Assessment of the carcass traits of lambs with ¾ of the Texel breed genotype

Thirty six ¾ Texel (T) and 32 Ideal lambs were grown in feedlot for two months postweaning to evaluate final liveweight (FLW), relative average daily gain (ADGr) and various carcass characteristics, including: cold carcass weight (CCW), total lean weight (TLW), loin weight (LW), and total fat weight (TFW). Differences were found between males of the two genotypes in FW (P<.01) and TLW (P<.05); and between the females in TFW (P<.05). There were no differences between genotypes in ADGr. A multiple regression analysis relating FLW, as dependent variable, and the carcass variables as independent, showed that 73% of the variation in liveweight of the¾T animals was associated withLW and TLW. At conclusion of the confinement feeding, blood plasma samples from three lambs of each genotype/sex were analyzed for relative proportions of the mayor fatty acids and concentrations of total cholesterol and triglycerides. A negative relationship was found between the proportion of oleic acid and degree of fatness, expressed as (TFW/CCW) (100), whereas for linoleic acid the relationship was positive

Body composition estimation in vivo and on the carcass of pigs raised on pastures

To compare the prediction of body composition in vivo and in slaughtered animals, a pig population with a broad genetical background, was used to determine the extent on which that prediction was affected by different characters (sex, slaughter body weight and lean percentage). Seventy-two barrows and 57 gilts were measured firstly ultrasonically (PigLog 105 - P) in vivo and then their carcasses were evaluated with a Fat-O-Meater apparatus (FOM) at the abattoir. Data were analysed by means of the Student t test for paired observations and subjected to linear correlation studies with the correlation coefficient. P and FOM measurements of lean percentage were positively and significantly associated (r = 0.68, P<0.01). Sensitivity, specificity, positive and negative predictive values of in vivo evaluations were also assessed. P measurements underestimated both muscle depth and fat thickness and did not show significant differences in lean percentage when compared to FOM values. As live evaluation showed a low sensitivity, lean percentage estimated in vivo with P can not be considered a good individual estimator of the same trait when measured in the carcass using FOM, notwithstanding its usefulness as an estimator of the average lean percentage of the group as a whole

Evaluación de modelos de crecimiento en diferentes condiciones de cultivo de pejerrey (Odontesthes bonariensis)

The pejerrey is one of the most important temperate native freshwater species of Argentina. Its culture is mainly done intensively and in recent years is being developed in floating cages in several Pampean lakes under semi-intensive and extensive conditions. To evaluate the growth of fish under different culture methodologies several models are used, most of which are based on the specific growth rate (SGR). The objective of this study is to compare how the SGR of pejerrey responds under different culture methods and generate a theoretical model to predict the growth that the species can reach. To carry out the models a data base was made with the available data of intensive, extensive and semi-intensive culture, to which an exponential and polynomial models were adjusted by the method of least squares and then the expected growth was simulated using the model that better fits. From the results it was observed that the polynomial model presented the best fit to different methods of culture. In all cases the models reflected the seasonality in the growth rates exhibited by the species, where SGR was lowest in winter and highest in spring. The growth simulation models also show that the semi-intensive culture could produce greater weight than other methods. Under these conditions, fish obtain zooplankton from the environment incorporating essential elements from its natural food source. This suggests that it is possible to improve the sizes of fish by using techniques that also incorporate natural food or its equivalent in the composition of the artificial diets.El pejerrey es una de las especies nativas de agua dulce templadas más importantes de Argentina. Su cultivo se realiza principalmente de forma intensiva y en los últimos años se está desarrollando en jaulas flotantes en varios lagunas pampeanas en condiciones semi-intensivas y extensivas. Para evaluar el crecimiento de peces bajo diferentes metodologías de cultivo, se utilizan varios modelos, la mayoría de los cuales se basan en la tasa de crecimiento específica (SGR). El objetivo de este estudio es comparar cómo responde la SGR de pejerrey bajo diferentes métodos de cultivo y generar un modelo teórico para predecir el crecimiento que la especie puede alcanzar. Para llevar a cabo los modelos se realizó una base de datos con los datos disponibles de cultivo intensivo, extenso y semi-intensivo, a los que se ajustaron los modelos exponencial y polinomial mediante el método de mínimos cuadrados y luego se simuló el crecimiento esperado utilizando el modelo que se ajusta mejor De los resultados se observó que el modelo polinomial presentaba el mejor ajuste para diferentes métodos de cultivo. En todos los casos, los modelos reflejaron la estacionalidad en las tasas de crecimiento exhibidas por la especie, donde SGR fue más baja en invierno y más alta en primavera. Los modelos de simulación de crecimiento también muestran que el cultivo semi-intensivo podría producir mayor peso que otros métodos. En estas condiciones, los peces obtienen zooplancton del ambiente incorporando elementos esenciales de su fuente de alimento natural. Esto sugiere que es posible mejorar el tamaño de los peces mediante el uso de técnicas que también incorporan alimentos naturales o su equivalente en la composición de las dietas artificiales

Evaluación de modelos de crecimiento de diferentes condiciones de cultivo de pejerrey (<i>Odontotesthes bonariensis</i>)

