Fractal scaling of apparent soil moisture estimated from vertical planes of Vertisol pit images

Image analysis could be a useful tool for investigating the spatial patterns of apparent soil moisture at multiple resolutions. The objectives of the present work were (i) to define apparent soil moisture patterns from vertical planes of Vertisol pit images and (ii) to describe the scaling of apparent soil moisture distribution using fractal parameters. Twelve soil pits (0.70 m long × 0.60 m width × 0.30 m depth) were excavated on a bare Mazic Pellic Vertisol. Six of them were excavated in April/2011 and six pits were established in May/2011 after 3 days of a moderate rainfall event. Digital photographs were taken from each Vertisol pit using a Kodak™ digital camera. The mean image size was 1600 × 945 pixels with one physical pixel ≈373 μm of the photographed soil pit. Each soil image was analyzed using two fractal scaling exponents, box counting (capacity) dimension (DBC) and interface fractal dimension (Di), and three prefractal scaling coefficients, the total number of boxes intercepting the foreground pattern at a unit scale (A), fractal lacunarity at the unit scale (Λ1) and Shannon entropy at the unit scale (S1). All the scaling parameters identified significant differences between both sets of spatial patterns. Fractal lacunarity was the best discriminator between apparent soil moisture patterns. Soil image interpretation with fractal exponents and prefractal coefficients can be incorporated within a site-specific agriculture toolbox. While fractal exponents convey information on space filling characteristics of the pattern, prefractal coefficients represent the investigated soil property as seen through a higher resolution microscope. In spite of some computational and practical limitations, image analysis of apparent soil moisture patterns could be used in connection with traditional soil moisture sampling, which always renders punctual estimates

Experimental model to estimate shading losses on PV arrays

This paper presents a simple mathematical model to estimate shading losses on PV arrays. The model is applied directly to power calculations, without the need to consider the whole current–voltage curve. This allows the model to be used with common yield estimation software. The model takes into account both the shaded fraction of the array area and the number of blocks (a group of solar cells protected by a bypass diode) affected by shade. The results of an experimental testing campaign on several shaded PV arrays to check the validity of model are also reported.

Fractal scaling of apparent soil moisture estimated from vertical planesof Vertisol pit images

Image analysis could be a useful tool for investigating the spatial patterns of apparent soil moisture at multiple resolutions. The objectives of the present work were (i) to define apparent soil moisture patterns from vertical planes of Vertisol pit images and (ii) to describe the scaling of apparent soil moisture distribution using fractal parameters. Twelve soil pits (0.70 m long × 0.60 m width × 0.30 m depth) were excavated on a bare Mazic Pellic Vertisol. Six of them were excavated in April/2011 and six pits were established in May/2011 after 3 days of a moderate rainfall event. Digital photographs were taken from each Vertisol pit using a Kodak? digital camera. The mean image size was 1600 × 945 pixels with one physical pixel ?373 ?m of the photographed soil pit. Each soil image was analyzed using two fractal scaling exponents, box counting (capacity) dimension (DBC) and interface fractal dimension (Di), and three prefractal scaling coefficients, the total number of boxes intercepting the foreground pattern at a unit scale (A), fractal lacunarity at the unit scale (?1) and Shannon entropy at the unit scale (S1). All the scaling parameters identified significant differences between both sets of spatial patterns. Fractal lacunarity was the best discriminator between apparent soil moisture patterns. Soil image interpretation with fractal exponents and prefractal coefficients can be incorporated within a site-specific agriculture toolbox. While fractal exponents convey information on space filling characteristics of the pattern, prefractal coefficients represent the investigated soil property as seen through a higher resolution microscope. In spite of some computational and practical limitations, image analysis of apparent soil moisture patterns could be used in connection with traditional soil moisture sampling, which always renders punctual estimates.

