Avaliação do conforto térmico de um aprisco para a cidade de Santa Maria/RS

Abstract

Sheep production has always played a fundamental role in society throughout history, and it has been highlighted as an important economic activity in Rio Grande do Sul, Brazil. Rio Grande do Sul presents climatic peculiarities that in some situations impose a condition of thermal discomfort in animals, generating heat stress, which is one of the main limiting factors of animal production. Seeking alternatives that provide better thermal comfort for confined animals and a consequent greater production is essential. This study was carried out with sheep and lambs confined in a fold (fenced enclosure area) at Universidade Federal de Santa Maria and aimed to evaluate the thermal comfort that the fold gives animals in a typical winter and summer day. We assessed environmental variables such as air temperature, radiant temperature, relative humidity, and air velocity. Subsequently, the Black Globe and Humidity Index (BGHI) and Thermal Comfort Index (TCI) were utilized to evaluate animal thermal comfort. Additionally, rectal temperature, respiratory rate, and skin temperature of the animals as well as thermographic images of the wool surface of the (fur) animals and fold were evaluated. Based on data gathering and calculation of the indices, it was possible to observe that the animals were in thermal discomfort for most part of the experiment. For the typical winter period, no reference values of BGHI and TCI were found; however, some animals had a rectal temperature of 35.5 ° C, which is below normal levels. The fold had thermal cushioning below 28%, imposing internal temperatures of 7.8 ° C in the animals. This temperature is out of the thermal comfort zone (TCZ), which lies between 25 and 30 ° C for newborns and between 15 and 30 ° C for adult animals, being close to 6 ° C, which is considered lower critical temperature (TCL). For the typical summer period, the building had a heat buffer below 10% and it was possible to assess comfort using BGHI and TCI. During the morning, BGHI was below 74, which represents thermal comfort values. On the other hand, the fold in the afternoon presented BGHI ranging between 74 and 79, which represents state of alert. As a conclusion, the fold studied does not provide thermal comfort for animals in most of the typical winter and summer period. As a consequence, it requires constructive improvements to ensure that animals are provided with comfort and well-being so that they reach their maximum productive and reproductive performance.