Thermal gradient of local sheep and goats reared in the Brazilian semi-arid region

Abstract

In the Brazilian semi-arid region, small ruminants reared in the field, especially in the dry period of the year, may be subjected to thermal stress, which can compromise their homeothermy. This study aimed to evaluate the climatic indices, rectal temperature (R_T), surface temperature (S_T), thermal gradient between rectal and surface temperatures and the ambient temperature of Santa Inês sheep and Moxotó goats, reared in the Brazilian semi-arid region in two periods of the year (less hot and hot) and at three times (13, 14 and 15 h), using 24 animals, 12 of each breed, 6 males and 6 females of each species, grouped in a completely randomized design in a 2 × 2 × 2 factorial scheme (species, genders and periods), with 6 replicates. Ambient temperature and black globe temperature and humidity index in the periods and times were above ideal for the species, with low relative humidity. In both periods, the means of R_T remained within the normality standard for the species, but higher in sheep. S_T remained high for the two species and higher in sheep at the times evaluated. The thermal gradients were below ideal, indicating damage to the physiological capacity of the animals to maintain homeothermy in the environment in which they were.