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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.
61

Influência dos tempos de aquecimento e armazenamento de ovos férteis de reprodutoras pesadas sobre a eclodibilidade e características de pintos de 1 dia / Influence of heating and storage times of the broiler breeders fertile eggs on hatchability and day-old chicks characteristics

Flávio Henrique Araujo Silva 18 March 2005 (has links)
Um experimento foi conduzido com os objetivos de avaliar a influência de diferentes tempos de aquecimento antes do armazenamento e diferentes tempos de armazenamento de ovos férteis de matrizes Cobb 500 com 44 semanas antes da incubação, sobre a eclodibilidade e características de pintos de um dia. Utilizou-se o delineamento inteiramente ao acaso em arranjo fatorial 3x3, com os fatores: aquecimento antes do armazenamento (37ºC por 0, 6 e 12h) e armazenamento antes da incubação (12ºC por 4, 9 e 14 dias), totalizando nove tratamentos com 22 repetições de 10 ovos cada. O procedimento de incubação foi o convencional adotado pela avicultura industrial. Avaliaram-se as características de eclosão (480 e 498h), peso do pintainho, perda de peso dos ovos durante o aquecimento e armazenamento, temperatura de superfície da casca, embriodiagnóstico, peso relativo de órgãos e características morfométricas e histológicas intestinais. O aquecimento por 6h não prejudicou a eclodibilidade em comparação ao não aquecimento dos ovos. O aquecimento por 12h resultou em menores taxas de eclosão. O peso dos pintainhos não foi influenciado pelo tempo de armazenamento dos ovos, no entanto, os ovos aquecidos por 0 e 6h produziram pintainhos com pesos superiores quando comparados com aqueles ovos aquecidos por 12h. As características de vilosidades intestinais não foram influenciadas pelos tratamentos, com exceção da profundidade de cripta. Conclui-se que o aquecimento pré-incubação de ovos férteis a 37ºC por 6h é adequado em manter as taxas normais de eclosão sem prejudicar as características de pintos de um dia, quando os ovos são armazenados por até quatro dias. / An experiment was carried out to evaluate the influence of different heating times before storage and different storage times of the fertile eggs from Cobb 500 broiler breeders, aged 44 weeks, before incubation on hatchability and day-old chicks characteristics. The experimental design was randomly assigned in a 3x3 factorial scheme: egg heating before storage (37ºC for 0, 6 and 12h) and egg storage before incubation (12ºC for 4, 9 and 14 days), totalizing nine treatments with 22 replicates of ten eggs each. The incubation procedure was the same used by the poultry industry. It was evaluated the hatchability characteristics (480 and 498h), day-old chick weight, egg weight loss during heating and storage, superficial eggshell temperature, and intestine morphologic and histological characteristics. The heating time of 6h did not impair hatchability of the eggs when compared to the control treatment (no heating 0h). On the other hand, heating eggs for 12h was observed significantly reduction of the hatchability. Day-old chicks weight was not influenced by the storage time, however, the eggs heated for 0 and 6h provided heavier day-old chicks than eggs heated for 12h. There were not influences of the treatments on intestine villous characteristics, except for crypt height. It was concluded that the pre-incubation fertile eggs heating at 37ºC for 6h is adequate to maintain normal rates of hatchability without impair day-old chicks characteristics when eggs are stored up to four days.
62

Influências dos Sistemas Artificial e Natural de Incubação e criação de emas (Rhea americana) nos índices produtivos de criadouros do Estado de São Paulo. / Influences of artificial and natural incubation and breeding management systems on the productive traits of São Paulo State greater rhea (Rhea americana) breeders.

