Palma forrageira como aditivo associada à ureia em silagem de grão de milho.

Abstract

The objective of this study was to evaluate the effects of different proportions of forage palm as an additive, associated with urea on chemical composition, ammonium nitrogen, microbial dynamics, fermentative losses, pH and aerobic stability in maize grains in the form of silage over storage periods. Two experiments were performed. For Experiment I, the design used was the one entirely casualized in a factorial arrangement (2 x 5 x 4), with three repetitions, totalling 90 experimental silos, where: (2) referring to the factors of urea addition or not, (1.5% MS) (5) forage palm proportions (0%, 5%, 10%, 20% and 40%) and (4) silo opening periods (0, 15, 45 and 90 days). In Experiment II, the factorial scheme was (2 x 5), with four repetitions, (2) referring to the factors with and without urea, (5) five different types of silage. Then there were 10 treatments with 4 repetitions, totalling 40 experimental silos type bucket, adapted with Bunsen valves, consisting of the same proportions of palm and urea. The control treatment corresponded to the added silage of water (without addition of palm and urea). There was interaction between the H x U (P<0.01) factors for the variables dry matter (MS), mineral matter (MM) and crude protein (PB). The hydration of corn grain silage with the different forage palm proportions influenced (P<0.01) the acid detergent fiber (FDA) and non-fibrous carbohydrates (CNF). For the inclusion of fixed urea rate (1.5%) there was an effect for (P<0.05) fiber in neutral detergent (FDN), FDA and CNF (P<0.01). There was interaction (P<0.01) among the factors (H x U) for ammoniacal nitrogen (N-NH3). There was an effect of increasing doses of palm (P<0.05) in the microbial population for different storage times. For silages with urea there was effect (P<0.05) of the additive on the microbial dynamics on the different opening days. Interaction H x U (P<0.01) was observed for dry matter recovery (MSR), presenting higher values in forage palm hydrated silages and lower values for the use of urea. There was interaction H x U (P<0.01) for hydrogen potential variable (pH), with an increase in treated silages of 1.5% urea and reduction for hydration since 15 days of storage. Hydrated silages with water broke aerobic stability after 40 hours of exposure (P<0.05), with no aerobic deterioration in silages treated with additives.