Valor nutritivo e aspectos anatômicos de clones de Pennisetum purpureum Schum. de diferentes portes

Abstract

The aim of this work was evaluating nutritive value of clones os elephantgrass of different sizes in response to successive harvests. The experiment was conducted at Experimental Sugar Cane Station of Carpina – EECAC, belonging to Federal Rural University of Pernambuco – UFRPE, located at Carpina. The experiment consisted of a competition among tall clones of Pennisetum purpureum (Elefante B and IRI – 381) and small ones (Taiwan A-146 2.37 and Mott) and a fixed harvest strategy at 60 days of growth. The experimental design was randomized in blocks with four treatments and four replications. The plots had 25 m2 (5m x 5m) of total area and 9 m2 (3m x 3m) of useful area. The bromatological composition and nutritive value of clones, as well as in vitro dry matter digestibility were determined from laboratory analyzes. Significant interactions (P <0.001) were observed between clones x evaluations for dry matter (DM), mineral matter (MM), Lignin, non-fibrous carbohydrate (CNF) and total carbohydrate (CT) in leaves. In stem, it was observed to MS, acid detergent fiber (FDA), lignin and CNF of the evaluated clones. It was observed a clone effect and effect of the evaluation, without significant interaction for the in vitro dry matter digestibility (DIVMS) in leaf and stem. In orthogonal contrast analysis between high and low size groups, a significant difference was observed in leaf, with higher results for high MS, (20,79%), FDA (29,86%) and FDN (67,21%) and, for low size, higher values for MM (8,62%) and CNF (16.18%). In stems, the highest results were observed in the high-size group in FDA (34,4%), FDN (69,7%) and lignin (5,91%), and in the low-size group, DIVMS (66,53%). The size of the plant influences on the nutritive value of leaves and stems of elephantgrass clones. Tall genotypes generally have smaller fibrous fractions and higher digestibility in leaves and stems, when compared to those of high size.