DIGESTIBILIDAD DE LA MATERIA SECA DE HENO DE MANÍ RIZOMA PERENNE (A GLABRATA) COSECHADO EN EL TRÓPICO CARIBEÑO

The in vitro true dry matter digestibility (IVTDMD) of rhizoma perennial peanut (RPP) forage was evaluated in trials at Lajas (PI no. 276233, 262826, 262833, 262839, and cvs Florigraze and Arbrook) and Juana Díaz (PI no. 276233, 262839, and cv Florigraze), Puerto Rico. At both sites, the forage was cut at six-, nine-, and 12-wk harvest intervals (HI) in each of the four seasons of the year. The digestibility of the forage was not influenced by genotype. Mean IVTDMD across HI and season of growth was 64.3 and 62.5% in the Lajas and Juana Díaz trials, respectively. The IVTDMD decreased in a quadratic manner (P < 0.01) as HI increased from six to 12 weeks. The digestibility of forage harvested at six and nine weeks was similar, with a relative decline of 6.6 and 10.6% as HI increased from nine to 12 weeks in Lajas and Juana Díaz, respectively. Season of growth influenced IVTDMD (P < 0.01). In both trials, the highest digestibility was obtained in forage grown in summer. The effect of season of growth on IVTDMD was greatest in forage harvested at 12 weeks, and least in forage harvested at six weeks. The high digestibility reported among genotypes evaluated suggests they are a viable alternative for the production of high quality hay in the Caribbean tropics. La digestibilidad verdadera de la materia seca in vitro (DVMSIV) del maní rizoma perenne (MRP) fue evaluada en Lajas (núm. Pl 276233, 262826, 262833, 262839 y los cvs Florigraze y Arbrook) y Juana Díaz (núm. PI 276233, 262839 y el cv Florigraze). En ambas localidades, el forraje se cortó a intervalos de seis, nueve y 12 semanas en cada una de las cuatro estaciones del año. La DVMSIV del forraje no fue afectada por el genotipo del MRP evaluado. Las medias fueron 64.3 y 62.5% para los MRP evaluados en Lajas y Juana Díaz, respectivamente. A medida que se alargó el intervalo de corte de seis a 12 semanas la DVMSIV se redujo (P < 0.01) en una forma cuadrática. En ambos estudios, la digestibilidad del forraje cosechado a las seis y nueve semanas fue similar; al aumentar de nueve a 12 semanas hubo una reducción relativa en la DVMSIV de 6.6 y 10.6% en Lajas y Juana Díaz, respectivamente. La estación de crecimiento afectó (P < 0.01) la DVMSIV. El forraje cosechado durante el verano tuvo la digestibilidad más alta en ambas localidades. El efecto de la estación de crecimiento fue mayor en el forraje cosechado a un intervalo de 12 semanas y menor en el forraje cosechado a las seis semanas de crecimiento. La alta digestibilidad de los genotipos evaluados sugiere que el MRP es una alternativa viable para la producción de heno de alta calidad en el trópico caribeño

Suplementación con concentrados con proteína no degradable en el rumen y el desempeño de vacas Holstein

Two experiments were conducted to determine the effects of level of concentrate supplementation with two concentrates differing in concentration and type of ruminally undegradable protein (RUP) on dry matter intake (DMI) and milk production of Holstein cows in late (E1) and early (E2) lactation. In both trials, concentrates were fed at the rate of 1 kg per 2.5 or 1.5 kg of milk, constituting low (LCS) and high (HCS) levels of concentrate supplementation, respectively. No significant effect of type of concentrate was observed on DMI, milk production, milk composition or efficiency of milk production in either experiment. HCS resulted in lower hay DM consumption by cows in late (9.8 vs. 11.3 kg/d) and early (6.4 vs. 8.1 kg/d) lactation, but also in greater total DMI by late (17.7 vs. 15.6 kg/d) and early (19.6 vs. 16.2 kg/d) lactation cows. Similarly, milk production was greater when late (13.1 vs. 11.8 kg/d) and early (25.5 vs. 22.6 kg/d) lactation cows were fed the HCS. In E2, contrary to E1, cows produced milk of higher fat concentration (2.66 vs. 3.18%) when the LCS was fed. HCS resulted in lower efficiency of concentrate use for milk and 3.25%-fat-corrected milk production, particularly during early lactation. However, income over feed cost was higher for HCS during early lactation. Thus, the practice of supplementing concentrates at a high level can be justified economically under conditions similar to those of this trial.Se realizaron dos experimentos para determinar los efectos del nivel de suplementación con dos concentrados con diferente concentración y tipo de proteína no degradable en el rumen (PND) en vacas Holstein en etapa tardía (E1) y etapa temprana (E2) de lactancia. En ambos estudios, los concentrados se suplieron a razón de 1 kg por cada 1.5 y 2.5 kg de leche, constituyendo los niveles alto (AS) y bajo (BS) de suplementación, respectivamente. Las diferencias en consumo de materia seca (MS), producción de leche, composición de la leche y eficiencia de la producción de leche debido al tipo de concentrado no fueron significativas (P < 0.05) en ninguno de los dos experimentos. El AS resultó en menor consumo de MS de heno en vacas en etapa tardía (9.8 vs. 11.3 kg/d) y temprana (6.4 vs. 8.1 kg/d) de lactancia, pero también resultó en mayor consumo de MS total en vacas en etapa tardía (17.7 vs. 15.6 kg/d) y temprana (19.6 vs. 16.2 kg/d) de lactancia. Igualmente, alimentar con AS resultó en mayor producción de leche en la etapa tardía (13.1 vs. 11.8 kg/d) y temprana (25.5 vs. 22.6 kg/d) de lactancia. En el E2, contrario al E1, la concentración de grasa láctea fue mayor con el BS (2.66 vs. 3.18%). Si bien AS resultó en una menor eficiencia del uso de concentrado para producir leche, particularmente en el E2, también aumentó el ingreso monetario sobre el costo de los alimentos en la lactancia temprana. Por consiguiente, el AS es justificable en términos económicos bajo condiciones similares a las de este estudio

