Effects of Used Bedding Straw and Drying it in Sunshine on Lying Behavior in Stable Horses

Abstract

This study investigated the lying behavior of horses in the stable with used bedding material (rice straw) that was dried in sunshine. Six geldings were used in this study. Three types of straw were prepared: fresh straw that was not used as bedding materials before (New), used straw that was dried in sunshine for eight hours (UD), and used straw that was kept in a shaded area (U). Horses' behavior was observed during the night (16:30-5:30). Although there were no significant differences in the total duration of the recumbent position on three types of straw, four and three geldings lay more than 60 min in the stable on New and UD straw, respectively, whereas no geldings lay more than 47 min on U straw. Furthermore, short lying bouts (less than ten minutes) were seen three times in the stable with U straw whereas such were never seen in the stable with New and UD straw. The water content of U straw was significantly higher than in New and UD, and there was no difference between New and UD. The airborne ammonia (ANH3) concentration in the stable with U straw was significantly higher than that in New straw, but there was no significant difference between UD and U straw. In conclusion, horse's lying behavior was disturbed in the stable with used straw, but drying the used straw in sunshine can relieve this disturbance. Nevertheless, drying in sunshine was not enough to remove the urine ammonia completely from used straw, and this might be one of the causes of incomplete relief of the disturbance.