In Feeding Many adult horses can maintain body condition on a complete forage diet with access to free choice trace mineralized salt. Adult horses should consume between 1.5 and 2 percent of their body weight in hay or a 1,000 lb. horse will eat 15 to 20 lb. of hay per day. Supplementation with grain is only necessary if horses have difficulty in maintaining body condition. Therefore, horses maintained in extremely cold conditions for an extended period, with minimal shelter may need grain supplementation to meet their energy demands. In most cases, an all forage diet is a more desirable way to meet a horses' elevated energy requirements.
Forages contain a much higher fiber content than grains.
Fiber is utilized through bacterial fermentation within the cecum and large intestine. This results in a greater amount of heat being produced through the utilization of forages than utilization of grain. Thus, a horse's increased energy requirements are better met by providing horses all the forage they will consume without wastage. Although winter conditions will greatly increase some horse's energy requirements, the duration of the cold, windy, wet conditions should be considered before alterations are made in the feeding program. Horses should be preconditioned by gradual increases in the amount of energy fed per day.