Understanding the influence of the weather on the energy requirements of horses living outdoors during winter is essential when estimating feed requirements. Measurements of heat production from live horses have only been made at different air temperatures. The influences of other weather parameters, such as precipitation and wind speed, which are known to increase the rate of heat loss in other domestic stock, have not been researched for horses. The aim of this study was to measure the effect of wetting the upper body surface of Shetland ponies in winter coat on their rate of heat production (W/kg) and on their skin and body temperatures (°C ).
Two mature Shetland pony stallions (178 and 200 kg liveweight) in full winter coat (coat parameters over the back; mean depth 2.38 cm; mean length 3.25 cm; mean density 79.25 mg/cm2), and in good body condition (condition score 2; Pollock, 1980), were housed at ambient temperature (range 2 - 9.5 °C) in an open-sided shed and fed meadow hay at maintenance energy requirements (NRC, 1989).