Objectives: To determine the physiological strain on industrial workers under thermal stress on extended shifts. To continuously measure deep body core temperatures, heart rates, fluid intake, changes in hydration state and physical fatigue in order to establish acceptable levels of physiological strain. To develop a rational heat stress index compatible with these limits. To design working-in-heat protocols for a self-paced workforce. Methods: A series of studies was conducted over 77 shifts on a group of approximately 50 male volunteers working in thermally stressful environments. Continuously- recorded deep body core temperatures, heart rates, fluid consumption, urinary specific gravity and physical fatigue were measured and recorded. A new field protocol was developed to assess physical fatigue over the working shift. An original methodology was developed to allow any heat stress index to be assessed on a comparative basis with any other index. A review of the commonly used occupational heat stress indices was conducted. A new rational heat stress index was developed, based on existing biophysical relationships and recommended physiological strain limits of deep body core temperature and sweat rate. New protocols designed for self-paced work incorporating the significant risk factors for heat illness were developed and implemented in a workforce of approximately 2000 workers exposed to heat stress. The previous protocols used a shortened shift as the primary intervention to protect worker health. The subsequent protocols removed the shortened shift and replaced this with a range of other interventions. Deep body core temperature, heart rate, fluid consumption, hydration state and fatigue were measured before and after the changes in protocols. / Results: Comparisons of heat stress indices confirmed the wide divergence in guidance provided by many of the commonly-used indices in terms of acceptable working environments. It also highlighted a number of serious shortcomings in the most widely-used indices, especially WBGT and ISO7933. A new, rational heat stress index called Thermal Work Limit (TWL) was developed. This included development of a computer model incorporating key thermal physiological parameters (deep body core temperature, mean skin temperature, sweat rate, skin wettedness). There was no increase in heat stress (as indicated by average workplace environmental conditions), deep body core temperature, mean heart rate, or changes in hydration status after the changes in protocols. Average environmental conditions were severe (WBGT 30.9° C, sd 2.0° C, range 25.7-35.2° C). Environmental conditions in the study were much hotter than those considered acceptable under standards such as the ACGIH. The results showed that miners regularly exceeded those limits allowable under most current indices in terms of maximum deep body core temperature (avg 38.3° C, std dev 0.4° C), maximum temperature rise (1.4° C, 0.4° C) and maximum heat storage (431 kJ, 163 kJ), without reporting any symptoms of heat illness. A significant component of the observed elevated core temperatures was due to the normal circadian rhythm, which was measured at 0.9° C (std dev 0.2° C). Evidence was found that workers "self-pace" when under thermal stress. Fluid intake averaged 0.8 l/h during exposure (sd 0.3 l/h, range 0.3-1.5 1/h). Average urinary specific gravity at start-, mid- and end of shift was 1.0251, 1.0248 and 1.0254 respectively; the differences between start and mid-shift, mid and end-shift, and start and end-shift were not significant. / However, a majority of workers were coming to work in a moderately hypohydrated state (urinary specific gravity avg 1.024, std dev 0.0059). Involuntary dehydration was not found to occur in the study group. This is in contrast to several other studies and some of the leading heat stress standards, which are based on the premise that workers are unable to maintain their hydration status when working in the heat, even when their fluid consumption is equal to their sweat rate. Continuous heart rates measured over a shift (avg 103 bpm, 14% of shifts exceeding avg 110 bpm, 5% exceeding avg 120 bpm) were in excess of those allowable under most current indices On average, workers experienced a peak 10- minute heart rate of 140 bpm and a peak 30-minute heart rate of 130 bpm during their shifts. There was a significant increase in fatigue in the first half of the working shift (P=0.001), with workers on average showing a significant recovery in the second half of their shift (p=0.04). Conclusions: Current heat stress indices provide little common agreement as to acceptable levels of thermal strain or stress for workers, at equivalent levels of environmental stress. IS07933 is seriously flawed and the ACGIH WBGT guidelines are too conservative for acclimatised workers and are unlikely to become widely adopted by industries with well-acclimatised workers. Many of the existing indices show internal inconsistencies. / Most of the physiological heat strain limits used in existing rational heat stress indices (in terms of deep body core temperature and heart rate) are conservative for self-paced, acclimatise d, non-dehydrating male workers. Involuntary dehydration is not unavoidable when acclimatised workers are exposed to thermal stress. Heat stress standards should not limit heat exposure durations for self- paced workers who have access to water on the basis of an unavoidable body water loss. Physical fatigue does occur in workers under heat stress on extended shifts; however, most workers show a significant increase in fatigue in the first half of their shift; whereas data indicates self-paced workers undergo significant recovery in terms of fatigue in the second half of the shift. As the heat exposures in this study cover a wide range of temperatures, humidity levels, wind speeds, body morphology and VO2max, these conclusions are applicable to most thermally stressful settings involving well-informed, well-acclimatised and self-paced male workers. The major category of work type not covered by this study is that of workers in fully-encapsulated (vapour-barrier) protective clothing. In addition, this study examined acute effects of heat stress and strain, not effects that might only be manifest with chronic exposure to heat.

