Anaesthesia of Atlantic cod (Gadus morhua) — Effect of pre-anaesthetic sedation, and importance of body weight, temperature and stress     

Inger Hilde Zahl  Anders Kiessling  Ole Bent Samuelsen  Magne Kjerulf Hansen 《Aquaculture (Amsterdam, Netherlands)》2009,295(1-2):52-59

The efficacy of the anaesthetic agents benzocaine, metacaine (MS-222), metomidate and 2-phenoxyethanol was studied in Atlantic cod (Gadus morhua) with average body weights of 10 ± 4 g, 99 ± 33 g and 1022 ± 274 g at water temperatures of 8 °C and 16 °C. The agents were tested individually and as combination anaesthesia comprising pre-anaesthetic sedation with a low dosage of metomidate or 2-phenoxyethanol followed by anaesthesia with benzocaine or MS-222. All agents were administered through bath immersion with an exposure time of 5 min. The different treatments resulted in average induction and recovery times ranging from 52 ± 6 s to 182 ± 16 s and 77 ± 26 s to 659 ± 46 s respectively. Induction and recovery times varied in relation to water temperature and were generally shorter at 16 °C for all weight groups and treatments compared to 8 °C. For benzocaine and MS-222 induction and recovery times were found to increase with increasing body weight. For metomidate the recovery time increased with increasing weight whereas there were no weight related differences in induction time. No differences in either induction or recovery times associated to body weight were found for 2-phenoxyethanol. Acute stress prior to anaesthesia with MS-222 resulted in significantly shorter induction time and prolonged recovery time, as well as deeper anaesthetised fish. The dosage of MS-222 had to be reduced in order to avoid mortality in fish subjected to acute stress. Combination anaesthesia allowed a reduction of the dosages used for inducing anaesthesia and produced markedly reduced recovery times compared to agents administered individually.  相似文献   

Characterizing phosphorus availability in waste products by chemical extractions and plant uptake     

Nina Hj Christiansen  Peter Srensen  Rodrigo Labouriau  Bent T. Christensen  Gitte Holton Rubk 《植物养料与土壤学杂志》2020,183(4):416-428

Background: The fertilizer value of phosphorus (P) in waste products relies heavily on its availability to the subsequent crop. Aim: We studied the link between extractable P in waste products and apparent P recovery (APR, i.e., difference in plant P uptake between P amended and un‐amended soils divided by the amount of P added) using spring barley grown on three sandy soils. Methods: The products included sewage sludge, biomass ash, struvite, compost, meat and bone meal, biochar from sewage sludge, and industrial sludge. Soft rock phosphate and triple‐superphosphate (TSP) were included for comparison. Availability of P was characterized by extraction with water and solutions of sodium bicarbonate, citric acid, oxalic acid, hydrochloric acid, ammonium acetate, ammonium fluoride and anion exchange resin membranes. TSP was used to establish mineral‐fertilizer‐equivalents (MFE). Water and bicarbonate extractions were also applied to products incubated with soil before extraction. Results: The APR ranged 26 to 31% for TSP and 0 to 30% for waste products. APR correlated most strongly with bicarbonate extractable P. The correlation increased when products were incubated with soil before extraction. Conclusions: We conclude that bicarbonate extraction is a good indicator of potential P availability. However, interactions between waste products and soil properties modify P availability.  相似文献   

Population structure of anchovy Engraulis encrasicolus L. in the Mediterranean Sea inferred from multiple methods     

Jon Bent Kristoffersen  Antonios Magoulas 《Fisheries Research》2008,91(2-3):187-195

Population structure of anchovy, Engraulis encrasicolus L., in the northern Mediterranean was investigated using multiple methods. Variation in body shape, otolith shape and growth was investigated in samples from the central Aegean and Ionian Seas. Intron length polymorphism from nuclear DNA, and mitochondrial DNA variation was investigated for samples from these basins, as well as northern Adriatic (ADR) and Gulf of Lions (LION). Two lineages (clades) of mtDNA that co-occur in the populations of anchovy throughout the region were compared with respect to growth, body shape, otolith shape, and intron variation, to check for any reproductive isolation within areas between the clades. The two clades were not different in any of the investigated parameters and appear to be completely crossbreeding. There were significant differences among areas with regard to mtDNA clade proportions, nuclear allele frequencies, body shape and otolith shape, indicating that several reproductively isolated populations of anchovy exists in the northern Mediterranean. There was an overall fair to good agreement between population structures inferred from the different classes of markers. The mitotype variation indicated a larger population differentiation than the two nuclear DNA loci, which may be related to the uniparental transmission and the lack of recombination of mtDNA.  相似文献   

