Empowering large litters: Can enhanced pen design with simulated udders improve piglet growth in their early life?

Abstract Hyper-prolific sows produce large litters, which results in greater birth weight variation and an increased need for nurse sows. This study explored ways to optimize expanded farrowing pen space, following European Food Safety Authority (EFSA) recommendations, to help loose-housed sows manage litter sizes that surpass their available teat capacity. The aim was to enhance piglet growth and mortality while maintaining efficient production. A total of 66 litters were randomly assigned to one of two groups at birth: a control group (CON; n = 33) or a treatment group (TRT; n = 33), and only piglets born weighing more than 750 g were included in each group. From birth until weaning, CON sows nursed 16 piglets per litter, while TRT sows nursed 20 piglets. During the first three days postpartum, an enclosure setup was present in the creep area of pens housing TRT litters. In this enclosure, the four smallest piglets (S) were confined for six hours with access to milk replacer (MR), followed by the next four smallest (M) for another six hours, while the four largest piglets (L) were confined overnight for 12 hours. The last eight piglets from the TRT group were reared by the sow (SRT). In contrast, piglets in the CON group remained with the sow without intervention. Piglet weights were tracked daily from day one to three, with additional measurements taken on days 11, 18, and 25. No difference in litter weight gain was observed between the two groups from day one to three. However, litter weight gain was higher in CON compared with TRT in the entire study period (2.529 vs. 2.034 kg/day; P = 0.005). No difference in mortality was observed between TRT and CON from days 1–3. However, it was significantly higher in TRT than CON from day 3–24 (18.4% vs. 9.0%; P = 0.0006). Within TRT, L piglets maintained the highest body weight, while S piglets had the lowest (6.674 vs. 4.104 kg at day 25; P < 0.0001). ADG differed only in the first three days, where SRT piglets grew fastest (108 g/day; P < 0.0001). Milk disappearance was consistently highest in L piglets (297 g/6 h corrected; P < 0.0001). Mortality was highest in S piglets (60%), intermediate in M (30%), and lowest in L (11%) and SRT piglets (18%; P < 0.0001). The enclosure setup might assist hyper-prolific sows in rearing large litters; however, no direct benefits on growth performance were observed. These findings suggest that further interventions are necessary to support piglets throughout the entire suckling phase.