Duodenal protein flow is steers fed concentrate and roughage diets

Abstract

Four cannulated steers were used to compare the effect of diet ( concentrate vs. roughage ) on the duodenal N and aminoacidos (AA) flow. Lignin and Cr₂O₃ were compared with automated total collection (ATC) for estimated duodenal N flow over 3 to 6 – day collection periods. Estimations based on Cr₂O₃ and lignin were about 10 to 15% great (P < 0.05 ) than direct flow measurements by ATC. Daily duodenal N flow was about 30 % great than daily N intake in the concentrate diet. Intake and duodenal flow of N were similar in the roughage diet. Duodenal AA flow values expressed as percentage of intake were greater in the concentrate diet than in roughage (P < 0.01), especially DAP, suggesting more bacterial synthesis in the concentrate diet. There was a net gain in AA due to a ruminal digestion in the concentrate diet. LYS, THR and ILE were the three EAA that increased the most in the concentrate diet and the only ones that increased in the roughage diet. The date suggest a beneficial effect on the duodenal N and EAA flow by increasing dietary nonstructural carbohydrate. Further studies are necessary to establish the value of the structural and non-out-flow reaching the duodenum.