Steering protein fermentation by adding fibres in pig diets

Area of Science:

• Animal Science
• Gastroenterology
• Nutritional Biochemistry

Background:

• Protein fermentation in pigs generates toxic metabolites linked to diarrhoea.
• Dietary fibres are explored as a strategy to mitigate these harmful metabolites.
• Understanding the interaction between fibre type and protein source is crucial for managing gut health.

Purpose of the Study:

• To investigate the impact of rapidly fermentable fibres (RFF) and slowly fermentable fibres (SFF) on protein fermentation metabolites in pigs.
• To compare the effects of different fibre types using low-digestible protein sources (bovine collagen and zein) versus a highly digestible source (whey protein isolate).
• To assess how fibre inclusion influences protein digestibility, digesta transit time, and metabolite concentrations and flows in the pig gastrointestinal tract.

Main Methods:

• 128 boars were fed diets with no added fermentable fibres (NFF), RFF, or SFF, using bovine collagen (BC) or zein (ZE) as protein sources, alongside whey protein isolate (WPI) controls.
• Digesta from the ileum, cecum, and colon were analyzed for protein digestibility and metabolite concentrations and flows after a 2-week feeding period.
• Metabolite flow served as a proxy for fermentation extent, while concentrations indicated direct intestinal exposure.

Main Results:

• Dietary fibres, especially SFF, reduced the concentrations of most protein-derived metabolites.
• Apparent ileal protein digestibility was unaffected by fibre, except when RFF were added to zein diets, reducing digestibility.
• Fibre effects on colonic metabolite flows varied; in zein-fed pigs, fibres reduced branched-chain fatty acids (BCFA), indole, and p-cresol flows, while in WPI-fed pigs, SFF increased BCFA, p-cresol, and biogenic amine flows.

Conclusions:

• Protein fermentation occurs from the ileum to the proximal colon, with metabolite production linked to precursor amino acid profiles.
• Dietary fibres can reduce metabolite concentrations, but their efficacy in controlling fermentation extent is highly dependent on the specific protein source.
• The choice of fibre and protein source significantly influences the gut environment and metabolite profiles in pigs.