Marcelo Américo de Almeida 16 December 2003 (has links)
Nos últimos anos, vem crescendo consideravelmente a criação de animais silvestres no Brasil, com a finalidade de se evitar o desaparecimento de espécies ameaçadas de extinção e a de produção comercial. A ema (Rhea americana) destaca-se devido ao seu alto potencial reprodutivo e produtos de excelente qualidade, muito procurados no mercado mundial, como; carne, couro, pluma e gordura. Existem dois sistemas de incubação de ovos e criação de filhotes até os 90 dias de idade, o artificial e o natural. O sistema artificial consiste em retirar diariamente os ovos dos piquetes de reprodução e incubá-los em máquinas incubadouras. Após o nascimento, os filhotes são criados em recintos e tratados por pessoas treinadas para esta função. O sistema natural permite que o macho choque os ovos no seu próprio ninho e depois da eclosão, ele e os seus filhotes vão para outro recinto, onde o pai cria-os. Diante destes dois sistemas, foram analisadas as suas influências nos índices produtivos mais significativos para a espécie. Os sistemas de incubação e criação não influenciaram a porcentagem de ovos férteis e a de ovos contaminados e nem o peso dos filhotes no nascimento. Por outro lado, o sistema natural apresentou melhores índices nas porcentagens de ovos eclodidos e de filhotes vivos até os 90 dias de idade, e o sistema artificial promoveu maiores porcentagens de ovos com morte embrionária, de filhotes natimortos e que vieram à óbito devido à retenção de saco vitelino, rotação tíbio-társica e paralisia gástrica, e também, influenciou no maior peso dos filhotes aos 90 dias de idade e no maior ganho de peso diário dos filhotes até os 90 dias de idade. / During the past years, in order to avoid the extinction of endangered species and also for commercial purposes there was a considerable increase on the number of wild animals breeders. Due to its high reproductive potential and superior quality of products, the greater rhea (Rhea americana) is of prominence importance. Products such as rhea meat, leather, feather and fat are of great acceptance all over the world. There are two systems of eggs incubation and breeding of chicks till they are 90 days old, the artificial and the natural. The artificial system consists in withdrawing the eggs of the reproduction farmyards every day and keep them in incubation machines. After the eggs outbreak, the chicks are raised in sites and treated by persons trained particularly for this function. The natural system consists of allowing the male to incubate the eggs on its own nest and also to raise the chicks after they born. The influences of both systems were evaluated taking into account the most significant productive traits of this specie. No effect of the systems of incubation and breeding was observed in the percentage of fertile eggs, contaminated eggs and weight of the chicks when they are born. The natural system showed better results when evaluating the percentage of outbreaked eggs and survival of the chicks till 90 days old. On the other hand, the artificial system showed higher percentages of embryonic death, born death chicks and chicks that died due to yolk sac retention, tibio tarsic rotation and gastric paralysis, and chicks raised through the artificial system were heavier when they were 90 days old and showed higher daily weight gain till 90 days old.
63

Improvement of fertility and hatchability of artificially incubated ostrich eggs in the little Karoo

Van Schalkwyk, Salmon Jacobus January 1998 (has links)
Ostriches are an important commercial species in South Africa and are becoming increasingly so in other parts of the world. Fertility and hatchability of artificially incubated ostrich eggs, however, is generally regarded as low compared to other poultry species and to ostriches in the wild. Investigation into specific farming practices at present indicated scope for an overall improvement in productivity through a sound breeding strategy. This thesis investigated factors that affect egg production, fertility, and hatchability of artificially incubated eggs in the Little Karoo region of South Africa. Specific breeding pair combinations accounted for the major variations in egg weight, hatchability, chick production and offspring weight at slaughter age. An appreciable proportion of variation in reproductive traits was attributable to the repeatable nature of breeding pair performance from year to year, even from first breeding attempts, suggesting that selection of good breeding stock can be made from an early age. Artificially incubated eggs showed improved hatchability when eggs were collected two to three hours after lay rather than the following morning. Storing position of eggs did not significantly effect hatchability when eggs were stored for a maximum of one week. The critical zero temperature for ostrich eggs, below which no embryonical development takes place, was found to be ± 25°C and cooling eggs to temperatures below 20°C for complete cessation of embryonic development during storage resulted in better hatchabilities compared to eggs stored at 25°C room temperature. Hatchability decreased when incubator temperatures were raised from 36 to 37.3°C. Large temperature fluctuations and gradients, which encompass detrimental temperatures, persist within forced draught wooden incubators of the type most commonly in use in the Little Karoo region. The highest temperatures occurred at the top of these incubators and will consequently have a negative impact on hatchability. The ontogeny of ostrich egg metabolism showed an exponential increase during the first 70% of incubation followed by a decline to 75% of the peak value between days 31 and 38 of incubation. From peak levels of embryonic development it was calculated that single stage incubators needs an airflow of 54.4 1/egg.hour to maintain oxygen levels just below 21% and carbon dioxide levels below 0.5%. Lower embryonic mortalities were observed when eggs were turned twenty-four times/day in an electronic incubator compared to hand turning twice a day. Eggs rotated through increasing angles between 60 and 90° resulted in a linear improvement in hatchability. In incubators where turning angles were fixed at 60°, lower hatchabilities were overcome by incubating eggs for 2 - 3 weeks in a horizontal position before placing them vertically. No specific farming practice could be singled out as the main cause of low fertility or hatchability but rather a combination of certain practices applied wrongly.
64

