Efecto de la carga de ovinos en la estructura y funcionamiento de praderas naturales de basalto en Uruguay

Programa de Posgrad

Efecto de la densidad de siembra en la productividad de un campo natural restaurado con Bromus auleticus

Título alternativo : Efeito da densidade de semeadura na productividade de um campo nativo restaurado com Bromus auleticusHigh stocking rate livestock management has determined the decline of native species of high forage value as Bromus auleticus Trin ex Nees in the Campos region of the Rio de la Plata grasslands. The species has some agronomic and ecological characteristics that define it as of high potential to be reintroduced in degraded natural grasslands. However, Bromus auleticus has not been sufficiently described, since commercial seeds and information regarding the establishment phase are scarce. Two field experiments were carried out in 2013 and 2014, reintroducing Bromus auleticus into native grasslands in the Basaltic region, aiming to evaluate the impact of sowing density in the forage productivity and their seasonal distribution. The treatments consisted of different sowing densities: 20, 40, 60 and 80 kg ha⁻¹ and one control treatment. Considering the management and the evaluated period (4 years for experiments 2013, and 3 years for experiments 2014), different sowing densities did not modify the forage production in any of the plantings for the evaluated period and compared to the control. However, the use of sowing densities of 40 kg ha⁻¹ or higher allowed modifying the seasonal distribution of forage production with a better contribution in autumn-winter, and more stable production throughout the year.El manejo ganadero con altas cargas ha determinado la disminución de especies nativas de alto valor forrajero como el Bromus auleticus Trin. ex-Nees en la región Campos de los pastizales del Río de la Plata. La especie posee características agronómicas y ecológicas que la definen como de alto potencial para ser reintroducida en campos naturales degradados. Sin embargo, no ha sido lo suficientemente difundida por la falta de semilla comercial e información sobre la etapa de instalación. Se realizaron dos experimentos de campo en 2013 y 2014, a partir de la reintroducción de Bromus auleticus en cobertura sobre campo natural en la región de Basalto, con el objetivo de evaluar el efecto de la densidad de siembra en la producción de forraje y la distribución estacional. Los tratamientos consistieron en diferentes densidades de siembra: 20, 40, 60 y 80 kg ha⁻¹ y un tratamiento testigo. Tomando en cuenta el manejo realizado y el período evaluado (4 años para el experimento 2013, y 3 años para el experimento 2014), la utilización de diferentes densidades de siembra no modificó la productividad total en ninguna de las siembras para el período evaluado y respecto al testigo. Sin embargo, la utilización de densidades de siembra iguales o superiores a 40 kg ha⁻¹ modificó la distribución estacional de la producción de forraje hacia un mayor aporte en el período otoño-invernal y una producción más equilibrada durante el año.O manejo da pecuária com altas cargas de animais tem determinado a diminuição de espécies nativas de alto valor forrageiro, como Bromus auleticus Trin. ex Nees na região do Bioma Campos. A espécie possui características agronômicas e ecológicas que a definem como tendo alto potencial para ser reintroduzida em campos naturais degradados. No entanto, não foi suficientemente estudado devido à falta de sementes comerciais e informações sobre a fase de instalação. Dois experimentos de campo foram realizados em 2013 e em 2014 a partir da reintrodução de Bromus auleticus em cobertura em campo natural na região do Basalto, com o objetivo de avaliar o efeito da densidade de semeadura na produção de forragem e sua distribuição sazonal. Os tratamentos consistiram em diferentes densidades de semeadura: 20, 40, 60 e 80 kg ha⁻¹ e um tratamento testemunha sem plantio. Considerando o manejo realizado e o período avaliado (4 anos para o experimento de 2013 e 3 anos para o experimento de 2014), o uso de diferentes densidades de semeadura não alterou a produtividade total de forragem em nenhum dos experimentos para o período avaliado e com relação ao controle. Porém, a utilização de densidades de semeadura iguais ou superiores a 40 kg ha⁻¹ permitiu modificar a distribuição sazonal da produção forrageira com maior contribuição no período outono-inverno e produção mais equilibrada ao longo do ano

What Factors Control the Crude Protein Content Variation of a Basaltic “Campos” Native Grassland of South America?

