Animal welfare

Genetics of maternal defensive aggressiveness in Swiss Landrace sows

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Abstract

Maternal behaviour has been suggested to be a temporally stable trait in mammals. In sows, maternal behaviour is a commercially important trait which affects sow and piglet welfare as well as the quality and safety of human-animal interactions, especially if free farrowing of sows without crates is in place. The aim of this study was to evaluate maternal behaviour and to estimate its quantitative genetic parameters in Swiss Landrace sows (SLR). The lactating sows, with an average lactation period of 29-30 days and different parities (one to eleven) at four nucleus farms of the Swiss breeding company SUISAG underwent a series of behaviour tests and observations during two data collection periods and in 24 weeks. The reaction towards a human when handling one of their piglets (Piglet Handling Test) was assessed in 569 sows, using a five-point scoring system. Furthermore, the reaction to the playback of unknown squealing piglets and the lying down behaviour (vocalising before lying down and time taken to lying down) were evaluated for 521 and 451 of these sows, respectively. The level of aggressiveness towards stockpersons as scored by the farmers using a three-point scale (Farmers' Aggressiveness Score) was available for 705 sows. Number of samples per measure varied between one and six. Given the non-Gaussian distribution of the traits, variance components were estimated based on Bayesian generalized linear mixed models with the R package brms, including as random effects the sow genetic effects and the permanent environmental sow effects. The additive genetic relationships were either computed from the pedigree (1,418 individuals across six generations), the genomic data (from 376 genotyped sows using SNP-Chip 60K), or the combination of both. All traits were found to be repeatable independently of how the additive genetic relationships were modelled, with means of the posterior distributions varying between 0.18 (95% CI = [0.01, 0.35]) and 0.66 (95% CI = [0.58, 0.74]). Both the Piglet Handling Test and the Farmers' Aggressiveness Score were found to be heritable (pedigree data: Piglet Handling Test: h2 = 0.44, 95% CI = [0.22, 0.69]; Farmers' Aggressiveness Score: h2 = 0.24, 95% CI = [0.04, 0.45]). These two measures were strongly correlated at the genetic level (rg = 0.70, 95% CI = [0.34, 1.00). An unfavourable genetic correlation between the Farmers' Aggressiveness Score and piglet survival traits emerged (number of deaths due to layovers: rg = -0.51, 95% CI = [-0.97, 0.00]; proportion of piglets surviving to weaning: rg = 0.28, 95% CI = [-0.59, 0.98]). Our results suggest that improvement of stockpersons' safety and sow welfare through genetic selection against aggressiveness would be feasible, although piglet survival should also be included in a balanced breeding index to ensure progress in both traits.

Keywords: 2026

How to Cite:

Maffezzini, N., Khayatzadeh, N., Turner, S., Roehe, R., Pong-Wong, R. & D’Eath, R., (2026) “Genetics of maternal defensive aggressiveness in Swiss Landrace sows”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286420. doi: https://doi.org/10.31274/wcgalp.23997

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