Juvenile sea stars exposed to acidification decrease feeding and growth with no acclimation potential

Ocean acidification has the potential to affect growth and calcification of benthic marine invertebrates, particularly during their early life history. We exposed field-collected juveniles of Asterias rubens from Kiel Fjord (western Baltic Sea) to 3 seawater CO2 partial pressure (pCO2) levels (ranging from around 650 to 3500 µatm) in a long-term (39 wk) and a short-term (6 wk) experiment. In both experiments, survival and calcification were not affected by elevated pCO2. However, feeding rates decreased strongly with increasing pCO2, while aerobic metabolism and NH4+ excretion were not significantly affected by CO2 exposure. Consequently, high pCO2 reduced the scope for growth in A. rubens. Growth rates decreased substantially with increasing pCO2 and were reduced even at pCO2 levels occurring in the habitat today (e.g. during upwelling events). Sea stars were not able to acclimate to higher pCO2, and growth performance did not recover during the long-term experiment. Therefore, the top-down control exerted by this keystone species may be diminished during periods of high environmental pCO2 that already occur occasionally and will be even higher in the future. However, some individuals were able to grow at high rates even at high pCO2, indicating potential for rapid adaption. The selection of adapted specimens of A. rubens in this seasonally acidified habitat may lead to higher CO2 tolerance in adult sea stars of this population compared to the juvenile stage. Future studies need to address the synergistic effects of multiple stressors such as acidification, warming and reduced salinity, which will simultaneously impact the performance of sea stars in this habitat.

Effects of feeding strategy, fiber source of the diet, and crude protein content on productive performance of broiler breeder hens

A 12-wk experiment was conducted to investigate the effect of feeding program, dietary fiber, and CP content of the diet on productive performance of Ross broiler breeder hens (41 wk of age). There were 12 treatments arranged factorially with 2 levels of CP (14.5 vs. 17.4%), 3 fiber sources (0 vs. 3% inulin vs. 3% cellulose), and 2 levels of feed intake (160 vs. 208 g/d) that corresponded to restricted (R) or ad libitum (AL) feeding systems. The experimental diets contained 2,800 kcal ME with either 0.65 (14.5% CP) or 0.78% Lys (17.4% CP).

Aquaponics: integrating fish feeding rates and ion waste production for strawberry hydroponics

Aquaponics is the science of integrating intensive fish aquaculture with plant production in recirculating water systems. Although ion waste production by fish cannot satisfy all plant requirements, less is known about the relationship between total feed provided for fish and the production of milliequivalents (mEq) of different macronutrients for plants, especially for nutrient flow hydroponics used for strawberry production in Spain. That knowledge is essential to consider the amount of macronutrients available in aquaculture systems so that farmers can estimate how much nutrient needs to be supplemented in the waste water from fish, to produce viable plant growth. In the present experiment, tilapia (Oreochromis niloticus L.) were grown in a small-scale recirculating system at two different densities while growth and feed consumption were noted every week for five weeks. At the same time points, water samples were taken to measure pH, EC25, HCO3 – , Cl – , NH4 + , NO2 – , NO3 – , H2PO4 – , SO4 2– , Na + , K+ , Ca 2+ and Mg 2+ build up. The total increase in mEq of each ion per kg of feed provided to the fish was highest for NO3 - , followed, in decreasing order, by Ca 2+ , H2PO4 – , K+ , Mg 2+ and SO4 2– . The total amount of feed required per mEq ranged from 1.61- 13.1 kg for the four most abundant ions (NO3 – , Ca 2+ , H2PO4 – and K+ ) at a density of 2 kg fish m–3 , suggesting that it would be rather easy to maintain small populations of fish to reduce the cost of hydroponic solution supplementation for strawberries.

HABIT o cómo medir la subjetividad en la movilidad en transporte urbano

Tradicionalmente en los modelos de transporte, las variables explicativas de la elección modal del usuario se reducen a las variables objetivas (coste del transporte, tiempo de viaje, etc.). Sin embargo, la literatura más reciente reconoce que el perfil del usuario así como sus percepciones, influyen también en la elección modal. Por ello, antes de formular un modelo de demanda de transporte, es conveniente integrar factores más subjetivos (percepciones y actitudes) de los usuarios del sistema de transporte. Para evaluar dicha influencia se ha optado por realizar una encuesta en las nuevas estaciones de la línea 2 de Metro, al Sureste de Madrid. Será una manera de medir la consistencia de los hábitos cuando una nueva infraestructura de transporte como el Metro se pone en marcha. La toma de datos se realiza a través de encuestas de preferencias reveladas a los usuarios del nuevo Metro. Gracias a dicha encuesta se puede conocer el anterior modo de viaje utilizado por los usuarios para realizar el mismo trayecto, por lo que se dispone de datos para evaluar el cambio de modo. En concreto, el encuestado responde a preguntas sobre el motivo del viaje, la disponibilidad de vehículo propio y el motivo principal para cambiar de modo. La encuesta de movilidad realizada en la nueva infraestructura permite recoger para desarrollar una metodología capaz de estimar los efectos de shock e inercia del cambio modal. Este artículo utiliza modelos de elección discreta integrando variables cuantitativas (coste del viaje, por ejemplo) y cualitativas (motivo del cambio modal) para explicar la elección modal. Los primeros resultados muestran que los viajes obligados (trabajo y estudios) que antes del Metro se realizaban en coche, presentan poca resistencia al cambio.

Influence of crude protein content, ingredient complexity, feed form, and duration of feeding of the phase I diets on productive performance and nutrient digestibility of Iberian pigs.

The influence of CP content and ingredient complexity, feed form, and duration of feeding of the Phase I diets on growth performance and total tract apparent digestibility -TTAD- of energy and nutrients was studied in Iberian pigs weaned at 28 d of age. There were 12 dietary treatments with 2 type of feeds -high-quality, HQ; and low-quality, LQ-, 2 feed forms -pellets vs. mash-, and 3 durations -7, 14, and 21 d- of supply of the Phase I diets.

Poultry production in Spain: New advances in feeding and nutrition practice.

Spain produces approximately 600 M broiler chickens per year and has a current laying hen census of 35 M birds. Production of other poultry species, such as turkeys and ducks, is quite limited. The number of birds slaughtered has remained quite flat for the last 10 years although final body weight (BW) has increased in this period by almost 200g per bird. The number of laying hens has decreased markedly (e.g. circa 50 M in 2010) and the proportion of brown -egg layers has increased from less than 10% in 1990 to more than 90% in 2013. In addition to egg color, brown eggs are preferred by the consumers because of bigger size and better shell quality.

Animal feeding strategies to reduce N2O and NH3 emission from surface-applied pig slurry to a grassland soil.

It is estimated that N losses from fertilized crops range between 50-70%, depending on management practices, climate and soil conditions. Ammonia (NH3) emissions following land application of animal manures give rise to a significant proportion of the total NH3 emissions from agricultural sources.