A visual framework to accelerate knowledge discovery based on dimensionality reduction minimizing degradation of quality

Tradicionalmente, el uso de t��cnicas de an��lisis de datos ha sido una de las principales v��as para el descubrimiento de conocimiento oculto en grandes cantidades de datos, recopilados por expertos en diferentes dominios. Por otra parte, las t��cnicas de visualizaci��n tambi��n se han usado para mejorar y facilitar este proceso. Sin embargo, existen limitaciones serias en la obtenci��n de conocimiento, ya que suele ser un proceso lento, tedioso y en muchas ocasiones infruct��fero, debido a la dificultad de las personas para comprender conjuntos de datos de grandes dimensiones. Otro gran inconveniente, pocas veces tenido en cuenta por los expertos que analizan grandes conjuntos de datos, es la degradaci��n involuntaria a la que someten a los datos durante las tareas de an��lisis, previas a la obtenci��n final de conclusiones. Por degradaci��n quiere decirse que los datos pueden perder sus propiedades originales, y suele producirse por una reducci��n inapropiada de los datos, alterando as�� su naturaleza original y llevando en muchos casos a interpretaciones y conclusiones err��neas que podr��an tener serias implicaciones. Adem��s, este hecho adquiere una importancia trascendental cuando los datos pertenecen al dominio m��dico o biol��gico, y la vida de diferentes personas depende de esta toma final de decisiones, en algunas ocasiones llevada a cabo de forma inapropiada. ��sta es la motivaci��n de la presente tesis, la cual propone un nuevo framework visual, llamado MedVir, que combina la potencia de t��cnicas avanzadas de visualizaci��n y miner��a de datos para tratar de dar soluci��n a estos grandes inconvenientes existentes en el proceso de descubrimiento de informaci��n v��lida. El objetivo principal es hacer m��s f��cil, comprensible, intuitivo y r��pido el proceso de adquisici��n de conocimiento al que se enfrentan los expertos cuando trabajan con grandes conjuntos de datos en diferentes dominios. Para ello, en primer lugar, se lleva a cabo una fuerte disminuci��n en el tama��o de los datos con el objetivo de facilitar al experto su manejo, y a la vez preservando intactas, en la medida de lo posible, sus propiedades originales. Despu��s, se hace uso de efectivas t��cnicas de visualizaci��n para representar los datos obtenidos, permitiendo al experto interactuar de forma sencilla e intuitiva con los datos, llevar a cabo diferentes tareas de an��lisis de datos y as�� estimular visualmente su capacidad de comprensi��n. De este modo, el objetivo subyacente se basa en abstraer al experto, en la medida de lo posible, de la complejidad de sus datos originales para presentarle una versi��n m��s comprensible, que facilite y acelere la tarea final de descubrimiento de conocimiento. MedVir se ha aplicado satisfactoriamente, entre otros, al campo de la magnetoencefalograf��a (MEG), que consiste en la predicci��n en la rehabilitaci��n de lesiones cerebrales traum��ticas (Traumatic Brain Injury (TBI) rehabilitation prediction). Los resultados obtenidos demuestran la efectividad del framework a la hora de acelerar y facilitar el proceso de descubrimiento de conocimiento sobre conjuntos de datos reales. ABSTRACT Traditionally, the use of data analysis techniques has been one of the main ways of discovering knowledge hidden in large amounts of data, collected by experts in different domains. Moreover, visualization techniques have also been used to enhance and facilitate this process. However, there are serious limitations in the process of knowledge acquisition, as it is often a slow, tedious and many times fruitless process, due to the difficulty for human beings to understand large datasets. Another major drawback, rarely considered by experts that analyze large datasets, is the involuntary degradation to which they subject the data during analysis tasks, prior to obtaining the final conclusions. Degradation means that data can lose part of their original properties, and it is usually caused by improper data reduction, thereby altering their original nature and often leading to erroneous interpretations and conclusions that could have serious implications. Furthermore, this fact gains a trascendental importance when the data belong to medical or biological domain, and the lives of people depends on the final decision-making, which is sometimes conducted improperly. This is the motivation of this thesis, which proposes a new visual framework, called MedVir, which combines the power of advanced visualization techniques and data mining to try to solve these major problems existing in the process of discovery of valid information. Thus, the main objective is to facilitate and to make more understandable, intuitive and fast the process of knowledge acquisition that experts face when working with large datasets in different domains. To achieve this, first, a strong reduction in the size of the data is carried out in order to make the management of the data easier to the expert, while preserving intact, as far as possible, the original properties of the data. Then, effective visualization techniques are used to represent the obtained data, allowing the expert to interact easily and intuitively with the data, to carry out different data analysis tasks, and so visually stimulating their comprehension capacity. Therefore, the underlying objective is based on abstracting the expert, as far as possible, from the complexity of the original data to present him a more understandable version, thus facilitating and accelerating the task of knowledge discovery. MedVir has been succesfully applied to, among others, the field of magnetoencephalography (MEG), which consists in predicting the rehabilitation of Traumatic Brain Injury (TBI). The results obtained successfully demonstrate the effectiveness of the framework to accelerate and facilitate the process of knowledge discovery on real world datasets.

