Low-protein diet supplemented with isomalto-oligosaccharide reduces diarrhea rate of weaned piglets by regulating intestinal function.

Excess protein in infant formula can harm the health of infants. Isomalto-oligosaccharide (IMO), a prebiotic, can be incorporated into infant formula. This study employed weaned piglets as a model to establish varying protein levels, investigating the impact of IMO in low-protein diets on the intestinal health. A total of 192 weaned piglets were randomly assigned to four groups, with each group containing six pens of eight piglets each. The control group was fed a diet containing 19% crude protein (CP), while the other three experimental groups were supplemented with 0.2% IMO, with CP levels of 19%, 18%, and 17%, respectively. The experiment lasted 28 days, with one piglet from each pen slaughtered at the end. There were no differences in growth performance among the groups. Nonetheless, the diarrhea rate in an 18% protein diet supplemented with IMO (18CP + IMO group) was reduced during d1-21 and 1-28 (p < 0.05). The diarrhea rate and the apparent total tract digestibility (ATTD) of acid detergent fiber (ADF) showed a quadratic correlation (p < 0.05). Meanwhile, 18CP + IMO group showed that the ATTD of dry matter and ADF increased (p < 0.05); the crypt depth of the jejunum decreased (p < 0.05), while the expression of intestinal barrier (ZO-1) and intestinal development (CDX2) related genes increased (p < 0.05); the abundance of beneficial bacteria (Bifidobacterium) increased (p = 0.06). Compared with 19CP group, the other three groups had lower contents of indole and skatole (p < 0.05). Our results showed that supplementing an 18% CP diet with 0.2% IMO decreased diarrhea incidence in weaned piglets, enhanced nutrient digestibility, intestinal barrier and microbiota, and reduced harmful metabolite production.