Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 13, 2004
Publication Date: August 27, 2004
Citation: Brown Brandl, T.M., Nienaber, J.A., Eigenberg, R.A., Hahn, G.L. 2004. Relative heat tolerance among cattle of different genetics. Meeting Abstract. 16th Biometeorology and Aerobiology Conference, Vancouver, British Columbia, Canada. 6B.5, CDROM. Technical Abstract: Heat stress in cattle causes millions of dollars of losses each year due to production losses, and death losses in extreme cases. A study was designed to determine severity of heat stress among four genotypes of cattle. One-hundred twenty-eight feedlot heifers of four different genotypes were observed throughout two summers. Respiration rates, panting scores, and surface temperatures were taken twice a day on a random sample of 10 animals/genotype for several weeks during the summers of 2002 and 2003. Results indicate all weather parameters had an impact on respiration rate; it appears that temperature had the largest impact (82.7%), followed by wind speed (12.9%), then solar radiation (4.1%), and finally dew-point temperature (0.3%). This study also found dark-hided cattle were more stressed than light-hided cattle. Twenty-four hour behavior measurements were recorded for two heat-stress and two thermoneutral days. Heat stress increased drinking and standing behavior, and decreased eating, lying, and agonistic behaviors. Overall, it was found that dark-hided cattle with higher condition scores were more affected by heat stress.