The extract viscosity of the experimental diets was determined by analysing 500 μL of the supernatant of aqueous extracts using a Brookfield DV-II + viscometer (Brookfield Engineering Laboratories Inc., Stoughton, MA, USA) with a CP40 cone and a constant shear rate of 750 s−1 at 37 °C. Feed aqueous extracts were made by suspending 1.0 g of feed in 4.0 mL KCl–HCl buffer (20 mmol/L, pH 3.0). The supernatants of these extracts were recovered after 2 centrifugation steps (2,800 × g for 10 min and 21,000 × g for 2 min at 7 °C; Himac CT15RE centrifuge, Hitachi, Japan).
Digesta viscosity was assessed immediately after sampling of the broilers according to the procedure described by Bautil et al. (2019) (link). A total of 2.0 g of ileal content was introduced in a tube and centrifuged at 21,000 × g for 15 min at 7 °C (Himac CT15RE centrifuge, Hitachi, Japan). The resulting supernatant was kept on ice and its viscosity value immediately measured by using a Brookfield DV-II + viscometer (Brookfield Engineering Laboratories Inc.) with a CP40 cone and a constant shear rate of 90 s−1 at 37 °C.
Digesta viscosity was assessed immediately after sampling of the broilers according to the procedure described by Bautil et al. (2019) (link). A total of 2.0 g of ileal content was introduced in a tube and centrifuged at 21,000 × g for 15 min at 7 °C (Himac CT15RE centrifuge, Hitachi, Japan). The resulting supernatant was kept on ice and its viscosity value immediately measured by using a Brookfield DV-II + viscometer (Brookfield Engineering Laboratories Inc.) with a CP40 cone and a constant shear rate of 90 s−1 at 37 °C.