Este estudo teve como objetivo avaliar o efeito da presença de corpo lúteo (CL) no início do protocolo de inseminação artificial a tempo fixo (IATF), no diâmetro do folículo ovulatório (DFO), na expressão de estro e na taxa de prenhez usando cipionato de estradiol (CE) ou GnRH como indutor de ovulação em novilhas de corte. No dia 0, novilhas [n = 414; 317 ± 23 kg; 3,08 ± 0,21 escore de condição corporal (escala de 1 a 5) entre 22 e 24 meses de idade] receberam um dispositivo intravaginal contendo 1g de progesterona (P4) e foram administrados 2 mg de benzoato de estradiol, IM. No dia 8, o dispositivo foi removido e as novilhas receberam 500 μg de cloprostenol sódico IM e foram divididas em dois grupos: CE [n = 213; 0,5 mg de CE, IM, no dia 8] e GnRH [n = 201; 25 μg de Licerelina, IM, no dia da IATF] e a IATF foi realizada 50 h após a remoção do dispositivo. As novilhas tiveram a região sacral pintada para verificar a expressão do estro entre a remoção do dispositivo de P4 e a IATF. No dia 0, foram realizados exames ultrassonográficos para verificar a presença de CL (com CL = 213, sem CL = 202), no dia 10 para medir o DFO e no dia 11 para confirmar a ovulação. As novilhas foram classificadas em 3 grupos de acordo com o DFO: pequeno (≤ 9,5mm), médio (9,6-11,5mm) e grande (≥ 11,6mm) para avaliar seu efeito na expressão de estro e prenhez. A expressão de estro foi confirmada quando a tinta estava removida no dia 10. A expressão de estro foi maior (P <0,05) no grupo CE em comparação com o grupo GnRH. O DFO diferiu (P <0,05) de acordo com a presença de CL ( P < 0,05), mas foi semelhante entre os tratamentos. A taxa de ovulação não diferiu nos grupos CE e GnRH. As taxas de prenhez foram semelhantes (P> 0,05) entre os grupos CE e GnRH, no entanto, a taxa de prenhez foi maior nas novilhas que expressaram estro (P <0,05), do que naquelas que não expressaram. A presença de CL no início do protocolo de IATF esteve associada a maior taxa de prenhez (P <0,05) no grupo GnRH em relação ao grupo CE, mas não diferiu entre novilhas sem CL. A manifestação de estro para novilhas tratadas com GnRH aumenta de acordo com DFO. O grupo CE apresenta alta manifestação de estro independente do DFO. A taxa de prenhez é maior à medida que o DFO aumenta. Em conclusão, as novilhas com CL no início do protocolo de IATF possuem maior folículo ovulatório, e quando tratadas com GnRH como indutor de ovulação atingem maiores taxas de prenhez. O tamanho do folículo ovulatório foi associado com o comportamento de estro e as taxas de prenhez nos tratamentos de CE e GnRH. / The aim of this study was to evaluate the effect of presence of corpus luteum (CL) at the onset of timed AI (TAI) protocol in ovulatory follicle diameter (OFD), estrus expression and pregnancy rate using estradiol cypionate (EC) or GnRH as ovulation inductor in beef heifers. On day 0, heifers [n=414; 317±23 kg; 3.08±0.21 body condition score (1 to 5 scale) and 22-24 months of age] received a 1g progesterone (P4) intravaginal device and 2 mg of estradiol benzoate, IM,. On day 8, device was removed, heifers received 500 μg of sodium cloprostenol, IM, and were divided in two groups: EC [n=213; 0.5mg EC, IM, on day 8] and GnRH [n=201; 25 μg of Licerelin, IM, at TAI] TAI was performed 50 h after device removal. The heifers had the base of the tail painted to verify estrus expression between P4 device removal and IATF. On day 0, ultrasound examinations were performed to verify the presence of CL (with CL = 213, without CL = 202).On day 10 to measure OFD and on day 11 to confirm ovulation. Heifers were classified into three groups according to OFD: small (≤ 9.5 mm), medium (9.6-11.5 mm) and large (≥ 11.6 mm) to evaluate their effect on estrus expression and pregnancy rate. Estrus expression was confirmed when ink marking was removed on day 10. Estrus expression was higher (P <0.05) in the EC group compared to GnRH group. The OFD differed (P <0.05) according to the presence of CL (P <0.05), but was similar between the treatments. The ovulation rate did not differ in CE and GnRH groups. Pregnancy rates were similar (P> 0.05) between the EC and GnRH groups, however, the pregnancy rate was higher in heifers who expressed estrus (P <0.05) than in those who did not express it. The presence of CL at the beginning of the IATF protocol was associated with a higher pregnancy rate (P <0.05) in the GnRH group in relation to the EC group, but did not differ between heifers without CL. The estrus manifestation for heifers treated with GnRH increases as the DFO increases, while the EC heifers has a high estrus manifestation independent of the DFO. The pregnancy rate also increases as DFO increases. In conclusion, heifers with CL at the beginning of the IATF protocol have increased ovulatory follicle size, and when treated with GnRH, as an ovulation inducer, attained higher pregnancy rates. The size of the ovulatory follicle was associated with higher estrus behavior and higher pregnancy rates in the EC and GnRH treatments.

