Maia, ASCdaSilva, R. G.Loureiro, CMB2014-05-202014-05-202005-09-01International Journal of Biometeorology. New York: Springer, v. 50, n. 1, p. 17-22, 2005.0020-7128http://hdl.handle.net/11449/32830The general principles of the mechanisms of heat transfer are well known, but knowledge of the transition between evaporative and non-evaporative heat loss by Holstein cows in field conditions must be improved, especially for low-latitude environments. With this aim 15 Holstein cows managed in open pasture were observed in a tropical region. The latent heat loss from the body surface of the animals was measured by means of a ventilated capsule, while convective heat transfer was estimated by the theory of convection from a horizontal cylinder and by the long-wave radiation exchange based on the Stefan-Boltzmann law. When the air temperature was between 10 and 36 degrees C the sensible heat transfer varied from 160 to -30 W m(-2), while the latent heat loss by cutaneous evaporation increased from 30 to 350 W m(-2). Heat loss by cutaneous evaporation accounted for 20-30% of the total heat loss when air temperatures ranged from 10 to 20 degrees C. At air temperatures > 30 degrees C cutaneous evaporation becomes the main avenue of heat loss, accounting for approximately 85% of the total heat loss, while the rest is lost by respiratory evaporation.17-22engthermoregulationHolstein cowsbody surfaceheat losstropical environmentArtigo10.1007/s00484-005-0267-1WOS:000231882600003Acesso restrito