The impact of environmentally enriched housing on sow motivation, behavior and welfare

Monica R Elmore, Purdue University

Abstract

The broad aims of this dissertation were to investigate the motivation of gestating sows for access to environmental enrichments in both stall and group settings and to determine the impact of resource provision on sow behavior. The overarching hypothesis, that sow motivation and behavior would vary according to the resource provided and due to dominance status when housed in a social context, was tested. To assess motivation, sows were trained to press an operant panel on an increasing schedule for access to resources. The highest schedule pressed (i.e. highest price paid) indicated motivational strength and could be used as an indicator of resource value. In Chapter 2, the impact of rubber mats on the health, behavior and welfare of group-housed sows was explored. Little work exists on the provision of rubber mats to swine; therefore, mat use and value was investigated prior to testing sow motivation for this resource in Chapters 4 and 6. When sows were housed in pens with rubber mats or full concrete flooring, sow behavior varied due to treatment (P < 0.001), especially resting behaviors. In particular, time spent in different resting postures (sternal versus lateral lying) varied (P = 0.03), where sows on mats spent more time lying laterally (P < 0.05), which is thought to indicate increased comfort. Additionally, sows on mats stood up and laid down more frequently (P = 0.001), which may indicate reduced slipping or reduced pain when making postural adjustments. Sows with mats had a lower total lesion score (P = 0.03), though lameness scores did not differ between treatments, likely due to the short length of this experiment. These results imply that the provision of rubber mats may provide welfare benefits to sows, especially in relation to lying comfort. In Chapter 4, the motivation of dominant and subordinate sows housed in standard gestation stalls for access to an enriched group pen, containing straw in a rack, compost in a trough, cotton ropes and a rubber mat, was investigated. Additionally, behavioral measures were obtained to determine the effect of social status on sow enrichment use while in the group pen. Subordinate sows compensated for early low enrichment use by increasing their use the following morning during non-peak times (P = 0.001). These findings demonstrate that regardless of social status, sows were able to access enrichments and valued an enriched group pen. In Chapters 5 and 6, the motivation of sows for access to environmental enrichment in an individual stall was investigated. In Chapter 5, sow motivation for access to compost in a trough or straw in a rack, in comparison to a positive (food) and negative (empty trough) control, was tested. This study demonstrates that compost (as indicated by operant responding) and straw (as indicated by behavioral measures) are valued by sows housed in barren stalls and the provision of these enrichments should be considered as a method to improve sow welfare on farms. In the final experiment, presented in Chapter 6, sow motivation for access to a cotton rope or a rubber mat, in comparison to a positive (food) and negative (empty trough) control, was tested. Sows showed high motivation for food compared to all treatments (all comparisons, P < 0.05), as indicated by an increase in the highest price paid and a reduction in latency to press the operant panel and enter the treatment stall. However, sow behavior did not differ due to treatment. Although sow motivation for a mat did not differ from an empty trough, previous work has demonstrated the welfare benefits associated with comfort flooring (see Chapter 2). The hypothesis that sow motivation and behavior would vary according to the resource provided and due to dominance status when sows were housed in a social context was supported by the results of all of the experiments described in this dissertation. In particular, sows showed high motivation for access to compost in a trough and straw in a rack, and the provision of these resources should be considered to improve sow welfare in captive settings. However, sows were not highly motivated for a cotton rope or a rubber mat, though mats may offer welfare benefits to sows and warrant further investigation. (Abstract shortened by UMI.)

Degree

Ph.D.

Advisors

Garner, Purdue University.

Subject Area

Animal sciences

COinS