Yeung Wan Kit. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2004-2005, design report."

Embora a tecnologia nuclear tenha aplicações benéficas para diversas áreas, como saúde, indústria, agricultura, produção de energia, entre outras, a sua aceitação ainda é restrita e há várias barreiras para o seu uso. A falta de conhecimento assertivo sobre essa tecnologia gera preconceito com relação à sua utilização. Preconceitos podem ser explícitos, que são conscientes, ou implícitos, inconscientes. No entanto, conscientes ou inconscientes, eles influenciam o comportamento e as atitudes. As experiências nas memórias explícita e implícita podem ser transferidas de uma para a outra. Assim, preconceitos ou associações inconscientes podem ser modificados pela memória explícita, ou seja, um novo conhecimento pode reduzi-los ou revertê-los. Para uma educação transformadora, o professor tem um papel central; entretanto, para que ele transmita o conhecimento de forma imparcial, é necessário que tenha uma visão livre de preconceitos. Esse trabalho visa desenvolver uma metodologia com apoio em neurociências por meio da qual as associações implícitas referentes às aplicações da tecnologia nuclear por parte dos professores de ciências sejam identificadas e possíveis preconceitos implícitos sejam modificados por meio de novos conhecimentos explícitos. Para identificar preconceitos implícitos são necessários testes específicos de memória implícita. O Teste de Associação Implícita (TAI) foi selecionado para esse trabalho. Seguindo as etapas fornecidas pelo software FreeIAT, o TAI foi customizado a fim de comparar as associações implícitas de participantes com relação às áreas nuclear e petróleo e sua consistência foi averiguada por um pré-teste aplicado a um grupo de especialistas (grupo controle) e de leigos, cujos resultados determinaram um bom valor de Alfa de Cronbach. Um programa multissensorial de 5 horas foi desenvolvido e realizado no Instituto de Pesquisas Energéticas e Nucleares (IPEN) para um grupo de professores de ciências. O TAI foi aplicado no início e ao término do programa e os resultados das associações implícitas foram comparados. Após seis meses, o TAI foi reaplicado ao mesmo grupo de professores para verificar se as associações implícitas se mantiveram estáveis. Esse programa multissensorial foi comparado com um programa de 12 semanas de ensino tradicional com aulas expositivas realizado no IPEN para alunos ingressantes na pós-graduação. O programa multissensorial foi efetivo para mudar e manter as associações implícitas dos professores referentes às aplicações benéficas da tecnologia nuclear, diferentemente do ensino tradicional com aulas expositivas. Esse trabalho demonstrou que é possível quebrar paradigmas e preconceitos. A abordagem multissensorial possibilitou um conhecimento enriquecido sobre as aplicações da tecnologia nuclear, ou seja, promoveu novas experiências na memória explícita que modificaram as associações prévias armazenadas na memória implícita. Assim, o programa multissensorial demonstrou ser uma ferramenta eficaz, capaz de produzir e manter mudanças nas associações implícitas, de baixo custo e pode ser aplicado em diversas áreas para mudar as associações implícitas e reverter preconceitos. Os resultados demonstraram que esse trabalho de doutorado teve êxito no que se propôs, contribuindo, assim, para a difusão do conhecimento das aplicações benéficas da tecnologia nuclear e, consequentemente, para a sua desmitificação. Essa metodologia completa poderá ser empregada em outras áreas para identificar, modificar e/ou reverter preconceitos ou estereótipos implícitos. / Although the applications of nuclear technology benefit several fields, such as health, industry, agriculture, energy production, among others, its public acceptance is still reduced and there are various barriers to its use. A lack of assertive knowledge about this technology generates prejudice against its use. Prejudices may be explicit at the conscious level or implicit operating outside awareness. Nevertheless, either conscious or unconscious, prejudices interfere with behavior and attitudes. The experiences in the explicit and implicit memories can be transferred from one to the other; thus unconscious prejudices or associations may be modified by the explicit memory, that is, new knowledge may reduce or even reverse them. The teachers play a critical role for transforming education; however, for sharing balanced knowledge they must have a perspective without prejudices. This work aims to develop a neuroscience-based methodology through which implicit associations of Brazilian science teachers towards nuclear technology may be assessed and possible implicit prejudices may be changed by new knowledge. In order to identify implicit prejudices, specific implicit memory tests are required. The Implicit Association Test (IAT) was chosen for this work. By following the steps provided by the software FreeIAT, the IAT was customized aiming to compare the implicit associations of respondents towards nuclear and oil. A pretest with nuclear specialists (control group) and lay people was administered to check the consistency of the customized IAT. The Cronbach\'s alpha was applied to measure the reliability of the test and showed good internal consistency. A 5-hour multisensory program for science teachers was designed and administered at the Instituto de Pesquisas Energéticas e Nucleares (IPEN). The IAT was administered at the beginning and at the end of the program and the results of the implicit associations were compared. After a six-month period, the IAT was re-administered to the same group of teachers to verify whether the implicit associations remained stable. This multisensory program was compared to a 12-week traditional teaching program with lecture classes held at IPEN for incoming post-graduation students. The multisensory program was effective for changing and maintaining the implicit associations of teachers towards the beneficial applications of nuclear technology, unlike the traditional teaching program with lecture classes. This work demonstrated that it is possible to break paradigms and prejudices. The multisensory program enabled an enriched knowledge about the applications of nuclear technology, that is, it promoted new experiences in the explicit memory, which modified the previous associations stored in the implicit memory. Therefore, the multisensory program has proven to be a successful, cost-effective tool, which is able to cause and maintain changes in implicit associations and can be applied in several areas where changes in implicit associations and prejudice reversal are desired. The results demonstrated that the proposed doctoral research was effective, thus contributing to the diffusion of knowledge of the beneficial applications of nuclear technology and, consequently, to its demythification. This methodology may be administered to other fields to identify, modify and/or reduce implicit prejudices or stereotypes.

