Effects over time of different types of sounds on gestating sows’ behavior

Noise can alter the behavior and welfare of pigs, although they have good adaptive abilities. The objective of this study was to determine the relationship between different regularly emitted sounds and the behavior of gestating sows as well as their potential time of habituation to these sounds. Two groups of gestating sows (n = 15, n = 17) were involved in the experiment over two consecutive weeks. During the first week, (“Base week”), no sound was emitted, while the following week ("Test week") one sound among 40 sounds grouped into 4 types (alarm, animal, metallic, and human) was emitted randomly every 10 min during the observed periods. The sows posture (lying, sitting, standing) and behavior (sleeping, observing, in the automations) were observed thanks to manual video analysis during a resting period (PM: 13:30 h – 18:30 h) and a feeding period (Night: 23:00 h – 04:00 h) on Mondays (for Base and Test weeks – Test1) and on Wednesday (only for Test week – Test2). Sows' location in the different areas of the room, posture, and behaviour were recorded. The sows spent less time sleeping during Test1 than Base but this behavior increased again during Test2. The number of behavior changes increased during Test1 and decreased in Test2. In Test1 during the PM time, the number of area, posture and behavior changes was higher during the emissions of Alarm sounds than during the emission of other sounds, but no difference among the type of sounds was observed during the Night. During the emission of Human sounds in Test2, the sows spent more time sitting and observing, and less time sleeping than with the emission of other sounds. They also changed position more during PM of Test2 with the emission of human sounds. To conclude, frequent emission of short sounds, even below 85 decibels, can reduce to time spent sleeping and cause behavior changes. However, gestating sows can habituate to the sound stimuli and return to normal behavior by the second day of testing. The effects of different types of sounds on sow behavior and posture are not yet fully understood and require further research based on the sounds characteristics. •Noise can alter the behavior and welfare of sows.•Sound emitted below 85 decibels can still induce behavioral changes of sows.•Sound emission can decrease the time spent sleeping of the sows.•First day of sound emission increased the number of behavior changes.•Gestating sows adapted quickly (less than three days) to sounds stimuli.