Native grasslands are the main source of food for livestock in the Campos region of South America. These forage resources are heterogeneous in species composition, grazing management, and soil fertility within a context of variable climate, all of which are factors that affect forage crude protein content over time and space. Despite the importance of protein in livestock nutrition, there is a gap in the knowledge of how fertilisation, sward height, and soil water availability influence the crude protein content of these grasslands. We used data from a long-term fertilisation experiment to construct a structural model aiming to identify the main factors influencing forage crude protein content of a basaltic native grassland in northern Uruguay. The structural model revealed that both fertilisation and the increase in soil water availability (through the improvement of the nitrogen content of green leaves) are the main pathways by which forage crude protein content increases. This new approach (which identifies and quantifies the main factors that drive forage crude protein content of native grasslands) could be used to support prediction models for forage protein content in order to improve grazing livestock nutrition of Campos native grasslands.EEA Concepción del UruguayFil: Núñez, Laura. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; UruguayFil: Hirigoyen, Andrés. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Forestal; UruguayFil: Durante, Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; ArgentinaFil: Durante, Martin. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; UruguayFil: Arroyo, José María. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA La Estanzuela. Programa Pasturas y Forrajes; UruguayFil: Cazzuli, Fiorella. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; UruguayFil: Bremm, Carolina. Universidade Federal de Rio Grande do Sul.Faculdade de Agronomia. Departamento de Plantas Forrageiras e Agrometeorologia. Programa de Pós-Graduação em Zootecnia; BrasilFil: Jaurena, Martín. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; Urugua

Building the GLENCOE Platform -Grasslands LENding eConomic and ecOsystems sErvices

To feed the rising population whilst also preserving ecosystem functions, creative solutions are needed for the ecological intensification of natural grassland-based livestock systems. In Uruguay, natural grasslands are the main nutritional resource for livestock production. In these ecosystems, cattle and sheep graze together all the year round, and grasslands are frequently heavily grazed. Considerable research has been generated concerning grassland management, but there is still no knowledge about the impact of decision rules that supports management actions on long-term ecosystem functioning, at the system level. To meet this deficit, a participatory working group of farmers, researchers, and consultants have developed the GLENCOE platform. This platform is a large-scale facility, supported by INIA-Uruguay, designed to answer the following question: How to intensify the grazing management to improve the sustainability of livestock systems based on natural grasslands? To build the platform three steps were followed: (I) definition of the research problem using a problem tree analysis; (ii) conceptualization of the platform and the design of the grazing systems to be evaluated; and, (iii) spatial allocation of the grazing systems according to the variability of soil, slopes, and seasonal dynamic of vegetation indexes. These criteria were considered across farmlets that were equivalent in the initial stage, allowing causal inferences for the systems trajectories on productive and environmental traits. The platform is composed of three independent farmlets of 50 ha each, where multiparous Hereford cows and Merinos wethers co-graze under three grazing management systems. Each farmlet is managed according to different spatio-temporal decisions of the specific management of vegetation communities, grazing methods, and the stockpile of forage that is allowed by the number of the existing paddocks. Farmlet-1; comprises less decisions (2 paddocks), Farmlet-2; intermediate (8 paddocks), and Farmlet-3; high level of decisions (32 paddocks). This innovative platform will be used as a participatory and interdisciplinary space for research and co-learning of management on processes that can only be observed in long-term evaluations, and at farmlet scale. We expect that this new approach will contribute to the developement and implemention of sustainable grazing management systems in Uruguay

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

Registro Español de Trasplante Cardiaco. XXXI Informe Oficial de la Asociación de Insuficiencia Cardiaca de la Sociedad Española de Cardiología