Inkubační strategie vybraných druhů kachen / Incubation strategies of selected duck species

Klvaňa, Petr January 2010 (has links)
- 9 - Incubation strategies of selected duck species Summary of the PhD. thesis Avian incubation is an energetically demanding process. It holds true especially for uniparental incubators in which all incubation efforts are restricted to one individual. All ducks species breeding in northern hemisphere are representatives of birds with uniparental care. High demands of clutch formation and incubation make from ducks perfect model for testing factors influencing parent investment decisions. On the other hand parental investment to actual breeding attempt depends on many factors including breeding season duration, food supply, female's age, risk of predation or resilt of previous nesting attempt. So investigation of this complex problematic is extremely difficult. This thesis is focused on the most important phase of breeding cycle - incubation of clutch. Clutch incubation is associated with high energy cost to maintenance optimal temperature conditions for developing embryos. Morover incubation process can has large effect on female's body mass because of reduction of feeding time. Incubation strategy of success female include many partial tactic reducing predation risk of clutch and incubating female or eggs cooling. The incubation strategies of three ducks species were investigated in this thesis - Mallard...
65

The effects of differential rearing and abstinence period on post-synaptic glutamate receptors and amphetamine seeking

Garcia, Erik Joseph January 1900 (has links)
Doctor of Philosophy / Department of Psychological Sciences / Mary E. Cain / Drug addiction is a chronic cyclical disease characterized by periods of drug use and abstinence. Drug craving increases as a function of abstinence period, such that longer periods of abstinence result in greater feelings of craving. Longer periods of abstinence may render cues to become more powerful motivators of drug seeking behavior because of the greater craving response. Neurobiological evidence suggests that changes in glutamatergic transmission in the nucleus accumbens (NAc) plays a pivotal role in the incubation of craving and drug seeking motivation. Specifically, the upregulation of Ca²⁺ permeable AMPA receptors may increase drug seeking following the presentation of a drug cue. Environmental housing manipulations also change the expression of metabotropic glutamate receptors (mGlur) and psychostimulant self-administration. In the current experiments, Sprague-Dawley rats were reared in enriched (EC) or isolated (IC) conditions from PND 21-51. Then rats were implanted with indwelling jugular catheters and allowed to self-administer amphetamine (0.1 mg/kg/infusion) or saline paired with a cue light for 16 days for 1h. Then rats went through a forced abstinence period of 1 day and were then tested in a cue-induced seeking test. Immediately after the seeking test, half the rats were sacrificed and the NAc was dissected and prepared for western blot analyses. The other half of rats rested for 40 days and were tested again in the cue-induced seeking test. Immediately following the seeking test, rats were sacrificed and their NAc was dissected. Factorial ANOVA results indicate that rearing in the IC environment increased drug seeking when compared to EC rats after 1 day of abstinence and after 40 days of abstinence, but drug seeking did not increase after 40 days. Rats in the saline groups showed an increase in seeking after 40 days of abstinence, providing evidence of increased responding. Saline responding was significantly lower when compared to rats that responded for amphetamine. When rats self-administered saline, generally IC rats had more responding than EC rats. Western blot analyses indicated that expression of AMPA subunits GluA1, and GluA2, as well as metabotropic glutamate receptors 1 and 5 (mGlur1, and mGlur5) were not different across the experimental groups, suggesting another mechanism could be implicated in drug seeking after short and long abstinence periods. These results suggest that early life experience can have long lasting effects into adulthood and increase the vulnerability of drug abuse. Our results provide mixed results of incubated seeking. Positive early life experiences reduce drug seeking motivation after short and long abstinence periods, providing evidence for further research to examine how early life experience changes the reward seeking and subsequent structures in the mesocorticolimbic pathway.
66

