Evaluating a New Shade for Feedlot Cattle Performance and Heat Stress

Heat stress in cattle results in decreased feed intake, lower daily gain and potentially death in susceptible animals under intense conditions. A study was carried out during the summer of 2013 on the USDA-ARS U.S. Meat Animal Research Center feedlot evaluating the impact of shade on environmental conditions and cattle performance. A novel two-tiered shade was utilized in half of the 14 pens, each holding 30 animals. The shades were designed to reduce solar heat load by 40 to 60% and to provide traveling shade across the pen providing varied amounts of shade area as well as varied solar reduction potential. The objective of this study was to determine if the shade was effective at improving performance (evaluated as average daily gain, feed intake, and feed to gain ratio) and reducing environmental conditions that cause heat stress. A group of mixed-breed cattle with varied genetics including both Bos taurus and Bos indicus were selected, penned on the basis of sex and were blocked by color. Production parameters of pen feed usage were measured daily and individual body weights were taken monthly. Environmental conditions including air temperature, relative humidity, wind speed, ground temperature, and black globe temperature with and without shade were measured. Solar load on the pens was reduced when shade was provided, with both ground temperature and black globe temperature showing reductions. Cattle showed nominally better performance; however, no significant differences were found with gain or feed intake. Panting scores were not significantly lower with shade provided; slopes of cattle respiration rate versus ambient temperature were significantly lower with shade during the afternoon period.