Influence of Dry Roasting of Whole Faba Beans (Vicia faba) and Whole Lupin Seeds (Lupinus albus) on Rumen Disappearance and Estimated Intestinal Digestion of CP Using the Optimal Three-Step In Vitro Technique in Dairy Cows

Abstract

The effects of dry roasting whole faba beans (WFB) and whole lupin seeds (WLS) at 110, 130 or 1507deg;C for 15, 30 or 45 min on rumen (RDCP%), estimated intestinal (IDCP%) and total tract disappearance of CP (TDCP%) and intestinal availability (IARUCP%) of rumen undegraded CP (RUCP%) were determined. The RDCP values were estimated by in sacco technique by incubating nylon bags for 8, 12 and 24 h in the rumen of dairy cows. The IDCP and IARUCP values were estimated using a sequence of ruminal incubation, in vitro incubation in acid-pepsin for 1 h and then in pancreatin for 24 h of three-step in vitro procedure technique. Dry roasting at 130 and 150°C decreased RDCP with correspondingly increasing IDCP. The IDCP value generally increased from 12.3 (raw) to 8.6, 14.8 and 39.6% (WFB) and from 28.3 (raw) to 33.7, 36.2 and 56.2% (WLS) at 8 h rumen incubation; from 2.9 (raw) to 2.9, 4.6 and 23.3% (WFB) and from 19.6 (raw) to 19.0, 24.0 and 46.6% (WLS) at 12 h rumen incubation; from 1.3 (raw) to 1.9, 1.7 and 11.0% (WFB) and from 4.4 (raw) to 4.2, 10.7 and 36,7% (WLS) at 24 h rumen incubation as the temperatures rose to 110, 130 and 150°C, respectively. The TDCP values were always high and increased by time in the rumen, the average values of which were 97.9, 96.6; 99.2, 96.9 and 99.6, 98.7% for WFB and WLS, respectively, at 8, 12 and 24 h rumen incubation. But within the same retention time, TDCP was generally unchanged. The average IARUCP increased from 87.3 (raw) to 87.4, 88.7 and 92.0% (WFB); from 87.6 (raw) to 88.9, 91.5 and 93.0% (WLS) at roasting temperatures of 110, 130 and 150°C, respectively. It was concluded that dry roasting can shift the digestion of CP from rumen to the lower gastrointestinal tract without depressing the digestion of RUCP, The best processing condition in this study was dry roasting at 150°C for 45 min in terms of effects on the disappearances and availability of CP. Research data on intestinal availability of individual amino acids need to be further investigated.