Environmental and genetic factors influencing the development of belly nosing in the early-weaned pig

Abstract

This study investigated environmental and genetic factors influencing the development of belly nosing in the early-weaned pig. The first experiment investigated the effects of gender, duration of liquid milk replacer supplementation, breed line and environmental enrichment designed to simulate components of a sow's udder, on the incidence of belly nosing and its associated behaviours in pigs weaned at 7 days-of-age. Both breed line and environmental enrichment were found to affect the incidence of oralnasal behavioural vices related to belly nosing. Differences between breed lines were found in the types of behavioural vices performed and whether these vices were generally focused or directed at specific regions of the body of penmates. Enrichment devices, designed for nosing, rooting, sucking, and biting were also found to be specific in the types of behavioural vices they effectively alleviated. Significant breed line by environmental enrichment interactions were found, with Yorkshire pigs more responsive to environmental enrichment than Duroc pigs. The second study documented the ontogeny of belly nosing from weaning into the grow-finish period in pigs weaned at 12-14 days-of-age and determined whether early belly nosing correlated with behavioural vices observed during the grow-finish period. The results of the study suggest that after belly nosing subsides, a number of other oralnasal behaviours take its place. Pigs that progressed from belly nosing to belly sucking, tended to continue to perform belly sucking behaviour into the grow-finish phase. In contrast, piglets which exhibited generalized nosing and sucking behaviours during the grow-finish period were more likely to tail bite and to engage in generalized biting of penmates. A direct correlation between belly nosing during the nursery phase and tail biting during the grow-finish period was not found. The third study investigated the effects of sire breed and individual sires within breed on belly nosing. Breed of sire affected whether nosing and sucking behaviours were generally focused or directed towards the belly of penmates. Specifically, Large White-sired pigs performed more belly nosing and belly sucking behaviour, while Duroc-sired pigs performed more generally directed nosing and sucking behaviours. The fourth study investigated the use of 'relevant' environmental enrichment devices to further clarify the underlying motivation for belly nosing. A second objective was to investigate the provision of such enrichment at two different developmental stages to determine whether a sensitive period exists for the introduction of environmental enrichment. While providing any type of environmental enrichment during the nursery phase reduced belly nosing, providing nosing enrichment in particular had the most significant effect, despite it being the least utilized. The sensitive period for providing environmental enrichment to reduce belly nosing was found to be during the early nursery phase, within the first two weeks following weaning. The final study investigated the thermal preference of early-weaned pigs as it relates to activity levels, huddling and belly nosing. Early-weaned pigs preferred cooler temperatures during the night, when they huddled to keep warm, and warmer temperatures during the day. Activity levels and belly nosing also demonstrated a diurnal pattern, with the highest incidence of belly nosing occurring during the transition from piglets being more active during the day to spending more time lying at night. Belly nosing is influenced by both environmental and genetic factors. Recognizing the circumstances in which belly nosing occurs will help in designing strategies to reduce the incidence of the behaviour, while still keeping the practice of early weaning as a viable option in disease eradication programs.