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ARS Home » Research » Publications at this Location » Publication #81038
Title: CATTLE RESPIRATION RATE AS A FUNCTION OF AMBIENT TEMPERATURE

Author
item Hahn, George
item PARKHURST, A - UNIV NEBRASKA-LINCOLN
item GAUGHAN, J - UNIV QUEENSLAND

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 5/2/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Respiration rate (breaths/minute) serves as an overall indicator of stress in livestock during hot weather. However, the relationship of respiration rate to air temperature has not been tested thoroughly enough to be useful as a guideline for possible management actions to protect animals subjected to stressful environments. This report summarizes the influence of air temperature on respiration rates of healthy cattle in cool to hot environments. These comparisons show 1) the relationship of respiration rate to air temperature, including a delay in the timing of the response following heating or cooling, and 2) provide guidelines for cattle managers observing their animals during hot weather. The response relationships provide a basis for actions to reduce stress and enhance well-being of the animals, with improved performance and efficiency.

Technical Abstract: This report qualitatively and quantitatively evaluates the influence of ambient temperature on respiration rates (RR) of healthy cattle in thermoneutral and hot environments. New research information is presented in the context of prior reports of RR for both beef and dairy cattle as a basis for improving cattle environmental management guidelines. Qualitatively, 1) RR increases with increasing air temperature; 2) rate of RR increase is not constant; 3) RR responses lag increases in air temperature; and 4) individual animal variability exists. Quantitatively, healthy cattle with RR under 60 breaths/min (bpm) indicate minimal to no thermal stress, while RR more than 120 bpm reflect excessive heat loads. For shaded feeder cattle acclimatized to heat, RR is poorly correlated with air temperatures less than 21C; above 21C, RR is strongly associated with air temperature, and increases about 4.3 bpm per degree C above a baseline RR of 60 bpm, with a lag of about 2h behind air temperature. Threshold estimates for increased RR in shaded lactating dairy cows and dairy calves are 15C and 22.5C, respectively, above which the rates of increase are about 2.8 bpm and 3.4 bpm per degree C (basal RR approximately 20-30 bpm). For unshaded cattle, available information suggests shifting the ambient temperature ranges downward by about 1.5 to 3C, depending on the radiant heat load. As RR reaches 160 bpm or higher in any category of cattle, consideration should be given to emergency actions for reducing those heat loads (e.g., wetting the animals).