Influence of long-time storage. Stress relaxation losses of prestressing steel wires

Prestressed structures are susceptible to relaxation losses which are of significant importance in structural design. After being manufactured, prestressing wires are coiled to make their storage and transportation easier. The possible deleterious effects of this operation on the stress relaxation behavior of prestressing steel wires are usually neglected, though it has been noticed by manufacturers and contractors that when relaxation tests are carried out after a long-time storage, on occasions relaxation losses are higher than those measured a short time after manufacturing. The influence of coiling on the relaxation losses is checked by means of experimental work and confirmed with a simple analytical model. The results show that some factors like initial residual stresses, excessively long-time storage or storage at high temperatures,can trigger or accentuate this damage. However, it is also shown that if the requirements of standards are fulfilled (minimum coiling diameters) these effects can be neglected.

Influencia de las condiciones de almacenamiento sobre la relajación de aceros de pretensado = Influence of storage conditions on prestressing steel relaxation losses

La pérdida de tensión por relajación en las armaduras activas afecta de forma importante a las estructuras de hormigón pretensado. Por ello se realizan ensayos de relajación de los alambres y cordones de pretensado tras su fabricación. Después, el material es enrollado y almacenado durante periodos que en ocasiones pueden superar el año de duración. Generalmente se desprecia la influencia que estas operaciones posteriores a la fabricación pueden tener sobre el material. Sin embargo, diversos fabricantes y suministradores han constatado experimentalmente que, en ocasiones, el material almacenado durante un periodo prolongado presenta pérdidas de relajación mayores que inmediatamente tras su fabricación. En este trabajo se realizan ensayos de laboratorio para comprobar la influencia que el radio de enrollamiento y el periodo de almacenamiento tienen sobre las pérdidas de relajación. También se propone un modelo analítico que permite predecir de manera razonablemente aproximada el valor del ensayo de relajación sobre un alambre sometido a un enrollamiento prolongado. Este modelo explica la evolución del perfil de tensiones durante el proceso de enrollamiento- almacenamiento-desenrollamiento, así como la influencia de las tensiones residuales.Stress relaxation losses on active reinforcement have significant impact on prestressed concrete structures. This is why relaxation tests are carried out on prestressing steel wires and strands after being manufactured. Then, these materials are coiled and stored for a long-term period, sometimes in excess of one year. The influence of these operations, carried out after manufacturing, is usually neglected. Nevertheless, some manufacturers and contractors have noticed that, sometimes, when relaxation tests are carried out after a long-term storage, the relaxation losses found are higher than those measured immediately after manufacturing. In this work, lab tests are performed to check the influence of the coiling radius and the period of storage on the relaxation test. In addition to this, an analytical model is presented to predict the results of a relaxation

Low losses power distribution network at X band in stripline

An asymmetric stripline is proposed in this paper. The main aim of this line is to distribute the power among subarrays in an array with minimum losses. Several vertical transitions to subarrays are shown besides some network designs at X band for a square array for satellite communications.

Farm nitrogen balances in six European landscapes as an indicator for nitrogen losses and basis for improved management.

Improved management of nitrogen (N) in agriculture is necessary to achieve a sustainable balance between the production of food and other biomass, and the unwanted effects of N on water pollution, greenhouse gas emissions, biodiversity deterioration and human health. To analyse farm N-losses and the complex interactions within farming systems, efficient methods for identifying emissions hotspots and evaluating mitigation measures are therefore needed. The present paper aims to fill this gap at the farm and landscape scales. Six agricultural landscapes in Poland (PL), the Netherlands (NL), France (FR), Italy (IT), Scotland (UK) and Denmark (DK) were studied, and a common method was developed for undertaking farm inventories and the derivation of farm N balances, N surpluses and for evaluating uncertainty for the 222 farms and 11 440 ha of farmland included in the study. In all landscapes, a large variation in the farm N surplus was found, and thereby a large potential for reductions. The highest average N surpluses were found in the most livestock-intensive landscapes of IT, FR, and NL; on average 202 ± 28, 179 ± 63 and 178 ± 20 kg N ha−1 yr−1, respectively. All landscapes showed hotspots, especially from livestock farms, including a special UK case with large-scale landless poultry farming. Overall, the average N surplus from the land-based UK farms dominated by extensive sheep and cattle grazing was only 31 ± 10 kg N ha−1 yr−1, but was similar to the N surplus of PL and DK (122 ± 20 and 146 ± 55 kg N ha−1 yr−1, respectively) when landless poultry farming was included. We found farm N balances to be a useful indicator for N losses and the potential for improving N management. Significant correlations to N surplus were found, both with ammonia air concentrations and nitrate concentrations in soils and groundwater, measured during the period of N management data collection in the landscapes from 2007–2009. This indicates that farm N surpluses may be used as an independent dataset for validation of measured and modelled N emissions in agricultural landscapes. No significant correlation was found with N measured in surface waters, probably because of spatial and temporal variations in groundwater buffering and biogeochemical reactions affecting N flows from farm to surface waters. A case study of the development in N surplus from the landscape in DK from 1998–2008 showed a 22% reduction related to measures targeted at N emissions from livestock farms. Based on the large differences in N surplus between average N management farms and the most modern and N-efficient farms, it was concluded that additional N-surplus reductions of 25–50%, as compared to the present level, were realistic in all landscapes. The implemented N-surplus method was thus effective for comparing and synthesizing results on farm N emissions and the potentials of mitigation options. It is recommended for use in combination with other methods for the assessment of landscape N emissions and farm N efficiency, including more detailed N source and N sink hotspot mapping, measurements and modelling.

