Management Strategies to Increase Festulolium Productivity and Persistence

A biennial hybrid of Lolium multiflorum x Festuca pratensis (Festulolium INIA Merlin) was released by the National Institute of Agricultural Research of Uruguay (INIA) in 2008. INIA Merlin is a tetraploid cultivar with a long growing season, semi-prostrate habit and high herbage quality (García 2003). These characteristics make it potentially useful to include Festulolium in short and intensive pasture-crop rotation systems. Grazing management can be used to modify growth, sward structure and persistence, and is known to be critical during the second year of production for stability and sustainability of farming systems that include this type of species. The objective of this trial was to measure the effect of different grazing strategies on the productivity and persistence of this novel cultivar

\u3cem\u3eTrifolium vesiculosum\u3c/em\u3e: Exploring Its Potential in the Uruguay Lowlands Rice Region

Trifolium vesiculosum, commonly known as arrowleaf clover, is a winter-growing annual legume native to Europe (Duke, 1981), with high persistence and low risk of bloat. Several reports show a wide annual production range between 1.9 and 9.8 t DM/ha/year (Gomes and Reis 1999; Evans and Mills 2008). It shows a high nutritional value (Tekeli et al. 2005) that declines with increasing maturity. Grazing management should consider the need for seed production to ensure natural re-seeding in subsequent years. Recently, INIA Uruguay released the T. vesiculosum cultivar Sagit (Glencoe EC1), characterized by intermediate growth habit and flowering period. The objective of this paper is to report the adaptation and performance of cv. Sagit (Glencoe EC1) in the lowlands rice region of Uruguay, under different grazing intensities with weaned calves

Causas y consecuencias de la entrada de nitrógeno por fijación biológica en campo natural

Tribunal: Pino, Amabelia del; Nabinger, Carlos; Piñeiro, GervasioLos pastizales del “Río de la Plata” representan un extenso ecosistema en América del Sur, dominado por pastizales naturales. Su productividad primaria neta área (PPNA) está limitada principalmente por el clima y la fertilidad de suelos. Estos pastizales altamente biodiversos utilizados para la producción ganadera extensiva tienen consistentemente niveles de fósforo (P) en suelo y en planta bajos a muy bajos. Para aumentar su productividad se ha considerado, i) la fertilización con P (CNP), ii) la incorporación de leguminosas junto con la fertilización P, sin eliminar el tapiz natural (MECN). A pesar de existir numerosos trabajos sobre CNP en la región, no existe aún acuerdo de su impacto, ni de los mecanismos subyacentes. Aquí, presentamos un metaanálisis de 48 estudios sobre fertilización con P (428 comparaciones) realizados en Argentina, Brasil y Uruguay. La fertilización aumentó la concentración de P en la pastura más frecuentemente (54 vs 31% respuestas independientes) y, en mayor magnitud (55 vs 27% efecto medio relativo), que la PPNA. La proporción N:P del forraje se redujo en 61% de los casos y con un efecto promedio relativo 32%. Otras limitantes, particularmente el nitrógeno (N) parecen ser más importantes en función de los niveles de N:P en la pastura. Los MECN han sido una tecnología efectiva para incrementar la productividad de estos sistemas a través de la fijación biológica de nitrógeno (FBN). Sin embargo, no existen estimaciones de FBN en MECN ni se han estudiado los factores que la condicionan ni tampoco el efecto de la FBN en el resto de la comunidad. En 69 sitios en Uruguay se estimó la FBN y las principales variables de suelo y planta. En promedio 67 ±26% del N proviene de FBN, con una eficiencia de 19,4 ±8,2 (kg N fijado Mg MS⁻¹), ambas con gran variabilidad. Las características de suelo explican muy poco los niveles de FBN, desatacando la fertilización acumulada de P. La relación N:P para gramíneas-C₄ y graminoides- C₃ muestra una deficiencia relativa de N o exceso de P a pesar del N incorporado por FBN

