Made available in DSpace on 2015-03-26T12:54:57Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1973320 bytes, checksum: aa4f936802e91a3fcfd777d09de0f494 (MD5) Previous issue date: 2013-10-11 / We aimed with this study to evaluate the effect of photoperiod changes on reproductive characteristics of Pêgabreed jennies along the year and to verify the embryo recovery rate and embryo characteristics on days 7, 8 and 9 postovulation. In Experiment 1, 279 estrous cycles of 44 jennies were evaluated during 3 consecutive years. The experimental groups were split in two periods according to photoperiod along the year in the southern hemisphere: P1: October to March (Long photoperiod); P2: April to September (Short photoperiod). The sexual behavior, ovarian and uterine characteristics, and fertility during 3 years were evaluated. Jennies were checked for estrous behavior by a jack and were evaluated by transrectal palpation every two days to identify females in estrous. Jennies with sexual signs of estrous or with anovarian follicle bigger than 25 mm in diameter were controlled daily until ovulation was detected.Artificial insemination or natural breed was performed every two days when a follicle reached ≥ 35 mm until ovulation. Pregnancy diagnose was done on days 13, 25 and 35 postovulation by ultrasonography using a transrectal linear transducer (5 MHz). Differences were not detected (P>0.05) between the two periods in the following characteristics: follicle diameter at the beginning of estrous (29.80 ± 0.18mm), follicle diameter at ovulation (44.61± 0.24mm), estrous length (7.44± 0.05days),interval from the onset of estrous to ovulation (5.99± 0.06days), interval from ovulation to the estrous end (1.45± 0.03days), follicle growth rate (2.50± 0.04mm/day)frequency of double (16.49%, 46/279) and triple (1.43%, 4/279)ovulations, frequency of ovulation in the left (52.65%, 146/279)and right (47,35%, 133/279)ovaries, and frequency of ovulations with visual signs in the pre-ovulatory follicle (77.85%, 217/279).Total pregnancy rate was 60%; a difference in pregnancy rate between the two periods was not detected (P>0.1).Photoperiod variation did not affect the characteristics of follicle growth, sexual behavior and fertility in jennies of Pêga breed under the present environment conditions.In Experiment 2, the recovery rate, development and quality of embryos on days 7, 8 and 9 were evaluated. For embryo recovery, 90 uterine flushes were performed in seven Pêga breed jennies, aging 6 to 14 years old. Sixty-three embryos from 90 flushes (70%) and 107 ovulations (58.9%) were recovered. Averaged embryo diameter was 747.38 ± 76.45 μm. The proportions of embryos development stages were as follow: morulas,1.59% (1/63);early blastocysts, 6.35% (4/63);blastocysts, 23.81% (15/63); and expanded blastocysts,68.25% (43/63). For quality grades, 90.5% (57/63) of embryos were classified as excellent or good (Grade I and II) and 9.5% (6/63) as regular or poor (Grade III and IV). No difference (P>0.1) in embryo recovery rate was detected between the two year periods. The embryo quality observed in the present study is considered satisfactory in a embryo transfer program. / Objetivou-se nesse estudo avaliar o efeito da variação do fotoperíodo sobre as características reprodutivas de jumentas da raça Pêga ao longo do ano; verificar a taxa de recuperação e viabilidade embrionária de lavados feitos nos dias 7, 8 e 9 pós-ovulação. No Experimento 1 foram avaliados 279 ciclos de 44 jumentas durante 3 anos consecutivos, sendo os grupos experimentais divididos de acordo com os períodos do ano: P1: outubro a março (período de fotoperíodo mais longo); P2: abril a setembro (período de fotoperíodo mais curto). Foram avaliadas as características de comportamento sexual, características ovarianas, uterinas e fertilidade. As jumentas foram rufiadas e avaliadas por palpação retal e ultrassonografia a cada dois dias. Aquelas que apresentavam comportamento de estro ou a presença de folículo maior que 25 mm de diâmetro em um dos ovários, foram controladas diariamente até a ovulação. Após a detecção de um folículo maior ou igual a 35 mm de diâmetro as jumentas foram artificialmente inseminadas ou cobertas a cada 48 horas até a ovulação. Os diagnósticos de gestação foram realizados aos 13, 25 e aos 35 dias após a ovulação por ultra-sonografia utilizando transdutor linear trans-retal de 5 MHz. Os