The influence of previous housing experience and social rank on sow preference for different types of stall housing

Lyndsey M. W Jones, Purdue University

Abstract

This thesis utilizes preference testing to determine if gestating sows display a preference for different housing conditions dependent upon housing background or social rank; investigate the relationship between a physiological measure, heart rate (HR), and choice and the environment; determine if behavior influences choice; and investigate if social factors influence space utilization. Two experiments were carried out to determine sow preferences for access to space and whether preference is influenced by previous experience or social factors. In the first study, sows of either housing background, gestation stalls or group housing, demonstrated a clear preference for the free-access (FA) stall which allows them freedom of movement and opportunity to demonstrate control and choice within their environment. Housing background did influence the preference to be near the other sow in the adjacent T-maze, as only group-housed sows displayed a same side preference. For sows from group housing, HR results indicated that the stronger the preference was for the FA stall during free trials, the higher the maximum HR (beats per minute, bpm) was when in the L stall during training. However, during free trials, the stronger the sows’ preference was for the UL stall, the lower the HR was when in the L stall. When sows were tested with a familiar companion sow the results were quite different, with no obvious preference for either stall type, FA or open-backed. Contradictory to our expected results, there was no same side preference as there was for group housed sows in the first experiment. Behavior of the sows while making a decision did not affect choice and stall type did not affect investigation, lying, and aggression during the free trials. The lack of stall preference may be due to the fact that sows had already developed a social relationship prior to testing, which minimized the need to use the FA stall to avoid aggressive interactions. However, if tested under conditions with greater social stress this preference may still exist. This thesis provides evidence that that when sows were tested individually there was a clear preference for an environment which provided more space, however, a preference for design, or quality, of the free space was unaffected by social rank. It also demonstrates that the welfare of gestating sows may be improved through the provision of space as results indicate that freedom of movement and/or opportunity to demonstrate control or choice within the environment are important to sows, especially those with a history of long-term confinement. These results are evidence that sows can demonstrate choice within a T-maze when presented with different housing options, which may be used as a foundation for housing modifications that may lead to improved welfare for gestating sows. The results of the first experiment demonstrated a clear preference when a simple, straightforward preference test was carried out. However, the results of the second experiment suggest that there are serious limitations when interpreting preferences, making it difficult to extrapolate results to more complex social situations that exist on farms.

Degree

M.S.

Advisors

Pajor, Purdue University.

Subject Area

Animal sciences|Behavioral Sciences

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