LAUSR

Abstract Beet pulp (BP) and cellulose (CE) are fibrous ingredients commonly used by pet food companies to produce diets targeting weight management and gut health. Miscanthus grass (MG) is a novel fibrous ingredient that might affect food manufacturing in a similar manner to CE. The objective was to determine the effects of these three fiber sources on extrusion processing and kibble characteristics of dog foods. Diets were composed of 90 % basal ration and 10 % of each MG (827.4 g/kg insoluble fiber, 72.6 g/kg soluble fiber), CE (1000 g/kg insoluble fiber), or BP (360.0 g/kg insoluble fiber, 263.7 g/kg soluble fiber). Three batches of each treatment were mixed separately prior to extrusion. During production, processing conditions were recorded every 20 min after steady state was achieved. At each time point, 10 kibbles were randomly sampled to measure diameter and length out of the extruder and exiting the dryer. Sectional expansion ratio index (SEI) was calculated using the die and kibble diameter. Diet total dietary fiber (TDF) was similar among treatments (MG = 199.7 g/kg, CE = 204.7 g/kg, BP = 175.9 g/kg). The fiber source did not affect preconditioner and extruder parameters, except specific mechanical energy (SME), in which BP was higher than MG and CE (P 0.10) to have greater volume than MG kibbles. MG kibbles had a smaller volume than CE and BP kibbles. CE kibbles were less dense than BP kibbles. These results indicate that a diet containing MG can be processed with similar conditions to a diet containing CE. In conclusion, the extrusion parameters were minimally affected by fiber source, and differences in kibble characteristics could be corrected with modest process adjustments.