The aim of this study was to evaluate the forage yield during the growing season of 2003/2004 as well as the ruminal dry matter degradability, neutral detergent fiber and acid detergent fiber concentration in the forage of five Panicum grasses (Mombaça, Tanzânia, Massai, Tobiatã and Atlas) in Piracicaba, SP. Rest period was fixed on 28 days for Atlas, Massai and Mombaça and 35 days for Tanzânia and Tobiatã, according to their morphologic and structural characteristics. The samples were incubated for 96; 48; 24; 12; 6; 3 and 0 hours. Mombaça (15500 kg DM ha-1) and Massai (20400 kg DM ha-1) were the highest yielding genotypes. Ruminal degradability showed that, although chemical composition is similar across genotypes, some parameters such as potential degradability, lag time and effective degradability are variable, suggesting contrasts in animal production potential.

Os citros encontram-se entre as espécies mais estudadas no mundo. Há
várias décadas, são conduzidos programas de melhoramento genético de cultivares
porta-enxerto e copa, principalmente na África do Sul, Austrália, Brasil, China, Espanha,
Estados Unidos, França, Israel, Itália e Japão. Das estratégias clássicas, e mais
recentemente as ferramentas da biotecnologia utilizadas no melhoramento genético
de citros, destacam-se a hibridação sexual controlada, a seleção de mutantes espontâneos
ou induzidos e de híbridos naturais, a hibridação somática via fusão de protoplastos,
o mapeamento genético, o sequenciamento de genoma e a transformação
de plantas que têm sido usados na obtenção de novas cultivares cítricas. Ressalta-se
a importância de aspectos relacionados a diversidade genética, taxonomia e biologia
reprodutiva de Citrus (L.) e gêneros afins, tais como a heterozigosidade, apomixia,
poliembrionia, ploidia, juvenilidade, partenocarpia, autoincompatibilidade, esterilidade
gamética e zigótica. Estes são apontados para as perspectivas futuras na área de
melhoramento genético de plantas cítricas.

The effects of land-use change (LUC) on soil carbon (C) balance has to be taken into account in calculating the CO2 savings attributed to bioenergy crops1, 2, 3. There have been few direct field measurements that quantify the effects of LUC on soil C for the most common land-use transitions into sugar cane in Brazil, the world’s largest producer 1, 2, 3. We quantified the C balance for LUC as a net loss (carbon debt) or net gain (carbon credit) in soil C for sugar-cane expansion in Brazil. We sampled 135 field sites to 1 m depth, representing three major LUC scenarios. Our results demonstrate that soil C stocks decrease following LUC from native vegetation and pastures, and increase where cropland is converted to sugar cane. The payback time for the soil C debt was eight years for native vegetation and two to three years for pastures. With an increasing need for biofuels and the potential for Brazil to help meet global demand4, our results will be invaluable for guiding expansion policies of sugar-cane production towards greater sustainability.

Phosphorus (P) and zinc (Zn) are important determinants of plant productivity, particularly in the tropical grasslands of Brazil. Nutrient deficiency is one of the most important factors limiting plant productivity, decreasing photosynthesis efficiency and plant development. The present study investigates in Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. ‘Marandu’: 1) the gas exchange measurements; 2) the total leaf area development; and 3) the dry matter production due to P and Zn nutrition. Plants of B. brizantha cv. ‘Marandu’ were grown in nutrient solution under five rates of P (0.1, 0.6, 1.1, 1.6, and 2.1 mmol L⁻¹) and five rates of Zn (0.00, 0.75, 1.5, 2.25, and 3.00 μmol L⁻¹), in a fractioned factorial. Plants were harvested two times. Phosphorus supply increased carbon dioxide (CO₂) assimilation and stomatal conductance, and decreased intercellular CO₂. The interaction P rates x Zn rates were significant for the total leaf area variables and shoot dry matter in the second growth period. The nutrition of P and Zn interfered in the B. brizantha productivity by changing the grass photosynthesis and leaf area.

Phosphorus (P) and zinc (Zn) availabilities are important to the nutrition of tropical forage grasses. In this manner, this study aimed to identify and quantify changes in metabolism, tillering, and root system of Brachiaria brizantha cv. ‘Marandu’ related to P and Zn availabilities. Plants of B. brizantha cv. ‘Marandu’ were grown in nutrient solution under five rates of P (0.1, 0.6, 1.1, 1.6, and 2.1 mmol L−1) and five rates of Zn (0.00, 0.75, 1.5, 2.25, and 3.00 μmol L−1), in a fractionated factorial. The interaction P x Zn rates and the Zn supply were not significant for the activity of acid phosphatase enzyme, P-use index, number of tillers, and root parameters. P-use index and enzyme activity decreased as P availability increased. The high efficiency in P use was a result of high acid phosphatase activity and P supply was essential to the development of ‘Marandu’ palisadegrass root system.

