Lying behavior in horses in relation to box size

To analyze if horsesʹ lying behavior is influenced by the size of their lying area, 8 horses were kept, first, in a large box—(2.5 × height of the horse)2m2—and then in a small box—(1.5 × height of the horse)2m2—or vice versa. After a 5-day adaptation period, the lying behavior (frequency and duration of sternal and lateral recumbency, rotating behavior just before lying down, and rolling behavior just before getting up) was observed from video recordings on 3 consecutive nights. The results showed that the duration of sternal recumbency was significantly longer in the large boxes than in the small boxes (P = .002). Furthermore, box size exerted an influence on the frequency of the rolling behavior shown before getting up, but box size was not the only factor affecting this behavior. We conclude that observations of the resting behavior of horses are necessary to make recommendations for the minimal size of stalls for horses.