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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Mécanismes neurobiologiques et comportementaux impliqués dans l'expression de la peur récente et ancienne à un contexte chez le rat / Neurobiological and behavioral mechanisms implicated in the expression of recent and remote contextual fear conditioning

Muller, Marc-Antoine 17 October 2012 (has links)
Chez le rongeur, lorsque l’expression d’une peur conditionnée au contexte s’appuie sur un souvenir ancien, des réponses de peur importantes sont souvent rapportées lors de l’exposition à un contexte différent de celui dans lequel les chocs électriques ont été administrés. Cette généralisation des réponses de peur serait liée à une réorganisation concomitante des réseaux sous-tendant l’expression de la peur, en particulier à un « désengagement » de l’hippocampe dans le rappel des informations contextuelles. Cependant, d’autres études suggèrent que des modifications dans les traitements amenant à l’expression de comportements défensifs, liés à la peur ou l’anxiété, puissent également se mettre en place avec le temps suite à un conditionnement. Ainsi, une incubation des réponses de peur, correspondant à une augmentation globale des niveaux de peur avec le temps, pourrait contribuer à la généralisation de ces réponses. Nos travaux, par une approche d’imagerie de gènes précoces immédiats ainsi que d’évaluation comportementale, ont visé à démêler les mécanismes impliqués dans la généralisation de la peur conditionnée au contexte accompagnant sa consolidation à long terme. Nos résultats suggèrent que la généralisation soit moins liée à une altération du souvenir du contexte qu’à des modifications portant sur le traitement et / ou l’expression des émotions. La nature de ces dernières modifications semble dépendre du statut prédictif initial du contexte (en avant- ou en arrière-plan). De manière cohérente avec l’observation d’une absence de dégradation de la trace du contexte avec le temps, le rôle de l’hippocampe dans le rappel de l’information contextuelle nous est apparu maintenu au cours du temps. Les réorganisations observées dans les réseaux sous-tendant l’expression des réponses de peur concerneraient plutôt des modifications liées au traitement associatif et / ou émotionnel des informations contextuelles. Dans leur ensemble, nos résultats soulèvent la nécessaire prise en compte du haut degré de complexité des traitements amenant à l’expression d’une peur conditionnée, pour qui souhaite évaluer la qualité de la représentation contextuelle sur la base de réponses de peur discriminantes. / At remote delays following contextual fear conditioning in rodents, generalization of fear responses is usually described, as fear responses are elicited by exposure to a context different from the one in which footshocks were delivered. This generalization has been proposed to rely on the degradation and/or transformation of the memory trace due to systemic consolidation. The latter corresponds to the time-dependent reorganization of structures implicated in contextual fear expression, from networks involving the hippocampus to mainly cortical networks. However, other studies suggest that changes in defensive behaviors’ expression tied to fear and anxiety might take place in the time period following a fear conditioning experience. Indeed, an incubation of fear responses, that is an overall increase in fear responses following contextual fear conditioning, has repeatedly been reported. Such changes in the processing of emotionally relevant information might represent an alternative explanation of a time-dependent generalization of fear responses. Using immediate early genes imaging and behavioral assessment, our studies aimed at disentangling the processes supporting fear generalization over time. Our results suggest that under some circumstances, changes in the fear responses’ specificity might less be due to the dynamics of a memory system supporting the context representation than to alterations attributable to emotional information processing and/or expression. They point out dissociations in the latter changes between animals conditioned to a foreground or a background context. Consistent with our observation of a preserved detailed context memory trace, they also suggest that changes in the brain networks supporting the expression of a remotely acquired contextual fear might not reflect a time-dependent hippocampal-independency. Rather, the observed reorganization of neuronal networks might sustain changes in the associative and / or emotional information processing evoked by context exposure. Altogether, our results point out the need to take account of the high complexity of information processing leading to the onset of fear responses, when trying to infer the quality of a contextual representation on the basis of fear discrimination between contexts.
82

