Can we improve maternal care in sows? Maternal behavioral traits important for piglet survival in loose-housed sow herds

The primary objective of this survey was to investigate the relationship between qualitative maternal behavioral scores (nest building activities, sow communication, and sow carefulness), piglet mortality, and the number of weaned piglets on commercial farms with loose-housed lactating (Norsvin Landrace x Yorkshire) sows. Second, the impact of these scores on productivity compared with the physical condition of sows (movement disorders, body condition, and shoulder lesions) was assessed. Data on maternal care behaviors and physical condition were collected on 895 sows from 45 commercial farms. Farmers scored sows on their physical condition (movement disorders [MD], BCS, and shoulder lesions [SL]) and qualitative maternal care behaviors (nest building activities [NEST] prior to farrowing and sow communication [COM] and sow carefulness [CARE] after farrowing, while sows were standing and moving and just before lying down). There was a low positive correlation between NEST and COM (r = 0.10, P = 0.026) and between NEST and CARE (r = 0.15, P = 0.010) but a high positive correlation between COM and CARE (r = 0.57, P < 0.001). Higher COM and CARE were associated with lower piglet mortality (P. 0.001 and P = 0.013, respectively), and a greater number of weaned piglets was associated with higher scores for NEST (P = 0.009), COM (P < 0.001), and CARE (P = 0.009). Maternal care behavior had a greater impact on piglet mortality and the number of weaned piglets than sow physical condition (MD, BCS, and SL). We tested 7 different models (combinations of behavioral scores) and compared their relative predictive accuracies using Akaike information criteria. The model including COM and CARE had the best predictive accuracy for piglet mortality/weaned piglets. There was between-sow variation in maternal care behaviors (COM and CARE), and both were unaffected by litter size. Because these behaviors were also easy to score for the farmers, combining COM and CARE has the greatest potential to be tested in nucleus herds for calculation of genetic variation and heritability and should be taken into account in future breeding programs for sows.