Bulens, A., Beirendonck, S., Van Thielen, J. et al. 2013. The enriching effect of non-commercial items in stabled horses. Applied Animal Behaviour Science 143(1), 46-51.

The effect of the provision of simple objects to stabled horses on their behaviour was investigated to determine whether these objects can affect horses' behaviour in a positive way and thus enrich their environment. A positive influence can for example be measured by a decrease in stereotypical or abnormal activities. In this study, 35 horses were observed in their boxes during three observation periods per observation day. Each observation period lasted one hour and during one hour, each horse was observed 30 times. The observation periods were at noon (11:00-12:00 h), in the afternoon (15:00-16:00 h) and in the evening (20:00-21:00 h). The horses were observed before the objects were provided to set a baseline and then during the presence of the objects. A plastic bottle filled with sand and a rope were chosen as potential enrichment items and placed in a box for one week. For an average of 3.85% (+/-0.420) of our observations, the horses exhibited behaviour involving the items. This frequency does not significantly reduce after a week. The frequency of item related behaviour was associated with the age and gender of the horse, with a higher frequency in younger horses (P = 0.0151) and in stallions (P = 0.0217). It was also associated with the quantity of hay, with the highest frequency when no hay was available. It is possible that horses are expressing either frustration of having no roughage towards the item or a need for fibres by chewing on the objects. It is suggested that oral activities show the motivation to eat, to attempt to supplement the concentrate feed or the absence of roughage with additional sources of fibres. The use of the items had the tendency to reduce one specific type of abnormal behaviour, i.e. the occurrence of licking walls and other objects (P = 0.0586). However, it is possible that horses redirect their abnormal behaviour towards the items. Biting behaviour was associated with the quantity of hay, with a higher frequency when no hay was available. This possibly also suggests a search for other sources of fibres when roughage is absent. Although horses exhibited item related behaviour, the used objects do not offer a food reward and arouse the interest only to a very limited extent, showing a limited enriching effect.