THE NITROGEN COMPOSITION OF CEREAL GRASSES. I. PRINCIPAL NITROGEN FRACTIONS

Abstract

The availability of winter cereal grasses in the Southwest during the late fall and early spring has focused attention on these plants as a source of feed for livestock and poultry. Extensive investigations have been conducted at this station by Staten (9) during the last few years to determine the total yield of grass for grazing livestock and the effect of clipping on grain yields. Most of the varieties tested have been analyzed for proximate constituents by Heller (4). Selected varieties have also been analyzed for carotene and certain vitamins of the B-complex by Moyer, et al. (?). One of the observations made during these studies was the high nitrogen content of these cereal grasses when clipped at grazing height. A crude protein content in the range of 20-40 per cent, on a dry weight basis (? ? 6.25) was common. In view of these high values, it became of interest to ascertain the distribution of the principal nitrogenous fractions. Little information on the nitrogen composition of these plants was available in the literature. Furthermore, much of the data had been collected using more mature plants. Miller (5) in an investigation of wheat showed in two varieties that the non-protein nitrogen of the leaves and stems constituted approximately 25 per cent, of the total, and occasionally approached 40 per cent. What portion of the non-protein nitrogen was present in the form of amino acids was not determined. The extensive investigations of Chibnall and his students (1) on the pasture plants and grasses of England and Australia have shown that only a portion of the nitrogenous constituents were of such a type as to be coagulable by acid and heat. Cultera (3) in studies on the nitrogen metabolism of wheat and oats had reported that approximately one-third of the total nitrogenous compounds are not precipitated with trichloroacetic acid. In view of these data, five representative species of cereal grasses and annual rye grass have been sampled throughout the fall and spring growing seasons for two consecutive years and analyzed for their principal nitrogenous constituents. The present communication presents the results of these determinations.