Fine cassava fibre utilization as a dietary fibre source for dogs: Effects on kibble characteristics, diet digestibility and palatability, faecal metabolites and microbiota

The objective was to evaluate through three experiments the effects of a fine cassava fibre (CA: 106 µm) on kibble characteristics, coefficients of total tract apparent digestibility (CTTAD) of macronutrients, diet palatability and faecal metabolites and microbiota of dogs. Dietary treatments consisted of a control diet (CO), without an added fibre source and with 4.3% total dietary fibre (TDF), and a diet with 9.6% CA (106 µm), with 8.4% TDF. Experiment I evaluated the physical characteristics of the kibbles. The palatability test was evaluated in experiment II, which compared the diets CO versus CA. In experiment III, 12 adult dogs were randomly assigned to one of the two dietary treatments for 15 days, totalling six replicates/treatment, to assess the CTTAD of macronutrients; faecal characteristics, faecal metabolites and microbiota. The expansion index, kibble size and friability of diets with CA were higher than the CO (p < 0.05). Additionally, the CA diet presented higher palatability than the CO (p < 0.05) but did not affect CTTAD except for those of fibre (p > 0.05). Moreover, a greater faecal concentration of acetate, butyrate and total short-chain fatty acids (SCFA) and a lower faecal concentration of phenol, indole and isobutyrate were observed in dogs fed the CA diet (p < 0.05). Dogs fed with the CA diet presented a greater bacterial diversity and richness and a greater abundance of genera considered to be beneficial for gut health, such as Blautia, Faecalibacterium and Fusobacterium when compared to the CO group (p < 0.05). The inclusion of 9.6% of a fine CA improves the expansion of kibbles and diet palatability without affecting most of the CTTAD of nutrients. Besides, it improves the production of some SCFA and modulates the faecal microbiota of dogs.