The development of unrestricted, group farrowing systems for sows
This thesis examines the activities of four groups of four sows, allocated to one of two space allocations, in a novel farrowing system design, over parturition and during lactation. The two pen configurations provided 13.4m² (L) and 8.6m² (S) per sow, respectively. A lactation diet providing 14MJ/kg DE and 18% CP was supplied ad libitum via a sow operated feeder, adapted to facilitate the calculation of individual feed intakes. The influence of environmental, physical, management and production factors upon the way in which sows allocated their time to different activities, suckling behaviour, feed intakes and feeding and drinking strategies was investigated. Sows in the small pen area were generally less active than those housed in the large pen configuration. During the first week of lactation, significantly more time was spent lying down (P<0.05) and fewer transitions were made between postures (P<0.001) in the reduced space allocation. Sows in the S pen configuration suckled their piglets significantly more frequently than sows in the L pen area (P<0.001). However, similar daily piglet weight gains were achieved in both the L and S pen configurations. Daily feed intakes of 7.69 kg (s.e. 0.31) and 7.72 kg (s.e. 0.35) were achieved during lactation, by sows in the L and S pen configurations, respectively. This was accomplished by sows taking a series of small feeds throughout the day. Sows in the S pen area made fewer visits to the feeder and spent less time per day feeding, compared with sows in the L pen area. However, more feed was consumed per visit by the S sows, resulting in similar daily feed intakes in both treatment groups. A marked increase in activity during the 24 hours prior to parturition was followed by a sharp reduction during day 1 of lactation in both treatment groups. Thereafter, activity levels increased gradually during week 1 of lactation. Most piglet deaths occurred in early lactation, 65.0% and 67.9% of which were during days 1 to 3 following birth in the L and S pen areas, respectively. Mortality of live-born piglets was unacceptably high at 19.6% in the L and 24.6% in the S pen areas. The relative advantages and disadvantages to sows and piglets within the novel farrowing system are considered in the general discussion.