Reduction of Nutrient Losses with Eroded Sediments by Post-Fire Soil Stabilisation Techniques

After an experimental fire in steep shrub land in a temperate–humid region (north-west Spain), the effects of two post-fire stabilisation treatments (grass seeding and straw mulching) on the chemical properties of eroded sediments,and the amount of nutrients lost with them, we reevaluated relative to control burnt soil, over a period of 13 months. Total C and N concentrations, and d 13 C, indicated that sediments were mainly contributed by charred plant and litter material. The highest concentrations of extractable base cations in the sediments occurred during the first 3 months following fire, especially for Na and K. As treatments had little or no effect on nutrient concentration in sediments, differences in nutrient losses were due to the 10-fold lower sediment production in mulching compared with other treatments. In control and seeding treatments, the accumulated amounts of nutrients lost with sediments were 989–1028kgha 1 (C), 77kgha 1 (N), 1.9–2.4kgha 1 (Ca), 0.9–1.1kgha 1 (Mg), 0.48–0.55kgha 1 (NH 4 þ –N), 0.39–0.56kgha 1 (K), 0.19–0.34kgha 1 (Na) and , 0.1kgha 1 (P and NO 3 –N) . These values accounted for 22–25% (total C and N) and 5–12% (NH 4 þ –N, Ca, P and Mg) of available nutrients in ash, and 1.0–2.4% of those in ash þ topsoil. As nutrient and sediment losses were strongly correlated, the reduction of the latter by mulching application leads to an effective decrease of post-fire nutrient losses.

Propagation losses by tunnelling in barrier optical waveguides

An analytical model is proposed in order to estimate the optical propagation losses due to tunnelling in barrier waveguides. The results are validated by means of a beam propagation method (BPM) simulations for different waveguides conditions.

Heat losses in a CVD reactor for polysilicon: comprehensive model and experimental validation

This work addresses heat losses in a CVD reactor for polysilicon production. Contributions to the energy consumption of the so-called Siemens process are evaluated, and a comprehensive model for heat loss is presented. A previously-developed model for radiative heat loss is combined with conductive heat loss theory and a new model for convective heat loss. Theoretical calculations are developed and theoretical energy consumption of the polysilicon deposition process is obtained. The model is validated by comparison with experimental results obtained using a laboratory-scale CVD reactor. Finally, the model is used to calculate heat consumption in a 36-rod industrial reactor; the energy consumption due to convective heat loss per kilogram of polysilicon produced is calculated to be 22-30 kWh/kg along a deposition process.

