Evaporative cooling and cutaneous surface temperature of Holstein cows in tropical conditions

Revista Brasileira de Zootecnia

Roberto Gomes Da Silva²  Alex Sandro Campos Maia¹ 

[1] ,Universidade Federal Rural do Semi-Árido Departmento de Zootecnia Mossoró RN ,Brazil

关键词: cutaneous evaporation;    cutaneous temperature;    Holstein cows;    evaporação cutânea;    temperatura cutânea;    vacas Holandesas;   

DOI  :  10.1590/S1516-35982011000500028

来源: SciELO

【 摘 要 】

The effects of skin temperature (T S) on the rate of heat loss by cutaneous evaporation (E S) in Holstein cows chronically exposed to sun, considering hair coat colour were studied. Sixteen purebred cows were measured for E S and T S at 01:00 p.m. after 6 hours of exposure to sun, on three body regions (flank, neck and gluteus) and considering dark and white spots separately. Sweating rate (S) and E S were measured by means of a ventilated capsule. Black skin areas presented mean S (138.9 ± 8.5 gm-2 h-1), E S (93.3 ± 5.7 Wm-2), and T S (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 and 32.6 ± 0.2°C, respectively). There is an exponential relationship among cutaneous temperature and cutaneous evaporation, which can be represented by the equation: E S = 31.5 + exp{(T S - 27.9)/2.19115}, with coefficient of determination r² = 0.68. Cutaneous evaporative heat loss remains almost constant around 48 Wm-2 until T S reaches nearly 31°C.

【 授权许可】

CC BY   
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