Recognition of Maternal Environment in Piglets: Effects of Age and Some Discrete Complex Stimuli

Abstract

Ethological evidence suggests that 1-week-old piglets can distinguish between their own mother or home environment and alien ones. The bases for this discrimination were investigated in two series of experiments employing a T-maze. In the first series, the apparatus was placed between two pens each housing a sow and its piglets, with each of the two goal-arms having a wire mesh end protruding into one of the pens. When piglets from each of these pens (as well as controls from other litters) were run individually in the apparatus, piglets of all ages from 1 to 14 days showed preferential responses towards their home environment. In the second series of experiments, various discrete but complex natural stimuli were placed at the end of the goal-arms: in each case, the stimuli in the two goal-arms were indentical in nature except in their derivation from the maternal pen or an alien one. One-week-old piglets showed a significant preference for their own mother (vs. another sow visible and audible through wire mesh), for wood shavings mixed with sow faeces from their own pen (on the floor of the goal-arm), and for air blown over maternal faeces and shavings. But they showed no evidence of distinguishing between a littermate and another piglet (penned at the other side of the wire mesh terminating a goal-arm).