Cattle ranching is one of the most important agricultural activities in Brazil. The impact of livestock on soil N2O emissions in Brazil has only been assessed using a Tier 1 approach of the IPCC guidelines, as there are no data available from field studies. Apart from the need for accumulating data for the development of proper direct N2O emission factors, we tested for possible differences between urine and dung as N2O sources and the difference in emissions between the dry and wet season. An area of Brachiaria brizantha at the Embrapa Rice and Bean Centre in the Cerrado (central savannah) region (Goiás state) was subdivided into plots where fresh cattle urine and dung were monitored for three consecutive periods (two in the rainy and one in the dry season) for N losses, principally N2O emissions and NH3 volatilization. 15N-labelled urine N was used in the first monitoring period for an N balance study which indicated that denitrification and NH3 volatilization were the most important processes for N loss. Percentages of N lost as N2O and as volatilized NH3 were greater for urine than for dung. In addition, N losses as N2O in the rainy season were much greater than during the dry season. Representing the Cerrado region and the extensive pasture systems common in this region, direct emission 0.007 g N2O–N g−1 (0.7%) excreta N, well below the EF3PRP of 0.020 g N g−1 (2%) used by IPCC for cattle N in excreta. The fraction of excreta N lost as NH3 of ∼15% was in line with the IPCC guidelines. Disaggregation of emission factors for excreta type is recommended.

The presence of some inorganic elements in biodiesel can compromise the fuel quality and
enhance the emission of pollutants. In this context, a new procedure for biodiesel sample preparation
using a high pressure asher (HPA) is presented, aiming the determination of Al, Ca, Cu, Fe, K, Mg,
Mn, Na, Ni, P, Sr, and Zn, in soybean, sunflower, animal fat, cotton and castor oil, by inductively
coupled plasma optical emission spectrometry (ICP OES). The digestion conditions of the HPA
were optimize to digest 1.5 g of biodiesel, with HNO3 and H2O2, at a temperature of 300 °C and
pressure of 435 psi, which considered the sample dilution factor, the total solids in solution and the
acidity for ICP OES determinations. Analytes concentrations in these biodiesels were calculated
using standard addition method. Detection limits from 0.05 to 0.7 mg kg–1 were suitable to attend
biodiesel quality parameters, government policy and legislations worldwide. Therefore, the
proposed procedure proved to be efficient to eliminate the major organic interferences typically
present in oil based samples allowing a fast, precise, interference-free and robust analytical
condition for biodiesel characterization.

Poor-quality roughages are widely used as fiber sources in concentrate-based diets for ruminants. Because roughage quality is associated with the efficiency of energy use in forage-based diets, the objective of this study was to determine whether differing the roughage source in concentrate-based diets could change the energy requirements of growing lambs. Eighty-four 1/2 Dorper × 1/2 Santa Inês ram lambs (18.0 ± 3.3 kg BW) were individually penned and divided into 2 groups according to primary source of dietary roughage: low-quality roughage (LQR; sugarcane bagasse) or medium-quality roughage (MQR; coastcross hay). Diets were formulated to be isonitrogenous (2.6% N) and to meet 20% of physically effective NDF. After a 10-d ad libitum adaptation period, 7 lambs from each group were randomly selected and slaughtered (baseline). Twenty-one lambs in each diet group were fed ad libitum and slaughtered at 25, 35, or 45 kg BW. The remaining 28 lambs (14 from each diet group) were submitted to 1 of 2 levels of feed restriction: 70% or 50% of the ad libitum intake. Retentions of body fat, N, and energy were determined. Additionally, 6 ram lambs (44.3 ± 5.6 kg BW) were kept in metabolic cages and used in a 6 × 6 Latin square experiment designed to establish the ME content of the 2 diets at the 3 levels of DM intake. There was no effect of intake level on diet ME content, but it was greater in the diet with LQR than in the diet with MQR (3.18 vs. 2.94 Mcal/kg, respectively; P < 0.01). Lambs fed the diet with LQR had greater body fat (g/kg of empty BW) and energy concentrations (kcal/kg of empty BW) because of a larger visceral fat deposition (P < 0.05). Using a low-quality roughage as a primary source of forage in a concentrate-based diet for growing lambs did not change NEm and the efficiency of ME use for maintenance, which averaged 71.6 kcal/kg0.75 of shrunk BW and 0.63, respectively. On the other hand, the greater nonfibrous carbohydrate content of the diet with LQR resulted in a 17% better efficiency of ME use for gain (P < 0.01), which was associated with a greater partial efficiency of energy retention as fat (P < 0.01). This increased nutritional efficiency, however, should be viewed with caution because it is related to visceral fat deposition, a nonedible tissue.

