Anatomia quantitativa, digestibilidade in vitro e composição química de cultivares de Brachiaria brizantha

Abstract

This study aimed to evaluate three Brachiaria brizantha cultivars (Marandu, Piata and Xaraes) in three cut ages, as the chemical composition, in vitro digestibility and quantitative anatomy. The experiment was conducted in a completely randomized design arranged in a factorial design, three cultivars, three cut ages and two insertion levels (apical and basal). For the variables related to chemical composition and digestibility the insertion level was not used. Areas of tissues were measured following the usual description in vegetable histology. The cv. Xaraes showed higher area of epidermis and sclerenchyma in the leaf blade and greater lignified vascular tissue+sclerenchyma and vascular bundle sheath parenchyma in the leaf sheath (p < 0.05). The cvs. Marandu and Piata showed greater parenchyma in the leaf sheath (p < 0.05). The sclerenchyma showed decreasing linear effect for all cultivars in the leaf blade between cut ages and increasing linear effect for cv. Xaraes in the leaf sheath (p < 0.05). The cv. Marandu showed higher crude protein and in vitro true digestibility of dry matter, and lower acid detergent fiber (p < 0.05). The cv.Marandu showed better nutritional value, digestibility and higher digestible tissues in the quantitative anatomy.