The objective of this research was to determine the thermal comfort indexes for sheep raising installations, analyze the physiological parameters and the thermal gradient of four sheep genetic groups in the semi-arid region of the state of Paraiba, Brazil. Forty animals were used, being ten individuals per genetic group; the groups were: 'Cariri', 'Morada Nova', 'Barriga Negra' and 'Cara Curta'. All of them females and randomly housed in four adequate installations. The environmental indexes inside the lodging, mainly from 11 a.m. to 13 p.m., remained above the thermal comfort zone for adult sheep, except for the relative humidity, that had a daily average of 67.5%. The rectal temperature of the animals was kept within the normal range, except for the genetic group 'Morada Nova' that presented the lowest values (38.6 ºC). The respiration frequency for each of the genetic group was above the normal value; with the 'Morada Nova' once again presenting the lowest values (43.5 mov min-1); the 'Cariri' and 'Barriga Negra' showed the highest frequency (48.0 and 47.3 mov min ¹, respectively). Animals with darker hair color and larger size, such as those belonging to the genetic group 'Cariri', presented a higher thermal gradient between air and body surface temperatures. Animals showed high tolerance to heat, in other words, they are well adapted to the tropical environment, except for the genetic group 'Cariri' that was the least adapted. The genetic group 'Morada Nova' was considered the best adapted group for the experimental conditions.
environment; thermal comfort; native animals
