Complejidad y transdiciplinariedad en el campo de la salud colectiva: evaluación de conceptos y aplicaciones

Objetivos: Presentar brevemente los principales enfoques que representan algún tipo de cambio paradigmático de un modo general en el seno de la ciencia. Abordar las interrogantes: ¿Cómo se ha intentado la construcción de esta nuova scienzia (nueva ciencia) en la práctica teórica y metodológica en el campo de la Salud Colectiva? Y ¿en qué medida las investigaciones conducidas en las disciplinas que componen este campo han incorporado elementos de los abordajes teóricos de la complejidad

Tiller Size/Density Compensation in Temperate Climate Grasses Grown in Monoculture or Intercropping Systems under Rotational Grazing

From the standpoint of tiller population dynamics, it is well known that the size and numbers of tillers in forage grasses are inversely related, where a greater tiller population density (TPD) is associated with smaller tillers and vice versa (Sbrissia et al. 2003; Hernandez-Garay et al. 1999; Matthew et al. 1995). This relationship has traditionally been made with the self-thinning power law described by Yoda et al. (1963), which considers the leaf area index (LAI) of the pasture constant when the slope of the relationship between numbers and size of tillers, on a logarithmic scale, is approximately -3/2 (Matthew et al. 1995). Notably few studies have assessed this relationship in intercropping systems. Moreover, although studies that evaluated intercrops showed relationships that were nearly -3/2 for the individually analysed species (Yu et al. 2008; Nie et al. 1997;White and Harper 1970), Nie et al. (1997) suggested that all plants that occur in the grass field should be used to properly estimate self-thinning in mixed species pastures. Thus, the aim of the present study was to test the main hypothesis that the tiller size/density compensation mechanisms operate in the same way in mixed pastures of oat and Italian ryegrass under rotational grazing and that the plant communities adapt their population to maintain a relatively constant LAI

Short-Term Herbage Intake Rate in Temperate Pastures Grasses Grown in Pure or in Intercropping Stands

Oat and ryegrass pastures grown in intercropping systems are the most common forages used during the fall and winter in subtropical and in some temperate climate regions. Nevertheless, it must be taken into account that the way in which the different species of plants are presented to the animals may lead to consequences for the efficiency of the grazing process (Prache and Damasceno 2006). Moreover, in hetero-geneous environments, animals may reduce intake rate due to a partial preference for a specific species (Gonçalves et al. 2009). Regarding the pasture development stage, it is known that the decrease of the leaf/stem ratio causes the animal to reduce the instantaneous herbage intake rate due to the reduction of the bite depth because of the physical barrier imposed by the stem (Benvenutti et al. 2006; Drescher et al. 2006) and/or the search for a higher food quality, in this case, leaf lamina (Soder et al. 2009). However, the dynamics of changes in temperate sward structures grown in pure stands compared to inter-cropping systems and its consequence in heifers\u27 short-term herbage intake rate (STHIR) are scarce. The objective of this work was to assess the changes in the STHIR in pastures of oat, ryegrass and their intercrop during the growing season. The hypothesis tested was that cattle reduce the STHIR in intercropping pastures compared to pure stands, and as the grazing season progress

Avaliação de impactos econômicos, sociais e ambientais - cenoura Cultivar Brasília.

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