Abstract
The present study was conducted to evaluate the effect of lipids with different fatty acid profiles on the intake, performance, and enteric CH4 emission of Nellore steers. A total of 45 Nellore animals with an average initial BW of 419 ± 11 kg (at 15 ± 2 mo) were distributed in a completely randomized design consisting of 5 treatments and 9 replicates. The roughage feed was maize silage (600 g/kg on a DM basis) plus concentrate (400 g/kg on a DM basis). The dietary treatments were as follows: without additional fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The lipid source significantly affected (P < 0.05) nutrient intake. The greatest intakes of DM, OM, and CP were observed in the animals that were fed the WF or PF diets, and the lowest intakes were observed in the animals that were fed the PO diet. Intake of NDF decreased (P < 0.05) with the addition of PO. Enteric methane emission (g/kg DMI) was reduced by an average of 30% when the animals were fed diets containing WS, LO, and PO (P < 0.05), and these diets caused a larger reduction in the energy loss in the form of methane compared to those without added fat and with added PF (3.3 vs. 4.7%). The different fatty acid profiles did not affect the backfat thickness or the loin eye area of the animals (P > 0.05). However, animals fed PO displayed lower daily weight gain (0.36 kg/d), feed efficiency (0.08 kg ADG/kg DM), HCW (245 kg), and hot yield percentage (52.6%) compared to animals that were fed the other diets. Therefore, PO compared to the other lipid sources used in this study reduces intake, performance, feed efficiency, and carcass yield. Therefore, PO is not suggested for feedlot-finished animals.

The use of swine manure (SM) as a nutrient source for pastures is increasingly common in Brazil, due to its low cost. However, this practice can cause N losses in agricultural soil, where ammonia (NH3) volatilization may be the main drawback, generating undesirable economic and environmental consequences. The objective of this study was to evaluate SM application methods that retain N within the system and determine how these methods affect forage yield and quality. The study was conducted in the municipality of Chapadinha, Maranhão, Brazil, and the following SM application methods were evaluated: (1) surface application, (2) incorporation at 5-cm soil depth, (3) incorporation at 10-cm soil depth, and (4) control when SM was not applied. Lower N losses due to NH3 volatilization and higher pasture yield and quality were found when SM was incorporated at 10-cm soil depth (83 kg N-NH3 ha-1 and 6.3 Mg DM ha-1, respectively, compared to 86 kg N-NH3 ha-1 and 1.5 Mg DM ha-1 for the control), whereas higher N-NH3 losses and lower pasture yield were observed when SM was applied to the soil surface (143 kg N-NH3 ha-1 and 2.6 Mg ha-1, respectively). Higher quality forage in terms of chemical composition was also observed when SM was incorporated at greater soil depth. Incorporating SM at 10-cm depth represents an efficient management to mitigate N-NH3 volatilization, and this application method is associated with significantly increased in DM yield and improved chemical composition.

Interpreting the geological record of Amazon biomass combustion requires comparing charcoal accumulation rates in various biomes at different time scales. Charcoal accumulation rates, a proxy for palaeofire records, were obtained in sediment cores from Amazon lakes surrounded by several vegetation types and from a reservoirs in an intense land use change region. The records presented in this study were obtained in the following areas i) a reservoirs in Alta Floresta region (northern Mato Grosso State); ii) Lago do Saci (southern Pará State), a lake close to Alta Floresta and located at the southern border of Pará State; iii) a bog in an ecotone area in the Humaitá region (southern Amazonas State); iv) lakes in lateritic iron crust of the Carajás Hills (southeastern Pará State); v) Lago Comprido, a floodplain lake close to the Amazon River and surrounded by tropical rain forest (Monte Alegre, Pará State; vi) Lagoa da Pata in the Morro dos Seis Lagos alkaline complex (São Gabriel da Cachoeira, Amazonas State) and vii) Lago Caracaranã, a secluded lake in the northern Amazon cerrado (Roraima State). The highest charcoal accumulation rates were observed for modern records related to an intense change in land use at Alta Floresta, which had no precedent during the Holocene history of the Amazon. High charcoal accumulation rates that were observed in the Carajás region during low lake level phases in the Amazon in the mid-Holocene were comparable to those at the onset of the human settlement in Alta Floresta region. An increase in charcoal accumulation rate was observed in the late Holocene when the lake level was high, suggesting an interaction between climates and human presence. Low charcoal accumulation rates are typical of modern high rainfall environments, as observed in Lagoa da Pata where the environment is not susceptible to occurrences of wildfires even during relatively drier climatic phases. Low charcoal accumulation rates also exist in the relatively dry cerrado (savanna type) biome even during relatively dry phases in the Caracaranã region where the savanna-type vegetation biomass is lower and thus generates less charcoal particles than forest ecosystems.

Genetically-modified soybean [Glycine max (L.) Merr.] resistant to glyphosate (N-phosphono-methyl-glycine) herbicide (GR) has turned out to be one of the most highly-used products of plant engineering. The impacts of the soybean, genetically transformed for glyphosate resistance, on the environment under Brazilian soil and climatic conditions are still unknown. For this purpose, two soybean genotypes, one genetically modified (GR BRS 244 RR) and a conventional isogenic genotype were grown under different weed-control methods: hand weeding and glyphosate or imazethapyr herbicide application. The study was performed in Rio Grande do Sul State with evaluations of soil microbial biomass and respiration, biological nitrogen fixation, isoflavone content in seed and glyphosate, and aminomethylphosphonic acid (AMPA) residues in seeds and soil. The use of GR did not affect soil microbial population, biological nitrogen fixation, or plant yield or isoflavone contents in seed. However, even though we used the recommended application doses, the glyphosate residues in the seeds were above levels permitted by Brazilian law. Also, AMPA residues were detected in the soil and the seeds.