The pejerrey is one of the most important temperate native freshwater species of Argentina. Its culture is mainly done intensively and in recent years is being developed in floating cages in several Pampean lakes under semi-intensive and extensive conditions. To evaluate the growth of fish under different culture methodologies several models are used, most of which are based on the specific growth rate (SGR). The objective of this study is to compare how the SGR of pejerrey responds under different culture methods and generate a theoretical model to predict the growth that the species can reach. To carry out the models a data base was made with the available data of intensive, extensive and semi-intensive culture, to which an exponential and polynomial models were adjusted by the method of least squares and then the expected growth was simulated using the model that better fits. From the results it was observed that the polynomial model presented the best fit to different methods of culture. In all cases the models reflected the seasonality in the growth rates exhibited by the species, where SGR was lowest in winter and highest in spring. The growth simulation models also show that the semi-intensive culture could produce greater weight than other methods. Under these conditions, fish obtain zooplankton from the environment incorporating essential elements from its natural food source. This suggests that it is possible to improve the sizes of fish by using techniques that also incorporate natural food or its equivalent in the composition of the artificial diets.Facultad de Ciencias Naturales y Muse

Evaluación de modelos de crecimiento de diferentes condiciones de cultivo de pejerrey (<i>Odontotesthes bonariensis</i>)

The pejerrey is one of the most important temperate native freshwater species of Argentina. Its culture is mainly done intensively and in recent years is being developed in floating cages in several Pampean lakes under semi-intensive and extensive conditions. To evaluate the growth of fish under different culture methodologies several models are used, most of which are based on the specific growth rate (SGR). The objective of this study is to compare how the SGR of pejerrey responds under different culture methods and generate a theoretical model to predict the growth that the species can reach. To carry out the models a data base was made with the available data of intensive, extensive and semi-intensive culture, to which an exponential and polynomial models were adjusted by the method of least squares and then the expected growth was simulated using the model that better fits. From the results it was observed that the polynomial model presented the best fit to different methods of culture. In all cases the models reflected the seasonality in the growth rates exhibited by the species, where SGR was lowest in winter and highest in spring. The growth simulation models also show that the semi-intensive culture could produce greater weight than other methods. Under these conditions, fish obtain zooplankton from the environment incorporating essential elements from its natural food source. This suggests that it is possible to improve the sizes of fish by using techniques that also incorporate natural food or its equivalent in the composition of the artificial diets.Facultad de Ciencias Naturales y Muse

The TRAPSENSOR facility: an open-ring 7 tesla Penning trap for laserbased precision experiments

APenning-trap facility for high-precision mass spectrometry based on a novel detection method has been built. This method consists in measuring motional frequencies of singly-charged ions trapped in strong magnetic fields through the fluorescence photons from laser-cooled 40Ca+ ions, to overcome limitations faced in electronic single-ion detection techniques. The key element of this facility is an open-ring Penning trap coupled upstream to a preparation Penning trap similar to those used at Radioactive Ion Beam facilities. Here we present a full characterization of the trap and demonstrate motional frequency measurements of trapped ions stored by applying external radiofrequency fields in resonance with the ions’ eigenmotions, in combination with time-of-flight identification. The infrastructure developed to observe the fluorescence photons from 40Ca+, comprising the 12 laser beams and the optical system to register the image in a high-sensitive CCD sensor, has been proved by taking images of the trapped and cooled 40Ca+ ions. This demonstrates the functionality of the proposed laser-based mass-spectrometry technique, providing a unique platform for precision experiments with implications in different fields of physics.This work was supported by the European Research Council (contract no. 278648-TRAPSENSOR), from the SpanishMINECO/ FEDER (project nos. FPA2012-32076, FPA2015-67694-P, FIS2015-69983-P, UNGR10-1E- 501, UNGR13-1E-1830), Ramón y Cajal Grant RYC-2012-11391, Juan de la Cierva grant IJCI-2015-26091, Centro Nacional de Partículas, Astropartículas y Nuclear CPAN13-TM01, and ‘Sistema Nacional de Garantía Juvenil y del Programa Operativo de Empleo Juvenil’; from the SpanishMECD(PhD grant nos. FPU15-04679 and FPU17/02596); from Junta de Andalucía/FEDER (project no. IE-57131) and ‘Programa de Empleo Juvenil; from Basque Government (PhD grant no. PRE-2015-1-0394) and (project no. IT986-16), and from the University of Granada ‘Plan propio-Programa de Intensificación de la Investigación PP2017-PRI.I-04’. I.A, L.L. and E.S acknowledge also support from projects OpenSuperQ (820363) and QMiCS (820505) of the EUFlagship on Quantum Technologies

Papel de la tecnología en la educación científica: una dimensión olvidada

El actual movimiento en pro de una 'alfabetización tecnológica' ha venido a cuestionar algunos supuestos implícitos en la orientación de la educación científica que se traducen, de facto, en el olvido de la dimensión tecnológica. En este trabajo se analizan dichos supuestos y se extraen algunas implicaciones que representan un enriquecimiento de la educación científica con la incorporación de aspectos esenciales hasta aquí ignorados. Se pretende, así mismo, mostrar la existencia de una convergencia básica en torno a unas propuestas de enseñanza-aprendizaje de las ciencias que superen las estrategias basadas en la simple transmisión-recepción de conocimientos, subrayando la contribución de la dimensión tecnológica al desarrollo de dichas propuestas