Study of the foundations, bearing soil and stability of the minaret-tower of Cordobas Mosque

This research in Cordoba's mosque tower main objective was to analyze and characterize the foundations and the underlying soil, calculating the stability of the monument as well as the settlement and deformations performed, using traditional calculation methods and also by finite elements, and to determine differences between both, as well as the stability factor of the Minaret Tower. The works done to study the soil, were drill bores and dynamic penetration tests, classification of samples by size, Atterberg limits, physical and chemical analysis, showing the typical geotechnical composition of the Guadalquivir valley: an alluvial material composed by sand, gravels and silt clays. To study the foundations, inclined bore samples were extracted with 10-65��, showing calcarenite stone ashlars and lime concrete alternating with stone and brick masonry.

Adobe's Mechanical Characterization in Ancient Constructions: The Case of Aveiro's Region

Adobe is commonly found in Aveiro's ancient constructions. Preservation and rehabilitation of those constructions, some of them with architectural and historical interest, has been forgotten for many years. As a result, in Aveiro region, the majority of existing constructions in adobe is structurally weak, and, in several cases, they are in the threshold of ruin. Rehabilitation and/or strengthening urge. Despite some efforts has been made, a great difficulty for technicians working on the rehabilitation of these constructions relies on the lack of knowledge on adobe's mechanical behaviour. In fact, in order to properly describe the structural behaviour of those constructions, there is a need to investigate the mechanical behaviour of adobe. Hence, this paper is based on a study intended to characterise the behaviour of adobe brick units. Specimens were prepared from selected representative constructions of the Aveiro region. The prepared specimens were tested in order to evaluate their mechanical behaviour in compression and tension

Validation and aplication of Bioelectrical Impedance (BIA) method to determine body and carcass composition and nutrient retention of growing rabbits = Validaci��n y aplicaci��n de la t��cnica de la Impedancia Bioel��ctrica (BIA) para determinar la composici��n corporal, de la canal y la retenci��n de nutrientes de conejos en crecimiento

Los objetivos de esta tesis fueron 1) obtener y validar ecuaciones de predicci��n para determinar in vivo la composici��n corporal y de la canal de conejos en crecimiento de 25 a 77 d��as de vida utilizando la t��cnica de la Impedancia Bioel��ctrica (BIA), y 2) evaluar su aplicaci��n para determinar diferencias en la composici��n corporal y de la canal, as�� como la retenci��n de nutrientes de animales alimentados con diferentes fuentes y niveles de grasa. El primer estudio se realiz�� para determinar y despu��s validar, usando datos independientes, las ecuaciones de predicci��n obtenidas para determinar in vivo la composici��n corporal de los conejos en crecimiento. Se utilizaron 150 conejos a 5 edades distintas (25, 35, 49, 63 y 77 d��as de vida), con un rango de pesos entre 231 y 3138 g. Para determinar los valores de resistencia (Rs,���) and reactancia (Xc,���) se us�� un terminal (Model BIA-101, RJL Systems, Detroit, MI USA) con cuatro electrodos. Igualmente se registr�� la distancia entre electrodos internos (D), la longitud corporal (L) y el peso vivo (PV) de cada animal. En cada edad, los animales fueron molidos y congelados (-20 ��C) para su posterior an��lisis qu��mico (MS, grasa, prote��na, cenizas y EB). El contenido en grasa y energ��a de los animales se increment��, mientras que los contenidos en prote��na, cenizas y agua de los animales disminuyeron