Aufgrund der zu erwartenden Klimaveränderungen, insbesondere durch eine Erhöhung der Temperaturen und einer Zunahme der Extremsituationen (Hitze- und Kälteperioden), sollte vermehrt über Effekte von Hitzestress auf das Wohlbefinden und Leistungsvermögen von Tieren nachgedacht werden. Um den Einfluss von klimatischen Bedingungen (Temperatur und Temperatur-Humiditäts Index) auf die Gesundheit und das Leistungsvermögen von Milchkühen zu untersuchen, wurden drei Studien durchgeführt. Zuerst wurden die Auswirkungen des Temperatur-Humiditäts Index (THI) auf die Behandlungsfrequenz von Milchkühen ermittelt. Hierfür wurden die Daten aus den Bestandsbüchern von 2003 und 2005 von acht Milchviehbetrieben ausgewertet. Die Behandlungen wurden in vier Komplexe unterteilt: Stoffwechsel, Fruchtbarkeit, Euter und Klauen, wobei 37,4% der Behandlungen zum Stoffwechsel-, 32,9% zum Euter-, 21,6% zum Fruchtbarkeits- und 8,1% zum Klauenkomplex gehörten. Es zeigten sich ein tendenzieller Anstieg der Stoffwechselinzidenzen mit steigendem THI und ein nicht signifikanter Anstieg von Euterbehandlungen mit abfallendem THI. Die zu analysierenden Daten bezüglich des Einflusses auf das Leistungsvermögen wurden im Rahmen eines einjährigen Feldversuches vom April 2010 bis März 2011 aufgenommen. Hierfür wurden aus einem Pool von niedersächsischen Milchviehbetrieben 20 Betriebe mit unterschiedlichen Haltungssystemen (gedämmte und ungedämmte Laufställe mit und ohne Weidegang) ausgewählt. Auf diesen Betrieben wurden klimatische Werte (Stalltemperatur, relative Stallluftfeuchtigkeit und THI) als auch Herden- bzw. tierindividuelle Leistungsdaten (4% fettkorrigierte Milchmenge (FCM), Milchinhaltsstoffe und somatischer Zellscore (SCS)) anhand von Tankmilchproben bzw. Einzeltiermilchproben im Rahmen der Milchleistungsprüfung erfasst. Insgesamt wiesen die Untersuchungen unterschiedlich hohe Hitzestresseffekte auf die Milchleistung, Milchinhaltsstoffe und den SCS in den verschiedenen Haltungssystemen auf. Für die Milchmenge ergaben sich Regressionskoeffizienten von -0,12 kg FCM/THI und -0,11 kg FCM/THI bei gedämmten Laufställen ohne und mit Weidegang sowie -0,21 kg FCM/THI für Außenklimaställe ohne und mit Weidegang. Für den SCS ergaben sich bei den Stallhaltungssystemen Regressionskoeffizienten von +0.03 SCS/THI für gedämmte Systeme und +0,07 SCS/THI für Außenklimaställe. Basierend auf den Ergebnissen der Arbeit kann geschlussfolgert werden, dass Milchkühe in Niedersachsen während der Sommermonate Hitzestress ausgesetzt waren, wohingegen sich die Auswirkungen je nach Haltungssystem differenziert darstellten. Des Weiteren konnte gezeigt werden, dass in dem System mit gedämmtem Dach niedrigere Auswirkungen mit steigendem THI zu finden waren.

