Ad libitum feeding systems for lactating sows: effects on productivity and welfare of sows and piglets.

The nutritional requirements of sows change during lactation and thus require adapted and dynamic feeding regimes that consider the sows' behavioral needs and production traits. The present study evaluated the effect of four different feeding systems on productivity and aspects of the welfare of 61 sows and their piglets during lactation. A non-ad libitum system (CON) was compared with two computer-monitored (COMP, COMP + ) ad libitum feeding systems, that allowed sows to access feed via displacement of an electronic sensor, as well as a third purely mechanical ad libitum feeding system (MECH). Daily feed disappearance, piglet growth, piglet growth per feed disappearance as well as sows' weight and conception rate were recorded. Health indicators of sows and piglets were scored as well as sow behavior analyzed for a total of 96 hours/sow from video recordings taken on days 2-4 and 23 postfarrowing (n = 35 sows). Sows from all three ad libitum systems (COMP, COMP+, MECH) showed a lower feed disappearance than CON (P < 0.01). Additionally, average daily piglet growth tended to be higher (P = 0.05) and piglet growth per sow feed disappearance was significantly higher in all three ad libitum systems than in CON (P < 0.01). Piglet mortality, sow weight loss and subsequent conception rates did not differ between treatment groups. Piglets in COMP and COMP + had fewer head lesions (P = 0.01). Sows in all three ad libitum systems spent more time with their head in the trough than in the non-ad libitum system (P < 0.01). Occurrence of sow stereotypies (vacuum chewing, biting fixtures) was rare (typically < 2% of scans) and did not differ between treatments. Our data suggest that sows fed ad libitum eat what they need and can convert feed more efficiently into the piglets' growth without additional weight loss. Furthermore, the increased time sows spent in ad libitum systems with their head in the trough points toward longer feeding times, which might be beneficial in terms of meeting pigs' behavioral need to forage. Taken together, our initial studies on sow feeding behavior and feed efficiency will benefit the development of new lactation feeding systems that promise to improve animal welfare and productivity while reducing feed costs.