The effects of skin temperature (TS) on the rate of heatloss by cutaneous evaporation (ES) in Holstein cows chronicallyexposed to sun, considering hair coat colour were studied. Sixteen purebredcows were measured for ES and TS at 01:00p.m. after 6 hours of exposure to sun, on three body regions (flank, neck andgluteus) and considering dark and white spots separately. Sweating rate (S)and ES were measured by means of a ventilated capsule. Blackskin areas presented mean S (138.9 ± 8.5 gm-2 h-1),ES (93.3 ± 5.7 Wm-2), and TS(33.1 ± 0.2°C) higher than those in the white areas (109.5 ±9.7 gm-2h-1), 73.6 ± 6.5 Wm-2 and32.6 ± 0.2°C, respectively). There is an exponential relationshipamong cutaneous temperature and cutaneous evaporation, which can be representedby the equation: ES = 31.5 + exp{(TS -27.9)/2.19115}, with coefficient of determination r2 = 0.68.Cutaneous evaporative heat loss remains almost constant around 48 Wm-2until TS reaches nearly 31°C.
