EFFECTS OF A SUPPLY OF RAW OR EXTRUDED WHITE LUPIN SEEDS ON PROTEIN DIGESTION AND AMINO-ACID-ABSORPTION IN DAIRY-COWS

Four cannulated, lactating cows were used to determine the effects of extruding white lupin seeds (WLS) on intraruminal CP degradation and a bsorption of AA from the small intestine. Raw lupin seeds (RWLS) and e xtruded lupin seeds (EWLS) were fed in diets containing 15.5% CP and c omposed of 22.4% WLS, 55.9% corn silage, 10.1% maize grain, and 10.6% Italian ryegrass on a DM basis; WLS provided approximately 50% of the total dietary CP. Spot samples of digesta were collected from the prox imal duodenum and terminal ileum during 72 h. Chromium EDTA, YbCl3, an d purines were used as liquid, particulate, and bacterial markers, res pectively. Because of the extensive ruminal degradation of dietary N w ith the RWLS diet compared with the EWLS diet (64.2 vs 38.8%), less to tal AA flowed to the duodenum (1,748 vs 2,347 g/d), and because of the decrease of availability (67.2 vs 79.0% of entering), absorption from the small intestine was lowest with this diet (1,175 vs 1,855 g/d). T he apparent digestion of individual AA in the small intestine (percent age entering) ranged from 46.5 to 88.4 when cows consumed RWLS and fro m 58.9 to 94.4 when they were fed the EWLS diet. Among the diets, appa rent absorption of histidine, lysine, glycine, and serine were higher than those of other AA; also, valine, alanine, and proline showed inte stinal absorptions that were somewhat lower than those of the remainde r of the AA.