In most areas of the world, cattle destined for slaughter are fattened on grass. In the southern U.S. this requires cattle that are well-adapted to the ambient conditions (high temperature and humidity) and it is usually expected that only Bos indicus or Bos indicus crosses can be sufficiently adapted to such conditions to grow rapidly and efficiently. Since both a light coat color and a short hair length contribute significantly to increased heat tolerance, it is possible that the combination of short hair and lighter coloration will result in an animal with high growth potential under grazing conditions in the southern U.S. without Bos indicus influence.
Over the past two decades black has become the preferred color of feedlot and slaughter cattle in the USA, including the Southern Region. As a result, not only has the influence of Angus cattle increased, but the black gene has been incorporated, through upgrading and selection, into a number of previously red breeds such as the Simmental, Limousin, Gelbvieh, etc. This is in spite of the fact that black colored cattle will absorb more solar radiation than red or other lighter-colored cattle. Studies by Mader et al. (2002) and Davis et al. (2003) both showed rather dramatic (up to 0.5º) lower body temperatures while under heat stress for white (dilute-colored Charolais crossbred) as compared to black feedlot steers. This advantage is comparable to the effect of the Slick hair gene for heat tolerance reported by Olson et al. (2003). The combined effects on heat tolerance of cattle that are both light colored and slick-haired have never been evaluated.