Calibration and validation of the soil organic matter dynamics of the Daisy model with data from the Askov long-term experiments     

Sander Bruun  Bent T ChristensenElly M Hansen  Jakob MagidLars S Jensen 《Soil biology & biochemistry》2003,35(1):67-76

Daisy is a semi-mechanistic model that simulates crop production, soil water and C and N dynamics in agro-ecosystems. In this study, the soil organic matter (SOM) submodel of Daisy was calibrated and validated with data from a series of long-term (30-100 yr) experiments dominated by cereal cropping systems. The experiments were conducted under temperate conditions at the Askov Experimental Station, Denmark. The recalibration of the Daisy model improved the model simulations considerably. The RMSE between simulations and observations of the experiments used for calibration improved from 33 to 19, whereas this measure improved from 32 to 9.0 for the experiments used for validation. The original calibration of the model appears to be based upon too low an input of organic matter (especially because rhizodeposition is ignored), too low an efficiency with which added organic matter is converted into more stable forms of SOM, and too low an overall decomposition rate. Our study suggests that the fraction of SOM involved in medium-term turnover is substantially larger than previously thought and inferred by most SOM turnover models. This may warrant a recalibration of current simulation models, and stresses the importance of using long-term experiments with widely differing treatments for model evaluation. Long-term treatments with widely contrasting initial C contents and annual C inputs, especially bare fallow treatments, appear to be valuable resources in this respect.  相似文献   

Studies on Milk Protein Polymorphism in Danish Cattle and the Interaction of the Controlling Genes     

Bent Larsen  Mariann Thymann 《Acta veterinaria Scandinavica》1966,7(1):189

In milk samples from 1520 heifers and 542 dams the α_sl-, β- and x-casein types and the β-lactoglobulin components, A and B, were determined simultaneously by means of electrophoresis in thin starchurea-gels.The theory of inheritance advanced within each system from previous investigations was confirmed. Family data on the transmission of the two x-casein components A and B are given (Table 3). The frequencies of the controlling genes in Danish cattle were computed for each of the systems (Table 2).With traditional starch-gel-electrophoresis, four components, termed A, B, G and D, could be demonstrated in the β-lactoglobulin (Figs. 3 and 4). The four components are presumed to be controlled by four allele genes.The α_sl-, β- and ϰ-casein phenotypes were not independently distributed and the segregation of casein types among offspring from bulls heterozygotic in two or three casein type-systems strongly suggests that the genetic variations of the α_sl-, β- and ϰ-casein are controlled by genes at a single locus. Then, a minimum of 8 alleles may account for the phenotypes observed among 521 Danish cows (Table 6).Linkage of less than five per cent recombination could be excluded between the casein types and the β-lactoglobulin types.  相似文献   

Predicting optimal combinations of by‐catch reduction devices in trawl gears: A meta‐analytical approach     

Valentina Melli  Bent Herrmann  Junita Diana Karlsen  Jordan Paul Feekings  Ludvig Ahm Krag 《Fish and Fisheries》2020,21(2):252-268

Global efforts to reduce unwanted catches have led to the development of a vast array of by‐catch reduction devices (BRDs), in particular for mixed trawl fisheries. Some of these BRDs could likely benefit from being combined. However, the number of possible combinations would be prohibitive to be tested experimentally. Therefore, in this study we propose a meta‐analytical approach that combines the data available on BRDs tested independently in a fishery and predict the theoretical selectivity of all possible combinations of those devices. This allows to identify promising BRD combinations, worth experimental investigation and flexible trawl configurations, where the selectivity can be substantially modified by adding or removing one BRD, thus aiding fishermen in adapting to high variability in catch composition and quota availability. To illustrate the approach, we used BRDs developed for the well‐studied Nephrops (Nephrops norvegicus, Nephropidae) directed mixed trawl fishery in the Skagerrak and Kattegat seas. We predicted the selectivity of 100 BRD combinations for Nephrops, cod (Gadus morhua, Gadidae) and haddock (Melanogrammus aeglefinus, Gadidae), compared them in terms of absolute selectivity and performance under realistic catch scenarios, from both single‐ and multispecies perspectives, and identified 15 BRD combinations that could be worth future experimental investigation. The meta‐analytical approach makes best use of existing knowledge and leads to new insights about the potential for improvement and flexibility in trawl selectivity. This could benefit a variety of mixed trawl fisheries and help developing a new generation of more flexible gears, with multiple BRDs integrated in their structure.  相似文献   

