Published online by Cambridge University Press: 27 March 2009
In tropical and subtropical areas many cattle suffer from heat stress for more than half of each year. Added to the environmental heat stress is the heat production associated with lactation (Berman et al. 1985) and the resultant increased storage of heat (Araki et al. 1984). While the net effect of lactation on body temperature has been evaluated in dairy cattle (Collier et al. 1982) its effect on beef breeds in tropical and subtropical areas has not been defined. This is now possible with improved telemetry equipment, which allows body temperatures of free-ranging cattle to be monitored up to distance of 400 m.