Dental ontogeny and its relationship to feeding and abnormal behaviour in commercial piglets
This thesis investigates the deciduous dental ontogeny of commercial piglets and the influence of teeth on the development of feeding and abnormal behaviour. It also examines the causal relationship between nutritional stress and abnormal behaviour in the post-weaning period. Artificial weaning in commercial pigs typically results in disruption of growth, and the development of abnormal repetitive behaviours such as belly nosing, which may be related to the inability to feed sufficiently. A successful transition at weaning requires not only learning of a novel food source and physiological adaptation of the gastrointestinal system, but also growth and muscular development of the masticatory apparatus. The objectives of this research were to (1) determine the natural time course of deciduous dental eruption in commercial large breed piglets and to examine its association with piglet, litter and sow characteristics, (2) compare premolar eruption and occlusion times between two commercial swine farms, (3) examine the relationship between premolar eruption and occlusion, feeding behaviour and feed ingestion prior to weaning, (4) examine the relationship between dental condition at the time of weaning and post-weaning growth, feeding behaviour and the development of abnormal behaviour in the following two weeks, and finally (5) examine the relationship between nutritional metabolic stress associated with weaning and the development of belly nosing behaviour. Premolar eruption occurred at later ages than reported in classic growth studies. The timing of eruption varied across individuals, litters, and farms with higher birth weight and weight gain being associated with earlier eruption. Gilts also had earlier eruption compared to barrows. Piglets under 17 days of age spent less time at the creep feeder when their premolars were erupted and occluded, possibly due to the gingival sensitivity. By 21 days they increased feed-oriented behaviour if they were in a more advanced dental stage. However, ingestion was not affected by dentition. Dental condition at 27 days showed little variation and did not influence post-weaning growth or the development of ingestive or abnormal behaviour. Finally, neither metabolic stress experienced immediately post-weaning or the restriction of feed, could predict or elicit belly nosing.