當伊斯蘭信仰與政治勢力結合時，往往能左右一地的宗教信仰與風俗習慣。雖然如此，伊斯蘭在對外傳播與發展的過程中仍吸收了許多各地的文化特質，使得伊斯蘭文化呈現出多元的面貌，意即具有地方性的特色。 　　伊斯蘭在中國即是一例。基本上伊斯蘭是隨著穆斯林的貿易與移民而傳入中國。在唐宋時期前來中國貿易之阿拉伯及波斯商賈中即有許多穆斯林定居中國。到了元代，由於中亞穆斯林助蒙古人入主中原有功，穆斯林在元朝政治、經濟上均扮演重要的角色。明代則由於明中央政府的漢化政策，穆斯林漢化的速度與程度均超過前代。漢化的加深相對地使得穆斯林之信仰顯得薄弱，大多數的穆斯林對伊斯蘭教義模糊不清，對他們而言伊斯蘭似乎只是一種生活習慣。穆斯林的社會地位也逐漸走下坡。比起元代，明代的伊斯蘭文化呈現衰退的狀態。 　　有鑑於此，中國穆斯林中的有識之士便試圖以著作的方式來振興伊斯蘭在中國的地位。明清時期的伊斯蘭漢文著述為數不少，本文擇其中較具代表性的幾本加以分析討論：王岱輿的 ＜正教真詮＞、馬注的 ＜清真指南＞、劉智的 ＜天方典禮＞、 ＜天方性理＞、馬德新的 ＜四典要會＞。這些兼通伊斯蘭經典與儒家學說的穆斯林學者著書闡述伊斯蘭教義，除了希望能讓中國的穆斯林正確地了解伊斯蘭教義，也希望能得到儒者的認同與支持，因此除了以漢文著作外，在詮釋上試圖以儒家學說輔為解釋，如孔子「天」的概念、宋明理學無極、太極、理氣之說等等。一方面強調伊斯蘭與儒家思想的一致性，一方面又不離認主獨一的信念。這樣闡述伊斯蘭教義的方式成為明清伊斯蘭漢文著作的特色，也逐漸形成具有中國特色的伊斯蘭。這些著作一方面顯現出儒家思想對伊斯蘭教義中國化的影響力，一方面也表示出穆斯林對中國大環境的適應之道。

This thesis is based on fieldwork carried out m Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China. The main focus of the work is the Dai people, one of China's fifty-five so called 'Minority Nationalities'. I aim to paint a picture of the complex processes through which Dai ways of being and images of them are created and recreated. This is not to suggest that the Dai constitute a bounded group. Although Chinese official discourse presents a static, rigid picture of the so-called 'Minority Nationalities', I hope to have demonstrated that the everyday experiences of those in Banna are governed by a fluid and dynamic relationality. Images of 'Minority Nationalities' abound in China, these images are multiple and often contradictory. The Dai are known throughout China for their beauty, a beauty often portrayed as highly erotic. In this thesis I explore the implications of this image and the role of the Dai in its formation and continuity. With this in mind I examine the ways that the striking Dai aesthetic is used in the intricate power plays of Xishuangbanna. This work examines aspects of the Dai lived aesthetic and as such it has chapters on tattoo, architecture and feminine beauty. Dai aesthetic knowledge is interlaced with strands of moral, philosophical and cosmological insight, thus this work also includes a chapter on morality, autonomy and cooperation. The penultimate chapter uses vivid ethnography of the Water Splashing festival as a example of play of identities in Xishuangbanna. The Conclusion reiterates that the processes by which images, identities and aesthetic understandings are generated, and by which limits are explored and transgressed in Xishuangbanna are dialogic in character.