Producción de leche y consumo de materia seca de vacas Holstein en lactación consumiendo dietas bajas en fibra en el trópico

Three stargrass silage (SGS)-based diets formulated to contain 20, 26 and 32% neutral detergent fiber (NDF) were compared as to their effect on dry matter intake (DMI) and milk production. Twelve lactating Holstein cows averaging 110 days in milk were arranged in four replications of a 3 x 3 Latin Square design. Treatments did not affect DMI or DMI as percentage of body weight (BW); mean values for these parameters were 15.4 kg/cow/day and 3.06%, respectively. However, cows consuming 32% NDF diet had a tendency toward lower (8.6%) intake of organic matter (OM) as percentage of BW than cows on the 20% NDF diet. Intake of NDF as a percentage of BW increased (P < 0.01) linearly (0.62 to 0.93%) as dietary NDF concentration increased. Milk production averaged 21.0 kg/cow/day and was not affected by dietary treatment. Reducing dietary NDF from 32 to 20% resulted in a reduction (P < 0.01) in milk fat from 3.09 to 2.66%.This reduction resulted in a 1.3 kg/cow/day increase (P < 0.05) in 3.25% fat-corrected milk (3.25% FCM) as the percentage of dietary NDF increased. Gross efficiency of energy (NEL) use for milk production and 3.25% FCM increased linearly with dietary NDF by 9.7 and 17.3%, respectively. Results point out that for mid-lactation cows at the observed level of production, diets lower than 32% NDF will not result in higher DMI and milk production, and will be less efficient in the use of energy for milk production.Se compararon tres dietas basadas en ensilaje de yerba estrella formuladas para contener 20, 26 y 32% de fibra detergente neutro (FDN) para evaluar su efecto sobre el potencial de consumo de materia seca (MS) y producción de leche de vacas Holstein a media lactancia (110 días). Las vacas se asignaron a tratamientos de acuerdo con un diseño de cuadrados latinos de 3 x 3, replicado cuatro veces. Los tratamientos no tuvieron efecto sobre el consumo de MS y MS a base del porcentaje de peso vivo (PV) de la vaca; los promedios generales fueron 15.4 kg/vaca/día y 3.06% del PV, respectivamente. Sin embargo, las vacas que consumieron la dieta con 32% FDN exhibieron una tendencia a un menor (8.6%) consumo de materia orgánica (MO) como porcentaje del PV comparado con la dieta con 20% FDN. El consumo de FDN como un porcentaje del PV aumentó (P < 0.01) linealmente de 0.62 a 0.93% según aumentó la concentración de FDN. El promedio de producción de leche fue 21.0 kg/vaca/día y éste no se afectó por los tratamientos. La reducción de 32 a 20% en la concentración de FDN resultó en una reducción (P < 0.01) en la concentración de grasa láctea de 3.09 a 2.66%. Como resultado hubo un aumento de 1.3 kg/vaca/día en la producción de leche corregida al 3.25% de grasa, según aumentó el FDN de 20 a 32%. Al aumentar la concentración de FDN de 20 a 32% la eficiencia de la utilización de la energía (NEL) para la producción de leche y leche corregida al 3.25% de grasa se incrementó en un 9.7% (P < 0.05) y 17.3% (P < 0.01), respectivamente. Según los resultados de este estudio a los niveles de producción observados, las dietas con menos de 32% de FDN no tendrán un efecto sobre el consumo de MS ni sobre la producción de leche integra, aún cuando estas dietas resultan en un mayor consumo de energía. Además, estas dietas son menos eficientes en el uso de energía para la producción de leche

Rendimiento de maní rizoma perenne (Arachis glabrata) cosechado a seis, nueve y 12 semanas en dos localidades semiáridas.