con la edad. Los valores medios de Rs, Xc, impedancia (Z), L y D fueron 83.5 �� 23.1 ���, 18.2 �� 3.8 ���, 85.6 �� 22.9 ���, 30.6 �� 6.9 cm y 10.8 �� 3.1 cm. Se realiz�� un an��lisis de regresi��n lineal m��ltiple para determinar las ecuaciones de predicci��n, utilizando los valores de PV, L and Z como variables independientes. Las ecuaciones obtenidas para estimar los contenidos en agua (g), PB (g), grasa (g), cenizas (g) and EB (MJ) tuvieron un coeficiente de determinaci��n de (R2) de 0.99, 0.99, 0.97, 0.98 y 0.99, y los errores medios de predicci��n relativos (EMPR) fueron: 2.79, 6.15, 24.3, 15.2 y 10.6%, respectivamente. Cuando el contenido en agua se expres�� como porcentaje, los valores de R2 y EMPR fueron 0.85 and 2.30%, respectivamente. Al predecir los contenidos en prote��na (%MS), grasa (%MS), cenizas (%MS) y energ��a (kJ/100 g MS), se obtuvieron valores de 0.79, 0.83, 0.71 y 0.86 para R2, y 5.04, 18.9, 12.0 y 3.19% para EMPR. La reactancia estuvo negativamente correlacionada con el contenido en agua, cenizas y PB (r = -0.32, P < 0.0001; r = -0.20, P < 0.05; r = -0.26, P < 0.01) y positivamente correlacionada con la grasa y la energ��a (r = 0.23 y r = 0.24; P < 0.01). Sin embargo, Rs estuvo positivamente correlacionada con el agua, las cenizas y la PB (r = 0.31, P < 0.001; r = 0.28, P < 0.001; r = 0.37, P < 0.0001) y negativamente con la grasa y la energ��a (r = -0.36 y r = -0.35; P < 0.0001). Igualmente la edad estuvo negativamente correlacionada con el contenido en agua, cenizas y prote��na (r = -0.79; r = -0.68 y r = -0.80; P < 0.0001) y positivamente con la grasa y la energ��a (r = 0.78 y r = 0.81; P < 0.0001). Se puede concluir que el m��todo BIA es una t��cnica buena y no invasiva para estimar in vivo la composici��n corporal de conejos en crecimiento de 25 a 77 d��as de vida. El objetivo del segundo estudio fue determinar y validar con datos independientes las ecuaciones de predicci��n obtenidas para estimar in vivo la composici��n de la canal eviscerada mediante el uso de BIA en un grupo de conejos de 25 a 77 d��as, as�� como testar su aplicaci��n para predecir la retenci��n de nutrientes y calcular las eficacias de retenci��n de la energ��a y del nitr��geno. Se utilizaron 75 conejos agrupados en 5 edades (25, 35, 49, 63 y 77 d��as de vida) con unos pesos que variaron entre 196 y 3260 g. Para determinar los valores de resistencia (Rs, ���) y reactancia (Xc, ���) se us�� un terminal (Model BIA-101, RJL Systems, Detroit, MI USA) con cuatro electrodos. Igualmente se registr�� la distancia entre electrodos internos (D), la longitud corporal (L) y el peso vivo (PV) del cada animal. En cada edad, los animales fueron aturdidos y desangrados. Su piel, v��sceras y contenido digestivo fueron retirados, y la canal oreada fue pesada y molida para posteriores an��lisis (MS, grasa, PB, cenizas y EB). Los contenidos en energ��a y grasa aumentaron mientras que los de agua, cenizas y prote��na disminuyeron con la edad. Los valores medios de Rs, Xc, impedancia (Z), L y D fueron 95.9��23.9 ���, 19.5��4.7 ���, 98.0��23.8 ���, 20.6��6.3 cm y 13.7��3.1 cm. Se realiz�� un an��lisis de regresi��n linear m��ltiple para determinar las ecuaciones de predicci��n, utilizando los valores de PV, L and Z como variables independientes. Los coeficientes de determinaci��n (R2) de las ecuaciones obtenidas para estimar los contenidos en agua (g), PB (g), grasa (g), cenizas (g) and EB (MJ) fueron: 0.99, 0.99, 0.95, 0.96 y 0.98, mientras que los errores medios de predicci��n relativos (EMPR) fueron: 4.20, 5.48, 21.9, 9.10 y 6.77%, respectivamente. Cuando el contenido en agua se expres�� como porcentaje, los valores de R2 y EMPR fueron 0.79 y 1.62%, respectivamente. Cuando se realiz�� la predicci��n de los contenidos en prote��na (%MS), grasa (%MS), cenizas (%MS) y energ��a (kJ/100 