A Saccharomyces cerevisiae, un increment de la temperatura comporta diversos efectes deleteris en l’organització interna de la cèl∙lula i indueix una inducció ràpida, massiva i transitòria d’expressió gènica, que es controla principalment pels factors de transcripció Hsf1 i Msn2/4. En aquest estudi, fent servir un crivatge genètic a gran escala, hem identificat el conjunt d’activitats que es requereixen per a l’adaptació cel∙lular a l’estrés tèrmic. A més, hem trobat que el complex de desacetilació d’histones de Rpd3 és un component essencial per a l’adaptació i la supervivència a l’estrés tèrmic, i que es requereix per a l’adequada regulació de l’expressió gènica. Concretament, Rpd3 es necessita per a l’activació dels gens depenents de Msn2/4 en resposta a estrés tèrmic. A més, hem trobat que és el complex gran de Rpd3, però no el petit, el qui media l’adaptació cel∙lular. Un increment en l’osmolaritat externa activa la quinasa activada per estrés (SAPK) Hog1, que és essencial per induir diverses respostes adaptatives, com la regulació de l’expressió gènica. Hog1 controla al menys cinc factors de transcripció. Aquí ensenyem que els factors de transcripció Rtg1 i Rtg3 regulen l’expressió d’un conjunt de gens en resposta a estrés osmòtic, d’una manera depenent de Hog1. En resposta a estrés osmòtic, Hog1 es requereix per a l’acumulació nuclear del complex de transcripció de Rtg1/3. Un cop al nucli, Hog1 es recluta als promotors i la seva activitat es requereix per a la unió de Rtg1/3 a la cromatina. A més, la fosforilació de Rtg3 per Hog1 és un pas important per a l’adequada activació transcripcional. / In Saccharomyces cerevisiae, increases in temperature lead to deleterious effects on the internal organization of the cell, and lead to a massive and transient induction of gene expression, mainly controlled by Hsf1 and Msn2/4 transcription factors. In this study, by using a genome‐wide genetic screen, we identified the network of essential activities required for cell adaptation to heat stress. Moreover, we found that the Rpd3 histone deacetylase (HDAC) complex is an essential component for adaptation and survival to heat stress and it is required for proper regulation of gene expression. Specifically, Rpd3 is needed for activation of the Msn2/4‐dependent genes in response to heat stress. Moreover, we found that the large, but not the small Rpd3 complex mediates cell adaptation. Increases in the extracellular osmolarity activate the Hog1 stress‐activated protein kinase (SAPK), which is essential for the induction of diverse osmoadaptive responses, such as regulation of gene expression. At least five transcription factors have been shown to be controlled by Hog1. Here we show that the Rtg1 and Rtg3 transcription factors regulate the expression of a set of genes upon osmostress in a Hog1‐dependent manner. In response to osmostress, Hog1 is required for the nuclear accumulation of the Rtg1/3 transcription complex. Once in the nucleus, Hog1 is recruited at promoters and its activity is required for the binding of Rtg1/3 to chromatin. Moreover, Rtg3 phosphorylation by Hog1 is an important step for proper transcriptional activation.

