Housing gestating sows in group pens

Study examines wound scores imposed by pen mates among gestating sows housed in two different group pen sizes.

In the fall of 2009, Michigan passed legislation (Public Act 117) that amended the Animal Industries Act (Michigan Public Act488 of 1988) to disallow housing gestating sows in individual stalls. Therefore, in Michigan, elimination of sow gestation stalls is set to become law by April 1, 2020.

The objective of this recent work was to compare wound scores among gestating sows housed in two different pen group sizes on a commercial farm. Groups of 10 (small) or 20 (large) sows provided 15.2 square feet of floor space per sow, at placement were compared across three replicates.

Wound scores imposed by pen mates and Body Condition Scores were evaluated on days 0, 7, 30, 60 and 90 after placement, respectively. Wound scores imposed by pen mates of the neck, shoulder, side, rump as well as the vulva were recorded.

Results of this study indicate that there were significant differences in shoulder wounds, side wounds and rump wounds with gestating sows housed in the larger groups having increased odds of wound occurrence.

Interestingly, observations from this study revealed that in each respective replication one individual sow had to be pulled from the large pen around day 60 due to significant injuries imposed by pen mates. More aggressive sows were observed chasing more submissive sows throughout the larger pen. At times, more aggressive and dominant sows would dominate the concrete feeding pad. Moreover, feed consumption by individual sows creates management challenges when housing gestating sows in groups in regard to appropriate body condition of individual sows.

As Michigan pork producers implement management practices to abide by the established legislative requirements, it will be imperative for pork producers and employees of these respective operations to be aware and knowledgeable of the many potential factors that may play a role when making decisions in regard to gestating sows in groups.

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