g MS), los valores de R2 fueron 0.68, 0.76, 0.66 and 0.82, y los de RMPE: 3.22, 10.5, 5.82 and 2.54%, respectivamente. La reactancia estuvo directamente correlacionada con el contenido en grasa (r = 0.24, P < 0.05), mientras que la resistencia guard�� una correlaci��n positiva con los contenidos en agua, cenizas y prote��na (r = 0.55, P < 0.001; r = 0.54, P < 0.001; r = 0.40, P < 0.005) y negativa con la grasa y la energ��a (r = -0.44 y r = -0.55; P < 0.001). Igualmente la edad estuvo negativamente correlacionada con los contenidos en agua, cenizas y PB (r = -0.94; r = -0.85 y r = -0.75; P < 0.0001) y positivamente con la grasa y la energ��a (r = 0.89 y r = 0.90; P < 0.0001). Se estudi�� la eficacia global de retenci��n de la energ��a (ERE) y del nitr��geno (ERN) durante todo el periodo de cebo (35-63 d), Los valores de ERE fueron 20.4��7.29%, 21.0��4.18% and 20.8��2.79% en los periodos 35 a 49, 49 a 63 y 35 a 63 d, respectivamente. ERN fue 46.9��11.7%, 34.5��7.32% y 39.1��3.23% para los mismos periodos. La energ��a fue retenida en los tejidos para crecimiento con una eficiencia del 52.5% y la eficiencia de retenci��n de la energ��a como prote��na y grasa fue de 33.3 y 69.9% respectivamente. La eficiencia de utilizaci��n del nitr��geno para crecimiento fue cercana al 77%. Este trabajo muestra como el m��todo BIA es t��cnica buena y no invasiva para determinar in vivo la composici��n de la canal y la retenci��n de nutrientes en conejos en crecimiento de 25 a 77 d��as de vida. En el tercer estudio, se llevaron a cabo dos experimentos con el fin de investigar los efectos del nivel de inclusi��n y de la fuente de grasa, sobre los rendimientos productivos, la mortalidad, la retenci��n de nutrientes y la composici��n corporal total y de la canal eviscerada de conejos en crecimiento de 34 a 63 d de vida. En el Exp. 1 se formularon 3 dietas con un dise��o experimental factorial 3 x 2 con el tipo de grasa utilizada: Aceite de Soja (SBO), Lecitinas de Soja (SLO) y Manteca (L) y el nivel de inclusi��n (1.5 y 4%) como factores principales. El Exp. 2 tambi��n fue dise��ado con una estructura factorial 3 x 2, pero usando SBO, Aceite de Pescado (FO) y Aceite de Palmiste como fuentes de grasa, incluidas a los mismos niveles que en el Exp. 1. En ambos experimentos 180 animales fueron alojados en jaulas individuales (n=30) y 600 en jaulas colectivas en grupos de 5 animales (n=20). Los animales alimentados con un 4% de grasa a��adida tuvieron unos consumos diarios y unos ��ndices de conversi��n m��s bajos que aquellos alimentados con las dietas con un 1.5% de grasa. En los animales alojados en colectivo del Exp. 1, el consumo fue un 4.8% m��s alto en los que consumieron las dietas que conten��an manteca que en los animales alimentados con las dietas SBO (P = 0.036). La inclusi��n de manteca tendi�� a reducir la mortalidad (P = 0.067) en torno al 60% y al 25% con respecto a las dietas con SBO y SLO, respectivamente. La mortalidad aument�� con el nivel m��ximo de inclusi��n de SLO (14% vs. 1%, P < 0.01), sin observarse un efecto negativo sobre la mortalidad con el nivel m��s alto de inclusi��n de las dem��s fuentes de grasa utilizadas. En los animales alojados colectivo del Exp. 2 se encontr�� una disminuci��n del consumo (11%), peso vivo a 63 d (4.8%) y de la ganancia diaria de peso (7.8%) con la inclusi��n de aceite de pescado con respecto a otras dietas (P < 0.01). Los dos ��ltimos par��metros se vieron especialmente m��s reducidos cuando en las dietas se incluy�� el nivel m��s alto de FO (5.6 y 9.5%, respectivamente, (P < 0.01)). Los animales alojados individualmente mostraron unos resultados productivos muy similares. La inclusi��n de aceite pescado tendi�� (P = 0.078) a aumentar la mortalidad (13.2%) con respecto al aceite de palmiste (6.45%), siendo intermedia para las