Effect of egg weight on hatchability and chick hatch-weight of Cobb 500 broiler chickens / Effect of egg weight on hatchability and chick hatch-weight of Cobb five hundred broiler chickens

Ramaphala, Oscar 06 1900 (has links)
This study was conducted to determine the effect of egg weight on hatchability and chick hatch-weight of Cobb 500 broiler chickens. A total of 396 Cobb 500 hatchable eggs classified according to three different egg weight groups as small: (<49 g) medium: (50-59 g) and large: (60-69 g) were used in the experiment. A complete randomized design of three treatments with three replicates and each replicate having” 44 eggs was used for the experiment. Simultaneously a linear type equation was used to determine the relationship between egg size and responses in hatchability values and chick hatch-weight. Results indicated that large-sized eggs produced chicks with higher (P<0.05) hatch-weight than medium and small-sized eggs. However, no differences were detected with fertility rate percentage, hatchability percentage and percentage hatch of fertile. It was therefore concluded from the result of the present study that sorting of Cobb 500 broiler chicken breeder eggs by weight prior to incubation might be advantageous in producing uniform size Cobb 500 broiler chicken hatchlings to meet specific market demands with improved efficiency. / Agriculture and  Animal Health / M. Sc. (Agriculture)
83

Ischemic Preconditioning Protects Adult Rat Cardiomyocytes Against Necrosis but not Apoptosis, via Activation of PKG

Caligtan, Marc J. 01 January 2005 (has links)
The role of cyclic guanosine monophosphate (cGMP) dependent protein kinase (PKG) in necrotic and apoptotic pathways of many cell types is well established; however its role in the ischemic preconditioning (IPC) of cardiomyocytes is not clearly defined. In the current study, we assessed the hypothesis that PKG protects against cell death following ischemidreperfusion injury in myocytes subjected to IPC. Freshly isolated adult rat ventricular myocytes were subjected to IPC by incubating in ischemic buffer for 30 minutes (min) followed by incubation in normal medium for 30 min. Prolonged simulated ischemia (SI) was created by incubating myocytes in the ischemic buffer for 90 min and reoxygenation (RO) for 120 min in the normal medium. Necrosis was determined by trypan blue exclusion and apoptosis was assessed by TUNEL assay. IPC reduced necrosis as shown by significant decrease in trypan blue positive cells as compared to virgin non-preconditioned myocytes subjected to SI and RO alone (p<.01). Similarly, the number of TUNEL positive myocytes following SI and 18 hrs of RO were significantly reduced in the IPC group. Treatment with PKG inhibitor, KT5832 (2pM) completely abolished the protection against necrosis by IPC. However, KT5832 failed to abolish the protective affect of IPC against apoptosis. Furthermore, myocytes infected with an adenoviral construct of PKG-la (1 x 1 o4 particles/cell) significantly reduced the number of trypan blue and TUNEL positive cells. These results suggest that the PKG signaling pathway plays an essential role in the preconditioning of myocytes against necrosis following SI / RO injury. Furthermore, while the overexpression of PKG protects myocytes against necrosis, as well as apoptosis, IPC may not induce a sufficient level of PKG during 18 hours of RO to induce protection against apoptosis.
84

Vztah mezi velikostí vajec a dobou inkubace u gekonů (Squamata: Gekkota) / Relationship between egg size and incubation time in geckos (Squamata: Gekkota)

Mrskočová, Jana January 2014 (has links)
Previous studies of the relationship between egg size and the embryonic development time showed a positive correlation between the two variables at interspecies level, thus offering the idea that the evolution of the latter could be a limiting factor for enlarging the size of eggs during evolution. Some research into interspecies and intraspecific level of reptiles doesn't confirm this correlation. At the same time, the relationship between the development time and egg size is influenced by many factors, such as shifts in ontogenetic stages of the embryo at the time of ablation of eggs, due to temperature and humidity, the presence of embryonic diapause during embryogenesis or synchronization of hatching time, of which the authors of previous studies took no account or filtered out inaccurately. I think that most of these factors can be well controlled in intraspecific studies, but, variation in egg size within species also tends to be small, which prevents a reliable test for correlation. The solution can be to compare closely related species with high variability in the size of the eggs, in our case the geckos of the genus Paroedura and family Eublepharidae. I eliminated temperature effects by comparing the time of incubation in two equal constant temperatures. The results show that, in this...
85

