1,720,963 research outputs found
Efecto de la suplementación proteica sobre la tasa de crecimiento y parámetros digestivos de novillos a pastoreo sobre sorgo granífero diferido
Get PDFTesis para obtener el grado de Magíster en Ciencias Agrarias, de la Universidad Nacional del Sur, en 2009El sorgo granífero (Sorghum bicolor (L.) Moench) es habitualmente utilizado como diferido por el ganado bovino en la región sudoeste de la Pcia. de Bs. As. De esta manera es posible minimizar el déficit de forraje que se presenta frecuentemente durante el período invernal debido a limitantes de temperatura y humedad. Este cultivo presenta una gran adaptabilidad a las condiciones climáticas de la región, desarrollando altas tasas de crecimiento durante la época estival, dando la posibilidad de transferir un gran volumen de forraje en pie para ser utilizado en la época invernal. El sorgo granífero diferido (SGD) se caracteriza por tener valores de proteína bruta que se consideran limitantes para el óptimo crecimiento de novillos a pastoreo. La suplementación nitrogenada puede subsanar esta carencia, mejorando la utilización de este forraje. El objetivo de este estudio fue evaluar el efecto de la adición de proteína suplementaria sobre el consumo voluntario, la tasa de crecimiento, y parámetros de digestión y metabolismo ruminal en novillos que pastorean SGD. El sorgo granífero SG 9538 fue sembrado el 22/11/2005 y la totalidad de la biomasa producida durante el ciclo de crecimiento, incluido el grano, fue diferida hacia el otoño para ser utilizada por los animales a partir del mes de junio de 2006. Se utilizaron doce novillitos Aberdeen Angus de 224 8 Kg de peso, que fueron asignados al azar a tres tratamientos durante 100 días. Los tratamientos fueron: Control (CON) = pastoreo de sorgo granífero diferido sin restricción, (GS) = SGD sin restricción + 1,257 Kg MS/d de grano de soja entero y (HG) = SGD sin restricción + 1,353 Kg MS/d de harina de girasol. Ambos suplementos fueron calculados de manera de cubrir el desbalance de proteína degradable en el rumen (- 203 g/d) que se genera en el animal al suministrarle la dieta de sorgo granífero diferido. La cantidad de proteína bruta que proporcionan ambos suplementos es de 0,450 kg/día, lo que equivale al 70% de los requerimientos diarios de proteína total de un novillo de 250 kg PV que gana 700 gr/d (NRC, 2000). El sistema de pastoreo del SGD fue frontal con cambios diarios, mediante el empleo de alambre eléctrico. Si bien los animales de todos los tratamientos pastorearon en forma conjunta, los suplementos fueron suministrados en comederos individuales diariamente a las 9:00 h. La composición química del sorgo granífero diferido fue de 71,6; 62,4; 33,0; 3,2 y 7,2%, para materia seca (MS), fibra detergente neutro (FDN), fibra detergente ácido (FDA), lignina detergente ácido (LDA) y proteína bruta (PB), respectivamente. La disponibilidad del cultivo diferido de sorgo granífero fue de 7775,0 kg MS/ha. Los suplementos proteicos presentaron valores de PB de 32,3 y 35,6% para la harina de girasol y el grano de soja, respectivamente. El consumo voluntario de materia seca (CVMS) de sorgo diferido disminuyó (p0,19) entre los distintos tratamientos en lo que respecta a la proporción de grano de sorgo recuperado en heces. A pesar de esto se observa una tendencia a pasar una mayor proporción de grano entero hacia las heces con el agregado de proteína a la dieta. La proporción media de grano que transitó por el tracto sin degradar fue del 27% aproximadamente. Para realizar las evaluaciones de ambiente ruminal se utilizaron 3 novillos fistulados Aberdeen Angus de 550 kg de peso los cuales recibieron los mismos tratamientos que en el ensayo de respuesta productiva, en un diseño de cuadrado latino con tres tratamientos y tres períodos de evaluación. La concentración de N-NH3 se duplico en aquellos animales suplementados con grano de soja y se cuadruplico en los que recibieron harina de girasol luego de que transcurrieran 2 horas desde la entrega del alimento. Luego del pico de concentración de N-NH3, 11,64 y 22,65 mg/dl para GS y HG, respectivamente, los valores comienzan a disminuir paulatinamente a medida que transcurre el tiempo, hasta el punto en que no se observan diferencias significativas entre las distintas dietas más allá de las 6 horas. La concentración de N-NH3 más baja fue observada alrededor de las 24 h, inmediatamente antes de la nueva comida. La concentración de AGV total aumentó (p0,19). However, there was a marked trend to recover more whole grain in the treatments receiving protein supplementation. Anyhow, the mean proportion of grain passing through the digestive tract without apparent degradation was 27% of the total grain estimated to be consumed. To determine ruminal parameters, three ruminally cannulated Aberdeen Angus steers (550 kg BW) were used. They received the same treatments described for the first experiment in a latin square design (3 treatments and three periods). The NH3-N concentration increased more than 2 times in those animals supplemented with soybean grain and more than 4 times in those receiving sunflower meal as protein supplements after 2 h since the supplements were fed. After a peak was reached there was a progressive decrease in the ruminal NH3-N concentration with time. The decrease was so sharp that no significant differences were observed after 6 h. The lowest NH3-N levels were observed at 24 h, immediately before the supplement was fed again. The total VFA concentration increased (p<0,05) 30% with the addition of sunflower meal. Although the total VFA was also numerically larger than CON the differences were not significant. It was observed a non significant trend to enhance the relationship propionate to acetate with protein supplementation. In conclusion, highly degradable protein supplementation as in HG and GS when fed to steers grazing SGD improved productivity parameters such efficiency of diet utilization and voluntary consumption of digestible nutrients. Higher concentration of NH3-N and total VFAs proved the benefit of feeding either soybean grain or sunflower meal. No meaningful differences between supplementation strategies were found for productivity, and both feeding programs can be considered as alternative to supplement SGD in southwestern Buenos Aires Province.EEA BordenaveFil: Lagrange, Sebastian Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; Argentin
