Changes in Composition of Sudangrass and Forage Sorghum with Maturity 1

Under three managements, stockpiled (no summer cut), hay (one summer cut), and pasture (three summer cuts), significant differences were noted in percent dry matter, crude protein, and crude fiber in the leaves, stems, and heads of ‘Piper’ sudangrass ( Sorghum sudanense (Piper) Stapf) and ‘RP30F’ forage sorghum ( Sorghum bicolor (L.) Moench) with advancing maturity. These changes were particularly striking when the forage was saved for fall use. Generally, sudangrass analyzed significantly higher in percent dry matter and crude fiber but lower in percent crude protein than forage sorghum. Percent dry matter in the leaves, stems, and heads of both species differed significantly with management and increased with maturity, except in the heads of sudangrass under the stockpiled management where percent dry matter increased until full maturation and decreased abruptly thereafter, possibly because of seed shattering and loss. In both sudangrass and forage sorghum, the heads were highest in percent dry matter, the leaves intermediate, and the stems lowest. Percent crude protein and crude fiber differed significantly between species, plant parts within each species, and dates of sampling. Percent crude protein generally decreased as the date of sampling was delayed. The leaves of both species were highest in percent crude protein, the heads intermediate, and the stems lowest. Percent crude fiber increased in the leaves and stems of sudangrass, but decreased in the leaves and stems of forage sorghum as plants matured. Percent crude fiber decreased in the heads of both species with advancing maturity.