dietas que conten��an SBO (8.10%). La fuente o el nivel de grasa no afectaron la composici��n corporal total o de la canal eviscerada de los animales. Un incremento en el nivel de grasa dio lugar a una disminuci��n de la ingesta de nitr��geno digestible (DNi) (1.83 vs. 1.92 g/d; P = 0.068 en Exp. 1 y 1.79 vs. 1.95 g/d; P = 0.014 en Exp. 2). Debido a que el nitr��geno retenido (NR) en la canal fue similar para ambos niveles (0.68 g/d (Exp. 1) y 0.71 g/d (Exp. 2)), la eficacia total de retenci��n del nitr��geno (ERN) aument�� con el nivel m��ximo de inclusi��n de grasa, pero de forma significativa ��nicamente en el Exp. 1 (34.9 vs. 37.8%; P < 0.0001), mientras que en el Exp. 2 se encontr�� una tendencia (36.2 vs. 38.0% en Exp. 2; P < 0.064). Como consecuencia, la excreci��n de nitr��geno en heces fue menor en los animales alimentados con el nivel m��s alto de grasa (0.782 vs. 0.868 g/d; P = 0.0001 en Exp. 1, y 0.745 vs. 0.865 g/d; P < 0.0001 en Exp.2) al igual que el nitr��geno excretado en orina (0.702 vs. 0.822 g/d; P < 0.0001 en Exp. 1 y 0.694 vs. 0.7999 g/d; P = 0.014 en Exp.2). Aunque no hubo diferencias en la eficacia total de retenci��n de la energ��a (ERE), la energ��a excretada en heces disminuy�� al aumentar el nivel de inclusi��n de grasa (142 vs. 156 Kcal/d; P = 0.0004 en Exp. 1 y 144 vs. 154 g/d; P = 0.050 en Exp. 2). Sin embargo, la energ��a excretada como orina y en forma de calor fue mayor en el los animales del Exp. 1 alimentados con el nivel m��s alto de grasa (216 vs. 204 Kcal/d; P < 0.017). Se puede concluir que la manteca y el aceite de palmiste pueden ser considerados como fuentes alternativas al aceite de soja debido a la reducci��n de la mortalidad, sin efectos negativos sobre los rendimientos productivos o la retenci��n de nutrientes. La inclusi��n de aceite de pescado empeor�� los rendimientos productivos y la mortalidad durante el periodo de crecimiento. Un aumento en el nivel de grasa mejor�� el ��ndice de conversi��n y la eficacia total de retenci��n de nitr��geno. ABSTRACT The aim of this Thesis is: 1) to obtain and validate prediction equations to determine in vivo whole body and carcass composition using the Bioelectrical Impedance (BIA) method in growing rabbits from 25 to 77 days of age, and 2) to study its application to determine differences on whole body and carcass chemical composition, and nutrient retention of animals fed different fat levels and sources. The first study was conducted to determine and later validate, by using independent data, the prediction equations obtained to assess in vivo the whole body composition of growing rabbits. One hundred and fifty rabbits grouped at 5 different ages (25, 35, 49, 63 and 77 days) and weighing from 231 to 3138 g were used. A four terminal body composition analyser was used to obtain resistance (Rs, ���) and reactance (Xc, ���) values (Model BIA-101, RJL Systems, Detroit, MI USA). The distance between internal electrodes (D, cm), body length (L, cm) and live BW of each animal were also registered. At each selected age, animals were slaughtered, ground and frozen (-20 ��C) for later chemical analyses (DM, fat, CP, ash and GE). Fat and energy body content increased with the age, while protein, ash, and water decreased. Mean values of Rs, Xc, impedance (Z), L and D were 83.5 �� 23.1 ���, 18.2 �� 3.8 ���, 85.6 �� 22.9 ���, 30.6 �� 6.9 cm and 10.8 �� 3.1 cm. A multiple linear regression analysis was used to determine the prediction equations, using BW, L and Z data as independent variables. Equations obtained to estimate water (g), CP (g), fat (g), ash (g) and GE (MJ) content had, respectively, coefficient of determination (R2) values of 0.99, 0.99, 0.97, 0.98 and 0.99, and the relative mean prediction error (RMPE) was: 2.79, 6.15, 24.3, 15.2 and 10.6%, respectively. When water was