Effect of temperature and air velocity on the thermal insulation of the fleece of sheep in climatic chamber

Ten Corriedale sheep were evaluated, five males and five females with 52.2 to 87.6 kg of body weight, to evaluate the effect of air velocity (0 and 5 m/s) and temperature (25, 30 and 40 degrees C) on rectal temperature (T(R), degrees C), skin temperature (T(E), degrees C), fleece surface temperature (T(V), degrees C), temperature inside the fleece (T(I), degrees C), and fleece thickness (E(V), cm) and their relationship with fleece thermal insulation. The results showed that air velocity did not affect the studied traits, suggesting that airflow < 5.0 m/s parallel to the fleece had little effect on fleece thermal insulation, regardless the air temperature. Air temperature was highly correlated with T(R), T(E), T(I) and T(V). Under air temperatures below 30 degrees C, the heat transfer through the fleece was dominated by conduction and free convection, while under high temperatures (> 40 degrees C), the sensible heat flow was not significant.