Body temperature and respiratory dynamics in un-shaded beef cattle

Area of Science:

• Animal Science
• Environmental Physiology
• Livestock Management

Background:

• Heat stress significantly impacts cattle welfare and productivity.
• Accurate monitoring of body temperature (BT) and physiological stress responses is essential for livestock management.
• Panting score (PS) is a visual indicator of heat stress in cattle.

Purpose of the Study:

• To evaluate the relationship between body temperature (BT) and panting score (PS) in Angus steers under outdoor conditions.
• To determine the effectiveness of PS as an indicator of heat stress at different times of the day.
• To inform heat load management strategies for cattle.

Main Methods:

• Collected body temperature (BT) data using implanted transmitters and panting score (PS) observations daily from 30 Angus steers over 120 days.
• Recorded environmental variables including ambient temperature, black globe temperature, solar radiation, humidity, wind speed, and rainfall.
• Developed second-order polynomial response curves to model the relationship between BT and PS at morning (AM), midday (MD), and afternoon (PM).

Main Results:

• A strong correlation was found between PS and BT, with PS being a good indicator of body temperature across different times of the day (R² values ranging from 0.83 to 0.94).
• Body temperature at midday (MD) corresponded to slightly lower PS compared to the afternoon (PM).
• Morning (AM) observations showed lower BT at given PS levels compared to MD and PM, suggesting active heat dissipation during cooler periods.

Conclusions:

• Panting score (PS) is a valid and practical indicator for assessing body temperature (BT) and heat stress in cattle.
• Morning observations of cattle are critical for proactive heat load management, especially preceding expected high heat conditions.
• Further research is needed to understand the influence of nighttime conditions on BT, PS, and respiratory dynamics during hot weather periods.