Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2005
Publication Date: 7/20/2005
Citation: Gaughan, J.B., Tait, L.A., Eigenberg, R.A., Bryden, W.L. 2004. Effect of shade on respiration rate and rectal temperature of angus heifers. Animal Production in Australia: Proceedings of the 25th Australian Society of Animal Production Conference, Melbourne, Australia. 25:69-72. Interpretive Summary: Summer heat provides stressful conditions for Bos taurus feeder cattle; in extreme instances these conditions can be lethal. One management option is to provide shade structures for feedlot animals. This study was conducted during January, February, and March of 2003 at the University of Queensland-Gatton, Australia to determine physiological responses of cattle under shade or no-shade conditions. Six heifers were assigned individual pens. Three pens were equipped with shade structures that allowed the heifers to choose shade; the remainder had no shade option. Animals were rotated through pen assignments during the heat stress season. Respiration rate and body temperature measurements were lower for cattle given shade. Further work is needed to determine an optimal design for shade structures.
Technical Abstract: The effect of shade on rectal temperature and respiration rate of grain-fed Angus heifers was examined in a 21-day study. Six heifers were housed in individual outside yards (15 square meters). Three of the yards had shade, and three did not. Each pen had an individual water bowl and feed bunk. Three data collection periods were used, during which time the cattle were exposed to hot conditions (mean heat load index > 83). Overall, the heifers with access to shade had lower rectal temperature and respiration rate than those without access to shade. The largest difference was seen in the afternoon (1201 - 1700 h), with little or no differences seen at other times of the day. Dry matter intake was not affected by treatment, however, there were changes in eating dynamics with un-shaded cattle eating more at night. Provision of shade resulted in lower rectal temperature and respiration rate during periods of peak heat load.