Nitrogen Components Reaching the Omasum and Abomasum of Lambs Fed Two Nitrogen Levels

Two semipurified diets, containing either 1.12 or 2.24% soybean meal nitrogen, were fed to four wether lambs fitted with both omasal and abomasal cannulas to quantitate the nitrogen constituents reaching the omasum and abomasum. Although daily nitrogen consumption was either 7.3 or 14.6 g/lamb, intake did not affect the daily amount of total nitrogen reaching the omasum or abomasum. Significantly more free amino nitrogen reached the omasum than abomasum with both diets; the reverse situation prevailed for bound amino nitrogen. Equal or greater amounts of all amino acids, except arginine, histidine, serine and glutamic acid, reached the omasum than was consumed daily in the 1.12% nitrogen diet. Quantities of all individual amino acids consumed were greater than those recovered in the omasum or abomasum of wethers consuming the 2.24% nitrogen diet. While no significant differences were found between individual or total amino acids recovered at the two collection sites of lambs fed 1.12% nitrogen, significantly greater amounts of threonine, valine, alanine and proline reached the omasum than abomasum of lambs fed the 2.24% nitrogen diet. The absolute quantities of total nitrogen and amino acid nitrogen recovered daily in the omasum and abomasum were not influenced by the level of dietary nitrogen in this study.