釣魚臺列嶼爭端是影響東海區域和平穩定的主要因素，該海域除蘊藏豐富生物及非生物資源外，更因其具有重大的地緣戰略利益，對亞太區域安全有深遠之影響。惟歷經歷史時局的演變，主權歸屬問題涉及中共、日本與臺灣等國，基於特殊歷史背景與國際間一中政策制約，使我國僅有海洋國家之名，同時影響我對於上述島嶼之主權主張。 中共挾著新崛起的大國氣勢，明確提出「海洋強國」之戰略目標，透過整合內部海上執法機關，展現維護國家海洋權益之決心，進而鞏固和擴大海洋維權成果。然囿於其海域被島鏈封鎖，戰略迴旋空間有限，為實踐其海洋戰略利益，面對周遭潛在的軍事威脅和海洋爭端，中共目前正積極拓展海上力量。臺灣應如何突破外交困境，並於維護國家尊嚴與人民福祉之間，尋求解決釣魚臺海域爭端之最佳途徑，作為在現今國際劣勢下，發展國家海洋戰略事務之借鏡，以達知彼知己，百戰不殆之效。 海上安全儼然已成為全球化新興環境的核心議題，在面對中共積極強化東海經營管理策略及戰略部署的同時，我國更應該思考如何強化海洋政策作為，藉此與世界接軌，構建與各大國間的等距平衡交往戰略，從中獲得外交自主性，以確保國家最大利益。 / The territorial disputes of Diao-Yu-Tai Islands are the decisive factors to the stability of the East China Sea (ECS). ECS has not only rich living and non-living resources, but also profound effects on the security of Asia-Pacific area due to the significant geo-strategic interests thereof. According to the evolution of historical events, the Islands’ sovereignty disputes among the neighboring countries of China, Japan and Taiwan. Based on the special historic background and constraints of the international realism of one China policy, Taiwan is merely a marine country and has a difficulty to claim the sovereignty right of the Islands. China, the rising power, specifically set out the strategy of establishing itself as a “marine power” by integrating the internal maritime law enforcement agencies to demonstrate the determination of maintaining its maritime rights and interests so as to consolidate and expand the outcome of safeguarded rights. However, blocked by the Island chain of Asian Pacific that leads to insufficient defense and response space, China actively reinforces the maritime power to fulfill its ocean strategic interests and manage the potential military threats and maritime disputes. Taiwan shall break through the diplomatic bottleneck to seek for the best solution on the disputes of the Diao-Yu-Tai Islands to assert the national rights and people welfare under the international adverse situation. The maritime security is the core issue of the Globalization development. Facing to the strengthened stewardship strategy and military arrangement in the ECS of China, Taiwan should think over the marine policy to synchronize with the world and seek for the balance among the neighboring countries. As a result, it is beneficial for Taiwan to win the independent authority in diplomacy to ensure national best interests.

