Thermal equilibrium of goats

Area of Science:

• Animal Science
• Environmental Physiology
• Thermoregulation in Livestock

Background:

• Understanding animal responses to heat stress is vital for livestock management in tropical regions.
• Anglo Nubian goats are a significant breed in various agricultural systems.
• Thermal equilibrium is crucial for animal health and productivity.

Purpose of the Study:

• To evaluate the effects of air temperature and relative humidity on the thermal equilibrium of Anglo Nubian goats.
• To determine the critical temperature thresholds for heat stress in this breed.
• To identify the primary mechanisms of heat loss in goats under tropical conditions.

Main Methods:

• Utilized an indirect calorimeter to measure metabolic gas exchange (oxygen consumption, carbon dioxide production, methane production) and expired air water vapor pressure.
• Monitored physiological parameters including rectal, skin, hair-coat, and expired air temperatures, along with respiratory rate and volume.
• Measured environmental parameters such as air temperature, relative humidity, and mean radiant temperature.

Main Results:

• No significant changes in respiratory/ventilation rates or latent heat loss were observed between 22°C and 26°C.
• In the 22-26°C range, heat loss primarily occurred via convection and long-wave radiation.
• Above 30°C, goats relied heavily on evaporative heat loss, showing significantly elevated respiratory rates, ventilation, and body temperatures.

Conclusions:

• The upper comfort limit for Anglo Nubian goats, when shielded from direct solar radiation, is approximately 26°C.
• Evaporative heat loss becomes the dominant thermoregulatory mechanism at higher temperatures (>30°C).
• Findings provide critical data for managing Anglo Nubian goats in hot, humid environments to prevent heat stress.