Effect of environmental enrichment on voluntary salt intake in horses

Abstract

The aim of this study was to evaluate whether horses consume a significantly different amount of salt from a salt block when a “toy” in the form of an empty plastic bottle was hung in their boxes compared to when no toy was presented to them. This would shed light on whether or not voluntary salt intake in horses housed under generally accepted conditions can be affected by a factor external to the horse and unrelated to salt requirement or balance. Twelve horses were observed for the total time of three weeks during which they had no access to a toy and then access to one according to a concurrent multiple baseline design. The data gathered was not normally distributed leading to a Wilcoxon test for matched pairs being carried out. Salt intake was significantly lower during the periods when the empty plastic bottle was available to the horses (T = 16, P < 0.1 and T = 15, P < 0.1, Wilcoxon’s test for matched pairs). Combined data from periods without toys and combined data from periods with toys showed an even greater difference with lower consumption when the bottles were available to the horses (T = 10, P < 0.05, Wilcoxon’s test for matched pairs). Throughout the study, no horse was found to eat an amount less than or equal to its estimated sodium requirements. The results found in this study showed a clear tendency for horses to consume less salt when a toy was hanged in their boxes. The results also support assumptions made in previous studies stating that salt lick over-consumption in horses might be linked to lack of stimuli. On a broader scale, these results call for a re-assessment of modern ways of keeping horses stabled rather than offer a solution to problems seen as a result of poor well-being in housed horses.