Effect of Diet on the Behaviour and Welfare of Pigs

The behaviour and hence the welfare of pigs can be affected by a number of factors related to their diet and the way that that diet is presented. When diets are fed at levels below the voluntary feed intake capacity of the pig (for example in the case of gestating sows) hunger can have a profound effect on behaviour. Problems arise because the diet of the commercial domestic pig is so different from that of its ancestor the wild pig. Whereas the wild pig’s diet is low density, low dry matter concentration (around 2025%) and high in crude fibre the commercial sow’s diet is high in dry matter (85-90%) with a crude fibre content of less than 10% and frequently less than 5%. In the last 15 years it has become apparent that feeding sows on high density, low fibre diets has a profound and negative effect on their behaviour and welfare and that conversely, providing sows with more bulky diets can have very positive effects on their wellbeing. When pigs are fed ad libitum on diets that apparently satisfy their nutrient requirements diet related behaviour problems can still arise. In this case the composition of the diet may influence the behaviour of the pig. Diet components can influence the incidence of vices in intensively kept grow-finish pigs, such as biting of tails, ears, or flanks. Imbalances in the diet can influence feed intake and resting behaviour. Diet composition can also affect the time that the pig spends eating and its demand for water, and hence time spent drinking. When feeding and drinking points are limited, changes in demand for access to feeders or drinkers may have an influence on behaviour. At best these changes will result in animals eating out of synchrony with their circadian rhythms and in particular eating and drinking during what should be their resting period. In other circumstances they cause considerable disruption to the behaviour of the individual or group. In the worst situations the available resources for feeding and drinking may be so limited that the pig’s requirements cannot be accommodated thereby compromising their welfare. 1 E-mail: [email protected]