Navegando por Assunto "Estresse térmico"

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Acesso aberto (Open Access)
Respostas termolíticas e qualidade seminal de ovinos naturalizados criados em ambiente tropical
(Universidade Federal do Pará, 2015-10-30) KAHWAGE, Priscila Reis; GARCIA, Alexandre Rossetto; http://lattes.cnpq.br/2678267039338224
The study aimed to deepen knowledge about anatomical and physiological features related to body heat loss ability and relation to semen quality of naturalized sheep Morada Nova and Santa Ines on tropical environment. Nine male Santa Inês and seven Morada Nova breed were subjected to two experiments. The first test included monitoring of coat features (amount of melanin, thick, length and diameter of the fibers), sweat rate, physiological indicators of thermal comfort (respiratory rate, heart rate, rectal temperature, surface temperature, skin temperature and scrotal surface temperature), sperm quality (sperm concentration, progressive motility, plasma membrane integrity, major defects, minor defects and total defects) and testicular parenchyma integrity coupled with the meteorological variables measured throughout the year. Statistical analysis was performed using the GLM and LSMEANS procedures of SAS software, version 9.1.3. Significant differences (P <0.05) were observed between the summer and fall and winter, with increase in termolitics parameters during the hot season. Already sperm quality did not vary throughout the year. The second experiment evaluated the capacity of rams to maintain body and testicular homeothermy under thermal challenge. Animals were subjected to heat tolerance test, which consists maintenance in the shade (period 1), followed by exposure to the sun (period 2) and return to the shadow (period 3). In the three periods were measured: respiratory rate, heart rate, body surface temperature, back, eyeball and scrotum, by infrared thermography. Adaptability of the animals was measured by heat tolerance index calculation. Sperm quality and testicular parenchyma integrity were evaluated before and after the heat challenge. In Period 1, the variables had baseline values for both genotypes. In Period 2, the variables involved in thermolysis significantly increased (P<0.05), which matches a thermal discomfort situation. In Period 3, the variables returned to baseline values and some values were lower than those in Period 1. Seminal and ultrasonographic variables did not share with thermal insult. It is concluded that MN and SIN rams had efficient thermolytic mechanisms that favor preserving gonadal functionality. The animals were considered resilient to a thermal challenge.
Acesso aberto (Open Access)
Thermoregulatory responses of female buffaloes reared under direct sunlight and shaded areas in the dry season on Marajó Island, Brazil
(Universidade Federal do Pará, 2018-08-16) JOSET, Waléria Cristina Lopes; SILVA, Jamile Andréa Rodrigues da; GODINHO, Letícia Athaíde; BARBOSA, Antônio Vinícius Corrêa; MARTORANO, Lucieta Guerreiro; LOURENÇO JÚNIOR, José de Brito
This research aimed to assess the effects of dry season climate variables on Marajó Island, Brazil, on the thermoregulatory responses of twenty female buffaloes, assigned to shaded (SD), and unshaded groups (US). Data on air temperature (AT), relative air humidity, wind velocity (WV), respiratory rate (RR), rectal temperature (RT), and body surface temperature (BST) were recorded at 6 a.m., 10 a.m., 2 p.m., 6 p.m., and 10 p.m. The temperature and humidity index (THI), practical buffalo comfort climatic conditions index (BCCCIp), and practical buffalo environmental comfort index (BECIp) were calculated. At 10 a.m. and 2 p.m., WV was the highest. The RR of animals in both treatments differed only at 10 a.m. and 2 p.m. A difference in RT between treatments was seen at 10 a.m., 2 a.m., and 6 p.m. Significant changes were seen in the BST of animals in both groups at 10 a.m., 2 p.m., and 10 p.m. BECIp was different between the groups at 10 a.m. and 2 p.m., with higher values for the US group. Buffaloes are prone to thermal stress, particularly between 10 a.m. and 2 p.m., when the highest values of AT, THI, and BCCCIp was observed.