The aim of this experiment was to investigate pigs’ preferences for rooting materials. Eighteen materials
were allocated to six categories each of which consisted of three similar materials based on characteristics such
as structure, size of particles,complexity, destructibility and digestibility.Twelve pairs of pigs chose among the
three materials of each of the six categories in a balanced design.Within each category each pair was given four
instantaneous choices among the three materials in a three-armed maze. ‘No choice’ was scored if the pigs did
not enter one of the maze-arms within 90 s. Thus there were four options in each choice situation. The results
were analysed using a random utility model incorporating random intercepts to account for the repeated testing
of the same animals. The pigs expressed clear preferences within the category EARTH,where compost and peat
were preferred to wood-shavings and no choice. In the category CHIP the most probable rank-order was spruce
chip, willow chip, fir chip and no choice, while in the category ROUGH the most probable rank-order was
maize-silage, grass silage, sugar beets and no choice.However, in these two categories none of the probabilities
were sufficiently large to signify a preference for any of the three materials although the probabilities of the ‘no
choice’ option were low.The pigs expressed no preferences among any of the four options including ‘no choice’
in the categories TOY(sisal robe, Bite-Rite,wooden beam),HAY(alfalfa hay mixed with straw, seed grass hay,
barley straw with under-seed), and STRAW (long straw, chopped straw and straw pellets).

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