Impacts of Fiber Supplementation in Sows during the Transition Period on Constipation, Farrowing Duration, Colostrum Production, and Pre-Weaning Piglet Mortality in the Free-Farrowing System

This study investigated how dietary fiber supplementation during the transition period in sows affects constipation, farrowing duration, colostrum production, milk yield, and pre-weaning piglet mortality in the free-farrowing system. A total of 92 Landrace × Yorkshire sows and their 1272 offspring were included in the study. Sows were divided into two groups by parity: control (<i>n</i> = 41) and treatment (<i>n</i> = 51). The control group was fed a standard lactation diet 7 days before farrowing, whereas the treatment group received the same diet with 75 g/day of a dietary fiber supplement. The dietary fiber content analyses were 4.30% and 5.53% in the control and treatment groups, respectively. Sows were fed with 3.89 ± 0.92 kg per day with a diet containing 17.8% crude protein, 3732 kcal/kg of metabolizable energy, and 1.1% lysine. Parameters including farrowing duration, litter characteristics, and the fecal condition of sows were measured. Piglet mortality rates were recorded at 3, 7, and 21 days of lactation. Sows had an average farrowing duration of 216 ± 159 min, with litter sizes of 13.8 ± 4.2 piglets per litter, and a 7.4% stillbirth rate. The treatment group showed a lower constipation rate compared to the control group (17.6% vs. 46.3%, <i>p</i> = 0.003). Farrowing duration did not significantly differ between groups, but the treatment group experienced a 43.6 min shorter duration. In sows with litter sizes of ≥16 piglets per litter, the farrowing duration for sows in the treatment group tended to be shorter than that of the control groups (202.0 ± 37.9 vs. 287.5 ± 41.3 min, <i>p</i> = 0.115). The mean colostrum intake of piglets in the control and treatment groups averaged 424.0 ± 13.7 g and 421.8 ± 12.6 g, respectively (<i>p</i> = 0.908). Likewise, the milk production of sows from Days 3 to 10 and from Days 10 to 17 of lactation in the treatment group (7.34 ± 0.27 and 8.76 ± 0.43 kg/day, respectively) did not differ from that of the control group (7.85 ± 0.30 and 9.55 ± 0.47 kg/day, respectively, <i>p</i> > 0.05). Pre-weaning piglet mortality was slightly lower in the treatment group (13.4% vs. 17.3%, <i>p</i> = 0.085). Across groups, piglet mortality rates within 3, 7, and 21 days were 10.3%, 11.9%, and 15.4%, respectively. Piglets with a ≤200 g colostrum intake had a higher pre-weaning mortality compared to those with a higher intake (<i>p</i> < 0.05), except for the 201–300 g intake (<i>p</i> = 0.472). In conclusion, introducing dietary fiber to sows during the transition period reduced constipation and tended to decrease farrowing duration, especially in sows with large litters. Additionally, it lowered pre-weaning piglet mortality by 3.9% in the free-farrowing system. Nonetheless, providing sows with a 75 g/day dietary fiber supplement for only 7 days before farrowing was not enough to enhance colostrum and milk production, nor did it lead to an increase in piglet colostrum consumption.