Variação anual de hormônios tireoideanos e características termorreguladoras de vacas leiteiras em ambiente quente

Morais, Débora Andréa Evangelista Façanha; Maia, Alex Sandro Campos; Silva, Alexandre Rodrigues; Vasconcelos, Angela Maria de; Lima, Patrícia de Oliveira; Guilhermino, Magda Maria

doi:10.1590/s1516-35982008000300020

Cited by 36 publications

(25 citation statements)

References 4 publications

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“…When temperature and humidity increase, evapotranspiration pathways such as panting and respiration rate increase, but as the heat dissipation mechanisms become insufficient, animals cannot control their body temperature and may be affected by hyperthermia (Morais et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

Access to shade changes behavioral and physiological attributes of dairy cows during the hot season in the subtropics

Vizzotto

Fischer

Neto

et al. 2015

Animal

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The effect of shade on behavior and physiological attributes of grazing cows in a high altitude subtropical zone is not well established. This work aimed to investigate how social and ingestive behaviors, as well as physiological and other attributes of dairy cows such as milk production, change in a subtropical environment during the hot season either with or without free access to shade. Fourteen lactating cows were kept on pasture either with no shade or with free access to shade for 5 days and their behavior was recorded with instantaneous scan sampled every 10 min, from sunrise, 0530 h (Greenwich mean time, GMT − 0200 h) to sunset, 2100 h (GMT − 0200 h). Behavior traits included (1) time spent in activities such as grazing, ruminating, resting, lying, standing, walking, seeking shade and staying in the proximity to the water trough and (2) number of events such as water ingestion, aggressive interactions, as well as competition for shade and water. Physiological attributes such as heart and respiratory rates, rectal temperature, number of rumen movements, panting score, as well as milk yield, were evaluated. Time spent in behavioral activities, number of behavioral events and physiological attributes varied between groups (with and without access to shade). Cows with no shade showed increased respiratory and heart rates and panting score at 1300 h, higher values for time of permanence near the water trough, number of competition and aggression events for shade. On the other hand, they showed lower values for time spent resting while lying, ruminating while standing, seeking shade. Access to shade did not change time spent lying, standing, walking with the head up, ruminating while lying, resting while standing, as well as milk yield and number of ruminal movements. Significant interactions between access to shade and days of measurements were detected for time spent walking, ruminating, grazing, resting, number of water ingestion events, competition events near the water trough and for shade, as well as for rectal temperature and panting score measured at 1700 h. In the high altitude subtropical region, access to shade minimizes negative heat stress effects on behavior and physiological aspects of dairy cows.

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Section: Discussionmentioning

confidence: 99%

Access to shade changes behavioral and physiological attributes of dairy cows during the hot season in the subtropics

Vizzotto

Fischer

Neto

et al. 2015

Animal

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“…The concentration of thyroid hormones and the production of metabolic heat decrease (Morais et al, 2008), whereas the blood concentration of cortisol increases (Marai and Haeeb, 2010) under heat stress. Thus, studying the variations in the concentrations of the thyroid and adrenal hormones is of utmost importance to determine the influence of heat stress on animal metabolism (White, 2009;Marai and Haeeb, 2010;Haque et al, 2012).…”

Section: Introductionmentioning

confidence: 97%

Hormonal changes in female buffaloes under shading in tropical climate of Eastern Amazon, Brazil

et al. 2014

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-The hormonal responses of 20 female buffaloes raised under the sun (SS group) or in the shade (CS group) in Belém, Pará, Brazil, were assessed. The CS group (n = 10) was kept in a silvopasture system featuring Racosperma mangium, whereas the SS group (n = 10) was kept in paddocks without shade featuring Brachiaria humidicola, drinking water, and mineral salt. The following parameters were measured for each treatment: dry-bulb temperature (AT), relative humidity (RH), and black-globe temperature in order to calculate the globe temperature and humidity index (GTHI). Blood sample collections to quantitatively determine levels of cortisol, triiodothyronine (T 3 ), and thyroxine (T 4 ) were performed every 14 days, at 13.00 h. Different seasons of the year were also assessed: rainy (January-April), transition (May-July), and less rainy (August-December). Analysis of variance revealed that AT and the index of global temperature and humidity (GTHI) differed between groups; specifically, higher values were found in the SS group, which shows how important silvopastoral systems are in buffalo farming in tropical climates. Relative humidity was significantly different across seasons and particularly high in the rainy season. The treatments influenced cortisol such that higher values were observed in the SS group. The highest mean cortisol levels were recorded during the rainy and less rainy seasons, whereas the highest T 3 and T 4 levels were recorded only during the rainy season. Triiodothyronine and thyroxine were negatively correlated with AT and GTHI and positively correlated with RH. Silvopastoral systems provide thermal comfort to buffaloes, and the less rainy season is more likely to cause heat stress.

