Genetic variation in sows' maternal behaviour, recorded under field conditions

The present study presents heritabilities for several maternal behavioural traits of sows recorded under field conditions (by the farmer) in Norwegian (N) and Finnish (SF) nucleus herds. Based on questionnaires to the farmers, maternal behaviour was scored on a scale from 1 to 7 for 11 traits in the Norwegian study and 5 of the same traits in the Finnish study. Based on the full relationship matrixes, significant heritabilities were found for the same traits in the two countries' breeding herds. The highest heritabilities were found for the sow's reaction to piglet screaming when handled (h2=0.16 (N), h2=0.12 (SF)), how often the sow showed fear during routine management (h2=0.14 (N), h2=0.17 (SF)), aggression towards humans (h2=0.11 (N)) and protests by the sow when moved to the farrowing pen (h2=0.00 (N) but h2=0.22(SF)). Except for the last trait, the results were very consistent across countries. The study shows that field recording of maternal behaviour with questionnaires is one way of detecting genetic variation between sows and seems to work in a large scale, under field conditions. Some of the estimated heritabilities were higher than corresponding heritabilities based on behavioural tests presented in previous studies. Sows' reaction to piglets screaming when handled, sows' fear of humans and sows' aggressive behaviour towards humans are possible candidate traits for selection.