Effect of grazing intensity and soil characteristics on soil organic carbon and nitrogen stocks in a temperate long-term grassland

The effects of different grazing pressures (GPs) on soil properties are not sufficiently understood. The objectives were to analyse the effects of three different extensive GPs on stocks of soil organic C and total N, soil microbial biomass C, basal respiration and mineral N in three different soil depths of a long-term pasture in Central Germany (FORBIOBEN field trial). No significant (p ≤ 0.05) effects of GP on weighted stocks of soil organic C, total N, soil microbial biomass C, mineral N and basal respiration rate were observed, suggesting that the C and N cycles are coupled in the three grazing treatments. Oxalate soluble Fe contents explained a marked part of the variation of soil organic C (multiple linear regression: R² = 0.64) and total N contents (R² = 0.64) in the soils, whereas almost all of the variability of soil microbial biomass C contents and basal respiration was explained by soil organic C contents. Overall, variabilities of soil organic C and N contents were largely explained by oxalate soluble Fe contents, whereas grazing intensity did not affect the C and N dynamics.     

Clinical pharmacology of methadone in dogs

ObjectiveTo investigate the pharmacokinetics and effects of methadone on behaviour and plasma concentrations of cortisol and vasopressin in healthy dogs.Study designRandomized, cross-over, experimental trial.AnimalsNine adult dogs (beagle and beagle cross breeds), four males and five females.MethodsMethadone hydrochloride, 0.4 mg kg^?1, was administered intravenously (IV) and subcutaneously (SC) with a crossover design. Drug and hormone analyses in plasma were performed using Liquid Chromatography–Electrospray Ionization–Tandem Mass Spectrometry and radioimmunoassay respectively. Behavioural data were collected using a standardized protocol.ResultsAfter IV administration, the plasma concentration of methadone at 10 minutes was 82.1 ± 9.2 ng mL^?1 (mean ± SD), the terminal half-life was 3.9 ± 1.0 hours, the volume of distribution 9.2 ± 3.3 L kg^?1 and plasma clearance 27.9 ± 7.6 mL minute^?1 kg^?1. After SC administration, time to maximal plasma concentration was 1.26 ± 1.04 hours and maximal plasma concentration of methadone was 23.9 ± 14.4 ng mL^?1, the terminal half-life was 10.7 ± 4.3 hours and bioavailability was 79 ± 22%. Concentrations of both cortisol and vasopressin were increased for an hour following IV methadone. The observed behavioural effects of methadone were decreased licking and swallowing and an increase in whining after SC administration. The latter finding is notable as it can be misinterpreted as pain when methadone is used as an analgesic.Conclusion and clinical relevanceWhen methadone was administered by the SC route, the half-life was longer, but the individual variation in plasma concentrations was greater compared with IV administration. Increased frequency of whining occurred after administration of methadone and may be a drug effect and not a sign of pain. Cortisol and vasopressin concentrations in plasma may not be suitable for evaluating analgesia after methadone treatment.     

Search of environmental descriptors to explain the variability of the bacterial diversity from maize rhizospheres across a regional scale

The regional scale variability of the bacterial community inhabiting the rhizosphere was studied with soil collected from maize fields located in the Santo Domingo Valley (SDV; Baja California Sur, Mexico), a semi-arid agricultural ecosystem of approximately 200 km². The bacterial community structure was visualized by single-strand conformation polymorphism (SSCP) profiles of PCR-amplified partial 16S rRNA genes of directly extracted rhizosphere soil DNA. SSCP profiles of different SDV sites and an external field site in Germany were evaluated for their similarities and the contributing bacteria were characterized by DNA sequence analyses. SSCP profiles from each site were significantly different from the others, as revealed by permutation of pairwise similarities (P < 0.05). In comparison to the German site, SSCP profiles from SDV were more similar to each other despite contrasting soil salinity levels. Correspondence analysis revealed that among SDV sites, salinity levels, soil organic carbon and calcium (Ca²⁺) were most influential on the bacterial community structure. Depending on the phylogenetic group analyzed (Bacteria, Alphaproteobacteria, Pseudomonas), the importance of these soil variables varied. Interestingly, the East–West direction also revealed an effect, suggesting that future explorations of bacterial diversity patterns should also consider landscape topography in search of explaining patterns of bacterial diversity in soils.     