Effects of radiation losses on very lean methane/air flames propagating upward in a vertical tube

The stationary upward propagation of a very lean methane/air flame in a long vertical tube open at the bottom and closed at the top is simulated numerically using a single overall chemical reaction to model combustion and assuming an optically thin gas and a transparent or non-reflecting tube wall to approximately account for radiation losses from CO2CO2 and H2OH2O. Buoyancy plays a dominant role in the propagation of these flames and causes a large region of low velocity of the burnt gas relative to the flame to appear below the flame front when the equivalence ratio is decreased. The size of this region scales with the radius of the tube, and its presence enhances the effect of radiation losses, which would be otherwise negligible for a standard flammability tube, given the small concentration of radiating species. Heat conduction is found to be important in the low velocity region and to lead to a conduction flux from the flame to the burnt gas that causes extinction at the flame tip for a value of the equivalence ratio near the flammability limit experimentally measured in the standard tube. The effect of radiation losses decreases with the radius of the tube. Numerical results and order-of-magnitude estimates show that, in the absence of radiation, a very lean flame front fails to propagate only after recirculation of the burnt gas extends to its reaction region and drastically changes its structure. This condition is not realized for the standard flammability tube, but it seems to account for the flammability limit measured in a tube of about half the radius of the standard tube.

Initializing the DSSAT-Century model: inverse calibration of carbon pools from apparent soil N mineralization

The CENTURY soil organic matter model was adapted for the DSSAT (Decision Support System for Agrotechnology Transfer), modular format in order to better simulate the dynamics of soil organic nutrient processes (Gijsman et al., 2002). The CENTURY model divides the soil organic carbon (SOC) into three hypothetical pools: microbial or active material (SOC1), intermediate (SOC2) and the largely inert and stable material (SOC3) (Jones et al., 2003). At the beginning of the simulation, CENTURY model needs a value of SOC3 per soil layer which can be estimated by the model (based on soil texture and management history) or given as an input. Then, the model assigns about 5% and 95% of the remaining SOC to SOC1 and SOC2, respectively. The model performance when simulating SOC and nitrogen (N) dynamics strongly depends on the initialization process. The common methods (e.g. Basso et al., 2011) to initialize SOC pools deal mostly with carbon (C) mineralization processes and less with N. Dynamics of SOM, SOC, and soil organic N are linked in the CENTURY-DSSAT model through the C/N ratio of decomposing material that determines either mineralization or immobilization of N (Gijsman et al., 2002). The aim of this study was to evaluate an alternative method to initialize the SOC pools in the DSSAT-CENTURY model from apparent soil N mineralization (Napmin) field measurements by using automatic inverse calibration (simulated annealing). The results were compared with the ones obtained by the iterative initialization procedure developed by Basso et al., 2011.

Effects of nutrition on digestión efficiency and gaseous emissions from slurry in growing pigs: III. Influence of varying the dietary level of calcium soap of palm fatty acids distillate with or without orange pulp supplemention

The aim of this study was to establish the relationships between faecal fat concentration and gaseous emissions from pig slurry. Five diets were designed to meet essential nutrient requirements: a control and four experimental feeds including two levels (35 or 70 g/kg) of calcium soap fatty acids distillate (CSP) and 0 or 200 g/kg of orange pulp (OP) combined in a 2 × 2 factorial structure. Thirty growing pigs (six per treatment) were used to measure dry matter (DM) and N balance, coefficients of total tract apparent digestibility (CTTAD) of nutrients, faecal and urine composition and potential emissions of ammonia (NH3) and methane (CH4). Increasing dietary CSP level decreased DM, ether extract (EE) and crude protein (CP) CTTAD (by 4.0, 11.1 and 3.5%, respectively, P < 0.05), but did not influence those of fibrous constituents. It also led to a decrease (from 475 to 412 g/kg DM, P < 0.001) of faecal concentration of neutral detergent fibre (aNDFom) and to an increment (from 138 to 204 g/kg, P < 0.001) of EE in faecal DM that was related to greater CH4 emissions, both per gram of organic matter (P = 0.021) or on a daily basis (P < 0.001). Level of CSP did not affect N content in faeces or urine, but increased daily DM (P < 0.001), and N (P = 0.031) faecal excretion with no effect on urine N excretion. This resulted in lesser (P = 0.036) NH3 potential emission per kg of slurry. Addition of OP decreased CTTAD of EE (by 7.9%, P = 0.044), but increased (P < 0.05) that of all the fibrous fractions. As a consequence, faecal EE content increased (from 165 to 177 g/kg DM; P = 0.012), and aNDFom decreased greatly (from 483 to 404 g/kg DM, P < 0.001), which in all resulted in a lack of effect of OP on CH4 potential emission. Inclusion of OP in the diet also led to a significant decrease of CP CTTAD (by 6.85%, P < 0.001), and to an increase of faecal CP concentration (from 174 to 226 g/kg DM, P < 0.001), with no significant influence on urine N content. These effects resulted in higher N faecal losses, especially those of the undigested dietary origin, without significant effects on potential NH3 emission. No significant interactions between CSP and OP supplementation were observed for the gaseous emissions measured.

