The digestion of forages is determined by chemical and anatomical factors, which are affected by the growing stage of species. As the growing plants show a variety of tissues in anatomy and composition, it's important to determine their relative participation in total dry matter production, as well their digestion rates. The aim of this paper was to determine the digestibility and chemical composition of leaf fractions (limbo, keel, sheath), as well as of the upper, median and lower part of stems of three elephant grass (Pennisetum purpureum Schumach.) cultivars (307-TESTO, 309-AREIA and ROXO). The plants were harvested with ten weeks of age for leaf and stem fractions separation. The AREIA cultivar was taller than the others with shorter stems and sheaths, which resulted in reduced contribution of these parts in the total dry weight. The several fractions showed different protein, lignin and digestibility rates. The mature lower part of stem and keel are the portions responsible for decreasing elephant grass quality. The contribution of fractions as well the lignification and digestibility levels showed little difference among the cultivars at the same growing stage. The cultivar AREIA showed the best quality, due to higher digestibility and protein values of the leaves. Stem and keel were the main barriers to digestion of elephant grass tissues.
cell wall; digestibility; forage; lignin; ruminants
