Dietary Supplementation of Milk Oligosaccharides Supports Intestinal Barrier Integrity and Enhances Immune Function in Weaned Pigs.

BACKGROUND

Milk oligosaccharides (MOs) play a crucial role in the development of the epithelial barrier function in newborn mammals.

OBJECTIVES

This study aims to explore the effects of 3 synthetic MOs-galactooligosaccharides (GOS), 2'-fucosyllactose (2'-FL), and 3'-sialyllactose (3'-SL)-on the growth performance and intestinal health of recently weaned piglets.

METHODS

Forty Duroc × Landrace × Yorkshire piglets (7.10 ± 0.25 kg) weaned at 21 d of age were randomly divided into 4 treatments and fed a basal diet (BD) or BD supplemented with 0.5% different MOs (GOS, 2'-FL, and 3'-SL).

RESULTS

2'-FL and 3'-SL significantly increased the growth performance of piglets as shown by decreases in the ratio of feed-to-gain and diarrhea ratio (P < 0. 05), whereas GOS showed limited effects on these indices. Compared with dietary GOS, the 2'-FL and 3'-SL supplementation induced a stronger digestibility of nutrients such as dry matter, crude protein, and crude fat, and also enhanced the activities of duodenal alkaline phosphatase and maltase as well as jejunal lactase (P < 0.05). Also, 2'-FL and 3'-SL not only increase the intestinal villus-to-crypt ratio but also elevate the abundance of zonula occludens-1 and secretory immunoglobulin A in the jejunal epithelium (P < 0.05). In addition, the abundance of total bacteria, Lactobacillus, and Bifidobacterium was numerically higher in the digesta of weaned pigs in the 2'-FL and 3'-SL groups than in those in the control group. Importantly, 2'-FL and 3'-SL selectively increased the ratio of CD4+/CD8+ cells in mesenteric lymph nodes (MLNs) but decreased the abundance of T helper 17 cells in MLNs and the content of interleukin (IL)-6 in serum. In addition, 2'-FL and 3'-SL supplementation increased the expression levels of SLC2A2 and SLC27A4 but significantly decreased the expression levels of IL-17A, IL-1β, and RELA in the jejunum (P < 0.05).

CONCLUSIONS

These results suggested that MOs show a significant beneficial effect on weaned pigs in a structure-dependent manner, because 2'-FL and 3'-SL were more effective than GOS, partly by improving nutrient absorption and intestinal barrier function.