Legume Overseeding along with P Fertilization Increase Forage Production of Temperate Natural Grasslands

Legume overseeding along with P fertilization is a common practice used in natural temperate and subtropical grasslands to increase forage production. This practice has been evaluated at experimental plots but not at the paddocks level of commercial farms. The latter are realistic evaluation units to generate knowledge for livestock management. In this study, the enhanced vegetation index (EVI), a proxy of forage production, was used to evaluate the effect of this practice on grazed paddocks in Uruguay. Twenty paired paddocks under similar grazing conditions were selected with natural grassland (NG) and natural grassland with legume overseeding and P fertilization (NG-LP). Paired paddocks were compared in terms of EVI mean and its temporal variability. After nine years of the intensification practice, mean annual EVI of NG-LP was 4% higher than that of NG, while the mean winter–spring EVI of NG-LP was 7.5% higher. EVI intra- and inter-annual variability of NG-LP was 8–11% higher than that of NG. Additionally, forage production was estimated using a radiative transfer model. Differences between NG-LP and NG were amplified six to seven times. Legume overseeding along with P fertilization increased forage production in pastoral livestock paddocks, particularly in the period of forage deficit, while it also increased intra and inter-annual variability of forage production.Fil: Rama, Gonzalo. Universidad de la República; UruguayFil: Oyarzabal, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Cardozo, Gerónimo. Universidad de la República; UruguayFil: Lezama, Felipe. Universidad de la República; UruguayFil: Baeza, Santiago. Universidad de la República; Urugua

Improving Livestock Production Assuring Natural Grassland Ecosystem Conservation: Three Key Management Practices at Farm Level

Ecosystem changes by human activities are a central topic in environmental discussions and temperate grasslands are among the most altered ecosystems on the planet (Millenium Ecosystem Assessment, 2005). The Rio de la Plata grasslands are among of the most extended temperate grasslands in the world, along with the prairie system of North America, the grasslands in east Europe and Mongolia, the grassvelds in South Africa and the New Zealand plains. They cover the central-eastern part of Argentina, Uruguay and south of Brazil. Natural grasslands are very rich in terms of number of species, reaching up to more than 3,000 vascular plants (Bilenca and Miñarro., 2004; Miñarro et al., 2008). Almost all Uruguayan lands are private property and most of them have some agriculture use. In this context, any conservation strategy must take into consideration production systems, including not only natural resources that are strongly related to production as soil and water, but also other ecosystem services, including biodiversity. On the other hand, natural grasslands have a high potential for meat production being of great economic importance for the country, and increasing the production efficiency is a main topic. Extensive livestock production seems to be compromise solution between conservation and production, but the main challenge is to maintain ecosystems functionality improving productive results. Considering all this, a re-designing production system strategy was developed with farmers in two different regions of the country. This work involved a co-innovation approach, which objective was to increase income and farmer´s family life quality involving management practices changes with none or minimum investment and ensuring environmental protection. In this article, in order to show the multi-dimensional approach for environmental information, we analyze a case study

Pyrethroid-Resistant and Susceptible Triatoma infestans (Klug, 1834) (Hemiptera, Triatominae): Analysis of Their Vectorial Characteristics by Metacyclogenesis, Feeding/Defecation Patterns, and Parasite Load

