A Commercial-Farm Study Shows that Targeted Fiber and Stimbiotic Supplementation During the Transition Period Reduces Constipation and Improves Pig Viability

By Jessica P. Acosta, Rachel Self, and Amy Petry

Modern sows require greater metabolic demands to produce larger litters and heavier weaned pigs.

However, during the transition period—a week before farrowing through the first three to five days of lactation—sows undergo several metabolic changes, which happens to lead to reduced feed intake during lactation, constipation at farrowing, and ultimately, an increase in preweaning mortality.

Because of this, pig researchers and nutritionists are actively exploring nutritional strategies to help sows move through farrowing more smoothly and support pig health.

One approach is the strategic use of fermentable fiber in sow diets, which can improve gut motility, reduce constipation, shorten farrowing duration, and better support pig viability through increased energy availability.

Because fermentable fiber sources can be limited in the United States, a stimbiotic (i.e., xylanase in combination with xylo-oligosaccharides) has been used to enhance fiber utilization by shifting the intestinal microbiome to favor fiber fermentation, resulting in improved energy use and digestive efficiency during late gestation and lactation.

Although both fiber supplementation and stimbiotic may be strategies to support sows during the transition period, their combined potential to enhance farrowing outcomes is not known.

Therefore, a recent study was conducted at a commercial farm to determine the impact of fiber and stimbiotic supplementation from late gestation through lactation in the farrowing performance, litter outcomes, and pig viability.

A total of 860 mixed parity sows (25% parity 1, 38% parity 2-3, 37% parity 4+) were used in the study from day 113 of gestation until weaning began.

Sows were housed in farrowing stalls and assigned to one of four dietary top-dress treatments in a 2 by 2 factorial arrangement with parity balanced across treatments. The treatments included: a corn-based control top dress with (CON+) or without (CON-) a stimbiotic (Signis, AB Vista, Marlborough, UK), and a fiber top dress, comprised of an equal blend of soybean hulls and wheat middlings, with (FIB+) or without (FIB-) a stimbiotic.

The top‑dress treatments were hand-fed twice daily on top of the standard lactation diet, beginning approximately 4.0 ± 1.5 days before farrowing and continuing for 17.9 ± 1.4 days after farrowing. Sows were hand-fed a lactation diet ad libitum from day 3 post-farrowing until the onset of weaning.

For each litter, the total born, number born alive, stillborn, and mummies were recorded. Cross-fostering was allowed within treatment groups during the first 24 hours, and all pig movements were also recorded.

At weaning, the number and age of pigs weaned were recorded, and pre‑weaning mortality was calculated. Sow body condition was measured at placement and weaning, and daily feed refusals were recorded throughout the study. Constipation was evaluated daily from day 1 until three days post-farrowing on a scale of zero to four, while pig viability was assessed in each litter at both 24 and 72 hours post-farrow using a four-point scale.

In the context of this study, a viable pig is considered to be a pig that did not appear to have excessive health challenges, good vigor exhibiting typical behavior, and was expected to survive to weaning began.

The study results indicated that feed refusals during the transition period were not influenced by sows fed dietary treatments. However, sows receiving the FIB treatment had less constipation both before and after farrowing.

Figure 1 shows the proportion of constipation scores pre- and post-farrowing over time. On day 1 before farrowing, constipation scores between sows fed CON and FIB treatments were not different, with most classified as score 1 (yellow bar, dry, pellet‑like feces) or score 2 (green bar, dry to normal feces).

On day 2, a greater proportion of sows fed FIB had scores 2 and 3 (blue bar, normal to soft feces), whereas CON sows remained predominantly score 1.

This trend continued on days 3 and 4, with sows fed FIB sows showing greater proportions of score 2 and 3, while sows fed CON showed increasing proportions of score 0 (orange bar, absence of feces) and score 1.

On day 1 post-farrowing, more than 70% of sows displayed score 0 regardless of treatment. But on days 2 and 3, sows fed FIB again demonstrated greater proportions of score 2 and 3, while CON sows remained more frequently classified as score 0 or 1.

These results indicate that fiber supplementation reduced pre‑farrowing constipation incidence by 27%, and post‑farrowing constipation by 22%, indicating that fiber is considered to be efficient to alleviate constipation but requires two to three days of supplementation, while fiber transits to the intestine, impacting gut motility.

Supplementing sows with fiber or stimbiotic increased the number of pigs born alive and reduced stillborns (Table 1). These effects were influenced by the parity of sows, as for parity 1 sows, both fiber and stimbiotic supplementation increased the number of pigs born alive, whereas in parities 2+, only fiber increased the number of pigs born alive. Stimbiotic reduced stillborns and increased pig viability by about 32% at 24 hours and 23% at 72 hours, regardless of parity and diet.

Similarly, parity 1 sows fed the CON+ weaned the most pigs, followed by the FIB+ treatment, whereas parities 2 and 3 fed the CON+ weaned the most pigs. However, pre-weaning mortality was decreased only in sows fed CON+.

The positive effects associated with fiber, such as increased gut motility, reduced constipation, and therefore, decreased obstruction of the birth canal, along with the additional energy obtained through fiber fermentation, combined with the stimbiotic capacity to modulate the gut microbiome and enhance immune function, may support the sow energy requirements during farrowing, allowing the sow to support her litter through milk.

However, the greater benefit observed in younger parity sows may reflect differences in energy utilization, as these sows continue to allocate nutrients toward their own growth and possess a less mature and less stable gut microbiota compared with older sows.

In conclusion, fiber supplementation in diets for sows in the transition period can reduce constipation, and fiber or stimbiotics improved farrowing performance and early pig viability.

However, young sows responded more favorably to both strategies, suggesting greater potential benefits for herds with a high proportion of parities 1 to 3 sows.

These findings highlight practical nutritional interventions that can be a valuable opportunity to enhance pig survival and sow comfort in commercial systems.

Jessica P. Acosta
University of Missouri

Jessica P. Acosta, from Bogotá, Colombia, earned her B.S. in Animal Science from the National University of Colombia and her M.S. (2022) and PhD (2025) in Nutritional Sciences from the University of Illinois. Currently, she is a Postdoctoral Fellow in the Monogastric Nutrition Laboratory at the University of Missouri.