Thermographic evaluation of the lower critical temperature in weanling horses.

This research study was conducted to determine the heat loss in weanling horses when exposed to low ambient temperatures during winter in northern latitudes and measured this through infrared thermography. The results reflect the importance of factoring the housing temperature when planning the feeding of these horses.

Objective of the study

• The main aim of this research was to measure the thermal regulation capacity of weanling horses in a cold environment. The researchers wanted to map the level of heat loss, especially in the neck and trunk regions, through infrared thermography in exceedingly cold conditions, particularly in the northern latitudes. This was done to assess the lower critical temperature, beyond which the body start losing heat at a rapid rate, and to readjust feeding plans accordingly.

Research methodology

• The study was based on nine weanling horses residing in loose housing. Throughout the winter, these exposed non-human subjects were subjected to low ambient temperatures, simulating the conditions in northern latitudes.
• The heat loss from the neck and trunk was measured with infrared thermography. The temperatures evaluated were -16 degrees C, 0 degrees C, and -9 degrees C.

Key findings

• The findings indicated that the heat loss rated at 73.5 to 98.7 W/m2 from the neck and 69.9 to 94.3 W/m2 from the trunk. The loss was higher at -16 degrees C than at 0 degrees C and -9 degrees C, depicting that the lower critical temperature could be in between -9 degrees C and -16 degrees C.
• Curiously, researchers found that the heat loss from the trunk was less at -23 degrees C than -16 degrees C. This was attributed to the frost on the surface of the hair, disturbing the thermographic readings, making it inappropriate for determining heat loss in extreme cold temperatures.

Implications of the findings

• The results of this investigation highlight the significance of accounting for housing temperature when designing feeding programs for weanling horses exposed to cold climates in northern latitudes.
• The study also brought forth the limitations of using thermography for determining heat loss in extremely cold temperatures, potentially paving the way for exploring more accurate tools or methodologies.