The role of genetic selection on agonistic behavior and welfare of gestating sows housed in large semi-static groups
Brajon, S., Ahloy-Dallaire, J., Devillers, N., Guay, F. (2020). The role of genetic selection on agonistic behavior and welfare of gestating sows housed in large semi-static groups. Animals, [online] 10(12), 1-20. http://dx.doi.org/10.3390/ani10122299
Plain language summary
Group-housing of gestating sows is becoming increasingly common worldwide
as it oers the sows the opportunity to exercise, display exploratory behaviors, and develop social
relationships. Despite its advantages, group-housing as it stands in modern industries also presents
several welfare issues such as overt aggression between pen-mates and resulting stress and injuries.
To date, breeding companies often largely focused their eorts on genetic selection based on individual
production characteristics (e.g., litter size, piglets’ growth, and meat quality) and traditionally ignored
the social behaviors and the ability to establish a dominance hierarchy without exacerbated aggression.
Hence, the extent to which agonistic behavior diers according to new genetic lines is unknown.
The objective of this study was to compare and investigate the influence of two genetic lines on the
welfare and performance of sows housed in large semi-static groups (up to 91 animals). While the
first genetic line was more aggressive toward pen-mates during gestation, the second had piglets with
a lower robustness and survivability. This study raises the diculty of finding an optimal genetic
line, including both positive welfare and productivity outcomes, and points to the urgent need of
considering social aspects when developing genetic lines for group-housing.
Confinement of gestating sows is becoming banished in favor of group-housing in countries worldwide, forcing breeding companies to develop genetic lines adapted for social living. This study aimed at assessing the influence of two genetic lines selected for high performance (HP1, HP2, derived from Landrace × Yorkshire) on welfare and reproductive performance of sows housed in large semi-static groups (20 groups of 46–91 animals) across several parities. To address this, agonistic behaviors were recorded on d0, d2, d27, and d29 post-mixing while body lesions were scored on d1, d26, and d84. Sows’ individual and reproductive performances were also recorded. HP2 sows were more aggressive than HP1 sows since they fought (p = 0.028) and bullied (p = 0.0009) pen-mates more frequently on d0–d2. HP2 sows had more total body lesions throughout gestation than HP1 sows at higher parities (p < 0.0001). Regarding reproductive performance, HP2 sows lost less piglets (p < 0.0001) and tended to wean more piglets (p = 0.067) than HP1 sows. In conclusion, while HP2 sows were the most aggressive, HP1 sows had piglets with lower survivability, which raises ethical issues in both cases and points to the need of considering social aspects when developing genetic lines for group-housing.