Agroforestry systems (AFS) are considered alternative land use options to help prevent soil degradation and improve soil microbial biomass and organic C status. However, it is unclear how different densities of babassu palm [Attalea speciosa (syn. Orbignya phalerata)], which is an important tree in Northeast Brazil, affect the soil microbial biomass. We investigated the soil microbial biomass C and activity under AFS with different densities of babassu palm associated with Brachiaria brizantha grass. Soil microbial biomass C (MBC), soil microbial biomass N (MBN), MBC:total organic C ratio, fluorescein diacetate hydrolysis and dehydrogenase activity showed highest values in plots with high density of babassu palm. On the other hand, the respiratory quotient (qCO 2 ) was significantly greater in plots without babassu palm. Brachiaria brizantha in monoculture may promote C losses from the soil, but AFS with high density of babassu palm may increase the potential of soils to accumulate C. ResumenLos sistemas agroforestales (AFS, por sus siglas en inglés) son opciones alternativas de uso de la tierra que ayudan a prevenir la degradación del suelo y mejorar la biomasa microbiana y el estado del carbono (C) orgánico. Babasú [Attalea speciosa (syn. Orbignya phalerata)] es una importante palma nativa que forma bosques en los estados Maranhão y Piauí, nordeste de Brasil; no obstante no se conoce su efecto sobre la biomasa microbiana del suelo cuando crece en diferentes densidades. En el estudio se evaluaron los efectos sobre el C y la actividad de la biomasa microbiana del suelo en AFS con 3 densidades de babasú en pasturas de Brachiaria brizantha. El C y el nitrógeno de la biomasa microbiana (MBC resp. MBN) del suelo, la relación de MBC:C orgánico total del suelo, la hidrólisis de diacetato de fluoresceína y la actividad de la deshidrogenasa mostraron valores más altos en las parcelas con alta densidad de babasú. Por otra parte, el cociente respiratorio (qCO2) fue significativamente mayor en las parcelas sin babasú. El pasto B. brizantha en monocultivo puede promover la pérdida de C del suelo, pero los AFS con alta densidad de la palma pueden aumentar el potencial de los suelos para acumular C.

The objective of this study was to evaluate the fermentative characteristics and chemical composition of cochineal nopal cactus silage additives with urea or Lactobacillus buchneri (LB), as well as the association of both additives in four storage times (7, 15, 60 and 120 days) and during aerobic stability, with evaluations at 0, 48 and 96 h. Four silages were used: no additive, addition of 2% urea, addition of LB and addition of 2% urea and LB. The study was divided into two experiments: the first experiment evaluated the silages at different storage times, and the second experiment evaluated the silages during the aerobic stability test. In both experiments, the experimental design was completely randomized in a factorial scheme (4 × 4 and 4 × 3) with three replicates per treatment. After the ensiling process, lactic acid bacteria predominated in all treatments. The concentration of lactic acid increased significantly from 60 days of ensiling. The concentration of acetic acid varied significantly between the storage times only for the silages treated with urea and LB alone. The silage treated with urea maintained a constant pH value up to 120 days of storage. During the 96 h aerobic stability test, no breaking in the stability of silages was observed. The exclusive or associated use of urea and LB promotes improvement in the fermentative characteristics of cochineal nopal cactus silage, without major alterations in the chemical composition or interfering with the aerobic stability of the silages.

SUMMARY This study aimed to determine the area occupied by different tissues present in the leaf blade and the in situ degradability of leaf and stem of elephant grass (Pennisetum purpureum Schum.) under different defoliation frequencies (30, 45, 60, 75 and 90 days). Plants were classified into three levels of insertion in the tiller (apical, medial and basal). The results were presented as a proportion of the area of each tissue in relation to the total area of the leaf blade, namely, parenchyma tissue (PT), lignified vascular tissue (LVT) and non-lignified vascular tissue (NLVT). The proportion of tissue in the leaf blade is altered in accordance with the insertion in the tiller and increase in cutting age of the plant. PT has greater proportion at lower cutting ages, LVT increases with frequency and NLVT is higher at 60 days. The parameters of DM degradation in the two fractions evaluated decreased significantly with increasing maturity of the plant. The effective degradability of CP in leaf and stem decreased with the increase in the rate of passage (2, 5, and 8% h-1). The highest rate (c) of CP degradation for the leaf fraction was obtained with a frequency of 60 days, for the stem, with 45 days. The advance in plant maturity increases the proportion of lignified vascular tissue, thus influencing the ruminal degradation parameters of elephant grass. The defoliation frequency of 60 days offers an optimal point regarding the proportion of anatomical tissues correlated with the degradation of elephant grass.