Ammonia and methane gas emissions from pig slurry: variability induced through feeding strategies

Esta Tesis doctoral fue desarrollada para estudiar las emisiones de amoniaco (NH3) y metano (CH4) en purines de cerdos, y los efectos ocasionados por cambios en la formulación de la dieta. Con este propósito, fueron llevados a cabo tres estudios. El experimento 1 fue realizado con el objetivo de analizar los factores de variación de la composición de purines y establecer ecuaciones de predicción para emisiones potenciales de NH3 y CH4. Fueron recogidas setenta y nueve muestras de piensos y purines durante dos estaciones del año (verano y invierno) de granjas comerciales situadas en dos regiones de España (Centro y Mediterráneo). Se muestrearon granjas de gestación, maternidad, lactación y cebo. Se determinó la composición de piensos y purines, y la emisión potencial de NH3 y CH4. El contenido de nutrientes de los piensos fue usado como covariable en el análisis. La espectroscopia de reflectancia del infrarrojo cercano (NIRS) se evaluó como herramienta de predicción de la composición y potencial emisión de gases del purín. Se encontró una amplia variabilidad en la composición de piensos y purines. Las granjas del Mediterráneo tenían mayor pH (P<0,001) y concentración de cenizas (P =0,02) en el purín que las del Centro. El tipo de granja también afectó al contenido de extracto etéreo (EE) del purín (P =0,02), observando los valores más elevados en las instalaciones de animales jóvenes. Los resultados sugieren un efecto tampón de la fibra de la dieta en el pH del purín y una relación directa (P<0,05) con el contenido de fibra fecal. El contenido de proteína del pienso no afectó al contenido de nitrógeno del purín, pero disminuyó (P=0,003) la concentración de sólidos totales (ST) y de sólidos volátiles (SV). Se obtuvieron modelos de predicción de la emisión potencial de NH3 (R2=0,89) y CH4 (R2=0,61) partir de la composición del purín. Los espectros NIRS mostraron una buena precisión para la estimación de la mayor parte de los constituyentes, con coeficientes de determinación de validación cruzada (R2cv) superiores a 0,90, así como para la predicción del potencial de emisiones de NH3 y CH4 (R2cv=0,84 y 0,68, respectivamente). El experimento 2 fue realizado para investigar los efectos del nivel de inclusión de dos fuentes de sub-productos fibrosos: pulpa de naranja (PN) y pulpa de algarroba (PA), en dietas iso-fibrosas de cerdos de cebo, sobre la composición del purín y las emisiones potenciales de NH3 y CH4. Treinta cerdos (85,4±12,3 kg) fueron alimentados con cinco dietas iso-nutritivas: control comercial trigo/cebada (C) y cuatro dietas experimentales incluyendo las dos fuentes de sub-productos a dos niveles (75 y 150 g/kg) en una estructura 2 × 2 factorial. Después de 14 días de periodo de adaptación, heces y orina fueron recogidas separadamente durante 7 días para medir la digestibilidad de los nutrientes y el nitrógeno (N) excretado (6 réplicas por dieta) en cerdos alojados individualmente en jaulas metabólicas. Las emisiones de NH3 y CH4 fueron medidas después de la recogida de los purínes durante 11 y 100 días respectivamente. La fuente y el nivel de subproductos fibrosos afectó a la eficiencia digestiva de diferentes formas, ya que los coeficientes de digestibilidad total aparente (CDTA) para la materia seca (MS), materia orgánica (MO), fracciones fibrosas y energía bruta (EB) aumentaron con la PN pero disminuyeron con la inclusión de PA (P<0,05). El CDTA de proteína bruta (PB) disminuyó con la inclusión de las dos fuentes de fibra, siendo más bajo al mayor nivel de inclusión. La concentración fecal de fracciones fibrosas aumentó (P<0,05) con el nivel de inclusión de PA pero disminuyó con el de PN (P<0,01). El nivel más alto de las dos fuentes de fibra en el pienso aumentó (P<0,02) el contenido de PB fecal pero disminuyó el contenido de N de la orina (de 205 para 168 g/kg MS, P<0,05) en todas las dietas suplementadas comparadas con la dieta C. Adicionalmente, las proporciones de nitrógeno indigerido, nitrógeno soluble en agua, nitrógeno bacteriano y endógeno excretado en