[Truncated abstract] Wheat is the main crop in Australia and there are stringent quality requirements. Preharvest sprouting induced by rainfall between maturity and harvest lowers grain quality from premium to feed grades and reduces yield. Wheat production has expanded into the southern Western Australian region where preharvest sprouting occurs in ~1 in 4 seasons and development of more preharvest sprouting tolerant genotypes is required. The main mechanism for improving preharvest sprouting tolerance is grain dormancy. There is genetic variation for dormancy based in the embryo and seed coat but dormancy is complex and is influenced by environmental conditions during grain filling and maturation. Screening and selecting for preharvest sprouting tolerance is problematic and the level of tolerance needed for regions which differ in the level of dormancy they impose, requires clarification. The research presented here aims to answer the underlying question for breeders of how much dormancy is required for preharvest sprouting tolerance in contrasting target environments of the central and coastal wheat belt regions of Western Australia. In the central and coastal wheat belt regions, field trials with modified environments were used to determine the environmental influence on dormancy. Water supply (without directly wetting the grain) and air temperature were modified during grain development in a range of genotypes with different mechanisms of dormancy to determine the influence of environment on dormancy. ... Genotypes with embryo dormancy were consistently the most preharvest sprouting tolerant, even though this dormancy was influenced by the environmental conditions in the different seasons. Pyramiding the embryo component with the specific seed coat component and/or awnless head trait removed some of the environmental variation in preharvest sprouting tolerance, but this was generally considered excessive to the environmental requirements. The methods developed here, of field imposed stresses may provide a valuable tool to further understand the influence of environment on the regulation of dormancy, as different phenotypes can be made with the same genotype. Moisture stress, sudden changes in water supply or high temperatures during the late dough stages influenced dormancy phenotype and should be considered and avoided if possible when selecting locations and running trials for screening for genetic differences in preharvest sprouting tolerance. In the Western Australian context, the embryo component of dormancy appeared to be sufficient and should be adopted as the most important trait for breeding for preharvest sprouting tolerance.

Orientador: Rodrigo Egydio Barreto / Resumo: Os caranguejos-chama-maré são espécies semiterrestres, sociais, que habitam margens de praias abertas, manguezais e marismas, tanto em zonas tropicais como temperadas. Cada indivíduo concentra suas atividades em torno de uma toca, com as fêmeas possuindo os dois quelípodo de mesmo tamanho, enquanto os machos possuem um dos quelípodo hipertrofiado, usados como armas durante interações agressivas para proteção do território ou durante a corte em um movimento característico de display, sendo excelentes modelos para estudos de competição e seleção sexual. Além disso, a escavação do solo para construção de suas tocas acarreta na maior oxigenação do mesmo, altera as condições de drenagem, distribuição de partículas, disponibilidade de matérias orgânicas e nutrientes, sendo assim considerados engenheiros do ecossistema. Portanto, alterações nos manguezais que influenciam na distribuição desse grupo de caranguejos podem intensificar potenciais impactos nessas regiões. A presente tese de doutorado foi dividida em três capítulos. O estudo do capítulo 1 foi realizado em manguezais do litoral centro/sul do Estado de São Paulo, onde investigamos o efeito do sombreamento na distribuição espacial, comportamento e fisiologia de duas espécies de caranguejos-chama-marés: Leptuca leptodactyla e Leptuca urugayensis. Já o estudo do capítulo 2 foi concretizado durante período de doutorado sanduíche no exterior, realizado na Austrália. Nele, examinamos o efeito da migração de espécies de áreas adja... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Made available in DSpace on 2016-08-12T19:15:22Z (GMT). No. of bitstreams: 1 MariaFSP_DISSERT.pdf: 658275 bytes, checksum: 251a44b08b0ba371e0d3c72f2bdc71f0 (MD5) Previous issue date: 2012-03-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The evaluation of the vigor is of fundamental importance in control programs of seed quality, and accelerated aging test can be used for this purpose. In this sense, the objective of this paper was to study the methodology of the accelerated aging test, seeking to verify their efficiency to identify differences between levels of seed lots vigor of coriander (Coriandrum sativum L.). During the experimental period, the seeds were packed in plastic bags and kept in a controlled environment (16 ° C and 50% RH). For this, the following cultivars Verdão, Super-verdão, Tabocas and Portugues were used, each one represented by three lots. The seeds were tested for germination, first count germination, seedling emergence, speed of emergence, shoot length, dry mass of shoots and accelerated aging (38 and 41 ° C for 48, 72 and 96 hours; method traditional and with use of saline solution), besides the determination of moisture content of seeds. The work was performed at the Laboratory of Seed Analysis and in the greenhouse of the Universidade Federal Rural do Semi-Arido Mossoró-RN. A completely randomized design with four replications of 50 seeds was used. The test results were evaluated individually. The analysis of variance was performed by F test and the means compared by Tukey test (P ≤ 0.05). It was concluded that the accelerated aging test was efficient to evaluate the physiological potential of coriander seeds, and that combinations 41°C/48h (traditional method) and 41°C/72h (with saline solution) constituted in an efficient procedure to detect differences of vigor among seed lots of coriander / A avaliação do vigor é de fundamental importância em programas de controle de qualidade de sementes, e o teste de envelhecimento acelerado pode ser utilizado para este fim. Nesse sentido, o objetivo deste trabalho foi estudar a metodologia do teste de envelhecimento acelerado, procurando-se verificar sua eficiência para identificar diferenças entre níveis de vigor de lotes de sementes de coentro (Coriandrum sativum L.). Durante o período experimental, as sementes foram acondicionadas em sacos plásticos e mantidas em ambiente controlado (16ºC e 50% UR). Para isso, utilizou-se as cultivares Verdão, Super-verdão, Tabocas e Português, cada uma representada por três lotes. As sementes foram submetidas aos testes de germinação, primeira contagem de germinação, emergência de plântulas, índice de velocidade de emergência, comprimento de parte aérea, massa seca de parte aérea e envelhecimento acelerado (38 e 41ºC; 48, 72 e 96 horas; método tradicional e com uso de solução salina), além da determinação do grau de umidade das sementes. Os trabalhos foram realizados no Laboratório de Análises de Sementes e em casa de vegetação, da Universidade Federal Rural do Semi-Árido, Mossoró-RN. Utilizou-se o delineamento inteiramente casualizado, com quatro repetições de 50 sementes. Os resultados dos testes foram avaliados individualmente, quanto à análise de variância pelo teste F e as médias comparadas pelo teste de Tukey (P ≤ 0,05). Diante dos resultados, conclui-se que o teste de envelhecimento acelerado mostrou-se eficiente para avaliar o potencial fisiológico das sementes de coentro; e que as combinações 41°C/48h (tradicional) e 41°C/72h (com solução salina) constituiu-se em procedimento eficiente para detectar diferenças de vigor entre lotes de sementes de coentro

Made available in DSpace on 2016-08-12T19:18:43Z (GMT). No. of bitstreams: 1 MariaFSP_DISSERT.pdf: 658275 bytes, checksum: 251a44b08b0ba371e0d3c72f2bdc71f0 (MD5) Previous issue date: 2012-03-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The evaluation of the vigor is of fundamental importance in control programs of seed quality, and accelerated aging test can be used for this purpose. In this sense, the objective of this paper was to study the methodology of the accelerated aging test, seeking to verify their efficiency to identify differences between levels of seed lots vigor of coriander (Coriandrum sativum L.). During the experimental period, the seeds were packed in plastic bags and kept in a controlled environment (16 ° C and 50% RH). For this, the following cultivars Verdão, Super-verdão, Tabocas and Portugues were used, each one represented by three lots. The seeds were tested for germination, first count germination, seedling emergence, speed of emergence, shoot length, dry mass of shoots and accelerated aging (38 and 41 ° C for 48, 72 and 96 hours; method traditional and with use of saline solution), besides the determination of moisture content of seeds. The work was performed at the Laboratory of Seed Analysis and in the greenhouse of the Universidade Federal Rural do Semi-Arido Mossoró-RN. A completely randomized design with four replications of 50 seeds was used. The test results were evaluated individually. The analysis of variance was performed by F test and the means compared by