This study aimed to evaluate the agronomic characteristics and nutritional value of Massai grass (Megathyrsus maximus 'Massai') pastures fertilized with different nitrogen levels and subjected to deferred grazing. A completely randomized experimental design (CRD) was adopted, with including five nitrogen levels (zero, 100, 200, 300, and 400 kg ha −1 ), and five replications (plots). The degradability trial used a CRD including a 6 × 5 factorial arrangement, consisting of six rumen-incubation times (6, 24, 48, 60, 84, and 96 h) and five levels of nitrogen in different plots. One fistulated sheep, with a live weight of 60 kg, was used in the experiment. Total herbage biomass, dead herbage biomass, and height showed a quadratic response to nitrogen fertilization levels of 100 to 200 kg ha -1 resulted in greater tillering. Protein and dry matter content increased linearly with nitrogen fertilization level, leading to increase in fibrous components. The increase in NDF and ADF contents might be a consequence of the reduction in NCE, and the high flowering rate of the grass, owing likely to the reduction in metabolism of the grass in an attempt to extend its lifetime. Nitrogen levels of 300 kg ha −1 or higher affected the productive characteristics positively, whereas the chemical characteristics were negatively affected. Key words: Deferred period. Degradability of dry matter. Megathyrsus. Nitrogen fertilization. ResumoObjetivou-se avaliar as características agronômicas e valor nutritivo do capim-Massai (Megathyrsus maximus 'Massai') submetido a diferimento e doses crescentes de nitrogênio. O delineamento experimental adotado foi o inteiramente casualizado (DIC) com cinco doses de nitrogênio (zero, 100; 200; 300 e 400 kg de N ha -1 ) com cinco repetições (parcelas). O ensaio de degradabilidade foi estruturado em DIC, com arranjo fatorial 6x5, seis tempos de incubação no rúmen (6, 24, 48, 60, 84 e 96 h) e cinco doses de N em parcelas diferidas. Utilizou-se um ovino fistulado com peso vivo de 60 kg. A biomassa de forragem total, morta e a altura respondeu à adubação nitrogenada de forma quadrática. A adubação nitrogenada nas doses 100 a 200 kg de N ha -1 proporcionou maior perfilhamento. A adubação nitrogenada proporcionou resposta linear sobre os teores de proteína e matéria seca em consequência também aumentou os constituintes fibrosos. O amento dos teores de FDN e FDA pode ser uma consequência da redução da ECN e da taxa de florescimento da gramínea, devido provavelmente à redução no metabolismo na tentativa de prolongar sua vida útil. A partir da dose de 300 kg de N ha -1 resultou em redução da degradação da matéria seca do capim-Massai. As doses de N influenciaram positivamente as características produtivas e negativamente as características químicas. Palavras-chave: Adubação nitrogenada. Degradabilidade da MS. Megathyrsus. Período de diferimento.

The aim of this study was to investigate the effects of Cactus (Opuntia spp) levels in total mixed ration silages based on Cactus and Gliricidia (Gliricidia sepium (Jacq.) Steud) on the fermentation profile, microbial populations, aerobic stability and taxonomic diversity. The completely randomized design was used in a 4 × 4 factorial design with four replications, being four rations with different levels of Cactus (15, 30, 45, 60% based on the dry matter) and four opening periods (0, 15, 30 and 60 days of fermentation). An interaction effect (P < 0.050) was observed among the diets and opening times for mould and yeast populations. An interaction effect for the levels of acetic acid was observed, where the diets 15, 30, 45 and 60% showed higher values at 60 days (0.44, 0.41, 0.35 and 0.40 g/kg DM, respectively). A significant difference was observed for the richness and diversity index (Chao1 and Shannon). The most abundant bacterial phyla were Proteobacteria and Firmicutes and the genera Lactobacillus and Weissella. Cactus can be added in total mixed ration silages up to the level of 60% in a way that it positively affects the qualitative indicators of the silages, modulating the taxonomic communities and allowing the predominance of important groups for preservation of the ensiled mass.

401Composição químico-bromatológica e degradabilidade in situ de capim-Marandu em sistemas silvipastoris formados por babaçu e em monocultivoChemical Composition and bromatologic degradability in situ of Marandu grass in silvopastoral systems formed by babassu and monoculture systems

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The current study aimed to evaluate the application effects of the preactivated Lactobacillus buchneri and urea on the fermentative characteristics, chemical composition and aerobic stability in corn silages. The design was completely randomized, in a 6 × 5 factorial arrangement, with six types of additive and five opening times. The treatments consisted of corn silage; corn silage with freeze-dried inoculant; corn silage with freeze-dried inoculant +1.0% urea; corn silage with activated inoculant; corn silage with activated inoculant +1.0% urea, and corn silage with 1.0% urea. Populations of lactic acid bacteria stabilized at the 70th day, with average values of 8.91 and 9.15 log cfu/g for corn silage with freeze-dried inoculant +1.0% urea and corn silage with freeze-dried inoculant, respectively. In contrast, the silages without additives showed significantly lower values of 7.52 log cfu/g forage at the 70th day. The silages with urea (isolated or associated with the inoculant) increased the total nitrogen content. The maximum temperature values were highest in the corn silages without additives, indicating that these silages were more prone to deterioration. The use of Lactobacillus buchneri activated proved to be more efficient in improving the fermentative profile of corn silages than the freeze-dried inoculant. The use of urea as an additive reduced the losses and improved the nutritional value and aerobic stability of corn silages. Additionally, the combination of Lactobacillus buchneri activated and urea may be used as a technique to improve the fermentative profile, chemical composition and aerobic stability of corn silages.