Carbon dioxide evolution from top- and subsoil as affected by moisture and constant and fluctuating temperature

Topsoil (0–25 cm) and subsoil (30–55 cm) samples were taken from clay soil which had been cropped with reed canarygrass (Phalaris arundinacea). After crumbling the soil into fragments <10 mm and removing visible organic debris, CO₂ evolution was measured in the laboratory at four moisture contents (17, 26, 36 and 50% H₂O for the topsoil and 16, 23, 31 and 41% for the subsoil) and at constant temperatures of −4, 0.3, 5, 15, 25, and temperatures fluctuating (weekly) between −4 and +5°C. Evolution of CO₂ after the addition of roots or stubble of P. arundinacea to the topsoil (25°C, 36% H₂O) was also studied. The CO₂ evolution increased significantly with temperature and moisture. The CO₂ evolution rate per unit of soil carbon was about two times higher for topsoil than for subsoil. Temperature fluctuation between −4 and +5°C did not enhance CO₂ evolution significantly compared with incubation at a constant 5°C and was even lower than or not significantly different from samples at 0.3°C.     

Modelling the effects of temperature and moisture on CO2 evolution from top- and subsoil using a multi-compartment approach

A novel approach, at least for laboratory conditions, for analysis of the dependence of soil C evolution on temperature is presented. A two-component (labile and refractory organic C) parallel first-order model was fitted to CO₂ evolution rates from top- and subsoil, incubated at different combinations of temperature (constant −4, 0.3, 5, 15, 25, weekly fluctuating between −4 and +5°C) and moisture (17, 26, 36 and 50% H₂O for the topsoil and 16, 23, 31 and 41% for the subsoil) and to the evolution of CO₂ after the addition of roots or stubble of Phalaris arundinacea in the topsoil, measured at 25°C and 36% H₂O (Lomander et al., 1998). The size of the pools and their respective first-order rate constants were optimized simultaneously by a least-squares method. The optimization was carried out separately for top- and subsoil. Quadratic functions were fitted to the temperature and moisture responses. For topsoil samples in which roots or stubble were added, a three-component model (labile, refractory and stubble or roots) was used. The initial partitioning of the soil C, the decomposition rate constants for each partition and the temperature and moisture responses were all assumed to be identical to those of pure topsoil, while the initial pool sizes of added roots and straw were measured. The calculated temperature at which CO₂ evolution ceased (T_min) was −0.83°C, and a recalculation to Q₁₀-values resulted in increasing temperature response with decreasing temperature (Q₁₀=2.2 at 25°C and 12.7 at 0.3°C). Simulated CO₂ evolution rates agreed well with the measurements (R_adj²=0.96 and 0.81) for top- and subsoil, respectively. The multi-compartment approach was superior to the single-compartment approach, which gave R_adj²=0.88 and 0.76 for top- and subsoil, respectively. In general, CO₂ evolution rates obtained from the laboratory experiment were higher than those measured in the field, even after differences in temperature and moisture were taken into account. After 300 d in the laboratory at 25°C and 36% H₂O, 99% and 86% of the added straw and roots, respectively, had disappeared according to the described model. The CO₂-evolution rate per unit of soil carbon was about two times higher for topsoil than for subsoil.     

Digestive enzymes present in Pacific threadfin Polydactylus sexfilis (Bloch & Schneider 1801) and bluefin trevally Caranx melampygus (Cuvier 1833)