Introducción y objetivos Se presentan las características clínicas y los resultados de los trasplantes cardiacos realizados en España con la actualización correspondiente a 2019. Métodos Se describen las características clínicas y los resultados de los trasplantes cardiacos realizados en 2019, así como las tendencias de estos en el periodo 2010-2018. Resultados En 2019 se realizaron 300 trasplantes (8.794 desde 1984; 2.745 entre 2010 y 2019). Respecto a años previos, los cambios más llamativos son el descenso hasta el 38% de los trasplantes realizados en código urgente, y la consolidación en el cambio de asistencia circulatoria pretrasplante, con la práctica desaparición del balón de contrapulsación (0, 7%), la estabilización del uso del oxigenador extracorpóreo de membrana (9, 6%) y el aumento de los dispositivos de asistencia ventricular (29%). La supervivencia en el trienio 2016-2018 es similar a la del trienio 2013-2015 (p = 0, 34), y ambas mejores que la del trienio 2010-2012 (p = 0, 002 y p = 0, 01 respectivamente). Conclusiones Se mantienen estables tanto la actividad del trasplante cardiaco en España como los resultados en supervivencia en los últimos 2 trienios. Hay una tendencia a realizar menos trasplantes urgentes, la mayoría con dispositivos de asistencia ventricular. Introduction and objectives: The present report describes the clinical characteristics and outcomes of heart transplants in Spain and updates the data to 2019. Methods: We describe the clinical characteristics and outcomes of heart transplants performed in Spain in 2019, as well as trends in this procedure from 2010 to 2018. Results: In 2019, 300 transplants were performed (8794 since 1984; 2745 between 2010 and 2019). Compared with previous years, the most notable findings were the decreasing rate of urgent transplants (38%), and the consolidation of the type of circulatory support prior to transplant, with an almost complete disappearance of counterpulsation balloon (0.7%), stabilization in the use of extracorporeal membrane oxygenation (9.6%), and an increase in the use of ventricular assist devices (29.0%). Survival from 2016 to 2018 was similar to that from 2013 to 2015 (P = .34). Survival in both these periods was better than that from 2010 to 2012 (P = .002 and P = .01, respectively). Conclusions: Heart transplant activity has remained stable during the last few years, as have outcomes (in terms of survival). There has been a trend to a lower rate of urgent transplants and to a higher use of ventricular assist devices prior to transplant

