Information on nutritive values of each plant part in each phenological stage could help range managers choose suitable grazing times to achieve higher animal performance without detriment to vegetation. Thus, nutritive value of different plant parts of 5 grass species in 3 phenological stages (vegetative, flowering, and seed production) from 2 sites were investigated. Species included: Agropyron tauri Boiss and Bal., Agropyron trichophorum Richt, Bromus tomentellus Boiss, Festuca ovina Hack, and Hordeum bulbosum L. Samples of leaf, stem, and flower from 5 locations at each site for each species were analyzed for dry matter ratio of plant parts, crude protein, acid detergent fiber, neutral detergent fiber, dry matter digestibility, and metabolizable energy. A completely randomized design with a factorial arrangement of species and phenological stage was analyzed with 5 replicates for each location. Plant part was included as a subplot factor in a split plot arrangement. Nutritive values differed significantly (P < 0.05) both within and among plant parts and phenological stages for each species. Phenological stages indicated a significant difference on nutritive value of plant parts, with leaves having the highest nutritive value. Thus, forage with a higher leaf-to-stem ratio should improve animal performance because at the beginning of the 2nd phenological stage, the plant had desirable quantity and quality of forage with higher leaf-to-stem ratio. Resu men La información del valor nutritivo de cada parte de la planta en cada estado fenológico pudiera ayudar a los manejadores de pastizales a elegir las épocas apropiadas de apacentamiento para alcanzar un mayor comportamiento productivo del animal sin detrimento de la vegetación. Se investigó el valor nutritivo de diferentes partes de la planta de 5 especies de zacates en 3 estados fenológicos (vegetativo, floración y producción de semilla) provenientes de dos sitios. Las especies incluidas fueron: Agropyron tauri Boiss y Bal., A. trichophorum Richt, Bromus tomentellus Boiss, Festuca ovina Hack y Hordeum bulbosum L. Muestras de hojas, tallo y flores de cada especie se tomaron en 5 localidades dentro del cada sitio y se analizaron para determinar la relación de materia seca de las partes de la planta, el contenido de proteína cruda, fibra ácido detergente, fibra neutro detergente, digestibilidad de la materia seca y energía metabolizable. El diseño experimental utilizado fue completamente al azar en arreglo factorial, los factores fueron las especies y los estados fenológicos, se tuvieron 5 repeticiones y los análisis fueron por localidad. Las partes de las plantas se incluyeron como subparcelas en un diseño de parcelas divididas. En cada especie, los valores nutritivos difirieron significativamente (P < 0.05) dentro y entre las partes de la planta y entre los estados fenológicos. Los estados fenológicos, presentaron una diferencia significativa en el valor nutritivo de las partes de la planta, el mayor valor nutritivo lo tuvo las hojas. Así, el forraje con la mayo...

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The adsorption of methylene blue dye (MBD) from aqueous solutions was investigated using a new composite made up of shrimp waste chitosan and zeolite as adsorbent. Response surface methodology (RSM) was used to optimize the effects of process variables, such as contact time, pH, adsorbent dose and initial MBD concentration on dye removal. The results showed that optimum conditions for removal of MBD were adsorbent dose of 2.5 g/L and pH of 9.0, and initial MBD concentration of 43.75mg/L and contact time of 138.65 min. The initial concentration of dye had the greatest influence on MBD adsorption among other variables. The experimental data were well fitted by the pseudo-second order kinetic model, while the Freundlich isotherm model indicated a good ability for describing equilibrium data. According to this isotherm model, maximum adsorption capacity of the composite was 24.5mg/g. Desorption studies showed that the desorption process is favored at low pH under acidic conditions

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