Abstract
This thesis examines in detail the feeding pattern of growing pigs and investigates how different components of the social and physical environment affect the feeding behaviour and production performance of the animals. Using a computerized single-space feeding system, currently used by most breeding companies in their selection programmes, four experiments were carried out looking at effects of the following factors: Group size, feeder design, trough space and individual housing.
Decreasing the accessibility of the food, either indirectly by increasing pig:trough ratio or directly by fitting an enclosed race in front of the trough, modifies the feeding behaviour of the animals in the direction of fewer, but longer visits to the trough.
Increasing the social constraint, either directly by increasing the group size or indirectly by offering low levels of protection from other pigs whilst feeding, increases the rate of eating. All pigs succeeded in adapting to the constraint placed on their feeding behaviour and adjusted to the lack of feeding space, as there were no significant effects of social and physical environment on production performance. No correlations were found between social behaviour (aggression level and rank) and any of the feeding behaviour and production variables.
A change in the social environment from group to individual housing resulted in only a small increase in feeder visits, regardless of the feeding pattern displayed by the pig whilst group housed. However, this had significant effects on the daily food intake of those animals with few, long visits, and suggests that these pigs were disadvantaged in terms of daily food intake rather than number of feeder visits when group housed.
The general discussion considers various criteria used in the literature to define ’a meal’, briefly discusses the validity of such classifications of visits to the trough, and elaborates on the relationship between food accessibility and feeding pattern. The effects on feeding rate are placed in the context of competition and preferred rate of eating. A large number of additional environmental factors and their influence on feeding behaviour is reviewed.