Impact of management intensification on native grassland ecosystems attributes

O manejo de campo nativo apresenta o desafio de desenvolver estratégias de intensificação sustentável para superar o dilema produçãoconservação. Embora a intensificação da produção através da agregação de insumos (fertilizantes e/ou sementes) seja possível, também pode causar mudanças negativas na sustentabilidade. Apesar das quantificações preliminares, existe uma lacuna no conhecimento acerca de como e quando são alteradas a diversidade, a estabilidade e a resiliência em processos de intensificação. Neste sentido, esta tese se concentra em identificar, através de dois experimentos: i) os principais fatores de controle da estabilidade temporal da produtividade de pastagens enriquecidas com nitrogênio (N), fósforo (P) e água; e ii) determinar os efeitos da fertilização fosfatada na diversidade de espécies e no estado da vegetação em campos nativos sobressemeados com leguminosas exóticas. O primeiro experimento apresenta o efeito de quatro anos de adição de N, P e água na produtividade e estabilidade temporal da produção. A adição de N e N + P diminuiu a estabilidade, processo associado à redução da constância da produção das espécies mais dominantes, enquanto que as adições de P e água incrementaram a estabilidade devido ao aumento da assincronia das espécies. Estas duas formas de controle da estabilidade são alternativas e a expressão está regulada pela limitação de N. Contrariamente ao proposto na teoria predominante “diversidade-estabilidade”, os resultados deste trabalho indicam que a estabilidade da produção depende principalmente do comportamento das espécies dominantes e não da diversidade de espécies. O segundo experimento expõe o efeito de mais de 10 anos de fertilização fosfatada na diversidade de espécies de um campo nativo sobressemeado com Trifolium repens e Lotus corniculatus. As respostas em riqueza e diversidade de espécies se relacionaram negativamente com a concentração de P do solo. Foram identificados limiares de concentração de P a partir dos quais se alcançaram as perdas máximas de diversidade e também foi desenvolvido um modelo de estados e transições da vegetação. Em síntese, esta tese contribui para ampliar o conhecimento do impacto de práticas de melhoramento em atributos de sustentabilidade (produtividade, diversidade, estabilidade, e resiliência) dos pastos nativos do bioma Pampa. A continuação destes esforços permitirá avanços na definição dos limites da intensificação baseados em critérios ecológicos, e assim contribuirá com o desafio de desenvolver estratégias de manejo sustentável.Native grassland management faces the challenge to develop sustainable intensification strategies to overcome the dilemma between production and conservation. Although the intensification of the production through addition of inputs (fertilizers and/or seeds) to be possible, it can potentially induces negative changes in the sustainability of the ecosystems. There is a gap in the knowledge about how and when diversity, stability and resilience are altered in the intensification process. The main body of this thesis consist of two experiments focused on: i) identifying the main factors that control the temporal stability of productivity of a native grassland enriched with nitrogen (N), phosphorus (P) and water; and ii) determining the effects of phosphorus fertilization in the diversity and the state of the vegetation of a native grassland overseeded with exotic legumes. The first experiment analyzed the effect of four years of N, P and water addition on the productivity and the temporal stability of a native grassland production. The single addition of N or combined with P decreased the temporal stability by reducing the constancy of the production of the most dominant species, whereas the additions of P and water increased the stability by increasing species asynchrony. Both controls of temporal stability appear to be alternative mechanisms, and the specific expression of each one would be regulated by the limitation of N. In the second experiment, the long term effects of two P fertilization doses on species richness and diversity of a native grassland overseeded with Trifolium repens and Lotus corniculatus were examinated. Extractable soil P was negatively related with species richness and diversity. Additionally, P concentration thresholds related to the maximum loss of species richness and diversity were identified, and a model of the states and transitions of the vegetation was developed. In summary, this thesis contributes to the understanding of the impact of intensification practices on sustainability attributes (productivity, diversity, stability and resilience) of native grasslands. The continuation of this research will focus on a detailed definition of the thresholds of the intensification based on ecological criteria, and thus contribute to the challenge to develop sustainable systems

