Effects of different levels of cassava fibre and traditional fibre sources on extrusion, kibble characteristics, and palatability of dog diets

Pet food companies often use fibres in extruded diets as a strategy to improve intestinal functionality and reduce energy density, but studies evaluating the effect of fibres on the extrusion process, kibble characteristics, and palatability of dog diets are scarce. Thus, the objective of this study was to evaluate the effect of cassava fibre (CA) levels and conventional fibre sources on the extrusion process, kibble characteristics, and palatability of diets. Seven diets were evaluated: control diet (CO), without the inclusion of fibre sources; three diets with increasing levels of CA-4, 8, and 12% (totalling 6.1, 7.2, and 8.3% total dietary fibre-TDF, respectively); diet with 3.8% cellulose (CE); diet with 6% beet pulp (BP); and diet with 3.8% lignocellulose (LC). Diets 12% CA, CE, BP, and LC presented approximately 8.0% TDF. Diet palatability was evaluated in 16 adult beagle dogs in a completely randomised design. Seven paired tests were conducted, with two consecutive days per test, totalling 32 repetitions. Diets with fibre sources had lower kibble density than the CO diet (p = .004). The inclusion of increasing dietary CA levels resulted in a linear increase in the kibble expansion index (p = .0001). Dogs preferred the 12% CA diet to the CO (p = .032) or BP diets (p = .0001). The evaluated insoluble fibre sources resulted in greater expansion and lower density kibbles than the CO diet. Furthermore, 12% of CA positively affected diet palatability in dogs.