Genetic analysis of on-farm tests of maternal behaviour in sows

Abstract In this field-study, four behaviour traits were genetically evaluated as possible selection traits for improving piglet survival: the sow’s reaction to a piglet scream, the sow’s reaction to her piglets being handled, avoidance of and aggression towards the stockperson. The scream test was recorded on the first day after farrowing, and the other tests around day 4. Variance components were estimated using a linear-threshold model and Gibbs sampling. Recordings were done in 10 herds and the analyses of the tests included 741–1335 records on Swedish Yorkshire sows. The estimated heritability for the scream test was 0.06, the handling test had a heritability of 0.01, and fear and aggression both had a heritability of 0.08. No phenotypic relation between either of the behaviour tests and piglet mortality was found; however, there were moderate genetic correlations between response in the scream test and mortality of piglets born alive (−0.24) and between avoidance and mortality (0.37). This indicates that selection for a strong response in the scream test, or selection against sows that avoid humans would result in a correlated genetic improvement in piglet survival. Avoidance may reflect underlying fear, and selection for lower levels of fear in sows would improve both sow and piglet welfare.

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