The digestion of nitrogen associated with plant cell wall in the stomach and small intestine of the sheep

Abstract

The digestion of dietary cell wall constituents was estimated during measurements of the passage of digesta from the stomach and intestines of sheep. Two groups of four sheep were used, and they were fed on either mature wheaten hay at 600 g/d or immature dried ryegrass at 800 g/d. Cell wall constituents comprised c. 58.7% and 39.8% of the organic matter in the two diets, while the nitrogen associated with cell wall was equivalent respectively to 14.1 and 24.6 % of dietary nitrogen. With wheaten hay, 45 % of cell wall organic matter and 25 % of cell wall nitrogen were digested in the stomach. The corresponding values for ryegrass were, respectively, 81 and 89 %. The nitrogen in cell wall contributed about 9% of non-ammonia nitrogen in digesta leaving the stomach and 15 % in digesta leaving the ileum with wheaten hay, but only 4-5 % at each site with ryegrass. Although the release of amino acids from cell wall in the small intestine was less than from the remaining crude protein in digesta, it was concluded that the amounts involved were too small to have much effect on the apparent release of amino acids in digesta passing through the small intestine.