I recall a photo SRBeef posted with his Herefords lying facing the sun at sunset. Seemed romantic, but later I read that since cattle struggle to get rid of body heat, they will face the sun to minimize the surface area being hit by sun, and also be less direct exposure. I would also think the whiteface would be cooler.
I was reading this publication from the Southern Association of Agricultural Experiment Station Directors. It outlines various research interests to improve performance in challenging environments. A lot of good reading on various subjects. Here is a section discussing color and its effect on heat stress. Note that the black cattle had tympanic (eardrum) temps 0.5 degrees Celsius higher than lighter colors. 0.5 C equals 0.9 degrees Fahrenheit, which can be a significant difference in the heat and explains the greater heat stress in black cattle, meaning less profit.
http://nimss.umd.edu/homepages/outline. ... ckID=11616
Objective 4. Bonsma (1949) discussed the appropriate coloration of cattle to be resistant to high temperatures and high solar radiation as having a white, yellow or reddish brown hair coat with yellow, reddish brown or black skin. Finch et al. (1984) reported that dark red and red Brahman and Shorthorn steers had a higher absorption of solar radiation than white steers. Mader et al. (2002) examined the effect of hair color in feedlot steers during Nebraska summer months and found that tympanic temperatures of dark steers (including pre-dominantly black but some red) were 0.5º C higher during the afternoon and early evening than those of white (presumably Charolais crossbred) steers. The dark steers also panted more and tended to bunch more than white steers under warm conditions. In a subsequent study, Davis et al. (2003) compared the tympanic temperatures of black vs. white Charolais ´ Angus crossbred steers while under severe heat stress and being full-fed. The temperatures of black steers were higher throughout the day than those of white steers and averaged 0.5º C higher at 1900. Hutchinson and Brown (1969) reported that black hair coats absorb more solar radiation than white hair coats but that the radiation penetrated further into white than black hair coats. da Silva et al. (2003) examined the reflectance, transmittance, and absorptance of haircoat and skin of black, red, white, and gray hide samples from Bos taurus and Bos indicus cattle. Red coats reflected more of the solar radiation than black, and white and gray coats tended to reflect even more.
