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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Nutrition, Growth and Physiology » Research » Publications at this Location » Publication #325472
Title: Physiological responses of feedlot heifers provided access to different levels of shade

Author
item Brown-Brandl, Tami
item Chitko-Mckown, Carol
item EIGENBERG, ROGER - Collaborator
item MAYER, JACOB - Settje Agri-Services & Engineering
item WELSH, TOM - Texas A&M University
item DAVIS, JEREMIAH - Auburn University
item Purswell, Joseph - Jody

Submitted to: Animal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2016
Publication Date: 8/1/2017
Citation: Brown-Brandl, T.M., Chitko-McKown, C.G., Eigenberg, R.A., Mayer, J.J., Welsh, T.H., Davis, J.D., Purswell, J.L. 2017. Physiological responses of feedlot heifers provided access to different levels of shade. Animal. 11(8):1344-1353. https://doi.org/10.1017/S1751731116002664.

Interpretive Summary: Heat stress has a significant impact on all livestock and poultry species causing economic losses and animal well-being concerns. Providing shade is one management option that has been studied for years. Material selected to provide shade for animals greatly influences the overall stress reduction provided by shade. A study was conducted to quantify both the environment and animal response, when cattle had no shade access during summer time exposure or were given access to shade provided by three different materials. Thirty-two black Angus heifers were placed in one of 4 pens. Each pen was assigned a shade treatment: No Shade, Snow Fence, 60% Aluminet Shade Cloth, and 100% Shade Cloth. Both physiological and environmental stresses were measured. Clear environmental differences between the shade treatments were found. The 100% Shade Cloth provided the best environment. The animal physiological responses showed pronounced different responses based on shade type; however, the 100% Shade Cloth and 60% Aluminet Shade Cloth offered similar protection. Complete blood counts and the serum cortisol were impacted by shade type as well. Sixty percent Shade Aluminet Cloth lowered the serum cortisol the most. Therefore, 60% Aluminet Shade Cloth was determined to offer the best protection based on the animal responses.

Technical Abstract: Heat stress has a significant impact on all livestock and poultry species causing economic losses and animal well-being concerns. Providing shade is one heat-abatement strategy that has been studied for years. Material selected to provide shade for animals greatly influences the overall stress reduction provided by shade. A study was conducted to quantify both the environment and animal response, when cattle had no shade access during summertime exposure or were given access to shade provided by three different materials. A total of 32 Black Angus heifers were assigned to one of the four treatment pens according to weight (eight animals per pen). Each pen was assigned a shade treatment: No Shade, Snow Fence, 60% Aluminet Shade Cloth and 100% Shade Cloth. In the shaded treatment pens, the shade structure covered ~40% of the pen (7.5m2/animal). Animals were moved to a different treatment every 2 weeks in a 4 × 4 Latin square design to ensure each treatment was applied to each group of animals. Both environmental parameters and physiological responses were measured during the experiment. Environmental parameters included dry-bulb temperature, relative humidity, wind speed, black globe temperature (BGT), solar radiation (SR) and feedlot surface temperature. Animal response measurements included manual respiration rate (RRm), electronic respiration rate (RRe), vaginal temperature (body temperature (BT)), complete blood count (CBC) and plasma cortisol. The environmental data demonstrated changes proportional to the quality of shade offered. However, the animal responses did not follow this same trend. Some of the data suggest that any amount of shade was beneficial to the animals. However, Snow Fence may not offer adequate protection to reduce BT. For some of the parameters (BT, CBC and cortisol), 60% Aluminet and 100% Shade Cloth offers similar protection. The 60% Aluminet lowered RRe the most during extreme conditions. When considering all parameters, environmental and physiological, 60% Aluminet Shade Cloth offered reductions of BGT, SR, feedlot surface temperature and the best (or equal to the best) overall protection for the animals (RRe, RRm, BT, blood parameters).