Korean researchers evaluated the effect of feeding raw potato starch on reducing the severity of Salmonella infections in weaned pigs, according to PigProgress.

Origins

Salmonella is a foodborne pathogen that disrupts the pig's intestinal microbiota. This leads to diarrhea, enterocolitis, and dehydration. A healthy intestinal microbiota reduces the severity of Salmonella infection.

Therefore, dietary supplements that enhance intestinal microbial populations help control Salmonella infections. Resistant starch is a source of carbohydrates accessible to the microbiota that increase short-chain fatty acids in the intestine, thereby improving intestinal barrier functions.

Raw potato starch is a common ingredient of resistant starch that enhances fermentation in the digestive tract and increases the levels of pro and anti-inflammatory cytokines.

Data Collection

The team randomly divided 12 castrated male pigs (Landrace × Yorkshire) aged 28 days into treatment and control groups. The treatment group's diet was supplemented with 5% raw potato starch for 21 days.

Subsequently, the researchers orally inoculated all pigs with colony-forming units of Salmonella Typhimurium. They euthanized them 14 days after bacterial inoculation.

The team collected fecal and intestinal tissue samples from the jejunum, ileum, colon, and cecum and immediately incubated them at 42°C for 24 hours. They fixed and stained tissue samples for histopathological evaluation and cytokine quantification.

They then extracted DNA and performed bioinformatic analyses. Additionally, they assessed the concentrations of short-chain fatty acids, including acetate, butyrate, and propionate, in all experimental pig fecal samples to investigate the effect of modified bacterial communities in both groups.

Growth Performance and Salmonella Fecal Shedding

Although a Salmonella infection reduces body weight and average daily gain, pigs fed a diet supplemented with raw potato starch had a higher average daily gain and lower Salmonella shedding during the Salmonella infection period.

These findings indicate a gut health-promoting effect in pigs receiving a diet supplemented with raw potato starch.

Intestinal Health

While researchers observed histopathological lesions in both groups, pigs fed raw potato starch had less severe lesions in the jejunum, ileum, cecum, and colon.

They also had a lower rate of Salmonella isolation from intestinal tissue. Furthermore, feeding raw potato starch improved intestinal health by maintaining the balance of beneficial bacteria and increasing the abundance of butyrate-producing and acetate-producing bacteria.

This prevented the colonization of pathogenic bacteria by reducing intestinal mucosal permeability.

High concentrations of acetate and butyrate/propionate can lead to a more invasive Salmonella infection. In addition, the relative mRNA expression levels of genes related to intestinal barrier function, including CLDN-1 in the cecum and MUC2 in the colon, were significantly lower in pigs fed raw potato starch, suggesting lower intestinal permeability.

Immune State

The relative mRNA expression of the proinflammatory cytokine IL-18, necessary for initiating mucosal inflammation, was significantly lower in the jejunum and colon of pigs fed a diet supplemented with raw potato starch, suggesting reduced Salmonella colonization.

On the other hand, among genes related to the intestinal barrier, the expression of the antimicrobial peptide gene Reg3γ was significantly higher in the cecum but lower in the colon of pigs fed a diet supplemented with raw potato starch. Reg3γ restricts bacterial colonization of the intestinal mucosal surface and maintains spatial segregation between bacteria and intestinal epithelium.

However, the anti-inflammatory cytokine IL-10 and the proinflammatory cytokine IL-17A were expressed less in the jejunum, cecum, and colon of pigs fed a diet supplemented with raw potato starch, as the overexpression of Reg3γ induced high immunosuppression and a dramatic reduction in cytokine gene expression.

The authors concluded that feeding weaned pigs with raw potato starch could improve intestinal health and reduce Salmonella infections.