Lupin and pea extrusion decreases the ruminal degradability and improves the true ileal digestibility of crude protein
Abstract The aim of this work was to evaluate the effect of the extrusion of dehulled lupins (Lupinus albus L.) and peas (Pisum sativum L.) on the ruminal degradability and intestinal digestibility of their protein contents. Ruminal degradability was evaluated in situ in the rumens of two fistulated cows. The true ileal crude protein (CP) digestibility was evaluated via a bioassay with Sprague Dawley laboratory rats as the animal model. Extrusion caused soluble fraction decreases in both feeds (P<0.05), with a 29 % decrease in the extruded dehulled lupins (EDL) and a 59 % decrease in the extruded peas (EP). The degradable fraction (B) in EP increased by 19 % compared to that in raw peas (RP) (P<0.05), and there was no effect of extrusion on the degradable fraction in lupins (P>0.05). Extrusion decreased the effective degradability (ED) of lupins by 12 % (P<0.05). Moreover, in EP, extrusion presented no effect on the ED (P>0.05). The extrusion process had a greater impact on the reduction of the effective degradability in lupins than it did in peas. Nevertheless, extrusion increased the true ileal CP digestibility of the ruminal postfermentation residues in both feeds.