Methods to quantify heat stress in ruminants: Current status and future prospects

Area of Science:

• Mammalian physiology
• Animal science
• Environmental stress biology

Background:

• Heat stress (hyperthermia) is a systemic condition affecting all mammalian body systems.
• Factors influencing heat stress response include animal characteristics, environment, and management practices.
• Accurate measurement of heat stress in production ruminants is challenging due to diverse systems and geoclimatic zones, exacerbated by climate change.

Purpose of the Study:

• To review the challenges in measuring heat stress in production ruminants.
• To evaluate the effectiveness of traditional bioclimatic indices like the Temperature-Humidity Index (THI).
• To explore advancements in technological and computational approaches for heat stress assessment.

Main Methods:

• Review of physiological studies from the 1950s-1980s.
• Analysis of recent technological advancements for heat stress measurement.
• Focus on infrared thermography, automated respiration rate monitoring, and radiotelemetry of internal body temperatures.

Main Results:

• Traditional bioclimatic indices like THI show limited correlation with core body temperature and respiratory changes during heat load.
• New technologies offer more precise physiological data but require further research to establish reliable decision-making thresholds.
• Progress in developing accurate, real-time heat stress monitoring tools is ongoing.

Conclusions:

• Existing heat stress measurement methods, including THI, are inadequate for production ruminants.
• Advanced technologies like infrared thermography and radiotelemetry show promise for improved heat stress assessment.
• Further research is crucial to establish reliable thresholds for animal welfare and management decisions in a warming climate.