Anesthesia induces stress in Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>), Atlantic cod (<Emphasis Type="Italic">Gadus morhua</Emphasis>) and Atlantic halibut (<Emphasis Type="Italic">Hippoglossus hippoglossus</Emphasis>)     

Inger Hilde Zahl  Anders Kiessling  Ole Bent Samuelsen  Rolf Erik Olsen 《Fish physiology and biochemistry》2010,36(3):719-730

Stress in response to anesthesia with benzocaine, MS-222, metomidate and isoeugenol was studied in Atlantic salmon (Salmo salar), Atlantic halibut (Hippoglossus hippoglossus), and Atlantic cod (Gadus morhua) with no concomitant stress from handling or confinement in association with anesthesia or sampling. All of the anesthetics tested induced a stress response in all species, displayed by a release of cortisol to the water. MS-222 anesthesia elicited the highest cortisol release rates, reaching maximum levels 0.5 h post-exposure and returning to basal levels after 3–4 h. Benzocaine anesthesia caused a bimodal response where the initial peak in cortisol release rate was followed by a second increase lasting towards the end of the trial (6 h). This bimodality was more profound in Atlantic salmon than in Atlantic halibut and Atlantic cod. Metomidate anesthesia induced the lowest release of cortisol of the agents tested in both Atlantic halibut and Atlantic cod, but resulted in a bimodal response in Atlantic salmon where the initial increase in cortisol release was followed by a larger increase peaking at 2–2.5 h post exposure before returning to basal levels after 5 h. The stress induced in Atlantic salmon by isoeugenol anesthesia resembled that of MS-222, but did not reach the same elevated level. Overall, the cortisol release was most profound in Atlantic salmon followed by Atlantic halibut and Atlantic cod.  相似文献   

The influence of timing the application of nitrogen fertilizer on early blight (Alternaria solani)     

Isaac K Abuley  Bent J Nielsen  Hans H Hansen 《Pest management science》2019,75(4):1150-1158

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Oral administration of a select mixture of Bacillus probiotics generates Tr1 cells in weaned F4ab/acR? pigs challenged with an F4+ ETEC/VTEC/EPEC strain     

Dong Zhou  Yao-Hong Zhu  Wei Zhang  Meng-Ling Wang  Wen-Yi Fan  Dan Song  Gui-Yan Yang  Bent Borg Jensen  Jiu-Feng Wang 《Veterinary research》2015,46(1)

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Annual variation in δC values of maize and wheat: Effect on estimates of decadal scale soil carbon turnover     

Bent T. Christensen 《Soil biology & biochemistry》2011,43(9):1961-2887

On sites where C4-plants have replaced C3-plants, changes in soil δ¹³C allow the turnover of C3- and C4-derived C to be separated. Studies of decadal scale turnover of soil C following conversion to C4-plants generally lack δ¹³C values for previous C4-residue inputs and assume that estimates of C4-derived soil C to be based on a fixed δ¹³C value. Further assumptions are that changes in the initial (time-zero) soil δ¹³C values are insignificant following conversion to C4-plants. We tested these assumptions by measuring: 1) the δ¹³C of annual samples of silage maize biomass (C4-plant) and winter wheat grains (C3-plant) grown during 1988 to 2006, and 2) the δ¹³C of soil kept under bare fallow during 1956 to 1983. The δ¹³C of plants was related to climate variables, and the impact of maize δ¹³C was based on estimates of maize-derived soil C using different approaches to establish the δ¹³C in maize inputs. The δ¹³C of both maize and wheat decreased with time, but the rate of change and annual variations were considerably larger for wheat than for maize. Maize as well as wheat δ¹³C was best related to year (probably reflecting a decrease in atmospheric δ¹³C) and the water balance during the active growth period. Using the smallest (−12.44‰) and the largest (−11.26‰) δ¹³C measured during 1988 and 2006, estimates of maize-derived C in soil after 18 years ranged from 13.2% to 14.2% of the soil total C. Despite a loss of 31% of the soil C pool under bare fallow, the increase in soil δ¹³C was significant only at P < 0.10. We conclude that annual variations in maize δ¹³C values and changes in the δ¹³C of the soil C fraction derived from the pre-conversion C3-vegetation have only little impact on estimates of maize-derived soil C that cover a few decades. For estimates covering several decades to centuries, the subtle but consistent changes in plant and soil δ¹³C need to be accounted for. The variability in δ¹³C in wheat grains suggest that the use of any fixed δ¹³C value for C3-residues in estimates of C turnover in soils on which C4-plants have been replaced by C3-plants can be associated with considerable uncertainty.  相似文献