Feeding Behaviour of Pre-pubertal Males is Genetically Associated with Maternal Defensive Aggression in Sows

Maternal defensive aggression towards humans reflects poor sow welfare and undermines stockpersons' safety. Selection on young boars using proxies for human-directed defensive aggression would be advantageous because their high reproductive contribution allows them to substantially influence the genetic composition of subsequent generations. We analysed feeding behaviours expected to reflect individual personality and social influences, in pre-pubertal male pigs and estimated their genetic correlations with maternal defensive aggression. Automatically recorded feeding data were available for group-housed Swiss Landrace (n = 725) and Swiss Large White (n = 943) boars and castrated males, from which we derived five traits: Average Daily Intake, Average Daily feeding Duration, Average Interval between Successive feeder Visits, Average Time from the group-level Peak of Activity at the feeder and Average Proportion of Visits at Night. Maternal defensive aggression was assessed in Swiss Landrace sows applying a Piglet Handling Test (n = 376) and a Farmers' Aggressiveness Score (n = 406). Genetic parameters were estimated using Bayesian linear mixed models, with a genomic relationship matrix computed based on 60 K SNP-chip genotypes. Feeding traits' heritabilities were moderate to high (estimate ± SE: 0.25 ± 0.04 to 0.50 ± 0.04). Average Daily Intake and Average Time from the Peak of Activity were genetically correlated with the Piglet Handling Test (0.28 ± 0.27) and the Farmers' Aggressiveness Score (-0.33 ± 0.23), respectively. Higher intake and visiting the feeder at busier times were genetically associated with sows' higher aggressiveness towards humans. Pre-pubertal feeding strategies are promising indirect selection criteria for calmer sows.