valores médios das características diâmetro folicular no início do estro, diâmetro folicular pré- ovulação, duração do estro, intervalo início do estro à ovulação, intervalo da ovulação ao fim do estro, taxa de crescimento folicular, foram de 29,80±0,18 mm, 44,61±0,24 mm, 7,44±0,05 dias, 5,99±0,06 dias, 1,45±0,03 dias, 2,50±0,04 mm/dia, respectivamente. A porcentagem de duplas e triplas ovulações, frequência de ovulações entre os ovários direito e esquerdo e porcentagem de ovulações com alterações do folículo pré-ovulatório foram de 16,49% (46/279), 1,43% (4/279), 52,65% (146/279), 47,35% (133/279) e 77,85% (217/279), respectivamente. A taxa de prenhez geral foi de 60%. Não foram observadas entre os períodos, diferenças (P>0,05) nas características avaliadas. A variação do fotoperíodo não afetou as características foliculares, comportamento sexual e fertilidade de jumentas da raça Pêga nas condições experimentais avaliadas. No Experimento 2 avaliou-se a taxa de recuperação, as características morfométricas e estádio de desenvolvimento embrionário de embriões coletados nos dias D7, D8 e D9. Foram realizados 90 lavados uterinos de 7 jumentas da raça Pêga com idade variando de 6 a 14 anos. Foram recuperados 63 embriões de 90 lavados (70%) referentes a 107 ovulações (58,9%). O diâmetro médio dos embriões foi de 747.38 ± 76.45 μm. Dentre os embriões colhidos, as mórulas corresponderam a 1,59% (1/63), os blastocistos iniciais a 6,35% (4/63), os blastocistos a 23,81% (15/63) e os blastocistos expandidos 68,25% (43/63), dos embriões totais. Quanto à qualidade, 90,5% (57/63) dos embriões foram classificados como excelentes ou bons (Graus I e II) e 9,5% (6/63) como regulares ou ruins (Graus III e IV). Não foi observada diferença da taxa de recuperação embrionária entre os períodos do ano. Os dados de qualidade dos embriões obtidos no presente estudo são considerados satisfatórios para um programa de TE.

It is often claimed that the first Fresnel zone associated with the dominant frequency represents the spatial resolution limit of traveltime tomography. We show, however, that the relevant Fresnel limit for tomographic resolution is the maximum, not the dominant frequency in the data. For physically realizable causal wavelets, the maximum frequency is infinite. In practice, noise lowers the effective possible maximum frequency. To demonstrate these points, synthetic seismic data were generated for traveltime picking and inversion for a single, small velocity anomaly embedded in a homogeneous background velocity. A variety of traveltime picking techniques were tested and compared for their ability to detect the presence of objects smaller than that Fresnel zone associated with the dominant frequency. All methods produced accurate ray-theoretical (infinite-frequency) picks from noise-free seismic data for objects smaller than the dominant-frequency Fresnel zone. For the lowest dominant frequencies with Fresnel zones many times larger than the object, picking methods that focus on features along the onset of the first arrival were the most accurate, while cross-correlation with a known wavelet preformed less accurately. First-onset picking methods perform better because they take advantage of the highest frequencies in the data, whereas the correlation wavelet is typically in line with the dominant frequency. All methods successfully detected the presence of objects smaller than a wavelength. The inversion of the traveltime picks from the different picking methods always recovered the position and shape of the object. Random noise at a range of signal-to-noise ratios was then added to the seismic data and the data were repicked. Pick times with different noise realizations are statistically centered on the noise-free pick, not the time that would be recorded in the absence of the object. Trace stacking prior to picking or the averaging of many picks improves the signal-to-noise ratio and can extract signal that is not detected on an individual pick. An averaging of traveltime picks also occurs during tomographic inversion. This inherent signal-to-noise improvement allows tomography to image objects that are undetectable in individual trace picks. The resolution of tomography is limited not by the Fresnel zone associated with the dominant frequency, but by the accuracy of the traveltime picks. Resolution is further improved by dense ray coverage. / Master of Science