Thesis (M.Sc.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Rehabilitation Science, Faculty of Rehabilitation Medicine. Title from pdf file main screen (viewed on February 16, 2010). Includes bibliographical references.

Este estudo teve como objetivo avaliar o efeito da presença de corpo lúteo (CL) no início do protocolo de inseminação artificial a tempo fixo (IATF), no diâmetro do folículo ovulatório (DFO), na expressão de estro e na taxa de prenhez usando cipionato de estradiol (CE) ou GnRH como indutor de ovulação em novilhas de corte. No dia 0, novilhas [n = 414; 317 ± 23 kg; 3,08 ± 0,21 escore de condição corporal (escala de 1 a 5) entre 22 e 24 meses de idade] receberam um dispositivo intravaginal contendo 1g de progesterona (P4) e foram administrados 2 mg de benzoato de estradiol, IM. No dia 8, o dispositivo foi removido e as novilhas receberam 500 μg de cloprostenol sódico IM e foram divididas em dois grupos: CE [n = 213; 0,5 mg de CE, IM, no dia 8] e GnRH [n = 201; 25 μg de Licerelina, IM, no dia da IATF] e a IATF foi realizada 50 h após a remoção do dispositivo. As novilhas tiveram a região sacral pintada para verificar a expressão do estro entre a remoção do dispositivo de P4 e a IATF. No dia 0, foram realizados exames ultrassonográficos para verificar a presença de CL (com CL = 213, sem CL = 202), no dia 10 para medir o DFO e no dia 11 para confirmar a ovulação. As novilhas foram classificadas em 3 grupos de acordo com o DFO: pequeno (≤ 9,5mm), médio (9,6-11,5mm) e grande (≥ 11,6mm) para avaliar seu efeito na expressão de estro e prenhez. A expressão de estro foi confirmada quando a tinta estava removida no dia 10. A expressão de estro foi maior (P <0,05) no grupo CE em comparação com o grupo GnRH. O DFO diferiu (P <0,05) de acordo com a presença de CL ( P < 0,05), mas foi semelhante entre os tratamentos. A taxa de ovulação não diferiu nos grupos CE e GnRH. As taxas de prenhez foram semelhantes (P> 0,05) entre os grupos CE e GnRH, no entanto, a taxa de prenhez foi maior nas novilhas que expressaram estro (P <0,05), do que naquelas que não expressaram. A presença de CL no início do protocolo de IATF esteve associada a maior taxa de prenhez (P <0,05) no grupo GnRH em relação ao grupo CE, mas não diferiu entre novilhas sem CL. A manifestação de estro para novilhas tratadas com GnRH aumenta de acordo com DFO. O grupo CE apresenta alta manifestação de estro independente do DFO. A taxa de prenhez é maior à medida que o DFO aumenta. Em conclusão, as novilhas com CL no início do protocolo de IATF possuem maior folículo ovulatório, e quando tratadas com GnRH como indutor de ovulação atingem maiores taxas de prenhez. O tamanho do folículo ovulatório foi associado com o comportamento de estro e as taxas de prenhez nos tratamentos de CE e GnRH. / The aim of this study was to evaluate the effect of presence of corpus luteum (CL) at the onset of timed AI (TAI) protocol in ovulatory follicle diameter (OFD), estrus expression and pregnancy rate using estradiol cypionate (EC) or GnRH as ovulation inductor in beef heifers. On day 0, heifers [n=414; 317±23 kg; 3.08±0.21 body condition score (1 to 5 scale) and 22-24 months of age] received a 1g progesterone (P4) intravaginal device and 2 mg of estradiol benzoate, IM,. On day 8, device was removed, heifers received 500 μg of sodium cloprostenol, IM, and were divided in two groups: EC [n=213; 0.5mg EC, IM, on day 8] and GnRH [n=201; 25 μg of Licerelin, IM, at TAI] TAI was performed 50 h after device removal. The heifers had the base of the tail painted to verify estrus expression between P4 device removal and IATF. On day 0, ultrasound examinations were performed to verify the presence of CL (with CL = 213, without CL = 202).On day 10 to measure OFD