Grazing diverse combinations of tanniferous and nontanniferous legumes: implications for foraging behavior, performance, and hair cortisol in beef cattle
No full textA diversity of forages with different types and concentrations of nutrients and plant secondary compounds may lead to complementary relationships that enhance cattle performance and welfare. We determined whether grazing combinations of tanniferous legumes (Lotus corniculatus, birdsfoot trefoil [BFT], Onobrychis viciifolia, sainfoin [SF]), and alfalfa [ALF] (Medicago sativa) influence foraging behavior, performance, and hair cortisol concentration in beef cattle compared with grazing the same legumes as monocultures. Twenty-one pairs of heifers grazed three spatial replications of seven treatments: monocultures of BFT, SF, or ALF, and all possible two- and three-way choices among strips of these legumes: SF-BFT, ALF-BFT, ALF-SF, and ALF-SF-BFT in two periods of 25 d each (adaptation phase + experimental period) during two consecutive years. The lowest incidence of grazing events occurred in the BFT treatment (42.0% of the total scans recorded; P 0.10), with two major grazing events (1 h after sunrise and 3 h before dark). No differences among treatments were observed for the number of steps taken by heifers on a daily basis, motion index, or the percentage of time heifers spent standing (1,599, 5,356, and 45.3%, respectively; P > 0.10), suggesting that heifers on choice treatments did not invest extra time in walking, searching, or patch switching activities relative to heifers grazing monocultures. Heifers grazing the three-way choice gained more body weight (1.27 kg/d) than the average gains observed for animals grazing in all legume monocultures (1.00 kg/d; P = 0.014) or two-way choices (0.97 kg/d; P = 0.007), suggesting a synergism among pasture species for the treatment with the highest diversity. No differences in hair cortisol concentration were observed among treatments, with values ranging between 1.4 (BFT) and 2.12 ng/g (three-way choice; P > 0.10). Thus, forage diversity has the potential to enhance animal performance without affecting grazing efficiency, likely explained by the spatial arrangement of the forage species presented in the study.EEA BordenaveFil: Lagrange, Sebastian Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; Argentina.Fil: Lagrange, Sebastian Pablo. Utah State University. Quinney College of Natural Resources. Department of Wildland Resources; Estados Unidos.Fil: MacAdam, Jennifer W. Utah State University. College of Agriculture and Applied Sciences; Estados Unidos.Fil: Stegelmeier, Bryan. Agricultural Research Service. Poisonous Plant Research Laboratory; Estados Unidos.Fil: Villalba, Juan J. Utah State University. Quinney College of Natural Resources. Department of Wildland Resources; Estados Unidos
The Use of Temperate Tannin Containing Forage Legumes to Improve Sustainability in Forage–Livestock Production
Get PDFGreenhouse gas emissions from ruminant livestock production systems contribute significantly to the environmental footprint of agriculture. Emissions are lower for feedlot systems than for grass-based systems primarily because of the extra time required for grass-finished cattle to reach slaughter weight. In contrast, legume forages are of greater quality than grasses, which enhances intake and food conversion efficiencies, leading to improvements in production and reductions in environmental impacts compared with forage grasses. In addition, the presence of certain bioactives in legumes such as condensed tannins (CT) enhance the efficiency of energy and protein use in ruminants relative to grasses and other feeds and forages. Grazing tannin-containing legumes also reduce the incidence of bloat and improve meat quality. Synergies among nutrients and bioactives when animals graze diverse legume pastures have the potential to enhance these benefits. Thus, a diversity of legumes in feeding systems may lead to more economically, environmentally, and socially sustainable beef production than grass monocultures or feedlot rations.EEA BordenaveFil: Lagrange, Sebastian Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; Argentina.Fil: MacAdam, Jennifer W. Utah State University. College of Agriculture and Applied Sciences; Estados Unidos.Fil: Villalba, Juan J. Utah State University. Quinney College of Natural Resources. Department of Wildland Resources; Estados Unidos
Manual de sorgo
Get PDFEste manual de sorgo fue planificado con el fin de dar respuesta a la carencia de información regional para productores donde se reunieron los principales conceptos y recomendaciones sobre el cultivo.EEA BarrowFil: Carrasco, Natalia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Barrow; ArgentinaFil: Zamora, Martin Sergio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Barrow; ArgentinaFil: Melin, Ariel Alejandro. Ministerio de Asuntos Agrarios de Buenos Aires. Chacra Experimental de Coronel Suárez; ArgentinaFil: Bolletta, Andrea Ivana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; ArgentinaFil: Marinissen, Josefina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi; ArgentinaFil: Gigón, Ramón. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Barrow; ArgentinaFil: Forjan, Horacio Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Barrow; ArgentinaFil: Lagrange, Sebastian Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; ArgentinaFil: Campos, Pablo Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bordenave; ArgentinaFil: Manso, Marina Lucrecia. Instituto Nacional de Tecnología Agropecuaria (INTA). Chacra Experimental Integrada Barrow; ArgentinaFil: Cicchino, Mariano Andres. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado. Agencia de Extensión Rural Chascomús; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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