Tukey test (P ≤ 0.05). It was concluded that the accelerated aging test was efficient to evaluate the physiological potential of coriander seeds, and that combinations 41°C/48h (traditional method) and 41°C/72h (with saline solution) constituted in an efficient procedure to detect differences of vigor among seed lots of coriander / A avaliação do vigor é de fundamental importância em programas de controle de qualidade de sementes, e o teste de envelhecimento acelerado pode ser utilizado para este fim. Nesse sentido, o objetivo deste trabalho foi estudar a metodologia do teste de envelhecimento acelerado, procurando-se verificar sua eficiência para identificar diferenças entre níveis de vigor de lotes de sementes de coentro (Coriandrum sativum L.). Durante o período experimental, as sementes foram acondicionadas em sacos plásticos e mantidas em ambiente controlado (16ºC e 50% UR). Para isso, utilizou-se as cultivares Verdão, Super-verdão, Tabocas e Português, cada uma representada por três lotes. As sementes foram submetidas aos testes de germinação, primeira contagem de germinação, emergência de plântulas, índice de velocidade de emergência, comprimento de parte aérea, massa seca de parte aérea e envelhecimento acelerado (38 e 41ºC; 48, 72 e 96 horas; método tradicional e com uso de solução salina), além da determinação do grau de umidade das sementes. Os trabalhos foram realizados no Laboratório de Análises de Sementes e em casa de vegetação, da Universidade Federal Rural do Semi-Árido, Mossoró-RN. Utilizou-se o delineamento inteiramente casualizado, com quatro repetições de 50 sementes. Os resultados dos testes foram avaliados individualmente, quanto à análise de variância pelo teste F e as médias comparadas pelo teste de Tukey (P ≤ 0,05). Diante dos resultados, conclui-se que o teste de envelhecimento acelerado mostrou-se eficiente para avaliar o potencial fisiológico das sementes de coentro; e que as combinações 41°C/48h (tradicional) e 41°C/72h (com solução salina) constituiu-se em procedimento eficiente para detectar diferenças de vigor entre lotes de sementes de coentro

O estresse calórico em gado leiteiro especializado torna-se um fator limitante para a produção de leite no estado do Rio Grande do Sul durante os meses de maior índice temperatura-umidade. O impacto fisiológico sobre o animal tem repercussão não somente sobre o metabolismo animal, mas também na quantidade e na qualidade do leite produzido. Não existem estudos prévios sobre o grau de impacto que o estresse por calor possa causar em gado da raça Holandesa no Rio Grande do Sul com enfoque no metabolismo e na qualidade do leite. O presente projeto estudou as alterações que o estresse calórico ocasiona em vacas leiteiras especializadas sobre indicadores clínicos, produtivos e metabólicos. Um total de 450 observações foram realizadas durante dois anos consecutivos em uma fazenda leiteira de alta produção da região do Planalto Médio do Rio Grande do Sul. O grau de estresse calórico foi considerado quando o índice temperatura-umidade (THI) ficou acima de 80. O estresse calórico foi evidente sobre os indicadores clínicos (temperatura corporal e frequência respiratória) e causou redução de 17% da produção de leite, bem como diminuição na quantidade de lactose e aumento na CCS, porém sem afetar o teor de gordura nem de proteína. Os indicadores metabólicos mais afetados foram proteínas totais, albumina e ureia, com respostas compatíveis com grau de desidratação leve, glicose com aumento atribuído à maior secreção de cortisol, e colesterol com aumento atribuído à menor secreção de tiroxina, em animais em estresse por calor. Lactato foi menor em animais estressados, sendo seu mecanismo objeto de futuros estudos. Ficou evidente uma condição de alcalose respiratória e a resposta compensatória de acidose metabólica. Conclui-se que o estresse calórico nos animais estudados repercute em mudanças clínicas, produtivas, metabólicas e ácido-básicas. / Heat stress is a limiting factor for milk production in high yielding dairy cows in Rio Grande do Sul (Brazil) during the months with the highest temperature-humidity index (THI). The physiological impact caused by high THI has not only consequences in the animal’s metabolism, but also in the animal’s milk yield and milk composition (quality). To our knowledge, there are no previous studies that related the impact of heat stress on metabolism and milk composition of high yielding Holstein cows in RG. The objective of the present study was to evaluate the effects of heat stress on clinical, productive, and metabolic parameters in high yielding dairy cows. A total of 450 observations were taken during 2 consecutive years in a commercial dairy farm in