Understanding feeding behaviour and associated welfare of pigs from a motivational perspective

Boumans, I.J.M.M.; Hofstede, G.J.; Boer, I.J.M. de; Bokkers, E.A.M.


Social competition for feed among pigs or inadequate feed quality, can reduce health, increase stress and may result in abnormal behaviours such as tail biting or stereotypies and therefore impair pig welfare. Gaining more insight in behavioural responses of pigs to obtain feed, and the effect of housing systems on the associated behaviours, can help to improve pig welfare. The aim of this study was to identify the key elements controlling feeding behaviour of growing pigs in order to provide a theoretical basis for an individual-based simulation of feeding behaviour and associated welfare issues. Based on empirical data and theories in literature, a conceptual framework was constructed to identify the essential elements affecting feeding behaviour. Behavioural patterns around feeding, including conflict behaviours (e.g. approach or avoidance) and time intervals between feeding, are the result of a complex interaction between various mechanisms that may operate at different levels. To understand how the different mechanisms interact, knowledge of ethology, physiology, psychology, and nutrition on animal, group and housing level is integrated in this framework. Theories of motivation are applied to explain behaviour and to understand how internal and external factors can affect behaviour. These theories state that animals have internal states that motivate an animal to perform certain behavioural patterns. The conceptual framework can be divided into two main processes. The first process is about the formation of feeding motivation and other motivational states in the pigs, the second process concerns decision making i.e. how pigs react behaviourally on the feeding motivation. Important factors affecting feeding motivation and behaviour in this framework are pig characteristics (e.g. gender, weight, growth capacity, coping style, social rank), internal drives (e.g. metabolic energy, nutrient balance, stress level, diurnal rhythm, other motivational states) and external incentives (e.g. temperature, presence of feed, availability feeding place, competition). This interdisciplinary and complex framework shows how individual variation among pigs and social influences interact multidimensional and affect feeding behaviour. The framework is further developed and being tested in an agentbased model to examine effects of interaction between pigs, characteristics of the housing, and management by the farmer on feeding behaviour and associated welfare of pigs.