They stay there until four days before farrowing. Clamp silage was found to be unsuitable - sows would walk over it and, because it warmed quickly, they would lie on it for warmth in winter. It kept sows occupied while they were waiting their turn at the feeding station. Sows also liked to take lumps away to eat in peace elsewhere - minimising conflict at the silage bale. Other Benefits of Feeding Silage Sows prefer silage to straw and therefore eat less of it.
Silage also reduces constipation.
The acidic content may also aid digestion. Very little of the wheat straw bedding was eaten.