Abstract
Simple SummaryIn most intensive pig production systems, pigs are often mixed into new groups. Sows are important to a production system, as they are the driver behind the farms’ productivity. The aggression that results from sows being mixed into new groups and formation of hierarchy can detrimentally affect production and welfare. This study aimed to determine the effect of providing access to materials on aggressive and play behaviors in gestating sows. Play behaviors were observed in the ‘enhanced’ pen and no play was observed in standard housing (without materials present). Aggression measures, salivary free cortisol concentrations, and injury counts were unaffected by treatment. The provision of point-source materials to sows at mixing had no impact on aggression; however, their presence maintained sow interest over the course of the experiment. Additionally, play behavior was observed in their presence, which may suggest that a more positive affect was induced when the materials were provided.When sows are mixed into groups, hierarchies form and resulting aggression and stress can affect production and welfare. This study determined the effect of providing point-source materials on aggressive and play behaviors in gestating sows. Large white cross Landrace sows were mixed after insemination; six pens of 12 sows were housed in ‘standard’ pens, and six pens of 12 sows were housed in ‘enhanced’ pens. The ‘enhanced’ pens each contained two rubber mats, eight strands of 24 mm-thick sisal rope and two yellow plastic disks, suspended from the roof. The sows remained in these pens until pregnancy confirmation. Salivary cortisol concentration, injury counts, and sow behaviors were recorded the day before mixing (day 1), mixing (day 0) and post-mixing day 1, day 4, day 7 and day 20. At farrowing, reproductive outcomes were obtained. Play was observed (including locomotor and object play) in the ‘enhanced’ pen, and percentage of time spent playing was greater on d4 (1.48 ± 0.3 Square root transformed data (2.84% non-transformed adjusted mean)), d7 (1.43 ± 0.3 (2.97%)) and d20 (1.64 ± 0.3 (3.84%)), compared to d0 (0.56 ± 0.3 (0.70%)) and d1 (0.87 ± 0.3 (1.67%) (p < 0.05)). No play was observed in standard housing. Aggression, salivary free cortisol concentrations and injuries were unaffected (p > 0.05). The provision of materials had no impact on aggression, although their presence maintained sow interest and play behavior, suggesting a positive effect.
Highlights
In most intensive pig production systems, pigs are often mixed into new groups
The effect of enrichment on sow aggression has been less conclusive and is fairly sparse, with reports that the provision of straw bedding [9] or using spent mushroom compost on suspended wood and wire flat rack [10] reduced sow aggression at mixing; some resulted in straw having no effect on aggression [11], whereas other groups demonstrated that providing straw, either as bedding or in racks, induced competition between sows and resulted in heightened aggression [12,13]
Fight number was affected by the number of days following mixing, with more fights recorded on d0 than any other day (p < 0.001)
Summary
In most intensive pig production systems, pigs are often mixed into new groups. Sows are important to a production system, as they are the driver behind farms’ productivity. The aggression that results from sows being mixed into new groups and formation of hierarchy can detrimentally affect production and welfare. The use of enrichment materials is one possibility to assist in reducing aggression in sows. In three recent reviews, focusing on pigs and the success of varying enrichments, the majority of studies focus on weaners or grower-finishers, with an average of 1.3% of all references focusing on sows [2,14,15]. It is difficult to draw conclusions on the large body of weaner or grower-finisher research, as the formation of sow hierarchies make it difficult to predict the effect of provided materials on aggression in sows, in comparison to younger animals. Low-ranking animals, in particular, are fearful of receiving aggression and the resulting injury, and might avoid interaction with a limited resource to reduce the risk of facing aggression [16], obscuring the value of enrichment
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