Investice do reprodukce a obrany hnízda u vrubozobých / Investment in reproduction and nest defense in waterfowl

Javůrková, Veronika January 2011 (has links)
Investment in reproduction is considered to be crucial component of life history traits. Reproductive success is however constrained by generally unpredictable environmental conditions. Based on "bet hedging" theory, individuals are forced to eliminate such unpredictability via the mixed strategy to maximize their long-term fitness. Predation represents underlying factor affecting individual reproductive success, and it undoubtedly lies behind the evolution of alternative reproductive strategies such as extra-pair paternity and conspecific brood parasitism. Behavioral mechanisms related to nest defense are thought to be investment in reproduction in accordance with trade-off between actual and residual reproductive value. Despite the extensive interest in the principles associated with parental investment into the nest defense, studies describing in detail the pattern of particular antipredator strategies are rare. Similarly, mechanisms responsible for maintenance of egg- viability during prolonged egg-laying period in species delayed the onset of incubation are poorly understood. In accordance with mentioned themes, this thesis includes publications aimed at aspects of reproductive biology and antipredator behavior in Mallards (Anas platyrhynchos). Particular publications concretely documented: a)...
86

Avaliação do manejo pré-incubação e incubação de ovos férteis sobre a qualidade do pintinho, desempenho e rendimento de carcaça de frangos de corte / Evaluation of management pre-incubation and incubation of fertile eggs on chick quality, performance and carcass yield of broilers