heces no fueron afectados por los tratamientos. Las características iniciales del purín no difirieron entre las diferentes fuentes y niveles de fibra, excepto para el pH que disminuyó con la inclusión de altos niveles de sub-productos. La emisión de NH3 por kg de purín fue más baja en todas las dietas suplementadas con fibras que en la dieta C (2,44 vs.1,81g de promedio, P<0,05). Además, purines de dietas suplementadas con alto nivel de sub-productos tendieron (P<0,06) a emitir menos NH3 por kg de nitrógeno total y mostraron un potencial más bajo para emitir CH4, independientemente de la fuente de fibra. El experimento 3 investigó los efectos de la fuente de proteína en dietas prácticas. Tres piensos experimentales fueron diseñados para sustituir una mescla de harina y cascarilla de soja (SOJ) por harina de girasol (GIR) o por DDGS del trigo (DDGST). La proporción de otros ingredientes fue modificada para mantener los contenidos de nutrientes similares a través de las dietas. El cambio en la fuente de proteína dio lugar a diferencias en el contenido de fibra neutro detergente ligada a proteína bruta (FNDPB), fibra soluble (FS) y lignina ácido detergente (LAD) en la dieta. Veinticuatro cerdos (ocho por dieta), con 52,3 o 60,8 kg en la primera y segunda tanda respectivamente, fueron alojados individualmente en jaulas metabólicas. Durante un periodo de 7 días fue determinado el balance de MS, el CDTA de los nutrientes y la composición de heces y orina. Se realizó el mismo procedimiento del experimento 2 para medir las emisiones de NH3 y CH4 de los purines de cada animal. Ni la ingestión de MS ni el CDTA de la MS o de la energía fueron diferentes entre las dietas experimentales, pero el tipo de pienso afectó (P<0.001) la digestibilidad de la PB, que fue mayor para GIR (0,846) que para SOJ (0,775), mientras que la dieta DDGST mostró un valor intermedio (0,794). La concentración fecal de PB fue por tanto influenciada (P<0,001) por el tratamiento, observándose la menor concentración de PB en la dieta GIR y la mayor en la dieta SOJ. La proporción de N excretado en orina o heces disminuyó de 1,63 en la dieta GIR hasta 0,650 en la dieta SOJ, como consecuencia de perdidas más bajas en orina y más altas en heces, con todas las fracciones de nitrógeno fecales creciendo en paralelo a la excreción total. Este resultado fue paralelo a una disminución de la emisión potencial de NH3 (g/kg purín) en la dieta SOJ con respecto a la dieta GIR (desde 1,82 a 1,12, P<0,05), dando valores intermedios (1,58) para los purines de la dieta DDGST. Por otro lado, el CDTA de la FS y de la fibra neutro detergente (FND) fueron afectados (P<0,001 y 0,002, respectivamente) por el tipo de dieta, siendo más bajas en la dieta GIR que en la dieta SOJ; además, se observó un contenido más alto de FND (491 vs. 361g/kg) en la MS fecal para la dieta GIR que en la dieta SOJ, presentando la dieta DDGST valores intermedios. El grado de lignificación de la FND (FAD/FND x 100) de las heces disminuyó en el orden GIR>DDGST>SOJ (desde 0,171 hasta 0,109 y 0,086, respectivamente) en paralelo a la disminución del potencial de emisión de CH4 por g de SV del purín (desde 301 a 269 y 256 mL, respectivamente). Todos los purines obtenidos en estos tres experimentos y Antezana et al. (2015) fueron usados para desarrollar nuevas calibraciones con la tecnología NIRS, para predecir la composición del purín y el potencial de las emisiones de gases. Se observó una buena precisión (R2cv superior a 0,92) de las calibraciones cuando muestras de los ensayos controlados (2, 3 y Antezana et al., 2015) fueron añadidas, aumentando el rango de variación. Una menor exactitud fue observada para TAN y emisiones de NH3 y CH4, lo que podría explicarse por una menor homogeneidad en la distribución de las muestras cuando se amplía el rango de variación del estudio. ABSTRACT This PhD thesis was developed to study the emissions of ammonia (NH3) and methane (CH4) from pig slurry and the effects caused by changes on diet formulation. For these proposes three studies were conducted. Experiment 1 aimed to analyse several factors of variation of slurry