Nutritional status of Lusitano broodmares on extensive feeding systems: body condition, live weight and metabolic indicators

Articles in International JournalsThe present research aimed to evaluate the effects of foaling season and feeding management in extensive systems on the nutritional status of Lusitano broodmares throughout the gestation/lactation cycle, by assessment of body condition (BC), body weight (BW), and some blood metabolic indicators. Four groups of Lusitano broodmares (A, B, C, D) were monitored during four years, in a total of 119 gestation/lactation cycles. All mares were kept on pasture, and A and B mares were daily supplemented. Monthly, mares were weighed and BC evaluated. Suckling foals from these mares were also monitored for BW and withers height. Glucose, non-esterified fatty acids, urea and albumin concentrations were determined in blood. BW changes were influenced by reproductive stage and foaling season (P<0.001), reflecting also pasture availability. Changes on BC were observed (P<0.05), although with small amplitudes within each group. Higher scores were reached at the end of spring, decreasing 0.25 point until late summer. Early foaling had also a marked effect, hindering the recovery of BC along the cycle. Glucose values decreased from late gestation to early lactation (P<0.05) and lower levels were recorded during the summer months. Uremia was mainly influenced by the reproductive stage (P<0.05). Under nutrition was not detected. Foals born in February-March had higher average daily gain than those born in April-May (P<0.05), probably reflecting differences in milk production of the mares. BC and BW changes and, particularly, blood indicators showed an overall balanced nutritional status, reflecting an adaptation to feed availability and climate.Portuguese Foundation for Science and Technolog

In-forest education without owning a forest - the HAFL approach to solve this challenge

The forest science education at the School of Agricultural, Forest and Food Sciences (HAFL, Hochschule für Agrar-, Forst- und Lebensmittelwissenschaften) uses in-forest education extensively. However, HAFL does neither possess its own forest area, nor does it have a land-lease or other long-lasting contract providing forest access. Therefore, a blended strategy is used to give access to forest areas for teaching purpose. Depending on subject different approaches are used, which are presented here

DEA-based deformable cell culture system

We present a deformable cell culture system based on dielectric elastomer actuator (DEA). Understanding how the mechanical environment can affect cells functions could lead to significant advances in diseases diagnosis and drug development. Most available technologies offer low screening throughput, an important limitation considering the statistical nature of cellular studies. We previously reported an array of micro-DEAs for cell stretching application. Our DEA-based solution has the potential to replace current technologies and overcome the high screening throughput limitation. We present a new generation of devices, developed to better address cell biologists requirements. Two different devices were developed to apply periodic (1-5Hz) compressive or tensile strain greater than 10% on a 2mm x 2mm biological sample. Their original designs exploit non-equibiaxial pre-stretch of a silicone membrane and stress induced in passive regions of DEAs. Our technology is now compatible with high resolution optical microscopy for real time monitoring of morphology and chemical activity of the biological sample. This new generation of devices also significantly improves the electric field confinement and provides a fully biocompatible environment

Recognition in Ants: Social Origin Matters

The ability of group members to discriminate against foreigners is a keystone in the evolution of sociality. In social insects, colony social structure (number of queens) is generally thought to influence abilities of resident workers to discriminate between nestmates and non-nestmates. However, whether social origin of introduced individuals has an effect on their acceptance in conspecific colonies remains poorly explored. Using egg-acceptance bioassays, we tested the influence of social origin of queen-laid eggs on their acceptance by foreign workers in the ant Formica selysi. We showed that workers from both single- and multiple-queen colonies discriminated against foreign eggs from single-queen colonies, whereas they surprisingly accepted foreign eggs from multiple-queen colonies. Chemical analyses then demonstrated that social origins of eggs and workers could be discriminated on the basis of their chemical profiles, a signal generally involved in nestmate discrimination. These findings provide the first evidence in social insects that social origins of eggs interfere with nestmate discrimination and are encoded by chemical signatures

Thin-film dielectric elastomer sensors to measure the contraction force of smooth muscle cells

The development of thin-film dielectric elastomer strain sensors for the characterization of smooth muscle cell (SMC) contraction is presented here. Smooth muscle disorders are an integral part of diseases such as asthma and emphysema. Analytical tools enabling the characterization of SMC function i.e. contractile force and strain, in a low-cost and highly parallelized manner are necessary for toxicology screening and for the development of new and more effective drugs. The main challenge with the design of such tools is the accurate measurement of the extremely low contractile cell forces expected as a result of SMC monolayer contraction (as low as ~ 100 μN). Our approach utilizes ultrathin (~5 μm) and soft elastomer membranes patterned with elastomer-carbon composite electrodes, onto which the SMCs are cultured. The cell contraction induces an in-plane strain in the elastomer membrane, predicted to be in the order 1 %, which can be measured via the change in the membrane capacitance. The cell force can subsequently be deduced knowing the mechanical properties of the elastomer membrane. We discuss the materials and fabrication methods selected for our system and present preliminary results indicating their biocompatibility. We fabricate functional capacitive senor prototypes with good signal stability over the several hours (~ 0.5% variation). We succeed in measuring in-plane strains of 1 % with our fabricated devices with good repeatability and signal to noise ratio