Furlan, Joyce de Jesus Mangini 01 July 2013 (has links)
Foram desenvolvidos dois experimentos para avaliação do efeito da temperatura e do período de estocagem de ovos férteis sobre os resultados da incubação, qualidade do pintinho de um dia de idade, bem como sobre o desempenho e rendimento de carcaça de frangos de corte durante as fases inicial e final. Experimento I - Utilizou-se 1620 ovos férteis da linhagem Cobb 500, oriundos de matrizes de 38 semanas de idade distribuídos em delineamento experimental inteiramente casualisado em arranjo de tratamentos em fatorial 2x2 com os fatores: período (5 e 10 dias) e temperatura (17 e 20oC) na estocagem de ovos, totalizando 4 tratamentos com nove repetições de 45 ovos cada. Após a estocagem procedeu-se a incubação em máquina de estágio único por vinte e um dias. Experimento II - Utilizou-se 504 pintos machos e fêmeas de um dia de idade, distribuídos em delineamento experimental inteiramente casualisado com os mesmos 4 tratamentos do experimento I sendo eles: Tratamento 1 (5 dias e 20oC), tratamento 2 (5 dias e 17oC), tratamento 3 (10 dias e 20oC) e tratamento 4 (10 dias e 17oC) com 9 repetições de quatorze aves cada para avaliação de desempenho e características de carcaça. Todos os dados foram analisados pelo Statistical Analysis System (SAS, 2008) e submetidos à análise de variância pelo procedimento MIXED ao nível de 5% de significância. Os dados que não respeitaram as premissas da análise estatística foram submetidos à análise não paramétrica de frequência pelo procedimento GLIMMIXED. No experimento I, não foi observado efeito significativo da interação entre os fatores analisados. Os melhores resultados de eclosão e eclodibilidade (77.28 e 77.86%, respectivamente) foram para ovos estocados por 5 dias. O efeito do período também foi observado no embriodiagnóstico, aumentando a ocorrência de mortalidade embrionária nas fases inicial e final em ovos estocados por 10 dias. A qualidade do pintinho foi superior em aves de ovos estocados durante os mesmos períodos. No experimento II, o desempenho não foi afetado significativamente pelos fatores, como também não houve efeito significativo da interação (p<0.05). Para as características de carcaça houve efeito significativo do fator temperatura (P<0,05) para peso vivo e rendimento de pernas. As aves de ovos estocados a 20oC foram mais pesadas aos 42 dias e apresentaram maior rendimento de pernas quando comparadas aos cortes de aves de ovos estocados a 17oC. Concluiu-se que a estocagem de ovos influencia os resultados da incubação bem como a qualidade do pintinho, principalmente no que diz respeito ao período em que permanecem estocados. Por outro lado o manejo pré-incubação não influenciou o desempenho de frangos de corte, mas sim características de carcaça, demonstrando que ambiência, sanidade, nutrição e melhoramento genético são fatores imprescindíveis na produção avícola mundial. / Two experiments were conducted to evaluate the effect of temperature and storage time of fertile eggs on the results of incubation, chick quality day old, as well as on the performance and carcass yield of broilers during the initial phases and final. Experiment I - was used in 1620 fertile eggs from Cobb 500, from breeders 38 weeks of age distributed in completely randomized design with treatments arranged in a 2x2 factorial with the factors: time (5 and 10 days) and temperature (17 and 20 o C) in the storage of eggs, totaling 4 treatments with nine replicates of 45 eggs each. After storage incubation proceeded in single stage machine for twenty-one days. Experiment II - was used 504 male and female chicks from one day of age in completely randomized design with 4 treatments of the same experiment I being: Treatment 1 (5 days, 20 o C), treatment 2 (5 days and 17 o C), treatment 3 (10 days and 20 o C) and treatment 4 (10 days and 17 o C) with 9 repetitions of fourteen birds each for performance evaluation and carcass characteristics. All data were analyzed using Statistical Analysis System (SAS, 2008) and subjected to analysis of variance by the MIXED procedure at the 5% significance level. Data that did not meet the assumptions of statistical analysis were analyzed by frequency nonparametric by procedure GLIMMIXED. In experiment I, there was no significant interaction between the factors. The best results hatching and hatchability (77.28 and 77.86%, respectively) were for eggs stored for 5 days. The effect of time was also observed in embryo diagnosis, increasing the occurrence of embryonic mortality in early and late in eggs stored for 10 days. Chick quality was higher in birds from eggs stored for long memos. In the second experiment, the performance was not affected by the factors, as there was no significant interaction (p <0,05). For carcass traits was no significant effect of temperature factor (P <0.05) on body weight and yield legs. Birds from eggs stored at 20 o C were heavier at 42 days and showed higher upside compared to cuts of poultry eggs stored at 17 o C. It was concluded that the storage of eggs influences the results of the incubation and chick quality, especially with regard to the period that remain stocked. On the other hand the management pre-incubation did not influence the performance of broilers, but carcass characteristics, demonstrating that ambience, sanitation, nutrition and genetic improvement are indispensable factors in poultry production worldwide.
87

Análise de processos de aprendizagem individual e organizacional em empresas incubadas de base tecnológica / Analysis of individual and organizational learning processes in technology-based incubated startups

