SOCIAL-LEARNING IN SIBLING PIGS

Three experiments were designed to assess the extent to which pigs can acquire information from their siblings. In Experiment 1, pigs were pre-exposed to the sight and smell of a novel diet, or to a sibling demonstrator eating the novel diet, or to a sibling demonstrator eating a familiar diet. In subsequent individual feeding trials, pigs from the first two treatment groups showed an enhanced preference for the novel diet relative to the third (control) group, but did not differ significantly from each other. In Experiment 2, food was hidden in three distinctly coloured and positioned troughs. Individual pigs observed a sibling demonstrator feed from one trough. In subsequent tests, ten out of 24 individuals discovered that food was available in the test room. Eight of these ten made their initial discovery of food in the same trough that their demonstrator had used. Thus, some combination of cues resulted in a significant bias in food searching behaviour towards a site where a demonstrator had previously eaten. In Experiment 3, pigs observed a trained sibling demonstrator press one of two panels for food reward during ten daily sessions. Control groups observed untrained siblings in the same apparatus. In subsequent tests, there were no significant effects of observation experience on rewarded panel pressing, but pigs that had observed demonstrators spent significantly more time facing the operant panels and directed more non-rewarded presses at the operant panels than controls. They also showed a significant discrimination for making non-rewarded presses at a panel of the same colour/position as that used by their demonstrator. Visual cues appeared to be more important than residual olfactory cues in attracting non-rewarded panel presses.