Measurement of Intestinal Digesta Viscosity

Following the procedure by Passos et al. (2015) (link) and Duarte et al. (2019) (link), digesta collected from the mid-jejunum was divided into two tubes (15 mL) and centrifuged at 1,000 × g for 10 min at 4 °C to obtain the liquid phase. The supernatant of each tube was collected into 2 mL tubes and centrifuged at 10,000 × g at 4 °C for 10 min. The supernatant obtained was transferred to another 2 mL tube and kept on ice for further assessment of viscosity. The amount of 0.5 mL of digesta supernatant was placed in the viscometer (Brookfield Digital Viscometer, Model DV-II Version 2.0, Brookfield Engineering Laboratories Inc., Stoughton, MA) set at 25 °C. The viscosity measurement was the average between 45.0 and 22.5 per s shear rates, and the viscosity values were recorded as apparent viscosity in millipascal-seconds (mPa.s).