Rasgos fisiográficos y geológicos del territorio del Lucus

Tesis inédita de la Universidad de Madrid, Facultad de Ciencias, leída en 1954.Universidad de MadridTRUEProQuestpu

Rasgos fisiográficos y geológicos del territorio del Lucus

Precede al tít.: Instituto de Estudios Africano

Basic operations and preliminary results on the growth and survival rates of tench (Tinca tinca L.) and lettuce (Lactuca sativa L.) in an aquaponic prototype

Este trabajo presenta el manejo básico de un prototipo acuapónico así como resultados preliminares sobre el crecimiento de tencas y lechugas en dicho prototipo. El sistema consta de una instalación de recirculación de agua con cuatro elementos en el siguiente orden de dirección del agua: depósito de peces, del que parten dos ramas: una de ellas hacia un biofiltro, zona de hidropónicos en NFT (“Nutrient Film Technique”) y colector; y la otra hacia la zona de hidropónicos en raíz flotante, que desemboca igualmente en el colector. Los resultados obtenidos durante 66 días de ensayo, criando las tencas a densidades entre 0,68 kg/m3 y 1,19 kg/m3, con raciones diarias entre el 0,8 y 1,23% de la biomasa, un volumen total de la instalación de 2.800 litros con tasa media diaria de recambio de agua del 1,26% y parámetros variables de la misma, con máximos y mínimos, respectivamente, de temperaturas, entre 15 y 25ºC; de nitratos, entre 32 y 105 ppm; y de pH entre 7,3 y 8,25, muestran una elevada supervivencia de las tencas (99,32%) y las lechugas (98%); y la finalización del ciclo de estas últimas alcanzando tamaños comerciales. El control de los parámetros citados, más los niveles de oxígeno, y una instalación sencilla de baja densidad de peces sin dispositivos de separación de sólidos, permitió la regulación óptima del sistema.This paper presents the basic operations of an aquaponic prototype and preliminary results on the growth of tench and lettuce. This prototype consisting in a water recirculating system made up of: fish rearing tank with two outlet pipes, one of this connected to a biofilter, NFT hydroponics device and sump; and the other one, to a raft hydroponic device draining to the same sump. Results showed a high survival rate of tenchs (99,32%) and lettuces (98%), and finalization of vegetative cycle of lettuce with commercial sizes, under the following assay conditions: tench stock densities between 0,68 kg/m3 and 1,19 kg/m3, with daily food rates between 0,88 y 1,23% of fishes biomass, a total system water volume of 2,8 m3 and 1,26% of water reposition daily rate, and water variables parameters between 15 and 25ºC temperature; 32 and 105 ppm of nitrate levels; and 8,25 and 7,3 pH values. Control of the above mentioned parameters, plus oxygen levels in water, maintaining fish at low densities and without solids removal devices, reached the optimum regulation syste

Composición química de la carne de conejo silvestre (Oryctolagus cuniculus) y viabilidad de su predicción mediante espectroscopía de infrarrojo cercano

En algunos países del entorno mediterráneo existe tradición de consumo de carne de conejo silvestre procedente de la caza. Sin embargo, las características de la canal y de la carne de esta especie cinegética han sido escasamente investigadas. Los objetivos de este estudio fueron analizar la composición química de la carne de conejo silvestre (Oryctolagus cuniculus algirus) procedente del sudoeste de la Península Ibérica y estudiar la viabilidad de la puesta a punto de una metodología rápida de análisis para su determinación mediante espectroscopía de infrarrojo cercano (NIRS). La carne de conejo silvestre de la subespecie O. c. algirus contiene un 23,7% de proteína bruta, 0,2% de grasa bruta, 74,9% de humedad y 1,2% de cenizas. Esta composición difiere de la publicada para conejos domésticos y para conejos silvestres de la subespecie O. c. cuniculus, siendo más magra debido a su mayor contenido de proteína y muy inferior valor de grasa. Se obtuvieron modelos basados en la espectroscopía NIR con buena capacidad de predicción para los parámetros proteína y humedad (r2 = 0,70 y ETVC = 0,39%; y r2 = 0,73 y ETVC = 0,38%; respectivamente); mientras que las calibraciones seleccionadas para grasa y cenizas no resultaron ser aceptables.Wild rabbit meat is commonly consumed in many Mediterranean countries. However, the characteristics of the carcass and meat of this game species have been scarcely investigated. This study was aimed at analysing the chemical composition of hunted wild rabbit (Oryctolagus cuniculus algirus) meat from Southern Iberian Peninsula, and studying the viability of a rapid analytical methodology for its determination by near infrared spectroscopy. Meat of the wild rabbit subspecies O. c. algirus has 23.7% of crude protein, 0.2% of crude fat, 74.9% of moisture and 1.2% of ash. This composition differed from the values published for domesticated rabbits and for wild rabbits of the O. c. cuniculus subspecies, it being leaner due to its higher protein content and its very lower fat content. NIR spectroscopy models obtained displayed a good predictive ability for the estimation of crude protein and moisture contents (r2 = 0.70 and SECV = 0.39%, and r2 = 0.73 and SECV = 0.38%, respectively), while the calibrations selected for crude fat and ash contents were not acceptabl

