Dynamic of Native Pasture Influenced by Deferment of Grazing and Fertilization

Native pastures of southern Brazil cover 12 million ha and are the main forage feed resource for most domestic livestock. However, their heavy and continuous use has reduced standing biomass and the presence of good forage species, reducing animal performance and jeopardizing the ecosystem sustainability. An alternative for better use of these pastures and their preservation is grazing deferment that allow natural reseeding. The objective of this research was evaluate native pasture dynamic after six years of grazing deferments (GD) periods and soil fertilization effects by point-quadrat method every season. All pasture components were affected by GD, with prostrate grasses increasing their frequency (P \u3c 0.05) under continuous grazing while periods of rest encouraged erect plants. Fertilization improved pasture condition by reducing frequencies of no forage species, litter and bare soil, and increasing frequencies and dry matter contribution of good ones like native legumes, especially Desmodium incanum

Investigation on virucidal activity of chlorine dioxide. Experimental data on Feline calicivirus, HAV and Coxsackie B5

Introduction. The aim of this study was to evaluate the efficacy of ClO2 with regard to viruses which show a particular resistance to oxidizing agent such as HAV and Norwalk and Norwalk-like viruses, and which play an important role in the epidemiology of viral foodborne diseases. In the food industry, disinfection of processing systems and equipment is a very important instrument to prevent secondary contamination and to guarantee food safety. Among disinfectants, chlorine dioxide (ClO2) presents a good efficacy at wide range of pH values, its action is rapid and generates few reaction byproducts if compared to hypoclorite. Experimental studies have highlighted that ClO2 shows a good bactericidal activity and it is also active towards viruses. Furthermore, the low concentrations and low contact times required to obtain microbial load reduction are favourable elements for the application of this compound in the industrial sanitizing practices. Methods. As it is impossible to cultivate the Norwalk virus in vitro, we tested the resistance of Feline calicivirus (F9 strain) vs. ClO2, in comparison with HAV (strain HM-175) and CoxsackieB5. Chlorine dioxide was used at concentrations ranging from 0.2 to 0.8 mg/l in water solution, at pH 7 and at +20 °C. Viral suspensions were added to disinfecting solution and, at pre-set times, were sampled to undergo to titration after blocking the disinfectant action with thiosulphate 0.05 M. On the basis of the data obtained, for each virus and in relation to different concentrations, mean reduction times were calculated for 99%, 99.9% and 99.99% using the regression analysis model. Results. As regards Feline calicivirus, at a concentration of 0.8 mg/l of ClO2, we obtained the complete elimination of the viral titre in 2 min while 30 min were required at concentrations of 0.2 mg/l. Coxackie B5 showed a similar behaviour, being completely inactivated in 4 min with 0.4 mg/l of ClO2 and after 30 min at a concentration of 0.2 mg/l. Inactivation was quicker for HAV, which was eliminated after only 30 sec at a concentration of 0.8 mg/l and after 5 min at 0.4 mg/l. Conclusion. Our data show that for complete inactivation of HAV and Feline calicivirus, concentrations ? 0.6 mg/l are required. This observation is true for Coxsackie B5 too, but this virus has shown a good sensitivity at all concentration tested according to regression analysis results. For Feline calicivirus and HAV, at low concentrations of disinfectant, prolonged contact times were needed to obtain a 99.99% reduction of viral titres (about 16 and 20 minutes respectively)

Herbage Allowance and Nitrogen Fertilization Effects on Morphological Characteristics of \u3ci\u3ePaspalum notatum\u3c/i\u3e Flügge

The grazing study was conducted at the Estação Experimental Agronomica – UFRGS, 30o S, on a native pasture, to evaluate the leaf area index and structural morphological traits of bahiagrass (Paspalum notatum Fl.), within the requirements of a Central Composite Rotatable experimental design, providing for equal precision, with two blocks, encompassing two factors at five levels each, namely: Herbage Allowance (HA) = 4.0; 5.5; 9.0; 12.5 and 14.0 kg green dry matter per 100 kg liveweight per day (% LW), in association with Nitrogen (N) fertilization levels of 0; 30; 100; 170 and 200 kg ha-1 as urea, The leaf length and leaf area index (LAI) were increased as HA and N levels increased. The tiller density was increased at higher HA where the N contribution showed to be more effective. More lenient grazing also increased leaf life span and leaf lamina length, while N promoted canopy density and reduced leaf life span and number of leaves per tiller. The higher LAI values developed were accomplished by reduced tiller densities that supported small number of leaves per tiller, with increased leaf sizes

Overexpression, purification and crystallization of a choline-binding protein CbpI from Streptococcus pneumoniae

The choline-binding protein CbpI from S. pneumoniae has been purified and crystallized and diffraction data have been collected to 3.5 Å resolution