The effect of straw on farrowing site choice and nest building behaviour in sows

Farrowing site choice was examined in 40 sows. In group 1, the preference of 16 sows was tested for pre-formed lying areas which incorporated the characteristics of previously observed farrowing nests: a hollow (H), a mattress (M), a nest box (B) and a flat control (C). None of the sows farrowed on C which indicated that choice was based on some evaluation of the lying surface. However, there was no significant preference for the three nest features: H6, M6, B 4. In group 2, C was replaced by a straw area (S). Four different amounts of straw were offered: 18, 9, 4·5 and 2·25 kg with four, four, eight, eight sows on trial at each amount respectively. All the sows farrowed on S at the 18, 9 and 4·5 levels; at 2·25 kg, three farrowed on S and five moved the straw to other lying areas on which they farrowed. The results indicated that the location of nest material has an important influence on farrowing site choice because it allows the performance of nesting behaviour. Although performance of the behaviour was not affected by the amount of straw available, 2·25 kg appeared to be inadequate for a satisfactory nest.