Sequential analysis of
belly nosing of early weaned pigs
Y.Z. Li, H.W. Gonyou, K.
Getson and C. Peterson
Prairie Swine Centre,
Inc., Saskatoon, Canada
Segregated early weaning improves disease-control and performance in pigs. However, it has been linked to an increased incidence of anomalous behaviours, which raises welfare concerns. A common anomalous behaviour is belly nosing, but the key causal factors of this behaviour are not clear. A study was conducted to determine the motivation of belly nosing of early-weaned pigs. Eight pens of 10 pigs, weaned at 12-14 days of age, were videotaped for 24 h on day 7 post-weaning. Behavioural time budgets and partial correlations for each pig were determined by scan sampling at 5 min intervals. Average time spent belly nosing was 2.4% (SE=0.82%) of actual time, with 81% of the pigs belly nosing. Belly nosing was negatively correlated with eating (r=-0.35, P<0.05) and lying (r=-0.58, P<0.05), but positively correlated with standing (r=0.28, P<0.05), suggesting that belly nosing may affect energy balance.
To study the motivation of belly nosing, 25 belly-nosing events identified by the scan sampling were randomly selected from each of 4 pens. These events were analyzed by continuous observation of the nosing pig, beginning 5 min before belly-nosing began and concluding 5 min after nosing ended. The average duration of the nosing segment was 538 (SE=36.7) sec, during which the focal pig spent 65.8% of time belly nosing with the mean duration of 64 (SE=9.9) sec. The number of two-event sequences tallied for the eight behaviours of interest (belly-nosing, eating, drinking, standing, lying, social interaction, idling, and ‘other’ behaviour) from each pen were 1088, 956, 769 and 612 respectively. A Chi-square analysis was performed for each two-event sequence to determine whether the observed frequencies of any of the sequences deviated from their expected values. The frequencies of social interaction leading to belly nosing (P<0.01) and belly nosing leading to social interaction (P<0.05) were higher than their expected means. Belly nosing led to ‘other’ behaviour (P<0.05), but the reverse sequence was not common. ‘Other’ behaviour served as a transition between eating and drinking, and from eating, drinking and belly-nosing to lying. Our results indicate that belly nosing more closely associated with social interaction, rather than eating and drinking.