Manejo de la alimentación en sistemas caprinos característicos de la raza payoya

Payoya es una raza caprina andaluza de aptitud lechera que actualmente se encuentra en peligro de extinción. Se ubica, principalmente, en la Sierra de Cádiz y la Serranía de Ronda (Málaga) y se explota en sistemas semiextensivos o semiintensivos donde el pasto natural y en ocasiones cultivado, constituyen la base de su alimentación. En este trabajo se presentan los resultados del seguimiento mensual de la alimentación en tres explotaciones caprinas, observándose variabilidad, entre explotaciones y entre épocas del año, en cuanto a uso del pasto. El conocimiento del manejo del pastoreo es básico para conseguir que la alimentación en la cabreriza complemente de modo adecuado a la alimentación en el campo, lo cual incidirá directamente en la calidad de los productos y en los beneficios de la explotación

Suitability and optimization of FAO's small-scale aquaponics systems for joint production of lettuce (Lactuca sativa) and fish (Carassius auratus)

Aquaponics is a developing technique that combines the simultaneous production of plants (hydroponics) and fish (aquaculture). With it, the use of resources (i.e., water, nutrients, land) is reduced whilst at the same time minimising residues’ discharge to the environment. Among its benefits, it allows the production of healthy vegetables and fish in reduced spaces by means of small-scale systems. In this work, three of them based on FAO models with different hydroponic subsystems (nutrient film technique -NFT-, floating raft, and vertical felt) are tested to produce lettuce (Lactuca sativa) and goldfish (Carassius auratus). Water parameters as well as the growth of plants and fishes were monitored in two different production cycles. The hydroponic subsystem that outperformed the best was the NFT, both in terms of crop production and water consumption. All systems showed similar results in fish production. Further research is needed to corroborate the outputs obtained when using other combinations of plants and fishes. Small-scale aquaponic systems are particularly interesting for self-production and even more so in urban environments with reduced available space

Economic Sustainability of Small-Scale Aquaponic Systems for Food Self-Production

Aquaponics involves the simultaneous production of plants and fish and it is increasingly being used with a self-consumption purpose. However, there are uncertainties and little information about the economic sustainability of small-scale self-managed aquaponic systems. The objective of this study was to obtain economic information about these systems, including the level of commoditization of food production as a measure of their autonomy. For this purpose, two small-scale aquaponic systems (SAS) based on FAO models were self-constructed using cheap and easy-to-obtain materials and monitored for a year. A total of 62 kg of tilapia and 352 kg of 22 different vegetables and fruits were produced, with an average net agricultural added value of 151.3 €. Results showed positive accounting profit but negative economic profit when labor costs were included. The degree of commoditization was around 44%, which allows a certain autonomy, thanks to the use of family labor force

Characterisation of aquaponic producers and small-scale facilities in Spain and Latin America

Aquaponics is a sustainable food production system combining hydroponics and aquaculture. Although the domestic/small-scale aquaponic production has proliferated worldwide, there is scarce knowledge about how it is performed. The objective of this study was to determine the profile and motivations of aquaponic producers, the characteristics of the facilities and the performance of the production. The average aquaponic producer is a middle-aged man, with a certain level of studies and a moderate household income. The main motivations reported were the production of high-quality, healthy food, the concern for the environment and the autonomy gained. These motivations conditioned the purposes of the aquaponic facilities (mainly education, production of food for self-consumption and as a hobby), which, excepting small sales, did not have an economic motive. Due to their characteristics, aquaponic facilities are particularly adapted for urban agriculture (many of them were located on rooftops) and most of those studied were constructed recently. The nutrient film technique was the most used hydroponic subsystem, followed by media beds, where mostly a polyculture of leaf and fruit vegetables and aromatics are produced. Tilapia was the most common fish species used. In general, there is a lack of proper knowledge and expertise about these complex systems in order to efficiently operate them

Optimisation of the predictive ability of NIR models to estimate nutritional parameters in elephant grass through LOCAL algorithms

Elephant grass is a tropical forage widely used for livestock feed. The analytical techniques traditionally used for its nutritional evaluation are costly and time consuming. Alternatively, Near Infrared Spectroscopy (NIRS) technology has been used as a rapid analysis technique. However, in crops with high variability due to genetic improvement, predictive models quickly lose accuracy and must be recalibrated. The use of non-linear models such as LOCAL calibrations could mitigate these issues, although a number of parameters need to be optimized to obtain accurate results. The objective of this work was to compare the predictive results obtained with global NIRS calibrations and with LOCAL calibrations, paying special attention to the configuration parameters of the models. The results obtained showed that the prediction errors with the LOCAL models were between 1.6 and 17.5 % lower. The best results were obtained in most cases with a low number of selected samples (n = 100–250) and a high number of PLS terms (n = 20). This configuration allows a reduced computation time with high accuracy, becoming a valuable alternative for analytical determinations that require ruminal fluid, which would improve the welfare of the animals by avoiding the need to surgically prepare animals to estimate the nutritional value of the feeds