Effects of straw bedding and high fibre diets on the behaviour of floor fed group-housed sows

Abstract

In group feeding systems, competition over access to food may be heightened by food restriction, as hungry sows remain active and motivated to feed. The behavioural effects of food restriction may be mitigated by satisfying feeding motivation more effectively or by providing sows with a substrate with which to express their foraging behaviour. Twenty groups of seven multiparous sows were used in a 2×2 factorial design to investigate the effects on behaviour of floor feeding sows the same daily weight of iso-energetic conventional (C) or high fibre (H; containing 600 g of unmolassed sugar beet pulp per kilogram of diet) pregnancy diets in strawed (S) or un-strawed (N) pens. Observations were conducted from the start of feeding for 2 h (0900–1100 h) and for 2 h in the afternoon (1300–1500 h). Sows on S treatments received more aggressive interactions ( P<0.01) and were displaced from the feeding area more frequently ( P<0.001) than sows on N treatments. S sows also spent more time standing during the feeding period ( P<0.001) than N sows, which appeared to account for the difference in the level of aggression observed. No improvement was found, in overall levels of aggression, in feeding sows the H diet, although damage to the vulva was significantly lower in H ( P<0.05) than C-fed sows. The presence of straw in the pen reduced the level of pen component manipulation and non-manipulative oral behaviours, during both observation periods. H-fed sows spent less time manipulating substrates during the afternoon observation period ( P<0.05) than C-fed sows, due to an increase in the time spent inactive ( P<0.05). While feeding sows in un-strawed pens may limit aggression in competitive feeding systems, providing sows with access to straw may reduce excessive levels of pen-directed behaviours. Feeding sows diets which are high in dietary fibre may reduce behaviours associated with a lack of satisfaction of feeding motivation, suggesting that there may be welfare benefits associated with feeding sows high fibre diets, although not necessarily in competitive feeding systems.