Cortisol levels and health indicators of sows and their piglets living in a group-housing and a single-housing system

Since the permanent fixation of pregnant sows is banned in Europe, it has become a matter of discussion as to whether the permanent fixation of lactating sows is still acceptable. A group-housing system for lactating sows offers the sows and their piglets the possibility to live in a more natural structure. The aim of this study was to compare sows from a group-housing system (GH; n = 80) with sows from a conventional single-housing system (SH; n = 64) with regard to health indicators and saliva cortisol levels. Data were collected in four batches with 20 GH sows and 16 SH sows per batch. All sows were moved one week before farrowing to the GH or the SH system, respectively. The nulliparous sows were housed separately from the multiparous sows during pregnancy. Thus, nulliparous and multiparous sows were unfamiliar when they moved to the GH system. The GH sows were housed in a group of ten sows and were separated into their individual free-farrowing pens from three days ante partum until six days post partum. A running area was shared by all sows and piglets. With regard to health indicators, the GH sows had fewer skin lesions of the udder and of the tail compared to the SH sows (p < 0.05). Moreover, the GH sows had more skin lesions on the body (p < 0.05) due to ranking fights and were dirtier (p < 0.05) because they used the running area as a resting and dunging area. Furthermore, the GH sows had a higher body condition after weaning (p < 0.05), which can be explained by ad libitum feeding and the fewer number and lighter weight of weaned piglets (p < 0.05). With regard to health indicators of the piglets, the interaction between housing system and batch showed that the GH piglets had fewer skin lesions of the face (p < 0.05). In addition, they had fewer skin lesions of the face one week post partum (p < 0.05) and did not differ from the SH piglets regarding their incidence of skin lesions of the face four weeks post partum. Furthermore, the GH piglets showed more skin lesions of the body compared to the SH piglets (p < 0.05) across almost all batches. With regard to the saliva cortisol levels, both the GH and SH sows did not differ in their basal levels two weeks ante partum. However, the GH sows had higher cortisol levels during lactation compared to the SH sows (p < 0.05). To conclude, no alarming health problems were documented for the GH sows and SH sows or their piglets. Moreover, the higher cortisol levels of the GH sows could be caused by factors as social interactions and increased physical activity.