Silva, Flávia Helen Moreira da 12 March 2019 (has links)
As empresas de base tecnológica, especialmente em fase inicial, têm a sua capacidade de criar valor de mercado em função das competências que estão incorporadas nas figuras dos empreendedores. Torna-se importante, portanto, analisar os processos que canalizam sistematicamente a aprendizagem individual para o nível organizacional e que, assim, criam novas estruturas, sistemas, procedimentos e rotinas e estratégias nas startups. O objetivo geral deste estudo foi analisar os processos de mobilização e transferência de competências de empreendedores, para a promoção da aprendizagem organizacional de empresas incubadas de base tecnológica. Para este objetivo geral ser alcançado, foram traçados três objetivos específicos, que determinaram a divisão do estudo em três etapas sequenciais. Os objetivos foram: 1) mapear as competências de empreendedores com startups de base tecnológica incubadas; 2) identificar quais são as competências mais aplicadas no negócio e processos de socialização e codificação mais utilizados em cada uma delas, de acordo com a visão dos empreendedores e, por último, 3) descrever os processos de mobilização, socialização e codificação de competências empreendedoras. Foram definidas 10 dimensões gerais de competências empreendedoras, a saber: planejamento em curto prazo, planejamento em longo prazo, liderança, gestão administrativa, relacionamento, visão empreendedora, aprendizagem empreendedora, maturidade, comprometimento e inovação. Estas dimensões são representativas de empreendedores no contexto de incubação, ou seja, em estágios iniciais, e retratam a relevância da aplicação de algumas (comprometimento, aprendizagem empreendedora e relacionamento) em detrimento de outras (liderança e planejamento em longo prazo). O mecanismo de socialização através de conversas informais foi apontado como o mais utilizado para a transferência de competências para a promoção de aprendizagem organizacional. Por outro lado, na análise dos episódios críticos de aprendizagem foi possível notar que os processos de codificação através de mudanças em práticas e políticas organizacionais também são frequentes, e por muitas vezes estão relacionadas às competências de inovação. Os episódios críticos de aprendizagem foram úteis para analisar o processo de aprendizagem que se dá a partir da aquisição da competência individual até a sua tradução para o nível organizacional da startup. Este estudo contribui para mitigar lacunas no que diz respeito aos processos de aprendizagem em empresas em estágios iniciais / Technology-based companies, especially in the initial phases, have the abilities to create market value according to the entrepreneurs skills. It is therefore important to analyze the processes that systematize the individual learning to the organizational level and thus create new structures, systems, procedures and routines and strategies in the startups. The objective of this study was to analyze the competencies mobilization and transfer processes for the promotion of organizational learning of the incubated technology-based startups. To achieve this general objective, three specific objectives were defined, which determined the division of the study into three sequential stages. The objectives were: 1) to map the competencies of entrepreneurs with incubated technology-based startups; 2) identify which are the competencies most applied by the entrepreneurs and the socialization and codification processes most used for each of them, according to the entrepreneurs\' perception and, finally, 3) describe the processes of mobilization, socialization and codification of entrepreneurial competencies. Ten general dimensions of entrepreneurship skills were defined: short-term planning, long-term planning, leadership, administrative management, relationship, entrepreneurial vision, entrepreneurial learning, maturity, commitment and innovation. These dimensions are representative of entrepreneurs in the context of incubation, that is, in the initial stages, and portray the relevance of the application of some (commitment, entrepreneurial learning and relationship) to the detriment of others (leadership and long-term planning). The mechanism of socialization through informal conversations was pointed out as the most used for the transfer of competences for the promotion of organizational learning. On the other hand, in the analysis of the critical episodes of learning it was possible to note that the processes of codification through changes in organizational practices and policies are also frequent, and are often related to innovation skills. Critical learning episodes were useful to analyze the learning process from the acquisition of individual competence to its translation to the organizational level of the startup. This study helps mitigate gaps in learning processes of early-stage companies
88

Incubation Temperature Effects on Loggerhead (Caretta caretta) and Green (Chelonia mydas) Sea Turtle Hatchling Vigor

Unknown Date (has links)
Climate change has the potential to expose sea turtle nests to higher temperatures, which may negatively impact sea turtle hatchling vigor. In this study, loggerhead and green hatchlings were sampled from the Boca Raton, Florida beach and via lab incubation, and hatchling vigor was determined. Elevated nest temperatures decreased loggerhead and green turtle hatchling performance and corticosterone levels, with the most significant effects found in hatchlings exposed to maximum incubation temperatures above 35°C during late development. Lab-incubated loggerhead post-hatchling corticosterone levels and growth rates were also determined. The differences seen in corticosterone levels with overall nest incubation temperatures, mean temperatures during early, middle or late stages of development, and its negative correlation with hatchling performance improves our understanding of the underlying physiological mechanisms linking elevated incubation temperatures and sub-lethal physiological effects that may significantly impact hatchling survival, a critical step for sea turtle conservation in south Florida and elsewhere. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection
89

