The aim of this experiment was to investigate pigs\u2019 preferences for rooting materials. Eighteen materials
\nwere allocated to six categories each of which consisted of three similar materials based on characteristics such
\nas structure, size of particles,complexity, destructibility and digestibility.Twelve pairs of pigs chose among the
\nthree materials of each of the six categories in a balanced design.Within each category each pair was given four
\ninstantaneous choices among the three materials in a three-armed maze. \u2018No choice\u2019 was scored if the pigs did
\nnot enter one of the maze-arms within 90 s. Thus there were four options in each choice situation. The results
\nwere analysed using a random utility model incorporating random intercepts to account for the repeated testing
\nof the same animals. The pigs expressed clear preferences within the category EARTH,where compost and peat
\nwere preferred to wood-shavings and no choice. In the category CHIP the most probable rank-order was spruce
\nchip, willow chip, fir chip and no choice, while in the category ROUGH the most probable rank-order was
\nmaize-silage, grass silage, sugar beets and no choice.However, in these two categories none of the probabilities
\nwere sufficiently large to signify a preference for any of the three materials although the probabilities of the \u2018no
\nchoice\u2019 option were low.The pigs expressed no preferences among any of the four options including \u2018no choice\u2019
\nin the categories TOY(sisal robe, Bite-Rite,wooden beam),HAY(alfalfa hay mixed with straw, seed grass hay,
\nbarley straw with under-seed), and STRAW (long straw, chopped straw and straw pellets).<\/p>\n