Populations of Triatomas infestans with different susceptibility to pyrethroid insecticides were reported to have distinct evolutionary and epidemiological characteristics. We aimed at evaluating metacyclogenesis and parasite load as measures of vector competence and feeding/defecation patterns as vectorial capacity estimates of a group of resistant (“R”) and susceptible (“S”) T. infestans. Third instar nymphs of each group were fed on mice infected with Trypanosoma cruzi (Tulahuén strain, DTU VI). Parasite concentration in blood was quantified by real-time PCR (qPCR) for each mouse. The time at which feeding started, the span of feeding, the volume of blood consumed, and the time taken to defecate were measured. At 30 days post-feeding, feces were analyzed in parallel by optical microscopy (percentage of metacyclic trypomastigotes, % MT), and qPCR (total T. cruzi DNA). The ratio of parasites consumed/defecated by nymphs of each group was used to estimate the parasites’ survival and multiplication inside the triatomines’ gut. It was estimated that for each blood trypomastigote consumed, 6.6 parasites were obtained in the feces of “R” nymphs, and 7.9 in “S”. “R” nymphs consumed a higher volume of blood, had lower % MT in their feces (lower vectorial competence), and took longer to defecate (lower vectorial capacity) than “S”.Fil: Guanuco, Andrea Paola. Provincia de Salta. Ministerio de Salud Pública; ArgentinaFil: Davies, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; ArgentinaFil: Poma, Hugo Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Gentile, Alberto Gerónimo. Provincia de Salta. Ministerio de Salud Pública; ArgentinaFil: Cardozo, Rubén Marino. Provincia de Salta. Ministerio de Salud Pública; Argentin

Demonstrating control of forage allowance for beef cattle grazing Campos grassland in Uruguay to improve system productivity

While low-cost technology can be applied within beef cattle systems to improve economic output and decrease economic risk, methodologies to increase adoption by farmers deserve attention. Here we report 4 case studies where low-cost, high-impact technology was applied on commercial farms in an endeavor to demonstrate increased physical output in what we describe as 'Producer Demonstration Sites'. Forage allowance (FA) affects forage growth, forage intake by animals and energy partitioning to maintenance or production. We decided to demonstrate the benefits to production from controlling forage allowance at specific recommended levels. While we focused on FA, other management tools, e.g. suckling restriction and energy supplementation of cows prior to breeding, were tested in different contexts and time periods to improve the critical responses mentioned. While increases in production from 3 of the farms were demonstrated, only 2 of the farmers showed interest in implementing the strategies on their farms subsequently. We conclude that control of forage allowance improved energy intake. For this approach to be successful and increase adoption, it is important to involve the farmers in discussions regarding the proposed changes from the outset as well as the monitoring of progress during the demonstration

Isolation of Beauveria Bassiana from the Chagas disease vector Triatoma Infestans in the gran Chaco region of Argentina: Assessment of gene expression during host-pathogen interaction

A native strain of the entomopathogenic fungus Beauveria bassiana (Bb-C001) was isolated from a naturally infected Triatoma infestans, Klug (Hemiptera: Reduviidae) adult cadaver in the Gran Chaco region, Salta province, Argentina. The isolate was both phenotypic and molecularly characterized in a context of fungus-insect interaction, by measuring the expression pattern of toxin genes during infection and immune response of T. infestans. The commercial strain GHA of B. bassiana, which was previously used in field interventions to control these vectors, was used as reference in this study. The phylogenetic trees based on both ribosomal internal transcribed spacer (ITS) and elongation factor 1-alpha (EF1-α) indicated that Bb-C001 fits into a B. bassiana cluster, and the sequence-characterized amplified regions (SCAR) showed that Bb-C001 is different from the GHA strain. There were no differences between both strains regarding viability, radial growth, and conidia production, either in the median survival time or insect mortality. However, Bb-C001 showed a higher expression than GHA of the bassianolide synthetase gene (BbbslS) during infection, and similar levels of the beauvericin synthetase gene (BbbeaS). Immune-related genes of T. infestans nymphs (limpet-2 and defensin-1, -2, and -6) were later expressed and thus insects failed to stop the infection process. These results showed that B. bassiana Bb-C001 is a promised fungal strain to be incorporated in the current biological control programs of T. infestans in Salta province, Argentina.Fil: Baldiviezo, Linda Vanesa. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; Argentina. Provincia de Salta. Ministerio de Salud Pública; ArgentinaFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Santana, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Mannino, Maria Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Nieva, Lucia Beatriz del Carmen. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Gentile, Alberto Gerónimo. Provincia de Salta. Ministerio de Salud Pública; ArgentinaFil: Cardozo, Rubén Marino. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Provincia de Salta. Ministerio de Salud Pública; Argentin