Antecedents of business incubator effectiveness: an exploratory study

Lish, Alan David 22 May 2012 (has links)
The purpose of this study is to develop a conceptual model based which examines the influence of various antecedents of the business incubation process. The conceptualized model will be tested empirically using data collected from North American business incubators. The data used are from the National Business Incubator Association's State of the Industry survey. The Partial Least Squares method of analysis is used to explore the identified antecedents, and is used to test validate the model. While a number of resources were identified as components of the incubation process and are considered antecedents of incubator effectiveness (e.g., social networking, access to funding, training, manager/staff intervention), the findings indicate the network of professional services (e.g., legal, marketing, MIS advice) assembled in and around the incubator have the most significant impact on incubator effectiveness. Other resources, such as training, links and management resources, can have an impact, but only insofar as they relate to the professional services resources. The application and screening process were confirmed as essential to find clients that have the proper "fit" within an incubator. The findings indicate that the physical and age characteristics of an incubator are not factors in effectiveness, nor is the networking activities among incubator clients, lending support to a burgeoning class of virtual incubators, accelerators and innovation centers. The results support resource-advantage theory as a foundation theory in the incubation process, and give researchers a basis for future work in this area. The study helps fill gaps in academic research on incubators, and confirms previously theorized work on the process of incubation. In practice, incubator managers and stakeholders can use these results to assemble the particular resources they need for their type of incubator, and more effectively select potential clients based on those resources. This should allow a smoother, more even flow through the incubator, a better use of scarce and valuable resources, and likely higher graduation rates. This study is the first empirical analysis of the incubation process to arrive at a statistically-validated model of business incubation.
67

Incubation humidity as an environmental stressor on the osmoregulatory developmental program of the chicken, Gallus gallus domesticus.

Bolin, Greta M. 08 1900 (has links)
Fetal programming results from stressors during fetal development and may influence the occurrence of disease later in life. Maternal nutritional status and/or environment can affect renal development by inducing limited nephron endowment at birth, which results in diseases such as hypertension and coronary heart disease in mammals. Birds are likely to be effective models for this process because, like mammals, they have high pressure cardiovascular systems, mammalian-type nephrons and are homeothermic. This project uses the chicken embryo to explore physiological responses of disrupted hydration state thereby providing insights into renal fetal programming. Under normal conditions the chorioallantoic membrane (CAM) and developing avian kidney work in unison to ensure a proper balance of ions and water within the egg. White leghorn chicken eggs were incubated at 37.5oC±0.5oC and either <35%, 55-60% (normal) or >85% relative humidity. Amniotic fluid serves as the drinking source for the embryo late in development; its composition is important to salt and water homeostasis. High amniotic fluid osmolality increased the blood osmolality for embryos exposed to low humidity incubation thereby indirectly influencing the renal developmental program of the embryos from this group. Indeed estimated filtering capacity was doubled in the low humidity group (6.77 ± 0.43 mm3) compared to normal (4.80 ± 0.33 mm3) and high (3.97 ± 0.30 mm3) humidity groups. The increased filtering capacity seen for those embryos from low humidity may indicate the ability for more efficient recovery of water if similarly stressed as an adult bird. All embryo populations maintained similar oxygen consumption (0.075 ml/min - 0.37 ml/min), hematocrit (15 % - 32 %) and hemoglobin values (4 g/dl - 9 g/dl), thus displaying control over these aspects of the internal environment despite the obvious environmental insult of extreme incubation humidity. These results signify the embryo's immature kidney, along with lower gastrointestinal tract, functions much like the adult form maintaining homeostasis, although the mechanisms may differ. The overall benefits of this research included better understanding of the role the kidney during embryonic development and determining whether environmental factors, such as humidity, leave an imprint on morphological and physiological aspects of the urinary system of the embryo and water compartments of the egg.
68

