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Dietary fiber can influence multiple physiological systems in sows, such as gut health, microbiota composition, immune response, and body condition.
Objective: This study tested the effects of total dietary fiber (TDF) level and the inclusion of fast-fermentable fiber on lactation performance, nutrient digestibility, immune response, and microbiota.
Methods: A total of 136 lactating sows were assigned to four diets: two with low TDF (15%) and two with high TDF (25%). Each TDF level included either a low or high proportion of fast-fermentable fiber. Fiber sources included sugar beet pulp, oat hulls, wheat millrun, and barley, selected based on their fermentability profiles. Primiparous sows were given 3kg of feed daily while multiparous sows were given 3.5kg. From day 2 post-partum, feed was increased by half a kg daily until reaching 7kg/daily for primiparous and 9kg for multiparous, and these maximum levels were kept until weaning. Sows were fed 3 times a day. Sow body weight and backfat thickness were measured on day −1 (pre-farrowing) and on days 2, 10, and 19 postpartum; fecal samples were collected on days 1 and 19, blood on day 19 (4 h post-meal), and colostrum and milk were sampled within 30 minutes of first piglet birth and on day 19 (after oxytocin), respectively; litter size and weight were recorded on days 2, 10, and 19, mortality was tracked until weaning, and litter weight gain was calculated using corrected piglet-days; fecal microbiota analysis was performed on 60 samples (15 per treatment), collected on day 19.
Results: Despite a reduction in apparent total tract digestibility (ATTD) of nutrients with high-fiber diets, there were no negative effects on feed intake or litter performance. In fact, sows on high-fiber diets lost more fat but preserved body protein better. Fast-fermentable fiber reduced body weight and protein loss, improved ATTD of energy and protein, and decreased serum IL-8 levels, suggesting a lower inflammatory response. Microbiota diversity decreased with high-fiber diets, often interpreted as negative, yet there was a clear enrichment of beneficial bacterial families such as Prevotellaceae, Ruminococcaceae, and Lachnospiraceae.
Conclusion: Overall, strategic inclusion of fiber, particularly fast-fermentable types, can benefit lactating sows, but blindly increasing fiber is not a solution. The source, fermentability, and inclusion level all matter.
Wang T, Langendijk P, Azevedo P, Fabà L, Zuo B, Zhao J, Yang C. Effects of fiber concentrations and fermentation rates on reproductive performance, nutrient digestibility, immune response, and microbiota of lactating sows. Journal of Animal Science. 2025; 103:skaf110. https://doi.org/10.1093/jas/skaf110
