Temporary confinement of loose-housed hyperprolific sows reduces piglet mortality

The objective of this study was to investigate piglet mortality in a commercial setting where sows were accommodated in a loose-housed system with an option to confine the sow for a few days around farrowing and during early lactation. The study was conducted in a Danish piggery where records were obtained from 2,139 farrowings. Sows were randomly allocated to 1 of 3 treatments: loose-loose (LL), looseconfined (LC), and confined-confined (CC). In LL, sows were loose housed from the time they entered the farrowing pens to weaning. In LC, sows were loose housed until farrowing was finished and then confined to d 4 after farrowing. In CC, sows were confined at d 114 of gestation to d 4 after farrowing. All sows were loose housed from d 5 to weaning. Total piglet mortality was analyzed at batch level to include piglets fostered by nurse sows and at sow level to analyze the effects of confinement during different time periods. Total piglet mortality was greater in LL (26.0%) and LC (25.4%) compared with CC (22.1%; P < 0.001). The proportion of stillborn piglets was not different between treatments (P = 0.21) but a larger proportion was crushed in LL (10.7%) compared with LC (9.7%; P = 0.03), which again was greater than CC (7.8%; P < 0.001). Piglet mortality before equalization was lower in CC (3.7%) than in LL (7.5%) and LC (7.0%; P < 0.001). Confinement reduced mortality from litter equalization to d 4 (7.6% for LL vs. 6.7% for LC; P = 0.01) but more so in CC (5.6%) than in LC (P < 0.001). From d 4 to weaning, LL had lower mortality (5.6%) than LC (6.9%) and CC (6.6%; P = 0.01). A larger proportion of sows in CC were classified as low mortality compared with LL and LC both before (P < 0.001) and after (P = 0.002) litter equalization. The results in this study emphasize that the period of time from the birth of the first piglet to litter equalization is important in relation to piglet mortality. The results also suggest that confinement for 4 d after farrowing can reduce mortality in this specific period, but only confinement from d 114 of gestation to d 4 after farrowing reduced total piglet mortality.