Rhizoma perennial peanut (RPP) is a forage legume of excellent adaptability and persistence «»nder subtropical and tropical conditions. Four accessions (USDA-TARS 17033,17050, 17052, and 17097, with PI nos. 276233, 262826, 262833, and 262839, respectively) and two cuitivars (Arbrook and Florigraze) of rhizoma perennial peanut (RPP) in Lajas, and two of the accessions (17033 and 17097) and cultivar Florigraze in Juana Díaz, Puerto Rico, were evaluated for dry matter yield (DMY) under irrigation during a full year.The RPPs were evaluated at six-, nine- and 12-wk harvest intervals (HI) in each of the four seasons of the year. At both sites, yield of accession 17033 was highest (P < 0.01) and averaged 35,779 kg DM/ha/yr. In Lajas, yield of accession 17097 was second best with an average of 30,151 kg DM/ ha/yr, yields of the other four RPPs were similar, averaging 25,374 kg DM/haV yr. Cultivar Florigraze, which produced 16% less than accession 17097 in Lajas, had similar productivity in Juana Díaz. On average, the total yields of accessions 17033 and 17097 and cultivar Florigraze declined (P < 0.01) by about 35 and 27% at the two locations, respectively, as HI increased from six to 12 weeks. Season of harvest had a strong influence on the DMY of RPP. At both locations, 69 and 64% of total yields were produced during spring and summer, respectively. Differences in height among RPPs were significant (P < 0.01) at both locations. Height averaged 26.0,17.6, and 18.5 cm for accessions 17033 and 17097 and cultivar Florigraze, respectively. The great adaptability of RPP to the tropical environment, and its high yield when harvested for hay, make it a crop with the potential of becoming one of the most important forages in the tropics.Cuatro accesiones (USDA-TARS líneas núm. 17033, 17050, 17052 y 17097; núm. Pl 276233, 262826, 262833 y 262839, respectivamente) y dos cultivares (Arbrook y Florigraze) de maní rizoma perenne (MRP) en Lajas, y dos accesiones {17033 y 17097) y Florigraze en Juana Díaz» Puerto Rico, se evaluaron para rendimiento de materia seca durante un año, en años consecutivos. Los MRP fueron evaluados a intervalos entre cosechas de seis, nueve y 12 semanas en cada una de fas estaciones del año. En ambas localidades el rendimiento de materia seca (WIS) de la accesión 17033 fue mayor (P < 0.01), promediando 35,779 kg MS/ha/año. En Lajas, el rendimiento de ía 17097 fue el segundo mayor con 30,151 kg MS/ha/año y el de los otros cuatro MRP fue similar y menor que et rendimiento de 17097, promediando 25,374 kg MS/ha/año. Florigraze produjo 16% menos MS que la 17097 en Lajas; sin embargo, en Juana Díaz la producción de las dos fue similar. A medida que el intervalo de cosecha se aumentó de seis a 12 semanas el rendimiento promedio de la 17033,17097 y Florigraze se redujo {P < 0.01) en alrededor de 35 y 27% en Lajas y Juana Díaz, respectivamente. En ambas localidades el 69 y el 64% del redi miento total de MS se produjo en la primavera y el verano, respectivamente. Las diferencias en la altura de la planta entre los MRP fueron significativas (P < 0.01) en ambas localidades. La altura promedio de las plantas fue 26.0, 17.6 y 18.5 cm para las accesiones 17033 y 17097, y Florigraze, respectivamente. La gran adaptabilidad del MRP al medio ambiente tropical y su alto rendimiento, cuando es cosechado para heno, hacen del mismo un cultivo con el potencial de ser uno de ios forrajes de mayor importancia en el trópico

Manejo de malezas durante y después del establecimiento de maní perenne.

