Fiber percentage alone does not predict digestive success in guinea pigs. Long-strand, structurally intact fiber slows fermentation, supports gut motility, and stabilizes microbial populations. Finely ground meals, powders, or highly processed fibers may meet fiber targets on paper, but they reduce chewing time and allow food to ferment too quickly. This increases gas production and destabilizes the cecum. For guinea pigs, fiber structure determines how predictably digestion occurs, how stable stool remains, and how reliably nutrients are absorbed.

Guinea pig digestion depends on steady intake and controlled fermentation within a highly sensitive cecum. Unlike animals adapted for rapid energy extraction, guinea pigs rely on fiber fermentation to produce usable energy gradually. When calorie-dense ingredients, excess protein, or rapidly fermentable carbohydrates displace structural fiber, fermentation accelerates beyond what the cecum can regulate. This favors gas-producing bacteria, destabilizes stool consistency, and increases digestive stress. A diet built around structural fiber allows protein and calories to be delivered within a stable digestive framework, supporting predictable fermentation, balanced microbial populations, and long-term gut health.