Impact of management intensification on native grassland ecosystems attributes

O manejo de campo nativo apresenta o desafio de desenvolver estratégias de intensificação sustentável para superar o dilema produçãoconservação. Embora a intensificação da produção através da agregação de insumos (fertilizantes e/ou sementes) seja possível, também pode causar mudanças negativas na sustentabilidade. Apesar das quantificações preliminares, existe uma lacuna no conhecimento acerca de como e quando são alteradas a diversidade, a estabilidade e a resiliência em processos de intensificação. Neste sentido, esta tese se concentra em identificar, através de dois experimentos: i) os principais fatores de controle da estabilidade temporal da produtividade de pastagens enriquecidas com nitrogênio (N), fósforo (P) e água; e ii) determinar os efeitos da fertilização fosfatada na diversidade de espécies e no estado da vegetação em campos nativos sobressemeados com leguminosas exóticas. O primeiro experimento apresenta o efeito de quatro anos de adição de N, P e água na produtividade e estabilidade temporal da produção. A adição de N e N + P diminuiu a estabilidade, processo associado à redução da constância da produção das espécies mais dominantes, enquanto que as adições de P e água incrementaram a estabilidade devido ao aumento da assincronia das espécies. Estas duas formas de controle da estabilidade são alternativas e a expressão está regulada pela limitação de N. Contrariamente ao proposto na teoria predominante “diversidade-estabilidade”, os resultados deste trabalho indicam que a estabilidade da produção depende principalmente do comportamento das espécies dominantes e não da diversidade de espécies. O segundo experimento expõe o efeito de mais de 10 anos de fertilização fosfatada na diversidade de espécies de um campo nativo sobressemeado com Trifolium repens e Lotus corniculatus. As respostas em riqueza e diversidade de espécies se relacionaram negativamente com a concentração de P do solo. Foram identificados limiares de concentração de P a partir dos quais se alcançaram as perdas máximas de diversidade e também foi desenvolvido um modelo de estados e transições da vegetação. Em síntese, esta tese contribui para ampliar o conhecimento do impacto de práticas de melhoramento em atributos de sustentabilidade (produtividade, diversidade, estabilidade, e resiliência) dos pastos nativos do bioma Pampa. A continuação destes esforços permitirá avanços na definição dos limites da intensificação baseados em critérios ecológicos, e assim contribuirá com o desafio de desenvolver estratégias de manejo sustentável.Native grassland management faces the challenge to develop sustainable intensification strategies to overcome the dilemma between production and conservation. Although the intensification of the production through addition of inputs (fertilizers and/or seeds) to be possible, it can potentially induces negative changes in the sustainability of the ecosystems. There is a gap in the knowledge about how and when diversity, stability and resilience are altered in the intensification process. The main body of this thesis consist of two experiments focused on: i) identifying the main factors that control the temporal stability of productivity of a native grassland enriched with nitrogen (N), phosphorus (P) and water; and ii) determining the effects of phosphorus fertilization in the diversity and the state of the vegetation of a native grassland overseeded with exotic legumes. The first experiment analyzed the effect of four years of N, P and water addition on the productivity and the temporal stability of a native grassland production. The single addition of N or combined with P decreased the temporal stability by reducing the constancy of the production of the most dominant species, whereas the additions of P and water increased the stability by increasing species asynchrony. Both controls of temporal stability appear to be alternative mechanisms, and the specific expression of each one would be regulated by the limitation of N. In the second experiment, the long term effects of two P fertilization doses on species richness and diversity of a native grassland overseeded with Trifolium repens and Lotus corniculatus were examinated. Extractable soil P was negatively related with species richness and diversity. Additionally, P concentration thresholds related to the maximum loss of species richness and diversity were identified, and a model of the states and transitions of the vegetation was developed. In summary, this thesis contributes to the understanding of the impact of intensification practices on sustainability attributes (productivity, diversity, stability and resilience) of native grasslands. The continuation of this research will focus on a detailed definition of the thresholds of the intensification based on ecological criteria, and thus contribute to the challenge to develop sustainable systems

PERENNIAL GRASSES TRAITS AS FUNCTIONAL MARKERS OF GRAZING INTENSITY IN BASALTIC GRASSLANDS OF URUGUAY

Natural grasslands in the basaltic region of Uruguay are threatened by an increase in stocking rates and changes in land use. To assess the effect of grazing intensification, plant functional types are proposed as simple tools to aid the monitoring and management of vegetation. In the present study we evaluated the effect of stocking rate increase at community level taking into account plant traits of 23 dominant perennial grass species. In order to identify plant functional types, we determined the grazing response in an experiment with two wethers stocking rates (0.78 and 1.56 livestock units ha-1) quantifying species cover and traits values. Leaf dry matter content (LDMC) and specific leaf area (SLA) were the traits that best described the perennial grasses response to the stocking rate increase and therefore are suggested to be used as functional markers. Three functional types were identified. Low stocking rates were related to functional type A (tall, warm season species with low SLA and high LDMC and functional type B (tall, cool-season species, with intermediate levels of leaf traits). On the other hand, high stocking rate encouraged functional type C (prostrate, warm season species, with high SLA and low LDMC). The classification of a highly diverse community into three functional types and the selection of traits as functional markers candidates is an innovative approach to develop simple and general methods to diagnosis the state of basaltic grasslands in Uruguay and to advise on its management