Case Study: Mitigation of heat stress in feedlot cattle by applying reflective pigments to the dorsal body surface

Abstract

Heat stress in feedlot cattle has serious animal welfare and economic implications. The objective of this experiment was to determine whether a titanium dioxide coating applied to the dorsal midline of cattle would reflect solar radiation and mitigate heat stress. Feedlot heifers (n = 30; 269 ± 27.6 kg) were randomly assigned to a noncoated (control) or titanium dioxide–coated treatment. Coating was applied to the dorsal midline except for a control area over the dorsal anterior midline. Reflectance was measured with a suspended modified digital camera in a blue band, a green band, and a near-infrared band. Skin surface temperature was measured with a suspended infrared thermal imaging sensor. Vaginal thermometers recorded the internal body temperature of heifers. Reflectance in the blue, green, and red edge to near infrared bands were found to be 5.7, 8.8, and 10.3 times greater (P < 0.001), respectively, for the coated areas compared with the noncoated areas. Dorsal surface temperature averaged 39.1 and 42.4°C for coated and noncoated areas, respectively (P < 0.001). Reflectance values and skin surface temperatures suggest that the coating decreased solar energy absorption. Over a 2- to 3-h period of exposure to natural solar radiation on a day with temperature–humidity index of 86.9, titanium dioxide–coated cattle had stable body temperatures, whereas the body temperatures of control heifers increased 0.8°C. A reflective coating applied to the dorsal midline could be an opportunity to decrease solar radiation energy absorbed by feedlot cattle.