Pacific threadfin Polydactylus sexfilis (Bloch & Schneider 1801) and bluefin trevally Caranx melampygus (Cuvier 1833) are warmwater marine finfish currently under development for aquaculture in the Pacific. Differences in specific activities of digestive enzymes extracted from the stomach and mid-gut were compared to gain insight into their feeding habits in the wild and to understand their nutritional needs. Adult fish were maintained in captivity and fed a commercial pelleted feed. Serine protease measured in all tissues was at least 20 times higher in threadfin than in trevally. Aspartic proteases were the major digestive enzymes found in trevally. There was a 34-fold increase in collagenase activity in the intestine of threadfin from the prefed to the fed state. Chitinase activity was found in the stomach, pylorus and intestine of both species. However, specific activity in pylorus and intestine of threadfin increased 2.75 and 4 times, respectively, but showed little change in trevally. Amlyases were found only in trevally. Increase in lipase specific activity in the gut of trevally was higher than that for threadfin. The results indicated that the two species have diverse digestive capabilities. This appears to be consistent with their feeding habits in nature. Threadfin are more adapted to a wider range of food protein sources than trevally, but appear to be less well adapted than trevally to using complex carbohydrates. These observations may provide a basis for practical diet formulations for these two species.     

The European College of Veterinary Pathologists (ECVP): the professional body for European veterinary pathologists

The European College of Veterinary Pathologists (ECVP) was established in 1995 with the aim of advancing veterinary pathology and promoting high standards within the specialty in Europe. The ECVP is one of 21 European colleges recognized by the European Board of Veterinary Specialisation (EBVS), which represents a quality-assurance system for European veterinary specialists. Until the ECVP was founded, there was no unified European system recognizing the specialty of pathology, and many European countries followed their own qualification systems, which varied in form and standard. The ECVP provides an annual certifying examination, the passing of which is required to gain membership (diplomate status) in the college. This qualification is now accepted on equal terms by the well-established American College of Veterinary Pathologists (ACVP). In line with EBVS requirements, the ECVP has also established a standard continuing professional development (CPD) and re-registration system for its membership. Furthermore, it has promoted and unified European post-graduate training in veterinary pathology by setting up requirements for residency training programs and making registration and monitoring of these programs by the ECVP a prerequisite for approval of an institution as a training facility. The concurrent establishment, together with the European Society of Veterinary Pathology, of an annual summer school that trains residents for the certifying examination has further fostered European post-graduate training. Within 10 years, the ECVP has succeeded in establishing common standards and a unified approach to veterinary pathology throughout Europe. This article describes the evolution and organization of the ECVP.     

Potential of acrylamide formation,sugars, and free asparagine in potatoes: a comparison of cultivars and farming systems

Glucose, fructose, sucrose, free asparagine, and free glutamine were analyzed in 74 potato samples from 17 potato cultivars grown in 2002 at various locations in Switzerland and different farming systems. The potential of these potatoes for acrylamide formation was measured with a standardized heat treatment. These potentials correlated well with the product of the concentrations of reducing sugars and asparagine. Glucose and fructose were found to determine acrylamide formation. The cultivars showed large differences in their potential of acrylamide formation which was primarily related to their sugar contents. Agricultural practice neither influenced sugars and free asparagine nor the potential of acrylamide formation. It is concluded that acrylamide contents in potato products can be substantially reduced primarily by selecting cultivars with low concentrations of reducing sugars.     

Biochar application to sandy soil: effects of different biochars and N fertilization on crop yields in a 3-year field experiment

During the past years, most biochar studies were carried out on tropical soils whereas perennial field experiments on temperate soils are rare. This study presents a 3-year field experiment regarding the effects of differently produced biochars (pyrolyzed wood, pyrolyzed maize silage, hydrothermal carbonized maize silage) in interaction with digestate incorporation and mineral N fertilizer application on soil C and N, crop yields of winter wheat, winter rye and maize and the quality of winter wheat. Soil C and plant available potassium were found to be significantly positive affected by pyrolyzed wood biochar whereas the latter only in combination with N fertilization. Crop yields of winter wheat, winter rye and maize were not affected by biochar and showed no interaction effects with N fertilizer supply. Wheat grain quality and nutrition contents were significantly affected by biochar application, for example, highest amounts of phosphorus, potassium and magnesium were determined in treatments amended with pyrolyzed maize silage biochar. Biochar induced an improved availability of plant nutrients, which apparently were not yield limiting in our case. These results limit the potentials of biochar for sustainable intensification in agriculture by increasing crop yields for the temperate zones. However, detection of other environmental benefits requires further investigations.