and on day 11 to confirm ovulation. Heifers were classified into three groups according to OFD: small (≤ 9.5 mm), medium (9.6-11.5 mm) and large (≥ 11.6 mm) to evaluate their effect on estrus expression and pregnancy rate. Estrus expression was confirmed when ink marking was removed on day 10. Estrus expression was higher (P <0.05) in the EC group compared to GnRH group. The OFD differed (P <0.05) according to the presence of CL (P <0.05), but was similar between the treatments. The ovulation rate did not differ in CE and GnRH groups. Pregnancy rates were similar (P> 0.05) between the EC and GnRH groups, however, the pregnancy rate was higher in heifers who expressed estrus (P <0.05) than in those who did not express it. The presence of CL at the beginning of the IATF protocol was associated with a higher pregnancy rate (P <0.05) in the GnRH group in relation to the EC group, but did not differ between heifers without CL. The estrus manifestation for heifers treated with GnRH increases as the DFO increases, while the EC heifers has a high estrus manifestation independent of the DFO. The pregnancy rate also increases as DFO increases. In conclusion, heifers with CL at the beginning of the IATF protocol have increased ovulatory follicle size, and when treated with GnRH, as an ovulation inducer, attained higher pregnancy rates. The size of the ovulatory follicle was associated with higher estrus behavior and higher pregnancy rates in the EC and GnRH treatments.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to develop a timed artificial insemination system (TAI) in suckled beef cows. For this, in 227 cows 60-80 days postpartum, received estradiol benzoate (5mg) and a vaginal device containing 250mg of medroxyprogesterone acetate (MAP; day 0). On day six, prostaglandin analogous (125μg), eCG (400IU) was administered and calves were removed for 88h. The device was removed on day seven (BioRep group) or on day eight (TAI group) and the cows of both groups received GnRH (100μg; day 9) 48h or 24h after device withdrawal, respectively. Experiment I: the follicular growth was daily monitored, from day 6 to day 9 (36h after GnRH), in 14 cows. The average of dominant follicle size on day nine was 11.1±0.99mm (BioRep, n=7) and 11.5±0.65mm (TAI, n=7) and all animals ovulated. Experiment II: in the BioRep group (n=106), the cows was observed for estrus behavior after withdrawal the device, twice a day during 48h and inseminated at 12h after detection; In the TAI group (n=107), the devices were withdrawn on day eight and after 24h these cows and those from the BioRep group, which were not stand in estrus, received 100μg of GnRH and TAI 16h later. The pregnancy rates were 57.6% (BioRep) and 52.3% (TAI). The time of MAP exposure and the period from MAP to GnRH did not affect the follicular dynamic and pregnancy rates. Furthermore, the treatment for eight days allows an efficient TAI system in suckled beef cows. / O objetivo deste estudo foi desenvolver um protocolo de inseminação artificial com tempo fixo (IATF) em vacas de corte amamentando, avaliando o intervalo entre a retirada do progestágeno e a aplicação de GnRH sobre a dinâmica folicular e a prenhez. Para isto, 227 vacas 60-80 dias pós-parto receberam benzoato de estradiol (5mg) e um pessário vaginal de acetato de medroxiprogesterona (250mg MAP; dia 0). No dia seis, cloprostenol sódico (125μg), gonadotrofina coriônica eqüina (400UI) e desmame temporário (88h). O MAP foi retirado no dia sete (Grupo BioRep) ou no dia oito (Grupo IATF) e, 48h ou 24h após os animais receberam GnRH (100μg; dia 9), respectivamente. No experimento I, o monitoramento das estruturas ovarianas de 14 vacas foi realizado a cada 24h, desde o dia seis até 36h após a aplicação de GnRH em