composition and to establish prediction equations for potential CH4 and NH3 emissions. Seventy-nine feed and slurry samples were collected at two seasons (summer and winter) from commercial pig farms sited at two Spanish regions (Centre and Mediterranean). Nursery, growing-fattening, gestating and lactating facilities were sampled. Feed and slurry composition were determined, and potential CH4 and NH3 emissions measured. Feed nutrient contents were used as covariates in the analysis. Near infrared reflectance spectroscopy (NIRS) was evaluated as a predicting tool for slurry composition and potential gaseous emissions. A wide variability was found both in feed and slurry composition. Mediterranean farms had a higher pH (P<0.001) and ash (P=0.02) concentration than those located at the centre of Spain. Also, type of farm affected ether extract (EE) content of the slurry (P=0.02), with highest values obtained for the youngest animal facilities. Results suggested a buffer effect of dietary fibre on slurry pH and a direct relationship (P<0.05) with fibre constituents of manure. Dietary protein content did not affect slurry nitrogen content (N) but decreased (P=0.003) in total solid (TS) and volatile solids (VS) concentration. Prediction models of potential NH3 emissions (R2=0.89) and biochemical CH4 potential (B0) (R2=0.61) were obtained from slurry composition. Predictions from NIRS showed a high accuracy for most slurry constituents with coefficient of determination of cross validation (R2cv) above 0.90 and a similar accuracy of prediction of potential NH3 and CH4 emissions (R2cv=0.84 and 0.68, respectively) thus models based on slurry composition from commercial farms. Experiment 2 was conducted to investigate the effects of increasing the level of two sources of fibrous by-products, orange pulp (OP) and carob meal (CM), in iso-fibrous diets for growing-finishing pig, slurry composition and potential NH3 and CH4 emissions. Thirty pigs (85.4±12.3 kg) were fed five iso-nutritive diets: a commercial control wheat/barley (C) and four experimental diets including two sources of fibrous by-products OP and CM and two dietary levels (75 and 150 g/kg) in a 2 × 2 factorial arrangement. After a 14-day adaptation period, faeces and urine were collected separately for 7 days to measure nutrient digestibility and the excretory patterns of N from pigs (6 replicates per diet) housed individually in metabolic pens. For each animal, the derived NH3 and CH4 emissions were measured in samples of slurry over an 11 and 100-day storage periods, respectively. Source and level of the fibrous by-products affected digestion efficiency in a different way as the coefficients of total tract apparent digestibility (CTTAD) for dry matter (DM), organic matter (OM), fibre fractions and gross energy (GE) increased with OP but decreased with CM (P<0.05). Crude protein CTTAD decreased with the inclusion of both sources of fibre, being lower at the highest dietary level. Faecal concentration of fibre fractions increased (P<0.05) with the level of inclusion of CM but decreased with that of OP (P<0.01). High dietary level for both sources of fibre increased (P<0.02) CP faecal content but urine N content decreased (from 205 to 168 g/kg DM, P<0.05) in all the fibre-supplemented compared to C diet. Additionally, the proportions of undigested dietary, water soluble, and bacterial and endogenous debris of faecal N excretion were not affected by treatments. The initial slurry characteristics did not differ among different fibre sources and dietary levels, except pH, which decreased at the highest by-product inclusion levels. Ammonia emission per kg of slurry was lower in all the fibre-supplemented diets than in C diet (2.44 vs. 1.81g as average, P<0.05). Additionally, slurries from the highest dietary level of by-products tended (P<0.06) to emit less NH3 per kg of initial total Kjeldahl nitrogen (TKN) and showed a lower biochemical CH4 potential , independently of the fibre source. Experiment 3 investigated the effects of protein source in practical diets. Three experimental feeds were designed to substitute a mixture of