The behaviour of farrowing sows with free and operant access to an earth floor

Abstract

The motivation of sows to utilize an earth floor for farrowing was measured in two experiments. In the first experiment, 6 sows housed individually in a concrete-floored pen had free access for 8 h per day to an earth-floored pen. The sows made regular visits to the pen each day and an increased number of visits on the day prior to farrowing. About 8 h before the birth of the first piglet, the sows commenced excavation of an earth nest, primarily by rooting movements of the snout. All sows dug a nest and farrowed in it. In the second experiment, an operant requirement was introduced so that the sows had to lift a lever to open a vertically sliding gate to gain access to the earth pen. This requirement interfered with the pattern of earth pen use. Three sows dug a nest hole and only one sow farrowed entirely within the nest. It appears that the operant requirement itself (lifts on a progressive fixed ratio) does not interfere with pen use, but that the uncertainty created by the opening and closing of the gate may affect nest site selection and nest use by the sows.