ambos os grupos. O tamanho médio do folículo dominante no dia nove foi de 11,1±0,99mm (BioRep n=7) e 11,5±0,65mm (IATF n=7) e todos os animais ovularam. No experimento II, no grupo BioRep (n=106), após a retirada do MAP, as fêmeas foram inseminadas com detecção de estro durante 48 horas. O restante dos animais do grupo BioRep e todos do grupo IATF (n=107) receberam 100μg de GnRH (dia 9) e, após 16h, IATF. Os índices de prenhez foram de 57,6% (BioRep) e de 52,3% (IATF). O intervalo de 24h entre a retirada do MAP, mantido por 8 dias, e a aplicação de GnRH não interfere na dinâmica folicular e prenhez, viabilizando inseminar vacas de corte amamentando sem observação de estro.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of the present study was to determine the action of gestagens and estradiol benzoate (EB) on the mechanism of premature regression of the first corpus luteum (CL) after parturition, and to develop an efficient artificial insemination system for suckling beef cows. The effect of pre-exposure to gestagens and EB on the expression of the alpha (ERα) and beta (ERß) estrogen receptors and progesterone receptor (PR) in the endometrium and CL was evaluated after the first postpartum ovulation. Thirty days after calving, ten anestrous cows were divided into a control group (AN) and a treatment group (AN+MAP). On day 0, animals of the treatment group received 250 mg medroxyprogesterone (MAP) in a vaginal device for 7 days and 5 mg EB. In both groups, the follicular wave was monitored and ovulation was induced for the formation of a CL. Luteal and endometrial tissues were collected after 7 days. The samples were submitted to the analysis of gene expression by RT-PCR and endometrial and luteal histological evaluation. Preexposure to gestagen during the first postpartum estrous cycle resulted in a higher endometrial expression of the PR (AN+MAP group; P<0.05) and inhibition of ERß expression in endometrial tissue (P<0.05). The height of the endometrial glandular epithelium and the total number of large luteal cells were higher in the AN+MAP group than in the AN group. In order to promote follicular growth compatible with the ovulatory response in postpartum cows, we analyzed the follicular dynamics to determine the best time for the application of eCG and EB in combination with MAP. The cows received MAP for 7 days and EB on day 0 or 1, followed by eCG on day 6 (B0E6 or B1E6) or 7 (B0E7 or B1E7). In two groups, the animals were not injected with eCG but received EB on day 0 (B0) or 1 (B1). All cows received a GnRH agonist 45 h after removal of the vaginal device. Animals of the B0E6 group maintained a mean follicular diameter of 8 mm until eCG application and reached a mean diameter of 13 mm at the time of GnRH agonist injection (45 h after MAP removal), showing an ovulation rate of 80%. Covariance analysis showed a difference in this curve (P=0.0001) compared to the other groups, which reached a mean final follicular diameter of 7 to 12 mm and ovulation rate of 40%. Based on these results, we investigated an ovulation and estrus reinduction for a mixed system of estrus detection and fixed-time artificial insemination (ETAI) in postpartum suckling cows. A total of 553 animals was divided into the following groups: hormonal induction (HI; day 0 = EB and MAP for 7 days, day 6 = eCG, PGF2α and temporary weaning), early weaning at 60 days, and natural breeding. No difference in pregnancy rates (85%) was observed among groups. However, at 7 months of age, calves of the HI group had reached a 38 kg higher mean weight than those weaned at 60 days. In order to adjust the eCG dose to the HI system, doses of 300, 400 or 500 IU eCG were tested. No difference in the pregnancy rates (78.7%) was observed. In