Avaliação física e química-bromatológica do capim-marandu e híbridos de Urochloa diferidos

Abstract

We aimed to evaluate the milling resistance and chemical-bromatological characteristics of tillers of Urochloa brizantha cv. Marandu (marandu grass) and three Urochloa hybrids (Mulato II, Mavuno and Ipyporã grasses) deferred. For this, a study was carried out at the Forage Culture Sector and at the Laboratory of Bromatology and Animal Nutrition (LABAN) of the Federal University of Uberlândia, in Uberlândia, MG, from September 2021 to March 2022. The experiment was conducted in a completely randomized design, with four replications and four treatments, totaling 16 plots. The treatments studied were four forage grasses: Urochloa brizantha cv. Marandu (marandu grass) and three Urochloa hybrids (Convert HD 364, Mavuno and Ipyporã grasses). The deferral period started in mid-March and ended in mid-June 2021, lasting 90 days. At the end of the deferral period, 50 reproductive tillers and 50 vegetative tillers were randomly collected close to the ground, in each plot, as well as samples of the forage mass. Samples of vegetative and reproductive tillers were analyzed to measure milling resistance, as described by HUGHES et al. (1998). Samples of forage mass, vegetative and reproductive tillers after drying, were ground to a particle size of 1mm and taken to Laboratory of Bromatology and Animal Nutrition (LABAN), where they were analyzed for DM, CP, NDF, ADF, lignin, iNDF, pdNDF and pdDM. For each trait evaluated, analysis of variance was performed in a completely randomized design in a split-plot scheme. The plots were the four forage grasses, while the subplots were the types of tillers (vegetative and reproductive). Subsequently, the effects of the levels of the factors were compared by the Tukey test, at the level of significance of 10 % of probability for the occurrence of type I error. The analysis of milling resistance was also correlated with the chemical-bromatological analyzes using the correlation of Pearson. Marandu, Mavuno, Mulato II and Ipyporã grasses showed no correlation between resistance to milling and chemical bromatological features. Ipyporã grass has a lower percentage of live stem and a higher percentage of live leaf, and lower NDF contents, which may indicate presence of more digestible tissues in this forage. Mavuno grass has less resistance to milling, which can become an interesting forage from a nutritional point of view, and can be consumed in larger quantities by animals without causing rapid rumen filling.