The influence of dietary fibre and the provision of straw on the development of stereotypic behaviour in food restricted pregnant sows

Abstract

The inability of sows to appropriately express feeding motivation has been identified as one of the major contributory factors in the development of stereotypic behaviour. It has been proposed that the development of these repetitive behaviours may be mitigated either by reducing feeding motivation, for example by feeding sows bulky diets which increase gut fill, or by providing sows with a foraging substrate. Forty-eight nulliparous sows were used in a 2×2 factorial design comparing the interactive effects of a high fibre diet and the provision of straw on the behaviour of food restricted pregnant sows. Sows were fed the same daily weight of iso-energetic conventional (C) or high fibre (H; containing 600 g of unmolassed sugar beet pulp per kg of food) diets during gestation and were housed in pens with straw (S) or without straw (N). Behaviour was recorded by direct observation and video during their second gestation. Levels of chain and bar-directed behaviour were highest in the hour immediately following food presentation. Although no difference was found in activity levels or levels of chain and bar manipulation between dietary treatments, sows fed the high fibre diet spent less time manipulating straw (C vs. H; 46.3 vs. 37.0%, P<0.05) than sows fed the conventional diet, after adjustment for the time spent feeding (C vs. H; 20.0 vs. 29.4%, P<0.001). In addition, increasing dietary fibre tended to reduce the level of manipulation of substrates other than straw, but only in the final hour of observation. This suggests that fermentation of sugar beet pulp may play a role in maintaining levels of satiety later in the day, when the satiety levels of conventionally fed sows are starting to decline. The provision of straw significantly reduced levels of chains and bar manipulation (S vs. N; 14.4 vs. 35.3%, P<0.01), and levels of non-manipulative oral behaviour (S vs. N; 0.4 vs. 3.8%, P<0.05). Although the daily provision of fresh straw may provide a reliable way of reducing pen component manipulation and the development of stereotypic behaviour, it is unclear to what extent welfare is improved by exchanging excessive pen component manipulation with the excessive manipulation of straw.