). The physiological (heart rate, respiratory rate, rectal temperature, surface body temperature, and vaginal temperature) and reproductive (estrus detection, conception rate, and rate of pregnancy loss) parameters were then assessed. The rectal temperature (p = 0.002); surface body temperature on the flanks, forehead, and shoulder (p < 0.001); and vaginal temperature (p < 0.001) of cows in the group with shading were significantly lower than those of cows in the group without shading. Estrus was higher (p = 0.08) in the shaded group; however, no effect was observed on conception and pregnancy loss rates. In conclusion, shading (5.8 trees/ha) provided better thermal comfort for Nelore animals in the tropical climatic region. However, this did not affect their performance after fixed-time artificial insemination.

HES1 (hairy and enhancer of split-1, effector of the NOTCH pathway) plays a role in oocyte maturation and has been detected so far mainly in somatic follicular cells. In this study, we aimed to investigate whether HES1 is present in both compartments of bovine cumulus oocyte complexes (COCs) and whether in vitro maturation itself has an effect on its distribution. We investigated the abundance of HES1 mRNA and protein in bovine COCs characterized by Brilliant-Cresyl-Blue (BCB) stainability by RT-PCR and immunofluorescence before and after in vitro maturation (IVM). To study the interaction of the compartments and the possible translocation of HES1, we injected GFP-HES1 mRNA into oocytes before maturation and analyzed fluorescence recovery after photobleaching (FRAP). The results showed that HES1 mRNA was detectable in oocytes but not in cumulus cells. The number of transcripts increased with maturation, especially in BCB-positive oocytes. In contrast, the protein was mainly visible in cumulus cells both before and after maturation. After GFP-HES1-mRNA injection into oocytes, a signal could be detected not only in the oocytes but also in cumulus cells. Our result shows a nearly exclusive distribution of HES1 mRNA and protein in oocytes and cumulus cells, respectively, that might be explained by the transfer of the protein from the oocyte into cumulus cells.

Este estudo teve como objetivo avaliar as estruturas ovarianas, intensidade do cio, medidas de carcaça por ultrassonografia e taxa de gestação de novilhas e vacas da raça Nelore com diferentes contagens de folículos antrais (CFA). Avaliamos 503 novilhas e 565 vacas Nelore, com idade média de 15,5 ± 2,2 e 69,8 ± 36,1 meses, respectivamente, submetidas a um protocolo de inseminação artificial em tempo fixo (IATF). No dia zero, todas as fêmeas foram examinadas por ultrassom para determinar a CFA. A CFA média das novilhas foi de 20 ± 8,6 e a das vacas foi de 22,5 ± 8,4 folículos. A área de olho de lombo (AOL) e a espessura de gordura (EG) das novilhas (n = 119 para AOL e n = 219 para EG) foram medidas utilizando imagens ultrassonográficas. As taxas médias de concepção na primeira IATF e no final da estação de monta foram de 35,8% e 57,5% e 45,1% e 78,9% para as novilhas e vacas, respectivamente. Demonstramos que a probabilidade de gestação na primeira IATF e no final da estação de monta, tanto para novilhas jovens quanto para vacas, foi maior quando a CFA era menor (P>0,001 e P=0,0123, respectivamente). A espessura da gordura e a AOL não mostraram nenhuma correlação com a CFA. A intensidade da expressão do cio foi negativamente correlacionada com o CFA (-0,46; P < 0,0001). Em conclusão, novilhas jovens e vacas da raça Nelore com menor CFA apresentam maior probabilidade de prenhez durante toda a estação de monta. Nenhuma relação entre a CFA e as características de carcaça foram observadas em novilhas Nelore. A CFA pode ser usada como uma ferramenta de seleção de novilhas com maior fertilidade sem influenciar as características de carcaça (AOL e EG).

This study aimed to evaluate the relationship between the antral follicle count (AFC) and the ovarian morphology of Bos indicus in different age groups: 12-23 months (G1), 24-35 months (G2), 36-47 months (G3), 48-59 months (G4), and >60 months (G5). Ovaries were collected individually and sent to the laboratory, where we measured AFC, the diameter and weight of the ovaries, dominant follicle (DF, ≥8mm), corpus luteum (CL), and small follicles (SF, <8mm). AFC were classified as high, intermediate-high, intermediate-low, and low. A group of ovaries was subjected to follicular aspiration to evaluate the morphological quality of the recovered cumulus oocyte complexes (COCs). Mean AFC did not vary between ages. The morphological characteristic that was most closely correlated with AFC was the weight of the small follicles. There was no relationship between AFC and the weight and diameter of the DF and CL. Quality of the COCs was superior in ovaries in which the CL was present, but it did not vary between the AFC classes. We conclude that AFC can be performed on a single ovary, regardless of the presence, diameter, and weight of the CL and DF in zebu between 12 and 60 months old.