MODIFICATION OF FORAGING BEHAVIOR AND PASTURE DAMAGE BY DIETARY MANIPULATION IN OUTDOOR SOWS

Food restricted sows under extensive conditions forage for considerabl e periods of time, and this can give rise to serious pasture damage. T he objective of this experiment was to study the effects of feeding a fibrous diet (containing 600 g/kg sugarbeet pulp), either at a restric ted or ad libitum level, on foraging behaviour and the consequences of this for pasture damage. Twenty-four multiparous outdoor sows, withou t nose rings, were selected in two consecutive batches of six pairs of sows. The pairs were allocated to one of three feeding regimes in a r eplicated 3 x 3 Latin square design: a control diet (C) fed at a restr icted level (2.5 kg) once daily, a fibrous diet fed at a restricted le vel once daily (RF) to supply the same energy as treatment C, and a re gime with ad libitum fibrous diet (AF). RF sows took longer to consume their ration than control sows (RF = 42, C = 18, SEM 2.7 min, p < 0.0 01). Liveweight gain over a two week period was highest for sows on th e AF regime (AF = 13.0, RF = 3.3, C = 1.0, SEM 2.75, p < 0.01), but th ere was no significant difference in backfat change. Time sampling of behaviour during 6 h/day showed that sows fed the fibrous diet spent m ore time lying than C sows (C = 219, RF = 249, AF = 259, SEM 5.1 min, p < 0.001) and less time engaging in foraging behaviours (C = 103, RF = 58, AF = 41, SEM 5.8 min, p < 0.001). Absolute values for pasture da mage were highest in C paddocks, but no differences were statistically significant (e.g., C = 12.7, RF = 7.4, AF = 5.0, SEM 3.39 change in % overturned earth per 2-week period). Feeding a high-fibre diet to out door sows, at either a restricted level or ad libitum, reduced foragin g behaviour but did not reduce pasture damage to commercially acceptab le levels. (C) 1998 Elsevier Science B.V.