Physiological responses of dairy cows during extended solar exposure

Kifle G. Gebremedhin, Chin N. Lee, Peter E. Hillman, Robert J. Collier

    Research output: Contribution to journalArticlepeer-review

    41 Scopus citations


    Sweating and respiration rates, and skin (dorsal) and core (rectal) temperatures of 12 Holstein dairy cows were measured in controlled environments at the William Parker Agricultural Research Complex, University of Arizona-Tucson. The focus of the study was: (1) to establish the pattern (linear or periodic) of sweating, (2) to establish whether skin or core temperature drives sweating, (3) to determine how cows respond to a prolonged solar exposure, and (4) to compare dairy cows physiological responses to hot and humid versus hot and dry environmental conditions. The 12 cows were divided into two groups of six cows each and were housed alternately between two chambers. The two chambers were identical, but one (experimental chamber) included solar lamps to simulate solar load. The cows were alternately exposed to 550 W/m 2 solar load, THI at 79.6, and air velocity in the measurement area (dorsal surface) was maintained at 1.0 m/s. Skin temperature was greater than 35° C (threshold for heat stress). There was considerable variation in sweating rates between cows. Cows sweat in a cyclic manner, and the results suggest that skin temperature is the primary driving force for sweating. The maximum sweating rate of dairy cows was around 660 g/m 2-h.

    Original languageEnglish (US)
    Pages (from-to)239-247
    Number of pages9
    JournalTransactions of the ASABE
    Issue number1
    StatePublished - 2010


    • Body temperature
    • Dairy cows
    • Heat stress
    • Respiration rate
    • Skin temperature
    • Sweating rate
    • Thermal response

    ASJC Scopus subject areas

    • Forestry
    • Food Science
    • Biomedical Engineering
    • Agronomy and Crop Science
    • Soil Science


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