Comparison of Continuous Monitoring and Scan Sampling for Monitoring Postural Changes in Sows Housed in Gestation Crates.

Continuous monitoring of the behavior of sows is the most accurate approach of measurement but is laborious. Scan sampling, which involves monitoring behavior at fixed intervals, can reduce labor requirements compared with continuous monitoring. However, the accuracy of scan sampling compared with continuous monitoring needs to be established. The objective of this study was to compare 2 sampling methods (continuous monitoring vs. scan sampling) for monitoring postural changes in individually housed sows after weaning. The study was carried out as a within-subject longitudinal study using 99 multiparous sows that were monitored over an 11-day period following weaning. Sows were housed in individual stalls and were checked daily for standing reflex from day 3 to 7 post-weaning. Video recording of the sows was carried out throughout the study period. The postures recorded were lying, standing, sitting, and active (standing + sitting). All recording of postures was carried out by a single trained observer. For the continuous monitoring, video recordings were observed continuously and the exact time and duration that sows exhibited each posture over the study period was recorded. The scan sampling method involved pausing the video recordings at 5 min intervals and recording the posture of the sow at each time. Postures recorded from the scan sampling were reported as the number of observations of each posture as a percentage of the total number of observations. Postures recorded from the continuous monitoring were reported as the time spent in each posture as a percentage of the total time. A repeated-measures analysis was carried out using PROC GLIMMIX of SAS; the model included the fixed effects of study day, sampling method, and the interaction. There was no difference (P > 0.05) between sampling methods for any of the postures on any study day or for the overall study period (Table 1). In conclusion, these results suggest that scan sampling at 5-minute intervals gives similar results to continuous monitoring for measuring the posture of newly weaned sows housed in individual crates. Further research is needed to define the maximum interval for scan sampling that maintains the accuracy of monitoring sow posture. [ABSTRACT FROM AUTHOR]