Análise das interações universidade-empresa em empresas incubadas e graduadas numa incubadora universitária de empresas

Oliveira, Aliomar Silva de January 2010 (has links)
No contexto de universidade empreendedora, as incubadoras de empresas são um locus onde se acolhe empreendedores apoiando-os para que seus projetos tornem-se realidade através da constituição de pequenas empresas. Estar no ambiente de uma incubadora universitária de empresas significa estar próximo à universidade e tendo facilitado e estimulado o acesso e colaboração com a Academia. Se poderia questionar que efeitos o processo de incubação provoca na universidade que mantém uma incubadora de empresas e; por outro lado, que vantagens uma empresa nascente teria em estabelecer-se dentro de uma incubadora. Para subsidiar a análise dessas questões, o objetivo da presente pesquisa é analisar as interações universidade- empresa, em empresas incubadas e graduadas, que ocorrem no âmbito de uma incubadora universitária de empresas. Foi estudado o ambiente de incubação da Incubadora de Empresas de Base Tecnológica da UNISINOS, conhecida por UNITEC, através de coleta de dados via questionário submetido às empresas que estavam residentes na Incubadora no ano de 2009. Este estudo foi conduzido do ponto de vista da empresa que passa pelo processo de incubação, materializado na visão de seu empreendedor, sendo respondido por 15 empreendedores que representam 15 das empresas incubadas e graduadas residentes. Os resultados obtidos permitiram identificar: as parcerias, a receita mensal regular das empresas incubadas, o baixo nível de endividamento, e a troca de informações técnicas com outras empresas, como efeitos do processo de incubação nas empresas. Também pemitiram identificar as palestras em sala de aula, as visitas de alunos nas empresas e a consultoria prestada por alunos, como principais efeitos na Universidade. Além disso, se pode identificar que as percepções dos executivos das empresas graduadas e incubadas, divergem na maioria das questões. / Considering the entrepreneurship university context, the business incubators are a kind of locus that holds entrepreneurs, helping them to make their projects come true via the establishment of small companies. Being inside university business incubator means to have easy access and stimulated collaboration with the University. It could be asked which effects the incubation process brings to a university that holds a business incubator and, on the other hand, which advantages could be reached by a startup company settled inside an incubator. In order to support the analysis of these kinds of questions, the objective of this research is to analyze the interactions university-industry that occurs in a university business incubator. This study considers the incubation environment at UNISINOS University (located in the southern Brazil), called UNITEC, throw data collected using a questionnaire that was submitted to companies that were resident at UNITEC incubation environment at the year 2009. This whole study considers the point of view of 15 companies that were passed through incubation process, including incubated companies and also graduated ones. From the obtained results, it´s possible to indentify: the partnerships among resident companies, the recurring monthly income of incubated companies, the low level of indebtedness of all companies and, the technical information exchange among the companies, as effects from the incubation process in the resident companies. It´s also to indentify that the lectures by entrepreneurs at university classes, the students visits at companies and, consultancy services by students, as the main effects of the incubation process at the University. Besides that, it´s possible to realize that entrepreneurs from the incubated and graduated companies diverge in most questions.
90

Resultados produtivos no incubatório e na granja de frangos de corte utilizando sistema de incubação em estágio múltiplo e estágio único / Productive results of broiler chickens at the incubatory and the farm using single and multiple incubation system