the RG’s plateau region. Heat stress was characterized as a THI greater than 80. Clinical parameters (rectal temperature and respiratory frequency) was clearly affected by heat stress as well as reduction of milk yield (17%), milk lactose, and increased milk somatic cells count However, milk fat and milk protein were not affected by heat stress. The metabolic parameters that were greatly affected by heat stressed Holstein cows were total protein, albumin, and blood urea concentrations corresponding to cow’s slight degree of dehydration; glucose concentration was increased and associated with a higher secretion of cortisol; and cholesterol concentration was increased due to lower secretion of tiroxine. Blood lactate concentration was lower in heat stressed animals when compared with non-stressed animals but the specific mechanism is still to be determined. Therefore, heat stressed cows evidently showed a state of respiratory alkalosis that was compensated by a state of metabolic acidosis. In conclusion, cows that experienced heat stress in the present study had altered clinical, productive, metabolic and acid-base parameters when compared with non-stressed cows.

Made available in DSpace on 2014-06-11T19:28:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-23Bitstream added on 2014-06-13T20:48:08Z : No. of bitstreams: 1 souza_lfa_me_jabo.pdf: 291371 bytes, checksum: 2921d3b2418a9b75c8fccd1974605cd7 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho avaliou o efeito da exposição ao calor crônico e cíclico sobre o desempenho, metabolização dos nutrientes, energia metabolizável aparente corrigida para balanço de nitrogênio (EMAn) e atividade de enzimas pancreáticas em frangos de corte. Foram utilizados 450 frangos, distribuídos em delineamento inteiramente casualizado com 5 esquemas de temperatura/alimentação (TN/Ad libitum, Crônico/Ad libitum, TN/restrito a Crônico, Cíclico/Ad libitum e TN/restrito a Cíclico). Assim, TN representa a temperatura termoneutra e os grupos TN/restrito a Crônico e TN/restrito a Cíclico receberam a mesma quantidade de ração que Crônico/Ad libitum e Cíclico/Ad libitum, respectivamente. A exposição crônica ao calor afetou o desempenho de frangos de corte com maior intensidade que a exposição cíclica, havendo efeito direto do calor crônico e cíclico. Os coeficientes de metabolização da matéria seca, gordura e a EMAn aumentaram com a idade. Os coeficientes de metabolização dos nutrientes foram diminuídos pela exposição crônica ao calor, havendo efeito direto da temperatura apenas para gordura. A restrição alimentar gerada pelo calor crônico causou aumento da atividade da amilase e redução na atividade da tripsina. A atividade da lipase aumentou devido ao efeito direto do calor crônico. A menor digestibilidade dos nutrientes foi associada à piora do desempenho das aves expostas ao calor crônico, porém não foi relacionada à piora dos índices zootécnicos dos frangos expostos ao calor cíclico. A redução da atividade da tripsina pode estar associada à menor digestibilidade da proteína causada pelo estresse por calor crônico. / This work evaluated the effect of the chronic and cyclical heat stress in performance, metabolization of nutrients, apparent metabolizable energy corrected for nitrogen balance (EMAn) and pancreatic enzymes activity in broiler chickens. 450 chickens, distributed in completely randomized design with 5 groups of temperature/feeding (TN/Ad libitum, Chronic/Ad libitum, TN/Chronic restrict, Cyclical/Ad libitum and TN/Cyclical restrict). Thus, TN represents the thermoneutral temperature and the TN/Chronic restrict and TN/Cyclical restrict had received the same amount from feed that Chronic/Ad libitum and Cyclical/Ad libitum, respectively. The chronic exposition to the heat affected the performance of chickens with bigger intensity that the cyclical exposition, having direct effect of the chronic and cyclical heat. The coefficients of metabolization of dry matter, fat and EMAn had increased with the age. The coefficients of metabolization of nutrients had been decreased by the chronic heat stress, having direct effect of the temperature only for fat. The feed restriction generated by the chronic heat caused increase of amylase activity and reduction in trypsin activity. The lipase activity increased due to direct effect of chronic heat exposure. The lesser metabolization of nutrients was associated with the worsening of the performance of the chronic heat exposed broilers, however it was not related to the worsening of performance of chickens exposed to cyclical heat stress. The reduction of the trypsin activity can be associated to the lesser digestibility of the protein caused for chronic heat stress.

