An investigation into the daily level of voluntary activity of stabled riding school horses

The importance of correct feeding practice has been highlighted by the increasing prevalence of obesity in horses. Human research has suggested that voluntary activity (VA) levels may influence digestible energy (DE) requirements, accounting for 15-50% of human daily energy expenditure. Therefore, the aim of this study was to investigate whether levels of non-structured exercise differed between stabled horses with similar bodyweight (BW) and similar structured workloads, but with different estimated DE intakes to maintain their BW. Twelve mature horses were selected based on their estimated DE intake and BW, and were paired according to their BW, breed, estimated DE intake, and structured exercise. Within each pair, one horse (L) was fed a relatively lower estimated DE intake than the other horse (H) to maintain a similar, constant BW and performing similar levels of structured exercise. Estimated DE intake was therefore significantly (P<0.01) different between Group L and Group H. Each pair was observed for 72 h during which structured exercise and non-structured exercise were measured. Heart rate was used as a measure of workload during the structured exercise. Two RT3 accelerometers, located on a roller (RT3-R) and head collar (RT3-H), were used to measure VA levels when stabled in addition to visual observations using focal sampling between 07:00 and 18:00 h. RT3-R and RT3-H activity levels were not significantly (P>0.05) different between individual horses. Median activity counts were significantly (P≤0.001) higher during the day time (06:30-18:29 h) compared to the night time (18:30-06:29 h). However, measured activity using RT3 accelerometers did not show a significant difference between horses in Group L and Group H (P>0.05). It was therefore concluded, that differences in VA levels during stabling could not explain the difference in estimated DE requirements between horses with a similar BW and workload.