Rosane Cláudia Rodrigues

Soil microbial biomass in an agroforestry system of Northeast Brazil

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. Keywords: Enzyme activity, tropical soil, babassu palm, silvopastoral system, soil quality. DOI: 10.17138/TGFT(3)41-48

Recuperação de matéria seca e composição química de silagens de gramíneas do gênero Cynodon submetidas a períodos de pré-emurchecimento

Objetivou-se avaliar o efeito de periodos de pre-emurchecimento das gramineas Estrela- Africana-Branca [Cynodon plectostachyus (K. Schum.) Pilg.] e Tifton 85 (Cynodon sp.) sobre algumas caracteristicas de suas silagens. Utilizou-se delineamento inteiramente casualizado com dez tratamentos e tres repeticoes. Os tratamentos foram dispostos em esquema fatorial 2x5, sendo duas gramineas (Estrela-Africana-Branca e Tifton 85) e cinco periodos de pre-emurchecimento da forragem (0, 1, 2, 3 e 4 h). As gramineas foram cortadas aos 50 dias de rebrotacao e permaneceram ensiladas por 55 dias em silos experimentais. O pre-emurchecimento promoveu aumento no teor de materia seca da forragem cortada e da silagem das gramineas Tifton 85 e Estrela Africana Branca. Houve diminuicao nos teores de N-amoniacal (N-NH3/N-total) da silagem do capim-estrela-africana-branca, a uma taxa de 1,66 unidade percentual por hora de pre-emurchecimento, mas nao houve alteracao nessa variavel da silagem do capim-tifton 85. A silagem do capim-tifton 85 apresentou maior recuperacao de materia seca, maior teor de FDN e menor teor de proteina bruta do que a silagem do capim-estrela-africana-branca. O pH e o teor de FDA das silagens nao foram influenciados pelo pre-emurchecimento.

Increasing levels of concentrate digestibility, performance and ingestive behavior in lambs

The objectives of this research were to determine the effects increasing levels of concentrate on nutrients digestibility, performance, economic viability of diets and ingestive behavior of lambs. Fifteen crossbred lambs were used in a randomized complete block design according to initial body weight and age. Lambs were penned individually during 55 days, being 10 days for adaptation of diets and 45 days for data collection. The treatments consisted in three isonitrogenous diets with increasing levels of concentrate: 40, 60, or 80%, in dry matter basis. No effect (P>0.05) were observed on dry matter intake, crude protein intake, crude protein digestibility and neutral detergent fiber digestibility, whereas the dry matter digestibility was lower (P<0.01) for lambs fed diets with 40% of concentrate. The addition of 80% concentrate decreased (P<0.05) neutral detergent fiber intake, however this treatment provided higher average daily gain, followed by 60 and 40% of concentrate. In relation to feeding behavior, the animals fed80% concentrate spent more time with feeding (P<0.05) compared to the other treatments. It is concluded that supplementation of concentrate between 60 to 80% improves dry matter digestibility and performance of crossbred lambs without relevant affect dry matter intake and ingestive behavior. A diet with 80% concentrate provides positive gross margin of profit.

Características morfogênicas e estruturais do capim-Xaraés submetido a intensidades de desfolhas

Aimed to evaluate the morphogenetic and structural characteristics of grass Xaraes subjected to five heights of sections (10, 20, 30, 40 and 50cm) with cutting interval based on (LI) by the canopy during regrowth (95% IL). We used a completely randomized design in a factorial 2x5 with five replications. The evaluations were conducted from March to November 2011, the following variables: leaf appearance rate (LAR), leaf elongation rate (LER), stem elongation rate (SER), final leaf length (LL), senescence rate leaf (SRL), life span of leaves (LSL), number of green leaves per tiller (NLL) and live tiller number (LNT). It was observed that the heights of cuts by 30 to 50 cm resulted in higher SER, LER, LAR, SRL, LLS, NLL and LL. The SER, LER, LAR, SRL, NLT and LL characteristics showed higher values during the rainy season. While the phyllochron and LLS at 40 cm showed higher values in the dry season. The LNT was not affected by the heights of cuts or time of year. The cutting height of the grass Xaraes recommended for these environmental conditions is between 30 and 50cm.