Mesquita, Mariana Alves 02 April 2013 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2014-09-01T15:12:17Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertacao Mariana Alves Mesquita.pdf: 1355511 bytes, checksum: ad943c28d6a8c5364f0a749ef4d896c9 (MD5) / Made available in DSpace on 2014-09-01T15:12:17Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertacao Mariana Alves Mesquita.pdf: 1355511 bytes, checksum: ad943c28d6a8c5364f0a749ef4d896c9 (MD5) Previous issue date: 2013-04-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The aim of this study was to compare the incubation systems in multiple stage and single stage, by evaluating the performance of the incubation process and the production performance of broilers originated from embryonated eggs incubated in the both systems. To evaluate the yield of incubation five experiments were performed, using eggs of Cobb broiler breeders. Each test was divided into two phases. In the first experimental phase, eggs weight, chicks weight, residual yolk weight, length and quality score of the chicks were analyzed using randomized block design with two treatments (single stage and multiple stage), and with blocks being each experimental trial. In each test, 140 eggs and all the chicks borned from those eggs from each treatment were assessed (experimental unit). In the second phase of the trial, a total of 25.360 eggs and was incubated and spread on trays for analysis of hatchability, hatch window, birth distribution and embryo diagnosis. For hatchability data and hatch window, a randomized block design in a 2x3 factorial arrangement (two incubation systems and three positions of the trays into the incubation machine) was used. The repetitions were composed by the trays, totaling 285. For the results of embryo diagnosis all unhatched eggs from 285 selected trays were evaluated. The productive performance was evaluated until 35 days of age by means of a completely randomized 2x2 factorial arrangement (chicks from two stages of incubation and both sexes), with six replicates. Each experimental unit consisted of 25 birds, totaling 600 birds. We concluded that incubation of fertile eggs from Cobb 500 broiler breeders in single stage machines enables to obtain better productivity of the hatchery than incubation in multiple stage machines, as a result of higher hatchability and better neonate quality. The productive performance of broiler up to 35 days of age was not affected by the type of machine used for incubation. / Objetivou-se comparar os sistemas de incubação em estágio múltiplo e estágio único, avaliando-se o rendimento do processo de incubação e o desempenho zootécnico de frangos de corte originados de ovos embrionados incubados nos dois sistemas. Para avaliar o rendimento da incubação foram realizados cinco ensaios experimentais, utilizando-se ovos de matrizes pesadas da linhagem Cobb. Cada um dos ensaios foi dividido em duas fases experimentais. Na primeira fase experimental foram analisados o peso dos ovos, peso dos pintos, peso do resíduo vitelino, comprimento e escore de qualidade dos pintos. Foi utilizado delineamento em blocos casualizados com dois tratamentos (estágio múltiplo e estágio único), sendo cada ensaio experimental os blocos. Em cada ensaio foram avaliados 140 ovos e 140 pintos de cada tratamento (unidade experimental). Na segunda fase experimental foi incubado um total de 25.360 ovos, distribuídos em bandejas para a análise da eclodibilidade, janela de nascimento, distribuição de nascimentos e embriodiagnóstico. Para os dados de eclodibilidade e janela de nascimento utilizou-se delineamento em blocos casualizados em esquema fatorial 2x3 (dois sistemas de incubação e três posições das bandejas dentro da máquina de incubação). As repetições foram constituídas pelas bandejas, totalizando 285 bandejas avaliadas. Para os resultados do embriodiagnóstico avaliaram-se todos os ovos não eclodidos das 285 bandejas selecionadas. O desempenho zootécnico foi avaliado até 35 dias de idade utilizando-se delineamento inteiramente casualizado em esquema fatorial 2x2 (pintos oriundos de dois estágios de incubação e dois sexos), com seis repetições. Cada unidade experimental foi composta por 25 aves, totalizando 600 aves. Conclui-se que a incubação de ovos férteis de matrizes pesadas da linhagem Cobb 500Ò em máquinas de estágio único possibilita a obtenção de melhor produtividade do incubatório em relação às máquinas em estágio múltiplo, como consequência da maior eclodibilidade e melhor qualidade dos neonatos obtidos. O desempenho zootécnico de frangos de corte até os 35 dias de idade não foi influenciado pelo tipo de máquina de incubação utilizada.

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