Networking skills of government-funded incubator managers as perceived by incubatees

De Beer, Aniel Caro 24 June 2012 (has links)
The link between entrepreneurship and economic growth is well-established. Incubators aim to stimulate entrepreneurship, and one of the factors which contributes to effective incubation is networking. Previous research on the role of networking in entrepreneurship has not focused on how incubatees experience the incubator managers’ networking skills and how these skills contribute to the performance of the incubatees’ ventures while in incubation. The main purpose of this research was to evaluate the contribution of the networking skills of government-funded incubator managers, as perceived by incubatees, to effective incubation. Networking skills were defined as the provision of access by incubator managers to their networks, to incubatees, as well as the facilitation of collaboration by incubator managers between their networks and incubatees. A quantitative study was performed, using a questionnaire to determine incubatees’ perceptions of the various networking skills of the relevant incubator managers, as well as the incubatees’ growth in sales. The population of the study consisted of 565 incubatees currently in incubation at government-funded incubators in South Africa who had access to the questionnaire, and a response rate of 18.4% was realised. The results indicated highly significant correlations, at the 1% level of significance between the networking skills of government-funded incubator managers, as perceived by incubatees, and effective incubation. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted
69

Vliv individuálních vlastností samic čejky chocholaté (Vanellus vanellus) na kvalitu snůšky, párovací status a inkubační úsilí samce / The role of individual traits in the Northern Lapwing (Vanellus vanellus) females on breeding performance, mating status and male incubation effort

Sládeček, Martin January 2015 (has links)
Feather ornaments and its role as a signals in sexual selection has been broadly studied topic in avian biology. However, vast majority of studies focus especially on role of male ornamentation and female preferences in sexual selection. Despite this fact, recent work shows, that similar palette of adaptive functions can be found for female feather ornaments, and male preferences for them, respectively. This study focuses on possible importance of female melanin-based ornaments and other individual on breeding performance in the Northern Lapwing (Vanellus vanellus), common polygynous wader breeding in agricultural landscape. No significant predictor of female investment to egg size was found. Long winged females with bigger proportion of secondaries changed during prenuptial moulting and bigger extent of melanin ornaments tended, surprisingly, to later timing of breeding. Contrary to this trend, extent of female ornamentation seems to be sexually selected trait by males. Analysis of male incubation behavior shows, that males incubate more in nests of more ornamented females, as well as in nests in later incubation stage. These findings seems to be in a good agreement with "Differential allocation hypothesis". On the other site, no effect of clutch egg sizes and timing of breeding was found....
70

Assessing The Impact Of University Technology Incubator Practices On Client Performance

O'Neal, Thomas 01 January 2005 (has links)
This research is designed to distinguish and describe or explain incubator practices that affect the performance of incubator clients of university technology incubator programs. The research focuses on understanding which practices significantly contribute to increasing job creation for the firms located in university based technology incubators. An increasing number of communities are embracing economic development strategies that target the high tech sector with high wage, high value jobs as a way to diversify their economies and boost local and regional economies. New economic development strategies include the notion of a creation strategy or "growing your own" instead of relying on recruiting of existing companies from other regions. In 1999-2000 (according to the most recent data), small businesses created three-quarters of U.S. net new jobs (2.5 million of the 3.4 million total). The small business percentage varies from year to year and reflects economic trends. Over the decade of the 1990s, small business net job creation fluctuated between 60 and 80 percent. Moreover, according to a Bureau of the Census working paper, start-ups in the first two years of operation accounted for virtually all of the net new jobs in the economy. The study is broken into three parts: (1) a review of the literature on incubation, focusing on its history, best practices, technology incubation, networking theory, and previous empirical studies (2) a review of previous data collected in a recent national survey and (3) case studies of the top performing incubators in the country based on employment growth of client firms contracted with case studies from non-top ten programs. The literature suggests that the study of incubation must be considered in the context of a larger enterprise development system of which the incubator will fill gaps in the larger regional enterprise development system. This notion is explored. In general, there is a great need for more empirical research into best practice of incubation. It is a non trivial task however as the nature of the industry limits the ability to obtain traditional, statistically defendable, measures.

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