This research was developed with the aim to characterize the effects of thermal ambience on physiological responses, comfort indexes and Holstein/Gir calves performance, housed in individual hutches covered with different materials. The experimental period was from January to March of 2012, lasting for 56 days, conducted by 24 crossbred calves with genetic of 7/8 Holstein-Gir. The treatments consisted of three types of covering materials, palm straw, recycled polymer tile and fiber cement tile. A completely randomized design was adopted and in order to compare means the Tukey test (p < 0.05) was used. The enthalpy and the radiant thermal load differed statistically in all treatments, being the lowest values presented by the recycled- tile-covered housings, 59.3 kJ kg-1 dry air and 444.8 W m-2, respectively. As for the physiological variables, there was no significant difference in any of the studied variables, however, the respiratory frequency in all treatments was high, and more emphasized on animals under fiber cement covered hutches (57.2 mov min-1) indicating that the animals were under heat stress.
animal ambience; dairy cattle; weight gain; roofing materials
