caa a22 4500 445367458 CHVBK 20180317142935.0 cr unu---uuuuu 170323e20110701xx s 000 0 eng 10.1007/s00484-010-0360-y doi (NATIONALLICENCE)springer-10.1007/s00484-010-0360-y Determinants of bovine thermal response to heat and solar radiation exposures in a field environment [Elektronische Daten] [Brad Scharf, Michael Leonard, Robert Weaber, Terry Mader, G. Hahn, Donald Spiers] Continuous exposure of cattle to summer heat in the absence of shade results in significant hyperthermia and impairs growth and general health. Reliable predictors of heat strain are needed to identify this condition. A 12-day study was conducted during a moderate summer heat period using 12 Angus x Simmental (Bos taurus) steers (533 ± 12kg average body weight) to identify animal and ambient determinations of core body temperature (T core) and respiration rate (RR) responses to heat stress. Steers were provided standard diet and water ad libitum, and implanted intraperitoneally with telemetric transmitters to monitor T core hourly. Visual count of flank movement at 0800 and 1500hours was used for RR. Dataloggers recorded air temperature (T a), and black globe temperatures (T bg) hourly to assess radiant heat load. Analysis was across four periods and 2 consecutive days averaged within each period. Average T a and T bg increased progressively from 21.7 to 30.3°C and 25.3 to 34.0°C, respectively, from the first to fourth periods. A model utilizing a quadratic function of T a explained the most variation in T core (R 2 = 0.56). A delay in response from 1 to 3h did not significantly improve R 2 for this relationship. Measurements at 0800 and 1500hours alone are sufficient to predict heat strain. Daily minimum core body temperature and initial 2-h rise in T a were predictors of maximum core temperature and RR. Further studies using continuous monitoring are needed to expand prediction of heat stress impact under different conditions. ISB, 2010 Cattle nationallicence Transmitter nationallicence Heat nationallicence Stress nationallicence Model nationallicence Scharf Brad Department of Animal Science, University of Missouri, 920 East Campus Drive, Columbia, MO, USA aut Leonard Michael US Air Force, Washington, DC, USA aut Weaber Robert Department of Animal Science, University of Missouri, 920 East Campus Drive, Columbia, MO, USA aut Mader Terry Haskell Agricultural Laboratory, University of Nebraska-Lincoln, 57905 866 Road, 68728-2828, Concord, NE, USA aut Hahn G. Meat Animal Research Center, USDA-ARS, PO Box 166, 68933-0166, Clay Center, NE, USA aut Spiers Donald Department of Animal Science, University of Missouri, 920 East Campus Drive, Columbia, MO, USA aut International Journal of Biometeorology Springer-Verlag 55/4(2011-07-01), 469-480 0020-7128 55:4<469 2011 55 484 https://doi.org/10.1007/s00484-010-0360-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00484-010-0360-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Scharf Brad Department of Animal Science, University of Missouri, 920 East Campus Drive, Columbia, MO, USA aut NATIONALLICENCE 700 1- Leonard Michael US Air Force, Washington, DC, USA aut NATIONALLICENCE 700 1- Weaber Robert Department of Animal Science, University of Missouri, 920 East Campus Drive, Columbia, MO, USA aut NATIONALLICENCE 700 1- Mader Terry Haskell Agricultural Laboratory, University of Nebraska-Lincoln, 57905 866 Road, 68728-2828, Concord, NE, USA aut NATIONALLICENCE 700 1- Hahn G. Meat Animal Research Center, USDA-ARS, PO Box 166, 68933-0166, Clay Center, NE, USA aut NATIONALLICENCE 700 1- Spiers Donald Department of Animal Science, University of Missouri, 920 East Campus Drive, Columbia, MO, USA aut NATIONALLICENCE 773 0- International Journal of Biometeorology Springer-Verlag 55/4(2011-07-01), 469-480 0020-7128 55:4<469 2011 55 484 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer