Why you should 'let the sow out'!

Sows spend most of their time lying down, and their lying behavior and, in return also, their activity level appear to be indicators of their welfare, as they reflect their ability to meet their physical and behavioral needs for rest or movement, which is especially important during parturition and lactation. The Animal Husbandry and Ethology Group (Lorenz Gygax and Edna Hillmann) investigated lying behavior of crated and free farrowing sows to compare how the distinct housing systems allow them to fulfill their needs for rest or movement and to evaluate the accuracy of accelerometer-based sow lying behavior classification. Check out their Journal of Animal Science Article!

Abstract

Accelerometers are useful in analyzing lying behavior in farm animals. The effect of the farrowing system on sow lying behavior has been studied around parturition, but not long-term. In a natural environment, sows increase activity 14 days post parturition, which we expected to be also evident in housed sows when they can move freely. The objective of this study was i) to validate the methodology to automatically measure sow lying bouts and duration with accelerometers and ii) to apply it to crated and free farrowing sows 24 hours pre-parturition until weaning. We used videos with manual behavior coding as gold standard for validation and calculated the agreement with an intraclass correlation coefficient (ICC), which was 0.30 (95% CI: -0.10-0.64) for the number of lying bouts. When transitional sitting bouts were excluded from the video dataset, the ICC for lying bouts increased to 0.86 (95% CI: 0.40-0.95). For lying duration, the ICC was 0.93 (95% CI: 0.26-0.98). We evaluated effects of housing, day relative to parturition, and time of day on lying using the accelerometer data and linear mixed models. In crated sows, the number of lying bouts increased toward parturition, peaking at about five bouts per six hours and decreased to almost zero bouts after parturition. Then, it increased again (P = 0.001). In free farrowing sows, the number of lying bouts gradually decreased from a high level towards parturition and was lowest after parturition. It remained constant, as in the crated sows, until day 15, when the number of bouts increased to eight bouts on day 20 (P = 0.001). Sows in both systems were lying almost all of the time between 18:00-00:00 and on all days (P = 0.001). The crated sows showed a very similar pattern in the other three quarters of the day with a reduced lying time before parturition, a peak after parturition, reduced lying time from days 5 to 20, and an increase again towards weaning (P = 0.001). Free farrowing sows had a similar pattern to the crated sows from 00:00 to 06:00, but without the reduction in lying time from days 5 to 20. They showed an increase in lying time toward parturition, which remained constant with a final decrease toward weaning, especially during the day (P = 0.001). This study proves the accuracy of accelerometer-based sow lying behavior classification and shows that free farrowing systems benefit lactating sows around parturition but also towards weaning in the nest-leaving phase by facilitating activity.