soybean meal and soybean hulls (SB diet) with sunflower meal (SFM) or wheat DDGS (WDDGS). The proportion of other ingredients was also modified in order to maintain similar nutrient contents across diets. Changes in protein source led to differences in dietary content of neutral detergent insoluble crude protein (NDICP), soluble fibre (SF) and acid detergent lignin (ADL). Twenty-four pigs (eight per diet), weighing 52.3 or 60.8 kg at the first and second batch respectively, were housed individually in metabolic pens to determine during a 7-day period DM balance, CTTAD of nutrients, and faecal and urine composition. Representative slurry samples from each animal were used to measure NH3 and CH4 emissions over an 11 and or 100-day storage period, respectively. Neither DM intake, nor DM or energy CTTAD differed among experimental diets, but type of feed affected (P<0.001) CP digestibility, which was highest for SFM (0.846) than for SB (0.775) diet, with WDDGS-based diet giving an intermediate value (0.794). Faecal DM composition was influenced (P<0.001) accordingly, with the lowest CP concentration found for diet SFM and the highest for SB. The ratio of N excreted in urine or faeces decreased from SFM (1.63) to SB diet (0.650), as a consequence of both lower urine and higher faecal losses, with all the faecal N fractions increasing in parallel to total excretion. This result was parallel to a decrease of potential NH3 emission (g/kg slurry) in diet SB with respect to diet SFM (from 1.82 to 1.12, P<0.05), giving slurry from WDDGS-based diet an intermediate value (1.58). Otherwise, SF and insoluble neutral detergent fibre (NDF) CTTAD were affected (P<0.001 and P=0.002, respectively) by type of diet, being lower for SFM than in SB-diet; besides, a higher content of NDF (491 vs. 361 g/kg) in faecal DM was observed for SFM with respect to SB based diet, with WDDGS diet being intermediate. Degree of lignification of NDF (ADL/NDF x 100) of faeces decreased in the order SFM>WDDGS>SB (from 0.171 to 0.109 and 0.086, respectively) in parallel to a decrease of biochemical CH4 potential per g of VS of slurry (from 301 to 269 and 256 ml, respectively). All slurry samples obtained from these three experiments and Antezana et al. (2015) were used to develop new calibrations with NIRS technology, to predict the slurry composition and potential gaseous emissions of samples with greater variability in comparison to experiment 1. Better accuracy (R2cv above 0.92) was observed for calibrations when samples from controlled trials experiments (2, 3 and Antezana et al., 2015) were included, increasing the range of variation. A lower accuracy was observed for TAN, NH3 and CH4 gaseous emissions, which might be explained by the less homogeneous distribution with a wider range of data.

Female preference for swords in Xiphophorus helleri reflects a bias for large apparent size

Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous “sword” ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design. We consider two alternative models of receiver behavior, each consistent with previous results. Females could respond either to specific characteristics of the sword or to more general cues, such as the apparent size of potential mates. We showed female swordtails a series of computer-altered video sequences depicting a courting male. Footage of an intact male was preferred strongly to otherwise identical sequences in which portions of the sword had been deleted selectively, but a disembodied courting sword was less attractive than an intact male. There was no difference between responses to an isolated sword and to a swordless male of comparable length, or between an isolated sword and a homogenous background. Female preference for a sworded male was abolished by enlarging the image of a swordless male to compensate for the reduction in length caused by removing the ornament. This pattern of results is consistent with mate choice being mediated by a general preference for large males rather than by specific characters. Similar processes may account for the evolution of exaggerated traits in other systems.