Conforto térmico de búfalas em sistema silvipastoril na Amazônia Oriental

Abstract

Resumo -O objetivo deste trabalho foi avaliar o efeito de um sistema silvipastoril no conforto térmico de 20 búfalas Murrah, das quais 10 criadas em piquetes sem sombra (SS) e 10 com sombreamento (CS) de Racosperma mangium, em Belém, PA. Os animais foram alimentados em pasto, com Urochloa humidicola, com acesso livre à água para beber e sal mineral. A cada três dias, foram mensuradas: temperatura do ar (TA), umidade relativa do ar (UR), temperatura de globo negro (TGN), temperatura retal (TR), frequências respiratória (FR) e cardíaca (FC), e a temperatura da superfície corporal (TSC), pela manhã (7h) e à tarde (13h). Os valores de TR, TSC, FR e FC foram maiores à tarde, especialmente no grupo SS. Mais altas no período menos chuvoso, a TR, TSC e FR apresentaram correlação linear positiva com a TA e o índice de temperatura e umidade (ITGU) e negativa com a UR. Tanto na estação mais chuvosa quanto na menos chuvosa, a FC apresentou correlações significativas positivas com a TA e ITGU e negativas com a UR, apenas no período mais chuvoso. A arborização da pastagem é eficiente para melhorar o conforto térmico das búfalas Murrah, principalmente à tarde.Termos para indexação: índice de temperatura e umidade, somreamento, bioclimatologia, Bubalus bubalis, Racosperma mangium, fisiologia. Thermal comfort of female buffaloes in a silvipasture system in the eastern AmazonAbstract -The objective of this work was to evaluate the effects of a silvipasture system on the thermal comfort of 20 female buffaloes, from which 10 raised in under nonshaded paddocks (SS) and 10 in paddocks shaded by Racosperma mangium (CS), in Belém county, PA, Brazil. All animals were fed in pastures with Urochloa humidicola, and had free access to drinking water and mineral salt. Every three days, measurements were made for air temperature (TA), relative humidity (UR), black globe temperature (TGN), rectal temperature (TR), respiratory rate (FR), heart rate (FC), and body surface temperature (TSC), in the morning (7 AM) and in the afternoon (1 PM). The values of TR, TSC, RR and FR, mainly for the SS group, were higher in the afternoon. The TR, TSC and FR showed a significant and positive correlation with TA and the temperature and humidity index (ITGU), and a negative correlation with UR. These correlations were higher for the less rainy period. The FR showed significant and positive correlations with TA and ITGU, during both the most and the less rainy seasons, and negative correlations with UR only in the rainy season. The forestation of pasture areas is efficient to increase the thermal comfort for Murrah females, especially in the afternoon.

Assessment of surface temperatures of buffalo bulls (Bubalus bubalis) raised under tropical conditions using infrared thermography

“…The RT values found are in accordance with values described by Haque et al (2012), of 37.2ºC and 38.9ºC for animals maintained in temperatures of 22ºC and 42ºC, respectively. Despite the RT variation, this was within the physiological limits (Silva et al, 2011). Thus, the smallest values for RT in the months of July and August demonstrated that the animals were efficient in the execution of thermolysis, maintaining their homeothermy.…”

“…Therefore, the data obtained are in accordance with the historical data found for the region (Alvares et al, 2013), only observing that the month of July was considered unusual regarding the habitual rainfall. Thus, the experimental period (April to August) included a period of seasonal transition, in which buffalo can be more susceptible to environmental stress (Silva et al, 2011). The solar radiation was more intense in the less rainy period, due to less cloudiness.…”

“…According to Benezra (1954), ICB values ≤2.0 represent greater adaptability of the animal to the environment. The increase of ICB through the months may have been caused by the transition between periods with more and less rainfall in the year (Silva et al, 2011), besides more intense solar radiation in the less rainy period.…”

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

“…This result emphasises the importance of using trees in management systems to provide greater thermal comfort for animals (Moraes Júnior et al, 2010;Silva et al, 2011) and improve their yield (Castro et al, 2008;Moraes Júnior et al, 2010;Garcia et al, 2011). Incorporating trees into pastures in hot, humid climate regions favors the microclimate and provides better thermal comfort conditions, since shading can lower GTHI compared with areas under full sunlight (Garcia, 2013).…”

“…The climate type is Afi (Köppen), with an mean annual rainfall of 3,001.3 mm, which is well distributed over the year (Silva et al, 2011). The rainy season ranges from January to June, and the less rainy season goes from July to December.…”