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No. of bitstreams: 1 JoaoPAFQ_TESE.pdf: 5938914 bytes, checksum: bab7746a655c3cdadf8c43cea1c55b3d (MD5) Previous issue date: 2016-05-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Because the thermoregulation of red-rumped agouti (Dasyprocta leporina Linneus, 1758) and Spix’s yellow-toothed cavy (Galea spixii Wagler, 1831) facing a semiarid environment remain unknown, this study aimed to determine the evaporative heat loss and heat exchanges by radiation and convection. Twenty red-rumped agoutis and twenty-eight Spix’s yellow-toothed cavies were used in different experiments. Red-rumped agoutis were subjected to eight samplings days, and the data collection was performed in five times (7h00, 9h00, 11h00, 14h00 and 16h00). Each Spix’s yellow-toothed cavy was subjected to three sampling days, with data collection performed at hourly intervals, from 6h00 to 13h00. The thermal environment was monitored in each data collection. The body surface temperature was measured by infrared thermography. The body regions considered in the thermograms of red-rumped agoutis were nose, eyes, pinna, body, fore and hindlimbs. In addition to those mentioned for agoutis, thermograms of Spix’s yellow-toothed cavies considered the vibrissae and periocular regions. Evaporative heat loss was determined by calorimetry. The pinna (13.10±1.17 W m-2) and hindlimbs (11.19±1.17 W m-2) of the agoutis were the main regions involved in heat loss by radiation, working as thermal windows. The radiation was higher in the periocular regions (45.23±0.81 W m-2), followed by the eyes surface (41.41±0.81 W m-2), pinna (31.56±0.80 W m-2) and vibrissae (27.03±0.80 W m-2). The periocular temperatures proved to be a valuable predictor of rectal temperature of the cavies, showing a correlation coefficient of 0.61. The convection in agoutis was more intense in the body and hindlimbs at all day times. In cavies, the convection was insignificant (0.54±0.56 W m-2). Evaporative heat loss in agoutis (52.53±1.64 W m-2) and cavies (143.69±1.37 W m-2) was more intense when the atmospheric temperature was higher. Thus, we observe that both non-evaporative and evaporative mechanisms are important for the maintenance of homeothermy in red-rumped agouti and Spix’s yellow-toothed cavy in a hot environment. These rodents use specialized body regions in the heat transfer, the thermal windows / Como a termorregulação de cutias (Dasyprocta leporina Linneus, 1758) e preás (Galea spixii Wagler, 1831) em um ambiente semiárido permanece desconhecida, o presente trabalho objetivou determinar a termólise evaporativa e a transferência de calor por radiação e convecção. Foram utilizadas 20 cutias e 28 preás em experimentos distintos. As cutias foram submetidas a oito dias de amostragem, sendo as coletas de dados realizadas em cinco horários (7h00, 9h00, 11h00, 14h00 e 16h00). Cada preá foi submetido a três dias de amostragem, com coletas de dados realizadas em intervalos de uma hora, das 6h00 às 13h00. O ambiente térmico foi monitorado em cada horário de coleta. A temperatura da superfície corporal foi mensurada por termografia infravermelha. As regiões corporais consideradas nos termogramas das cutias foram: focinho, olhos, orelhas, corpo, membros torácicos e pélvicos. Nos termogramas dos preás foram consideradas, além daquelas mencionadas para cutias, as vibrissas e as perioculares. A termólise evaporativa foi determinada por calorimetria. As orelhas (13,10±1,17 W m-2) e os membros pélvicos (11,19±1,17 W m-2) foram as principais regiões envolvidas na perda de calor por radiação em cutias, funcionando como janelas térmicas. A termólise por radiação em preás foi mais elevada nas regiões perioculares (45,23±0,81 W m-2), seguida dos olhos (41,41±0,81 W m-2), orelhas (31,56±0,80 W m-2) e vibrissas (27,03±0,80 W m-2). As temperaturas das regiões perioculares mostraram ser valorosas preditoras da temperatura retal de preás, exibindo coeficiente de correlação de 0,61. A termólise convectiva em cutias foi mais intensa no corpo e membros pélvicos em todos os horários. Nos preás, a transferência de calor por convecção foi irrisória (0,54±0,56 W m-2). A termólise evaporativa em cutias (52,53±1,64 W m-2) e preás (143,69±1,37 W m-2) foi mais intensa no horário com maior temperatura atmosférica. Assim, observamos que tanto mecanismos não-evaporativos quanto evaporativos são importantes para a manutenção da homeotermia de cutias e preás em ambiente quente. Estes roedores utilizam regiões corporais especializadas na transferência de calor, que correspondem às janelas térmicas / 2017-04-26