Background: Animal fibers (AF) are animal tissues (e.g., tendons, feathers, cartilages) poorly digested enzymatically, but fermentable in the colon. While fiber is not an essential nutrient for carnivores, AF might contribute to health, functioning similarly to plant fiber.
Objectives: Assess fecal microbiome and metabolome in cats fed four isonutrient kibble diets differing in fermentable organic matter sources: vegetable (sugarcane, SC; and beet pulp, BP) and animal (feather meal, FM; and chicken protein hydrolysate residue, CPHr). Animals: Thirty-two healthy adult mixed-breed cats.
Methods: Extruded diets were administered in a randomized block design for 31 days (8 cats/diet). Fecal metabolites, long-chain fatty acids (LCFA), sterols, and bile acids (BA) were measured by mass spectrometry. Fecal microbiome was evaluated by qPCR for core bacteria and 16S rRNA gene sequencing.
Results: Increased arachidonic acid was detected in BP, FM, and CPHr groups (P-value = 0.028); other LCFAs did not differ. Increased cholesterol and phytosterols were detected in BP group (P-value = 0.002). Total BAs were higher with CPHr, FM, and BP groups (P-value = 0.001), yet BA conversion was unaffected. FM-fed cats showed minor increases in Peptacetobacter hiranonis, Bacteroides, and Blautia, but abundances and Dysbiosis Index remained within reference intervals. Similarly, sequencing revealed no difference in microbial diversity, and only small changes in microbial composition (Bray-Curtis: BP vs. CPHr (R2 = 0.146, P-valueAdj = 0.023) and between SC vs. FM (R2 = 0.203, P-valueAdj = 0.023). Conclusions and Clinical Importance – Animal and vegetable fibers exhibited similar influences on the fecal microbiome and metabolome in cats.