Made available in DSpace on 2014-06-11T19:28:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-23Bitstream added on 2014-06-13T19:16:15Z : No. of bitstreams: 1 deantonio_j_me_jabo.pdf: 657213 bytes, checksum: 374031f1e29e0df005c8fe1ed5dc8c25 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O estresse por calor é considerado um dos fatores de maior impacto na criação de frangos de corte, já que exerce grande influência no desempenho e na qualidade da carcaça, bem como no perfil de expressão de genes relacionados ao crescimento e desenvolvimento animal. Assim, o presente trabalho objetivou verificar o efeito da temperatura e da restrição alimentar no desempenho, composição de carcaça e nos padrões de expressão de genes envolvidos na regulação do crescimento e desenvolvimento (GHR, IGF-I e IGF-IR), aos 21 e 42 dias de idade dos frangos de corte pela técnica de PCR quantitativo em tempo real. Os resultados evidenciaram que a restrição alimentar imposta pela exposição ao calor reduziu o desempenho e rendimento de peito e aumentou o rendimento de coxas+sobrecoxas. O estresse por calor e o consumo de ração alteraram o rendimento de asas, mas não influenciaram o rendimento de carcaça e de gordura abdominal. O calor aumentou o teor de extrato etéreo no peito e nas asas e diminuiu o de matéria mineral nas coxas+sobrecoxas. Independente da temperatura de criação, a restrição alimentar exerce um efeito negativo na expressão do gene do GHR no fígado das aves jovens, sem maiores reflexos na expressão do gene do IGF-I. O estresse térmico afeta a expressão dos genes hepáticos GHR e IGF-I somente nas aves adultas, as quais apresentam perfil inverso ao das aves restritas pelo “pair-feeding”. A reação de amplificação do gene IGF-IR apresentou formação de produtos de amplificação inespecíficos, assim como formação de estruturas secundárias das moléculas dos iniciadores (dímeros e “hairpins”), o que impossibilitou a análise dos resultados / Heat stress is considered one of greatest impact factors on broiler chicken production, once that it has great influence on the performance and carcass quality, as well as on the expression profile of genes related to growth and animal development. Thus, the present work had the objective of verifying the effect of temperature and food restriction on the performance, carcass composition and expression pattern of genes involved in the growth regulation and development (GHR, IGF-I and IGF-IR), at 21 and 42 days of age of the broilers using the PCR quantitative real-time technique. The results showed that the food restriction imposed by heat exposure, affected negatively the performance and breast yield and, positively, the tight and drumstick yield. The heat stress and feed intake altered the yield of wings, but did not affect carcass yield and abdominal fat. The heat increased both ether extract content in the breast and wings and reduced the mineral matter content in the tights and drumsticks. Independent of temperature, in the young bird’s livers, food restriction endorses a negative effect on the GHR gene expression, without greatest reflects on IGF-I expression. Only on adult bird’s, thermal stress affects the expression of GHR and IGF-I hepatic genes, that exhibit an inverse profile of restricted pair-feeding birds. The amplification reaction of IGF-IR gene showed both formation of nonspecific amplification products, as well as secondary structures of the primers of the molecules (dimerous and hairpins), precluding the analysis of results