Silage quality of six sorghum cultivars for sheep.

The objective of this work was to evaluate the silage quality, fermentation profile, intake, and digestibility of six sorghum cultivars for sheep feeding. 'SF 15', 'IPA 2502', 'BRS 655', 'BR 601', 'BRS 506', and 'Sudão' were cultivated in randomized complete block designs with five replicates, harvested, and ensiled when plants reached the soft-dough grain stage. Silage quality was determined in laboratory silos. Intake and apparent digestibility were determined during 22 days, using 24 Santa Inês lambs (35.5±2.21 kg) randomly distributed in the treatments. Silage from 'IPA 2502' had the lowest contents of dry matter, neutral detergent fiber, and acid detergent fiber; the highest nonfibrous carbohydrate and total digestible nutrient contents; and the greatest dry matter degradability. Silages from 'BR 601' and 'BRS 506' showed the highest values of crude protein, whereas those of 'SF 15' and 'Sudão' had the highest levels of fibrous fractions. Lambs fed silage from 'IPA 2502' consumed more dry matter and nonfibrous carbohydrates, and their crude protein digestibility was also greater than that from the consumption of other cultivar silages. 'IPA 2502' stands out for its nutritional characteristics, which resulted in better animal performance.Título em português: Qualidade das silagens de seis cultivares de sorgo para ovinos

Estimating aboveground biomass in tropical forests: Field methods and error analysis for the calibration of remote sensing observations

Mapping and monitoring of forest carbon stocks across large areas in the tropics will necessarily rely on remote sensing approaches, which in turn depend on field estimates of biomass for calibration and validation purposes. Here, we used field plot data collected in a tropical moist forest in the central Amazon to gain a better understanding of the uncertainty associated with plot-level biomass estimates obtained specifically for the calibration of remote sensing measurements. In addition to accounting for sources of error that would be normally expected in conventional biomass estimates (e.g., measurement and allometric errors), we examined two sources of uncertainty that are specific to the calibration process and should be taken into account in most remote sensing studies: the error resulting from spatial disagreement between field and remote sensing measurements (i.e., co-location error), and the error introduced when accounting for temporal differences in data acquisition. We found that the overall uncertainty in the field biomass was typically 25% for both secondary and primary forests, but ranged from 16 to 53%. Co-location and temporal errors accounted for a large fraction of the total variance (<65%) and were identified as important targets for reducing uncertainty in studies relating tropical forest biomass to remotely sensed data. Although measurement and allometric errors were relatively unimportant when considered alone, combined they accounted for roughly 30% of the total variance on average and should not be ignored. Our results suggest that a thorough understanding of the sources of error associated with field-measured plot-level biomass estimates in tropical forests is critical to determine confidence in remote sensing estimates of carbon stocks and fluxes, and to develop strategies for reducing the overall uncertainty of remote sensing approaches. © 2017 by the authors; licensee MDPI, Basel, Switzerland

Assessment of Physical-Chemical Characteristics of Water and Sediments from a Brazilian Tropical Estuary: Status and Environmental Implications

The environmental quality of the Jacuípe River's estuary (very important in northeastern Brazil) was assessed during 2007 and 2008. In water, concentrations (mg L−1) of NO2− (<0.004 to 0.016), NO3− (0.01 to 0.33), soluble PO43− (<0.02 to 0.22), dissolved oxygen (3.9 to 9.6), total contents (mg L−1) of Cd (<0.001), Cu (<0.01), Pb (<0.01), and Zn (<0.1), pH (5.60 to 8.00), and electrical conductivity (0.12 to 48.60 mS cm−1) agreed with environmental standards. In sediments, clay and total organic matter (%, m/m) varied, respectively, from 8.8 to 12.0 and from 1.1 to 8.8, while infrared, thermogravimetric profile, electronic micrograph, as well as X-Ray analyses showed desirable adsorptive characteristics. However, maximum exchangeable levels (mg kg−1) of Cd (1.3), Cu (44.6), Pb (35.7), and Zn (43.7) and their respective maximum pseudototal concentrations (mg kg−1): 19.4, 95.1, 68.2, and 30.3 were below the recommended limits. In this sense, it was possible to demonstrate good environmental preservation even with the growing number of industries and touristic activities in the evaluated estuarine area