Investigating duration of nocturnal ingestive and sleep behaviors of horses bedded on straw versus shavings

Horses are stabled overnight for a number of practical reasons; however, there is little research quantifying nocturnal equine behavioral patterns or the extent to which different environments influence nocturnal behavior. The aim of this study was to establish whether differences in duration of sleep and ingestive behaviors were apparent for horses bedded on straw (group 1) or shavings (group 2). Ten geldings of mixed breed (mean age: 7.3 ± 3.53 years) bedded on either shavings (n = 5) or straw (n = 5) were observed between 7 pm and 7 am. Duration of behaviors according to a predefined ethogram was recorded in minutes using a video recorder and continuous focal sampling. Mann–Whitney U tests were used to identify whether any significant differences in duration of ingestion and sleep behaviors occurred for horses bedded on straw compared with shavings. Of the total observation period, group 1 spent, on average, 29.3% of their time budget engaged in recumbent behaviors, compared with 12.2% for group 2. However, no significant differences in duration were established between horses bedded on straw or shavings for standing sleep, sternal recumbency, and lateral recumbency behaviors (P > 0.05). Ingestive behaviors occupied approximately one-third of the time budget, with no significant difference (P > 0.05) observed between groups. On average, group 1 spent a longer proportion of the observation period ingesting bedding (8.1%) compared with group 2 (1%). Duration of bedding ingestion appeared to peak between 1 am and 7 am for both groups. Although not quantified, general observations revealed horses were motivated to alternate between eating hay and bedding in both groups, owing to the prevalence of bedding ingestion. The results indicate that straw bedding facilitates the display of ingestive and sleep behaviors, whereas horses bedded on shavings spent a greater proportion of their nocturnal time budget engaged in “other” behaviors. Further research is required to investigate the extent to which different types of bedding material enrich the environment of horses that are stabled overnight.