COMPOSIÇÃO BROMATOLÓGICA DE CULTIVARES DE CAPIM ELEFANTE EM DIFERENTES ÉPOCAS DE AVALIAÇÃO

Abstract

The increasing expansion of Brazilian livestock has required the supply of high-yielding pastures of good bromatological quality that meet the nutritional requirements of the ruminant diet. In this sense, the elephant grass Pennisetum purple Schum is a tropical grass that has been standing out for its characteristics of adaptability to climate, ease to manage, high forage yield, and nutritional value. This paper aimed to analyze the nutritional bromatological composition and productivity of elephant grass cultivars in different regrowth periods and seasons of the year. The experiment was carried out at Goiano Federal Institute, Ceres Campus, Goiás State (GO), Brazil, in a randomized block design with split plots and four replicates. Six elephant grass cultivars were evaluated (Cameroon Comum, Cameroon Roxo, BRS Capiaçu, BRS Canará, BRS Kurumi, and Napier); data were collected over two planting seasons (dry, under irrigation, and rainy seasons), and in each season, three regrowth periods (forty-five,

sixty, and seventy-five days) of the grasses were also evaluated in each of the twenty- four plots. The variables evaluated were: (a) dry mass productivity (DMP); (b) dry

matter content (DM); (c) ash (CZ); (d) ethereal extract (EE); (e) crude protein (CP); (f) neutral detergent fiber (NDF); (g) acid detergent fiber (ADF); (h) neutral detergent insoluble nitrogen (NIDNms, NIDNnt) and acid (PIDA); (i) neutral detergent insoluble nitrogen (NIDNms, NIDNnt) and acid; (j) dry matter and total nitrogen (NIDAms and NIDAnt); (k) non-protein nitrogen (NNPms and NNPnt); and (l) in vitro digestibility of dry mass (DIVms). The results were analyzed by multivariate statistics based on the Principal Component Analysis (PCA) and univariate statistics. The indices Nb1b2, Pb1b2, CNF, CHOb2, and CHOt were analyzed separately because they were obtained from previous variables. The first two main components together explained 67.4% of the variability contained in the original data. The cultivar Kurumi, the dry season, and the regrowth period at forty-five days are associated with high values of PIDN, NIDNms, DIVms, and CZ. Regarding indices, the first two main components explained 71.9% of the variability contained in the original data. The cultivars differed from each other and Kurumi stood out among the others. The water season provided higher values

9 of Nb1B2 and CHOb2 in CP1, and CHOt, and CNF by CP2. The results of CP2 and CP1 showed higher values of Pb1b2, Nb1b2, and CHOb2 at forty-five days of regrowth period compared to other periods. The regrowth period affects elephant grass forage in crude protein, soluble carbohydrates, and fiber contents. The cultivar BRS Kurumi and the regrowth at forty-five days showed higher nutritional value in the study conditions.