The influence of protein intake on the digestion of dry matter in various sections of the digestive tract of the intact sheep.

Grass cubes, a synthetic diet with casein as virtually the only source of nitrogen and one without casein were given at a fixed level of intake to sheep iIi which the flow of digesta was exteriorized by means of re-entrant cannulae fitted in various sections of the digestive tract. Nitrogen intake on the diets in the same order was 1429, 782 and 027 gm daily. The diet lowest in nitrogen accumulated in the reticulo-rumen and no valid'indications could be obtained for the digestion of dry matter in the different compartments of the digestive tract. Of the quantities of dry matter digested while the grass cubes and casein-containing diets were given, 56 to 64 per cent disappeared in the proventriculi and abomasum, 16 and 30 per cent in the small intestine and 28 and 6 per cent in the large intestine of sheep respectively. The concentration of volatile fatty acids in the reticulo-rumen increased with increasing protein intake. The addition of protein to nitrogen-low but energy-adequate diets enhanced dry matter digestion in particularly the proventriculi.