A comparison of free access, multiple stimulus without replacement, and concurrent schedule preference assessment methods for evaluating food preference

Abstract

Outcomes from three preference assessment methods were examined in a study of food preference with goats. The methods used were: free access, multiple stimulus without replacement, and a concurrent schedule analysis. Results from each method were compared, in terms of the preference ranking they produced. Two male goats, one domesticated wild goat and one Saanen, were used as subjects in this study. Each method yielded similar results, although the concurrent schedule test provided more comprehensive information than either of the other methods. There was moderate agreement between the multiple stimulus without replacement and the concurrent schedule tests, however the free access procedure identified only the two most highly preferred items and provided limited information on preference level of the remaining food items. Five foods were tested in this experiment, all of different texture and composition – crushed maize, sheep and goat pellets, chopped lucerne, lucerne haylage, and timothy and lucerne haylage. During the free access, goats were given unrestricted access to a particular food for 12 seconds. During the multiple stimulus without replacement, goats were presented with all five foods simultaneously and allowed to make one choice. Once the subject had selected a food by pressing the respective cover with their muzzle, that cover was removed to allow access to that food only. When the subject stopped eating, the cover was replaced - subjects could then select another food. This process was repeated until either all five feeds had been sampled or goats had not made contact with any covers for fifteen seconds. The concurrent schedule test involved making two foods available concurrently. Food delivery was determined by a VI 60s schedule and controlled by a computer software program that was linked to the apparatus. The assessment procedure was arranged so that each food was tested alongside every other food. Data was analysed in terms of the proportion of time and responses allocated to each food. Proportion of time and responses varied considerably depending on the food that was available concurrently.