EVALUATION OF CULTIVARS OF Megathyrsus sp. and Urochloa sp. UNDER HARVEST FREQUENCIES FOR SILAGE PRODUCTION
Harvest; Silage; Tropical grasses; Management.
The objective of this study is to evaluate seven cultivars of tropical grasses of the genre Megathyrsus sp. and Urochloa sp. under three frequencies of harvest for silage production. The field experiment will be conducted in the experimental area of the Igarapé-açu school farm (FEIGA) of the Federal Rural University of Amazon (UFRA), covering the period from January to August 2021. Laboratory analyzes will be conducted at the Animal Nutrition Laboratory (LABNUTAN) at UFRA, in Belém-PA. The design used will be in randomized blocks, in a 7 × 3 factorial arrangement, with seven cultivars of tropical grass and three frequencies of harvest, with four blocks (n = 84). Experimental plots (3 × 4 m) implanted in June 2019, in previously prepared soil (correction and fertilization) will be used. For agronomic characteristics will be evaluated: the height of the canopy, height of the extended plant, the interception of light (IL) by the canopy, height of the apical meristem and regrowth vigor. For the morphogenic and structural characteristics will be evaluated: leaf appearance rate (LAR), leaf expansion rate (LER), leaf senescence rate (LSR), phyllochron (PHYLO), leaf life span (LLS), elongation rate stem + sheath (ERS), final leaf size (FLS), number of live leaves (NLL), tiller demographic pattern (TDP) and tiller population density (TPD). For the bromatological analysis, the content of ether extract (EE), dry matter (DM), acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP) and mineral matter (MM) will be evaluated. Then, in vitro digestibility, soluble carbohydrate content, buffering capacity, pH, ammoniacal nitrogen content and soluble solids content will be analyzed. Variance analysis will be performed using the PROC MIXED procedure of the SAS (Statistical Analysis System), using the LMEANS command and tukey test at 5% significance level, to compare the averages in each factor. The cultivars and the cutoff frequencies will be considered as fixed effects and the effect of the blocks will be considered random effect.