Whole pulse ingredient inclusion in macronutrient-balanced diets increased fecal concentrations of propionic acid but not total bile acids in healthy adult large-breed dogs after 20 weeks

TL;DR

This study found that including up to 45% whole pulse ingredients in dog diets does not increase bile acid excretion but may improve gut health by boosting short-chain fatty acids.

Contribution

The study demonstrates that high pulse inclusion in dog diets does not disrupt bile acid recycling and may enhance gut health markers.

Findings

Dogs fed diets with up to 45% pulses had no increase in total bile acid excretion compared to a grain-inclusive diet.

Pulse diets increased fecal propionic acid concentrations, suggesting improved short-chain fatty acid production.

Grain-inclusive diets had higher branched-chain fatty acids, while pulse diets increased arabinose concentrations.

Abstract

This study investigated the effects of up to 45% inclusion of whole pulse ingredients in grain-free (GF) diets on the excretion of bile acids (BAs) and other fecal metabolites in healthy large-breed dogs. Twenty-eight adult Siberian Huskies were fed 1 of 4 experimental diets formulated to meet the same macronutrient profiles for 20 wk: 1) grain-inclusive diet with 45% corn (Ctl), 2) GF diet with 15% pulses (Pulse15), 3) GF diet with 30% pulses (Pulse30), 4) GF diet with 45% pulses (Pulse45). All diets included chicken meal and pea starch. Fecal samples were collected on weeks 2 and 19. Bile acids were analyzed using ultra-performance liquid chromatography-MRM/MS technology, while fecal metabolites were analyzed using Agilent HP1000 high-performance liquid chromatography. Bile acids and fecal metabolite data were analyzed using the PROC GLIMMIX procedure in SAS studios (SAS version 9.4, SAS Inst., Inc., Cary, NC). All means were separated using the Tukey–Kramer adjustment (significant when P < 0.05). After 20 wk of feeding, concentrations of lithocholic acid were greater in Pulse15 and Pulse30 than Ctl (P = 0.001), but all were similar to Pulse45. Concentrations of deoxycholic (P = 0.054), lithocholic (P = 0.001), total secondary (P = 0.022), and total BA (P = 0.045) tended to be linearly associated with dietary pulse inclusion. Dogs consuming Pulse30 had greater fecal propionic acid concentrations than Ctl (P = 0.017), but both were similar to Pulse15 and Pulse45. Total branched-chain fatty acids (P = 0.001) and iso-butyric acid (P < 0.0001) were greater in Ctl than in all pulse groups. Inversely, arabinose concentrations were greater in all pulse groups compared to Ctl (P = 0.001). In summary, diets with up to 45% inclusion of whole pulse ingredients do not increase total BA excretion but may contribute to greater short-chain fatty acids production.

The inclusion of up to 45% whole pulse ingredients in extruded canine diets that exceed the American Association of Feed Control Officials’ minimum nutrient recommendations does not increase fecal bile acid concentrations but may contribute to greater fecal short-chain fatty acid and less branched-chain fatty acid concentrations. This suggests that pulse ingredients do not negatively impact bile acid recycling and may have positive effects on gut health in healthy large-breed dogs.