Genetic analysis of the individual pig behaviour in backtests and human approach tests

Publication Type:
Journal Article
Year of Publication:
K. Scheffler, E. Stamer, I. Traulsen, J. Krieter
Applied Animal Behaviour Science
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The most recent development in pig production has focused increasingly on the well-being of the individual pig and animal-friendly housing conditions, i.e. the launch of the group housing of sows in the EU. In this regard, however, standard procedures which may be stressful to the animals and thus have an impact on their health and welfare (i.e. mixing, iron injections, vaccinations) are undertaken in all commercial farm production. Therefore, there is a need to assess individual pig behaviour in such situations and furthermore to take into consideration differences related to age. Hence, in this study, pigs were evaluated for their response to two standardised stress situations—the backtest and the human approach test. The data were collected on one research farm using German Landrace, Large White and crossbred pigs. The backtest (n = 1382) was performed on pigs at 12 and 19 days of age and the number of escape attempts (NEA), the duration of escape attempts (DEA) and the latency to the first escape attempt (LEA) were recorded. Additionally, the human approach test was performed four times with weaned pigs (n = 1317) and once with gilts (n = 272) while recording the latency (LC) of the pigs to touch the human. The heritabilities of the different traits were estimated univariately and correlations between all observed variables were obtained from bivariate analyses with the average information-restricted, maximum-likelihood procedure as implemented in the DMU software package. The random litter effect had the largest impact on the LEA backtest variable (15%). Smaller values for NEA and DEA were obtained. The LEA backtest variable and the LC variable of the human approach test of weaned pigs and gilts were not influenced by the litter effect. The highest heritability was estimated for LEA (h2 = 0.29) and NEA (h2 = 0.19), followed by DEA (h2 = 0.10) and the heritability of the human LC approach test variable of weaned pigs was similar with h2 = 0.20. However, the heritability of the LC of gilts was low (h2 = 0.03) but the estimation provide no reliable values due to the small number of gilts. The genetic correlations between LEA and DEA were very high (rp = −0.88). Also, the first and second backtests for all variables were highly genetically correlated (rp = 0.69–0.90). This means that the variables and the first and second backtests shared the same genetic base. Therefore, performing just one backtest is sufficient for practical breeding purposes. The genetic correlations between four LC human approach test variables of the weaned pigs were very high (rp = 0.65–0.87) especially between consecutive tests. Hence, under practical conditions, the performance of one human approach test might be sufficient since the behaviour shown in all the human approach tests with weaned pigs depended on the same genetic base. The genetic correlations between backtest variables and human approach test variables of weaned pigs and gilts were very low, which indicates that both tests partly measure different behavioural patterns and that the reactions of the pigs in the tests were not related.


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