Inheritance of resistance to pyrethroids in Triatoma infestans, the main Chagas disease vector in South America

An outbreak of pyrethroid resistance was recently detected in Triatoma infestans from northern Argentina. To analyze the inheritance of the resistant phenotype, we carried out experimental crosses between resistant (R) and susceptible (S) strains captured in Argentina during 2005. The R strain was collected from sprayed houses in the north of the province of Salta while the S strain was collected in the province of Chaco. Both strains were bred in the laboratory for reciprocal crosses (F1), intercrosses (F2) and backcrosses (BC). The descendents were tested by a standard insecticide resistance bioassay. Resistance ratios were 1 for S strain, 103.36 for R strain and 18.34 for F1. The regression lines of F1 generations (R. × S and S. × R) showed no significant differences and were closer to that of the R parents, indicating that inheritance of deltamethrin resistance in T. infestans is autosomal and incompletely dominant (D=0.20). Chi-square analysis from responses of intercross and backcross progenies rejected the hypothesis of a single gene being responsible for resistance. The minimum number of independent segregation genes was three, as calculated with Lande's method. The genetic basis here described for the resistant phenotype indicate that, under pyrethroid selective pressure, the resistant genotypes could be easily spread to susceptible insects from resistant individuals, posing a major threat to vectorial control of Chagas disease.Fil: Cardozo, Rubén Marino. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Laboratorio de Patología Experimental; ArgentinaFil: Panzera, Francisco. Universidad de la República. Facultad de Ciencias; UruguayFil: Gentile, Alberto Gerónimo. Provincia de Salta. Ministerio de Salud Pública; ArgentinaFil: Segura, Maria Asuncion. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; ArgentinaFil: Pérez, Ruben. Universidad de la República. Facultad de Ciencias; UruguayFil: Diaz, Renee Analia. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Laboratorio de Patología Experimental; ArgentinaFil: Basombrío, Miguel Ángel Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; Argentin

Apreciaciones sobre la Muerte en Estudiantes del Último Año de Medicina.

Objective: To characterized attitudes of last year students of medicine in Universidad de Carabobo, Venezuela, towards death and the process of dying and how they rate their their university training in these subjects. Methodology: Observational study of 61 voluntaries who responded a survey. Results: The majority of respondents (82.7%) think that they will deal with death as part of their professional duties. 78.7% define death as a natural event, but 57,9% feel that they are not prepared to deal properly with it and think necessary to have undergraduate training in this subject. 62,2% support the practice of euthanasia.El estudio de la muerte es un área compleja por sus múltiples dimensiones, significados e impactos que produce. Objetivo: caracterizar como asumen los estudiantes de medicina del último año de la carrera en la Universidad de Carabobo-Valencia. Venezuela, la situación del morir y la muerte y su preparación universitaria al respecto, Metodología: Estudio observacional, en 61 estudiantes voluntarios, mediante aplicación de encuesta. Resultados: 82,7% de los encuestados piensan con frecuencia que enfrentarán la muerte en su profesión. Aunque 78,7% define la muerte como algo natural, 40.4% tiende a su negación, habiéndola vivenciado en algún familiar en 73,8%. Un 51,78% y 57,9%, manifiesta no estar preparado ante la muerte de un familiar o de un paciente, respectivamente; 90% creen necesario instruirles en pregrado, mientras que 67,2% apoya la práctica de la Eutanasia. Conclusiones: aunque hay una posición variable frente a la muerte, existe una tendencia en los estudiantes a pensar con frecuencia que la van a enfrentar en su ejercicio profesional, y reconocen que necesitan ser preparados en su formación universitaria para su manejo. Igualmente, siendo esta área de investigación compleja y multidimensional, requiere de la incorporación de equipos y proyectos de investigación multidisciplinaria que consideren nuevas metodologías para su abordaje