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“…The decrease of T 3 during the dry season, leads to a greater conversion of T 4 to T 3 with the aim of maintaining the metabolic activities (MORAIS et al, 2008). Therefore, it can be suggested that there were no increase in T 4 secretion during the dry season but a greater conversion of T 4 to T 3 in the wet season, thus causing this difference.…”

Section: Discussionmentioning

confidence: 99%

Thermoregulatory responses and blood parameters of locally adapted ewes under natural weather conditions of Brazilian semiarid region

Costa

Façanha

Leite

et al. 2015

SCA

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The effect of the natural weather conditions on respiratory rate, rectal temperature and hematologic parameters such as glucose, total cholesterol, triacylglycerol, total protein, albumin, globulin, red blood cells, microhematocrit, mean corpuscular volume, serum triiodothyronine (T 3 ) and thyroxine (T 4 ) levels was evaluated in red (RMN) and white (WMN) coat colored Morada Nova ewes, of different class of body condition score (CBCS), during the dry (from july to december) and wet (from january to june) seasons, which exhibited different (P<0.05) air temperature, relative humidity and radiant thermal load averages. Tukey's test was used and the difference considered was to P<0.05. Significant greater averages of respiratory rate were observed in the dry period compared to the rainy period (42.26±8.96 and 36.89±8.20 breaths min -1 , respectively), mainly in the RMN (45.54±8.23 breaths min -1 ) compared with the WMN (39.27±8.57 breaths min -1 ). No differences were observed in rectal temperature measurements between the dry and the wet periods (38.59±0.58 and 38.60±0.56 o C, respectively), but the WMN had higher values than the RMN (38.77±0.54 and 38.40±0.54 o C, respectively). The glucose and total cholesterol were higher in the wet season, with no variation due to breed variety and CBCS. The triacylglycerol did not change between breed varieties and seasons. The albumin was similar between varieties and in different seasons, being different in CBCS. Total protein and globulin serum were higher during the wet season, but total protein was higher and globulin was lower in better CBCS. T 3 and T 4 levels were higher in the rainy season (0.25±0.07 and 6.74±11.37 µg dL -1 , for T 3 and T 4 , respectively) than in the dry season (0.18±0.08 and 6.31±1.64 µg dL -1 , for T 3 and T 4 , respectively). The red blood cells showed no difference, but microhematocrit was higher in WMN and in the better CBCS and mean corpuscular volume was higher in the dry season. The concentration of T 3 was lower in the RMN than in the WMN (0.19±0.07 and 0.24±0.08 µg dL -1 , respectively), while T 4 did not differ between them (6.53±1.51 and 6.52±1.46 µg dL -1 , respectively). The Morada Nova sheep showed positive physiological responses to the heat stress, notably an increase of respiratory rate and a reduction of T 3 and T 4 levels. All another hematologic parameters analyzed were within the normal range for all sheep, indicating a good ability to cope with the climatic changes of the Brazilian semiarid region. Both varieties were heat tolerant, but the red variety required major adjustments to maintain homeothermy. Key words: Adaptation, blood metabolites, blood parameters, sheep, thermoregulatory responses, thyroid hormones ResumoNeste estudo foram avaliados os efeitos da época do ano nas características fisiológicas de frequência respiratória e temperatura retal e nos parâmetros hematológicos glicose, colesterol total, triglicerídeos, proteínas totais, albumina, globulina, contagem total de hemácias, hematócrito, volume corpu...

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Variação anual de hormônios tireoideanos e características termorreguladoras de vacas leiteiras em ambiente quente

Cited by 36 publications

References 4 publications

Access to shade changes behavioral and physiological attributes of dairy cows during the hot season in the subtropics

Access to shade changes behavioral and physiological attributes of dairy cows during the hot season in the subtropics

Hormonal changes in female buffaloes under shading in tropical climate of Eastern Amazon, Brazil

Thermoregulatory responses and blood parameters of locally adapted ewes under natural weather conditions of Brazilian semiarid region

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