A field study was conducted to evaluate the effect of dimethenamid and imazethapyr followed by clethodim and bromoxynil, on rhizoma perennial peanut (Arachis glabrata) during and after establishment.There were no significant differences in any of the parameters measured among rhizoma perennial peanut accessions as a result of the effects of herbicides. Excellent grass control was obtained when dimethenamid (preemergence) at 1.68 and 3.36 kg ai/ha was applied during the first month as compared with the use of imazethapyr. At 26 weeks after herbicide application (WAH) excellent grass control was obtained in all herbicide treatments. At 52 WAH no differences were observed for broadleaf and grass density. No differences were detected for dry weight of rhizoma perennial peanut and weeds among herbicide treatments at the 26- and 52-WAH harvests. Plots receiving imazethapyr as an early postemergence (POE) had 44 g/m2 more dry weight of weeds than plots with dimethenamid at the lowest rate, but no differences were found among the other treatments. The lowest weight of rhizoma perennial peanut was with imazethapyr early POE, as compared with the three other herbicide treatments. No difference was observed with dimethenamid at either rate. After two years, density of broadleaves was the highest (55.6 plants per square meter) with imazethapyr applied early POE. Density of grasses was lower with imazethapyr preemergence and dimethenamid at a lower rate than with the other two herbicide treatments. Overall, taking into account all rates and dates of herbicide applications, the best weed control was obtained with the early application dates. Se estableció un experimento de campo para evaluar el efecto de dimethenamid e imazethapyr seguido de clethodim y bromoxynil en maní perenne (Arachis glabrata), en y durante el establecimiento del mismo. No hubo diferencias significativas entre las variedades de maní perenne para el efecto de herbicida en ninguno de los parámetros medidos. Se obtuvo un excelente control de gramíneas con dimethenamid a 1.68 y 3.36 kg ¡a/ha el primer mes después de la aplicación en comparación con la aplicación de imazethapyr. A las 26 semanas después de la aplicación de los herbicidas se obtuvo excelente control de gramíneas con todos los tratamientos de herbicidas. A las 52 semanas después de la aplicación no hubo diferencias en la densidad de malezas de hoja ancha ni de gramíneas en ninguno de los tratamientos de herbicidas. No hubo diferencias en el peso seco del maní ni en el de malezas entre los tratamientos de herbicidas a las 26 y 52 semanas después de la aplicación. El peso seco de las malezas que recibieron imazethapyr postemergente temprano fue 44 g/m2 mayor que el de las malezas que recibieron dimethenamid a la dosis menor, pero no se observó diferencias entre los otros tratamientos. El menor rendimiento del maní perenne se obtuvo con la aplicación de imazethapyr postemergente temprano. Después de dos años de establecido, imazethapyr aplicado postemergente temprano produjo la mayor densidad de malezas de hoja ancha, con 55.6 plantas por metro cuadrado. La densidad de gramíneas fue menor con imazethapyr preemergente y con dimethenamid a la dosis de 1.68 kg ¡a/ha que con los otros dos tratamientos. En general, las aplicaciones de los herbicidas de forma preemergente resultaron en mayor rendimiento del maní perenne.

The biogeochemical context of marine planktonic ecosystems

En prens

Secular Changes in Eta Carinae's Wind 1998-2011

Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and we analyze the progression of spectral changes in the direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a time scale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude-dependent and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.Comment: 42 pages, 12 figures, 2 table

Relationship of runoff, erosion and sediment yield to weather types in the Iberian Peninsula

Precipitation has been recognized as one of the main factors driving soil erosion and sediment yield (SY), and its spatial and temporal variability is recognized as one of themain reasons for spatial and temporal analyses of soil erosion variability. The weather types (WTs) approach classifies the continuumof atmospheric circulation into a small number of categories or types and has been proven a good indicator of the spatial and temporal variability of precipitation. Thus, themain objective of this study is to analyze the relationship betweenWTs, runoff, soil erosion (measured in plots), and sediment yield (measured in catchments) in different areas of the Iberian Peninsula (IP) with the aimof detecting spatial variations in these relationships. To this end, hydrological and sediment information covering the IP from several Spanish research teams has been combined, and related with daily WTs estimated by using the NMC/NCAR 40-Year Reanalysis Project. The results showthat, in general, a fewWTs (particularly westerly, southwesterly and cyclonic) provide the largest amounts of precipitation; and southwesterly, northwesterly and westerly WTs play an important role in runoff generation, erosion and sediment yield as they coincide with the wettest WTs. However, this study highlights the spatial variability of erosion and sediment yield in the IP according to WT, differentiating (1) areas under the influence of north and/or north-westerly flows (the north coast of Cantabria and inland central areas), (2) areas under the influence of westerly, southwesterly and cyclonic WTs (western and southwestern IP), (3) areas in which erosion and sediment yield are controlled by easterly flows (Mediterranean coastland), and (4) lastly, a transitional zone in the inland northeast Ebro catchment,wherewe detected a high variability in the effects ofWTs on erosion. Overall results suggest that the use of WTs derived fromobserved atmospheric pressure patterns could be a useful tool for inclusion in future projections of the spatial variability of erosion and sediment yield, as models capture pressure fields reliably

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data