expressed as percentage, the R2 and RMPE were 0.85 and 2.30%, respectively. When prediction of the content of protein (%DM), fat (%DM), ash (%DM) and energy (kJ/100 g DM) was done, values of 0.79, 0.83, 0.71 and 0.86 for R2, and 5.04, 18.9, 12.0 and 3.19% for RMPE, respectively, were obtained. Reactance was negatively correlated with water, ash and CP content (r = -0.32, P < 0.0001; r = -0.20, P < 0.05; r = -0.26, P < 0.01) and positively correlated with fat and GE (r = 0.23 and r = 0.24; P < 0.01). Otherwise, resistance was positively correlated with water, ash and CP (r = 0.31, P < 0.001; r = 0.28, P < 0.001; r = 0.37, P < 0.0001) and negatively correlated with fat and energy (r = -0.36 and r = -0.35; P < 0.0001). Moreover, age was negatively correlated with water, ash and CP content (r = -0.79; r = -0.68 and r = -0.80; P < 0.0001) and positively correlated with fat and energy (r = 0.78 and r = 0.81; P < 0.0001). It could be concluded that BIA is a non-invasive good method to estimate in vivo whole body composition of growing rabbits from 25 to 77 days of age. The aim of the second study was to determine and validate with independent data, the prediction equations obtained to estimate in vivo carcass composition of growing rabbits by using the results of carcass chemical composition and BIA values in a group of rabbits from 25 to 77 days. Also its potential application to predict nutrient retention and overall energy and nitrogen retention efficiencies was analysed. Seventy five rabbits grouped at 5 different ages (25, 35, 49, 63 and 77 days) with weights ranging from 196 to 3260 g were used. A four terminal body composition analyser (Model BIA-101, RJL Systems, Detroit, MI USA) was used to obtain resistance (Rs, ���) and reactance (Xc, ���) values. The distance between internal electrodes (D, cm), body length (L, cm) and live weight (BW, g) were also registered. At each selected age, all the animals were stunned and bled. The skin, organs and digestive content were removed, and the chilled carcass were weighed and processed for chemical analyses (DM, fat, CP, ash and GE). Energy and fat increased with the age, while CP, ash, and water decreased. Mean values of Rs, Xc, impedance (Z), L and D were 95.9��23.9 ���, 19.5��4.7 ���, 98.0��23.8 ���, 20.6��6.3 cm y 13.7��3.1 cm. A multiple linear regression analysis was done to determine the equations, using BW, L and Z data as parameters. Coefficient of determination (R2) of the equations obtained to estimate water (g), CP (g), fat (g), ash (g) and GE (MJ) content were: 0.99, 0.99, 0.95, 0.96 and 0.98, and relative mean prediction error (RMPE) were: 4.20, 5.48, 21.9, 9.10 and 6.77%, respectively. When water content was expressed as percentage, the R2 and RMPE were 0.79 and 1.62%, respectively. When prediction of protein (%DM), fat (%DM), ash (%DM) and energy (kJ/100 g DM) content was done, R2 values were 0.68, 0.76, 0.66 and 0.82, and RMPE: 3.22, 10.5, 5.82 and 2.54%, respectively. Reactance was positively correlated with fat content (r = 0.24, P < 0.05) while resistance was positively correlated with water, ash and protein carcass content (r = 0.55, P < 0.001; r = 0.54, P < 0.001; r = 0.40, P < 0.005) and negatively correlated with fat and energy (r = -0.44 and r = -0.55; P < 0.001). Moreover, age was negatively correlated with water, ash and CP content (r = -0.97, r = -0.95 and r = -0.89, P < 0.0001) and positively correlated with fat and GE (r = 0.95 and r = 0.97; P < 0.0001). In the whole growing period (35-63 d), overall energy retention efficiency (ERE) and nitrogen retention efficiency (NRE) were studied. The ERE values were 20.4��7.29%, 21.0��4.18% and 20.8��2.79%, from 35 to 49, 49 to 63 and from 35 to 63 d, respectively. NRE was 46.9��11.7%, 34.5��7.32% and 39.1��3.23% for the same periods. Energy was