Forage intake and performance of cattle in silvo-pastoral systems and monoculture of Marandu in Pre-Amazon region

This work aimed to evaluate dry matter intake (DMI) and performance of F1 Nellore x Guzera with live weight (LW) of 180±15 kg (5 months) on pastures of Brachiaria brizantha cv. Marandu in silvo-pastoral systems composed of babassu palm (Attalea speciosa) and monoculture systems in Pre-Amazonic region of Maranhão state, Brazil. Animals were evaluated in four systems: 0, 80, 131 and 160 adult palms ha -1 , characterizing monoculture (MC), low density (LD), average density (AD) and high density palm trees (HD), respectively, during the rainy (RS) and dry season (DS). Comparing seasons, only DMI in MC and AD were affected. DMI was between 2.6% LW for the RS and 2.8% LW for the DS, These values are very close as suggested by NRC, which is 2.7% LW for animals in this category. Higher average daily gain per ha was observed in animals kept in pastures with LD (0.750 g.day -1 and 84.37 kg.ha -1 , respectively). It was observed that animal performance was influenced by density of palm trees and the DMI by season, probably by the sward structure. Animal performance and production forage biomass were higher in 0 and 80 palm systems. This greater forage biomass allow higher stocking rate and, consequently higher animal production per ha.

Porcentagem de proteína em suplementos para ovinos mantidos em pasto de capim-aruana na época seca

The aim of this study was to evaluate the forage intake and grazing sheep performance keep on Aruana grass subjected to increasing crude protein (CP) levels in the supplement on dry season. Twenty Santa Ines male lambs were used, with initial body weight of 31.80kg by a completely randomized design with five treatments and four replications. The supplements were provided daily at 1% of body weight, with protein levels of 0, 15, 20, 25 and 30%. The increase of the crude protein levels promoted a squarely effect on dry matter intake (kg/day and % of BW), with maximum estimated values of 1296g and 3.2% of DM in CP levels of 21.48 and 21.89, respectively. The maximum forage intake estimated of 893g/day occurred in CP level de 21.51%. The increased of crude protein level in supplements increased squarely the average daily gain, with a maximum of 104g/day, for the 23% crude protein in the supplement. Thus, the use of the multiple supplements supplied in 1% of body weight with CP levels ranged 21 a 23% is indicated for sheep grazing Aruana grass on dry season.

Quantitative anatomy and in situ ruminal degradation parameters of elephant grass under different defoliation frequencies

Universidade Federal do Maranhão, Centro de Ciências Agrárias e Animais, Departamento de Zootecnia, Chapadinha, Maranhão, Brasil. Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Zootecnia, Fortaleza, Ceará, Brasil. Universidade Federal da Paraíba, Centro de Ciências Agrárias, Departamento de Zootecnia, Areia, Paraíba, Brasil. Universidade Federal do Piauí, Centro de Ciências Agrárias, Departamento de Ciência Animal, Teresina, Piauí, Brasil. *Endereço para correspondência: ricardo_zoo@hotmail.com

Nutrient intake and economic analysis of young bulls reared in silvopastoral systems with babassu palm trees in the Pre-Amazon region

Universidade Federal do Ceara, Centro de ciências Agrárias, Departamento de Zootecnia, Fortaleza, Ceará, brasil. Universidade Federal do Maranhão, Centro de Ciências Agrárias e Animais, Departamento de Zootecnia, Chapadinha, Maranhão, Brasil. Universidade Federal da Paraíba, Centro de Ciências Agrárias, Departamento de Zootecnia, Areia, Paraíba, Brasil. Universidade Estadual do Piauí, Centro de Ciências Agrárias, Departamento de Agronomia, Parnaíba, Piauí, Brasil. Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, Piauí, Brasil. Instituto Federal de Educação, Ciência e Tecnologia do Maranhão, São Luís, Maranhão, Brasil. *Endereço para correspondência: ricardo_zoo@hotmail.com

Agronomic and nutritional characteristics of Massai grass subjected to deferred grazing and nitrogen fertilization

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.

Acúmulo de forragem e estrutura do dossel do capim-Xaraés submetido a intensidades de cortes

The aim of this work was to evaluate the forage accumulation and sward structure of Xaraes grass subjected to five residue heights (10; 20; 30; 40 and 50 cm) with cutting interval based on light interception (LI) by sward during the regrowth (95% of LI). The experiment was conducted in forage production sector of the Agrarian and Environmental Sciences Center of the Federal University of Maranhao, in Chapadinha, in the period from March to November of 2011. A completely randomized design with five repetitions was used. The rest period based on 95% LI strategy varied according to the residue heights and time of year. There was effect of cutting heights for the production of forage, the density of tillers, the number of living tillers, sward height and volumetric density of forage. Only the leaf/stem ratio and the rate of forage accumulation were not influenced by the factors studied, in the rainy season of 2011. In the dry season, the pastures of Xaraes grass were affected in a negative way for all features evaluated, regardless of heights of residue. In General, more drastic cuts intensities (10 cm) promote higher forage production, greater density of tillers, larger number of dead tillers and higher density, however, results in less number of cuts and greater interval between cuts. The reverse occurs with more lenient cuts intensities (40 and 50 cm).