Heat stress alleviation and dynamic temperature measurement for growing beef cattle

• Published in: Journal of animal science Vol. 98; p. 192
• Main Authors: Augenstein, Sheyenne M, Harrison, Meredith A, Klopatek, Sarah C, Oltjen, James W
• Format: Journal Article
• Language: English
• Published: Champaign Oxford University Press 01-11-2020
• Subjects: Adaptation; Ambient temperature; Beef; Beef cattle; Body temperature; Cattle; Dairies; Feedlots; Flow velocity; Heat stress; Heat tolerance; High temperature; Intensive farming; Low temperature; Meat quality; Morning; Pens; Solar radiation; Sprinkler systems; Sprinklers; Sprinkling; Stress; Temperature measurement; Weather; Wind speed
• ISSN: 0021-8812; 1525-3163

Heat stress continues to be a challenge for feedlot producers, forcing physiological adaptations in beef cattle that can have a negative impact on gain and carcass quality. Feedlots may want to incorporate systems that aid in mitigating heat stress, including sprinkler systems, which are commonly found on dairies. The objective of this study was to determine the impact of sprinkler systems on the body temperature of growing feedlot steers applied at three different temperature thresholds. Thirty-two Angus-cross beef steers (298 ± 15 SD days of age) were randomly assigned to 8 pens. Treatments were assigned to pens according to location to avoid drainage issues, with one replicate located on the eastern side of the feedlot and the other replicate located on the western side. Treatments including no sprinklers (C), high temperature threshold sprinklers (HT), moderate temperature threshold sprinklers (MT) or low temperature threshold sprinklers (LT). Sprinklers (flow rate: 5.11 L/min) were activated at 33°C (HT), 28°C (MT), and 23°C (LT) for five minutes at corresponding temperatures every thirty minutes for 57 days. Rectal temperature of steers in their pens was measured in the morning (0800 h), afternoon (1500 h), and evening (1900 h) three days each week (Monday, Wednesday, Friday) for a total of 19 experimental days. Weather measurements, including ambient temperature, windspeed, humidity and solar radiation were recorded at each measurement time along with the maximum values for each day. The change in body temperature (ABT) between the morning and afternoon was affected by ambient temperature (P < 0.01); MT (P = 0.02) and LT (P = 0.02) - different than C. There was no significant difference between sprinkler treatments and the control group (P > 0.05). Day affected (ABT) between the morning and afternoon (P < 0.05) and the afternoon and evening (P < 0.05). When averaged by day, the control group was significantly higher than MT (P = 0.04) between the morning and afternoon. The control group was also significantly higher than LT between the morning and afternoon (P = 0.03) and the afternoon and evening (P < 0.01). The change in steer body temperature between afternoon and morning was affected by ambient temperature, and averaged across days, lowering the temperature threshold for sprinkling decreased in the afternoon and evening body temperature increase in steers.