retained in body tissues for growth with an efficiency of approximately 52.5% and efficiency of the energy for protein and fat retention was 33.3 and 69.9%, respectively. Efficiency of utilization of nitrogen for growth was near to 77%. This work shows that BIA it���s a non-invasive and good method to estimate in vivo carcass composition and nutrient retention of growing rabbits from 25 to 77 days of age. In the third study, two experiments were conducted to investigate the effect of the fat addition and source, on performance, mortality, nutrient retention, and the whole body and carcass chemical composition of growing rabbits from 34 to 63 d. In Exp. 1 three diets were arranged in a 3 x 2 factorial structure with the source of fat: Soybean oil (SBO), Soya Lecithin Oil (SLO) and Lard (L) and the dietary fat inclusion level (1.5 and 4%) as the main factors. Exp. 2 had also arranged as a 3 x 2 factorial design, but using SBO, Fish Oil (FO) and Palmkernel Oil (PKO) as fat sources, and included at the same levels than in Exp. 1. In both experiments 180 animals were allocated in individual cages (n=30) and 600 in collectives cages, in groups of 5 animals (n=20). Animals fed with 4% dietary fat level showed lower DFI and FCR than those fed diets with 1.5%. In collective housing of Exp. 1, DFI was a 4.8% higher in animals fed with diets containing lard than SBO (P = 0.036), being intermediate for diet with SLO. Inclusion of lard also tended to reduce mortality (P = 0.067) around 60% and 25% with respect SBO and SLO diets, respectively. Mortality increased with the greatest level of soya lecithin (14% vs. 1%, P < 0.01). In Exp. 2 a decrease of DFI (11%), BW at 63 d (4.8%) and DWG (7.8%) were observed with the inclusion of fish oil with respect the other two diets (P < 0.01). These last two traits impaired with the highest level of fish oil (5.6 and 9.5%, respectively, (P < 0.01)). Animals housed individually showed similar performance results. The inclusion of fish oil also tended to increase (P = 0.078) mortality (13.2%) with respect palmkernel oil (6.45%), being mortality of SBO intermediate (8.10%). Fat source and level did not affect the whole body or carcass chemical composition. An increase of the fat sources addition led to a decrease of the digestible nitrogen intake (DNi) (1.83 vs. 1.92 g/d; P = 0.068 in Exp. 1 and 1.79 vs. 1.95 g/d; P = 0.014 in Exp. 2). As the nitrogen retained (NR) in the carcass was similar for both fat levels (0.68 g/d (Exp. 1) and 0.71 g/d (Exp. 2)), the overall efficiency of N retention (NRE) increased with the highest level of fat, but only reached significant level in Exp. 1 (34.9 vs. 37.8%; P < 0.0001), while in Exp. 2 a tendency was found (36.2 vs. 38.0% in Exp. 2; P < 0.064). Consequently, nitrogen excretion in faeces was lower in animals fed with the highest level of fat (0.782 vs. 0.868 g/d; P = 0.0001 in Exp. 1, and 0.745 vs. 0.865 g/d; P < 0.0001 in Exp.2). The same effect was observed with the nitrogen excreted as urine (0.702 vs. 0.822 g/d; P < 0.0001 in Exp. 1 and 0.694 vs. 0.7999 g/d; P = 0.014 in Exp.2). Although there were not differences in ERE, the energy excreted in faeces decreased as fat level increased (142 vs. 156 Kcal/d; P = 0.0004 in Exp. 1 and 144 vs. 154 g/d; P = 0.050 in Exp. 2). In Exp. 1 the energy excreted as urine and heat production was significantly higher when animals were fed with the highest level of dietary fat (216 vs. 204 Kcal/d; P < 0.017). It can be concluded that lard and palmkernel oil can be considered as alternative sources to soybean oil due to the reduction of the mortality, without negative effects on performances or nutrient retention. Inclusion of fish impaired animals�� productivity and mortality. An increase of the dietary fat level improved FCR and overall protein efficiency retention.