Dietary energy intake does not influence diet selection of familiar and novel forages by horses

Equine studies have been able to show that horses have the ability to discriminate nutrient deficit diets or "balance" macronutrients (e.g. protein or carbohydrates) by increasing their intake or changing food preference (Laut et al., 1985; Cairns et al., 2002; Redgate et al., 2014). These studies used either familiar concentrates or forages alone, but in grazing systems horses are likely to exploit familiar foods in combination with novel foods on a continuous basis. The acceptance of nutritious novel foods and the influence of the animal's nutritional status on diet selection (e.g. partial preferences) warrant further research. Therefore this study aimed to investigate the effect of energy intake on foraging behaviour patterns in horses and the selection of familiar (FF) and novel (NF) forages. It was hypothesised that horses would have a preference for FF, but horses on a low energy diet would show a greater acceptance of the nutritious NF.