Horses consumed less water in the winter compared to the fall. Feeding mash to horses was helpful in increasing overall water intake.
Many horse owners in northern climates feed a grain mash (i.e. grain plus water) to horses in cold weather. It is thought that by providing an additional source of water, potential dehydration related colic could be avoided. Water intake varies according to both outdoor temperatures and the temperature of water. Cold weather has been reported to decrease water intake by 6 to 12%. In addition, consumption of water decreases as total dry matter intake in the diet decreases. Therefore, it is unknown if the horse simply drinks less liquid water in response to increased water present in the mash. Thus, water intake in two different seasons in horses fed a dry grain or a mash was compared by researchers at the University of Wisconsin River Falls.
Ten mature horses were used and were housed in individual stalls, in a heated barn for trial 1 (Winter), and an unheated barn for trial 2 (Fall). Horses were divided into two groups, one which received pelleted concentrate at 0.5% of their body weight, and one which received the same pelleted feed with water added at a rate of 0.25 gallons per pound of feed. Alfalfa hay was offered at a maximum of 2% of their body weight, divided into two equal feedings, morning and night. A total of 8.5 gallons of water was provided in two buckets at each feeding. Any water and feed remaining was measured prior to the next feeding. Horses were on their respective treatments for four days and then returned to their original pastures for at least two days before switching treatments. The same study was then repeated during the winter.
In the winter, horses on the mash diet had a tendency to consume more water than the horses on the dry concentrate, but no difference was observed in the fall. Horses did consume significantly less water in the winter compared to the fall. There was a significant interaction between treatment and season, with horses consuming dry grain in the winter drinking significantly less water than mash fed horses in the winter and fall. Therefore, feeding mash to horses does appear to be helpful to increase their overall water intake. Horses consuming mash drank equal to or more water than horses on the dry grain, in addition to the water they consumed in their feed.
Summarized by Shanna Privatsky, University of Minnesota