conclusion, MAP and EB regulate steroid receptors in the endometrium and CL, indicating an important role for these hormones in the mechanism of premature postpartum luteolysis. In addition, steroids participate in the postpartum restructuring of the endometrium and CL and, when applied 60 days after calving together with eCG administered one day before removal of the vaginal implant, increase the reproductive efficacy of beef cows. / O objetivo do presente estudo foi de elucidar a ação dos gestágenos e benzoato de estradiol (BE) no mecanismo de regressão prematura do primeiro corpo lúteo (CL) pós-parto, e desenvolver um sistema eficaz de inseminação artificial para vacas de corte amamentando. O efeito da pré-exposição a gestágenos e BE na expressão de receptor de estrógeno alfa (REα), beta (REβ) e receptor de progesterona (RP) no endométrio e CL foi avaliado após a primeira ovulação pós-parto. Dez vacas em anestro, 30 dias após o parto, foram divididas em grupo controle (AN) e tratamento (AN+MAP). No dia 0, os animais do grupo tratamento receberam 250 mg de medroxiprogesterona (MAP) em pessário vaginal por 7 dias e 5 mg de BE. Em ambos os grupos, a onda folicular foi acompanhada e a ovulação induzida para formação de um CL. Após 7 dias, foram obtidos tecidos luteal e endometrial. As amostras foram destinadas a expressão gênica (RT-PCR) e avaliação histológica endometrial e luteínica. A pré-exposição ao gestágeno no primeiro ciclo estral pós-parto resultou em uma maior expressão endometrial do RP (grupo AN+MAP; P<0,05) e um bloqueio da expressão dos REβ no tecido endometrial (P<0,05). No grupo AN+MAP, a altura do epitélio glandular endometrial e número total de células luteais grandes foram maiores do que no grupo AN. Visando promover o crescimento folicular compatível com resposta ovulatória, em vacas pós-parto, foi avaliada a dinâmica folicular, para determinar o melhor momento de aplicação do eCG e BE em associação ao MAP. As vacas receberam MAP por 7 dias e BE no Dia 0 ou 1, seguido de eCG no Dia 6 (B0E6 ou B1E6) ou 7 (B0E7 ou B1E7). Em dois grupos, os animais não foram injetados com eCG, mas com BE no Dia 0 (B0) ou no Dia 1 (B1). Todas as fêmeas receberam agonista de GnRH 45 h após remoção do implante vaginal. Os animais do grupo B0E6 mantiveram um diâmetro folicular médio de 8 mm até a aplicação do eCG e atingiram a média de 13 mm no momento do GnRH, com taxa de ovulação de 80%. Por análise de covariança, essa curva diferiu (P=0.0001) das demais, as quais atingiram média folicular final entre 8 e 12 mm e taxa de ovulação de 40%. A partir desses resultados, foi investigado um sistema de reindução de ovulação e estro e inseminação artificial em um processo misto de observação de estro e tempo fixo (IAETF) para vacas amamentando no período pós-parto. Um total de 553 animais foi dividido em indução hormonal (IH; Dia 0= BE e MAP por 7 dias, Dia 6= eCG, PGF2α e desmame temporário), desmame precoce aos 60 dias e monta natural. Não foi observada diferença nos índices de prenhez (85,0%) entre os grupos. No entanto, os terneiros do grupo IH, aos sete meses de idade, atingiram a média de 38 kg a mais do que os desmamados aos 60 dias. Com o objetivo de adequar a dose da gonadotrofina no sistema de IH, foram utilizadas 300, 400 ou 500 UI de eCG, não havendo diferença nos índices de prenhez (78,7%). Em conclusão, o MAP e BE regulam os receptores esteróides no endométrio e CL, evidenciando uma importante participação no mecanismo de luteólise prematura pós-parto. Além disso, esses esteróides participam da reestruturação pós-parto do endométrio e CL e, aplicados aos 60 dias pós-parto, associados ao eCG um dia antes da retirada do implante vaginal, resultam em maior eficácia reprodutiva em vacas de corte.