By Alexa Gormley and Sung Woo Kim
Weaning is widely regarded as the most difficult period in the life of a growing pig. In commercial production, pigs are typically weaned between 3 to 4 weeks of age, when the small intestine is physiologically immature, with insufficient digestive enzyme production and a naive intestinal immune system.
A major challenge associated with weaning is the abrupt dietary transition from sow milk to solid feed.
Sow milk is nutrient-dense and easily digested by suckling pigs, whereas nursery diets rely on feedstuffs like corn and soybean meal that are less digestible for newly weaned pigs due to antinutritional compounds, including allergenic proteins, trypsin inhibitors and nonstarch polysaccharides. These factors can impair nutrient digestibility and compromise the integrity of the small intestine.
Weaning also drives significant changes in the mucosal microbiota, from populations adapted to milk components to those capable of fermenting plant-derived nutrients. Reduced digestive efficiency postweaning period allows nutrients to remain available to microbes, promoting excessive fermentation, intestinal inflammation, diarrhea, reduced growth performance and increased disease susceptibility.
The 3 P’s of Dietary Intervention
To mitigate these challenges, numerous dietary interventions have been investigated to support the small intestine postweaning.
Given its central role, many strategies focus on supporting the mucosal microbiota, such as through the use of prebiotics, probiotics and postbiotics. A series of research projects conducted by the Kim Lab of Monogastric Nutrition and Digestive Physiology at North Carolina State University has investigated the effects of these interventions on intestinal health in nursery pigs.
- Prebiotics are substrates selectively utilized by beneficial bacteria to support their activity.
- Probiotics are live microorganisms that can establish a more favorable microbial balance.
- Postbiotics include inactivated microbial cells or metabolites that can interact with the intestinal epithelium and immune system to exert beneficial effects.
Providing prebiotics, probiotics or postbiotics during the postweaning period may help stabilize the mucosal microbiota during dietary transition.
The Kim Lab’s work is unique in its focus on the mucosa-associated microbiota of the small intestine, which directly interacts with the small intestinal epithelium. This is particularly relevant as the small intestine is the primary site of nutrient digestion and absorption, as well as immune activity. Beneficial microbes interact with pattern recognition receptions to promote anti-inflammatory signaling, mitigating intestinal inflammation and diarrhea and improving growth performance, whereas harmful microbes induce pro-inflammatory responses that damage intestinal tissue and impair performance.
Strategic application of prebiotics, probiotics and postbiotics offers an opportunity to improve intestinal health postweaning. By supporting the mucosal microbiota and associated immune interactions, these interventions may reduce performance losses in the postweaning period. As the nursery period is the time with the greatest potential for growth efficiency, maximizing health and performance during this time is of significant interest to pig producers. Therefore, nutritional strategies targeting the mucosal microbiota could serve as an important nutritional intervention for nursery pigs.
Alexa Gormley is a graduate research assistant, and Sung Woo Kim is the William Neal Reynolds Distinguished Professor and University Faculty Scholar at North Carolina State University.
